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The Prevention and Control of Surgical Infections
The Prevention and Control of Surgical Infections w.
A. ALTEMEIER, M.D., F.A.C.S. W. R. CULBERTSON, M.D.
THE prevention of surgical infections, as well as their diagnosis, proper treatment and prognosis, depends upon a thorough understanding of various basic sciences dealt with in medicine. A working knowledge of bacteriology and immunology and a complete familiarity with the physiologic responses of the body to bacterial invasion and growth are particularly essential. To prevent infection in wounds, the surgeon uses knowledge gained from bacteriology and immunology for the most effective methods of aseptic and antiseptic techniques, for ways of improving the resistance of his patient to infecting bacteria, and for means of inhibiting or attenuating the growth of contaminating micro-organisms. To minimize morbidity and mortality in treating established surgical infections, he employs bacteriologic information for accurate diagnosis, for anticipating routes of spread, for antibiotic or other antibacterial treatment, for timing of necessary operative procedures, for localization of the process, and for supportive treatment. Until the studies of Pasteur and their surgical application by Lister, it was universally thought that a part of the natural process of the healing of wounds was the development of pus and other signs of the process now recognized as infection. Methods of treatment prior to Pasteur were, of necessity, completely blind and directed toward symptomatic relief rather than an attack upon the etiologic agent or its source of spread. Any elective surgical procedure was approached with great reluctance because of the feared development of "hospital gangrene" rather than the occurrence of "laudable pus." Consequently, most elective surgical operations were minor or superficial until 60 years ago. Today it is possible routinely to prevent infection in planned operative wounds, an achievement which is one of the great milestones of surgery. In addition, great progress has been made in preventing or attenuating From the Department of Surgery, University of Cincinnati, and the Cincinnati General Hospital, Cincinnati, Ohio.
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infection in accidental wounds or wounds of violence. Because of this success, many surgeons believe that the control of infection is no longer a prominent problem in surgery. This belief is treacherously incorrect. Most of the old problems continue to exist, and the complexity of the new methods of diagnosis and treatment requires more thought and care than ever before. GENERAL CONSIDERATIONS
Factors in the Developll1ent of Infection
The bacteriologist's premise that infection is the unfavorable result of the equation expressed as "dose mUltiplied by virulence and divided by resistance" is still applicable to both surgical and medical infections. Nearly all surgical infections are the result of the entry of pathogenic bacteria into the tissues of the body through a site of injury, which may be large or small and accidentally or intentionally produced. Most bacteria cannot invade the physiologic interior of the body through the intact mucous membrane or skin. Pathogenic bacterial invasion may also be prevented by the local or humeral defenses of the body after the entrance of bacteria has been provided by trauma. On the other hand, certain micro-organisms, such as spirochetes, E. typhosus and M. tuberculosis, have the ability to penetrate mucous membranes without preexisting trauma. Fortunately, these are all of minor surgical importance. Time Lapse. The lapse of time between the entry of organisms and the development of signs of infection is the incubation period which is of great importance to the surgeon in dealing with accidental wounds. It is the "Golden Period," during which, the greatest effects toward prevention of the establishment of infection can be obtained by means of proper debridement, establishment of passive immunologic states against specific organisms, and development of body resistance by general measures as well as specific antibacterial treatment. The bacteria in wounds of less than four hours' duration are generally considered to be relatively inactive, while they may be growing actively on the surface of the wound during the four to eight hour period. In wounds older than eight hours, the bacteria have usually invaded the adjacent tissues and may have started their spread along the lymphatics, in fascial planes or the blood stream. It must be remembered that bacteria of low virulence or saphrophytes can cause infections in the presence of devitalized avascular tissues. Invasiveness of the Infection. Infections limited to the area of the wound are considered to be local, and those spreading beyond the wound are invasive. Lesions spreading along fascial planes or lymphatics are designated as regionally invasive; those extending through the blood stream are systemically invasive, being either a bacteremia or a septicemia. In a bacteremia the area of infection distributes bacteria into the blood stream
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once or intermittently, while in a septicemia it distributes the microorganisms more or less constantly. Although bacteria are necessarily the basis of infection occurring within wounds, experience has shown that micro-organisms may be present in the wound without producing evidence of infection and that many other factors are of importance in the development of infection. Tissue Resistance. The resistance of normal healthy tissues to bacterial infection is well established. On the other hand, devitalized, irritated or unhealthy tissues are susceptible to bacterial growth and favor the development of local septic processes. It must be remembered that tissues can become devitalized early by the injury, and later as a result of factors which impair the blood supply, such as arterial thrombosis, subfascial hematoma, constricting bandages, tight casts or operative repair under tension. The importance of the thorough removal of all devitalized tissue and foreign bodies from wounds and the restoration of the local physiologic state of the wound to normalcy is obvious. The General Condition of the Patient. This may also be an important factor. Anemia, shock, malnutrition and dehydration are conditions which may lower the resistance and favor bacterial invasion. Metabolic diseases, such as diabetes mellitus and arteriosclerosis, may also decrease his local and general powers of resistance. Surgical infections may, therefore, subside spontaneously, remain localized, spread to regional or distant areas, become chronic, or result in death or prolonged disability. Principles of Successful Therapy
Great progress has been made during the past two years in the control or management of surgical infections through the co-ordinated use of antibiotic agents with indicated surgical procedures. Experience has emphasized the importance of observing certain factors and principles of therapy in the successful management of surgical infections, and, as a rule, these principles have remained essentially unchang;ed. In general, the use of the antibiotic agents is adjunctive to clinical application of the established surgical principles of treatment. The proper use of the antibiotic agent has produced profound effects on the prevention and control of infections, but improper use has resulted in limited, incomplete or absent clinical results. Among the various factors which are important in the control of surgical infections and which determine the effectiveness of antibiotic therapy are the following. Early Diagnosis. The influence of early diagnosis and early treatment upon morbidity, mortality and functional results cannot be overemphasized. Antibacterial treatment is most apt to produce a prompt and rapid control of the invasiveness of the infection, with its complete and spontaneous resolution when the diagnosis is established early. Local tissue destruction or other complications are likely to be minimal. Late
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diagnosis permits the process to become more established, with the development of local necrosis, abscess, or systemic invasion. Under these circumstances, treatment produces more limited and delayed results, and complications are usually more numerous. The invasive qualities of the infection are generally overcome and the process is localized, but extensive necrosis of tissue may occur. At times the use of early, specific antibacterial therapy will so control the invasive qualities of certain infections that emergency surgical decompression or excision of infected areas either becomes unnecessary or can be replaced by more conservative types of surgery done at a time when the patient's condition has been improved. When the infection has become disseminated, with the production of metastatic abscesses or other infectious complications in remote areas, its control is much more difficult. Accurate and Complete Diagnosis. The necessity of a correct clinical diagnosis, including the site of infection, the responsible bacteria, the patient's general condition, the existence and location of metastatic abscesses or other complications, and the contributing causes and the stage of the process is obvious. Failure of the elevated temperature and other general signs of infection to begin to recede within 72 hours of the start of treatment, including antibacterial therapy, suggests the coexistence of a neighboring abscess, metastatic infections, such as intraperitonea; abscess, embolic pneumonitis, meningitis, pericarditis and thrombophlebitis, or resistance of the infecting bacteria to the chemotherapeutic agent in use. Information regarding the infecting micro-organism can be obtained by the immediate examination of stained smears of infectious material and by culture of exudates obtained by incision and drainage or aspiration with needle and syringe from the actual site of infection. Biopsy of the lesion is often very helpful in establishing the nature of the infection, particularly in chronic infections of a specific nature, such as tuberculosis, syphilis and actinomycosis. It must be kept in mind that errors in diagnosis can be made by accepting the report of the laboratory from cultures made of surface lesions. Such positive cultures may actually represent secondary invasion and not the true pathogen. This error is being made more and more frequently. Selection of Proper Chemotherapeutic Agent. The choice of antibacterial agent effective for the particular etiologic agents in any given case is extremely important in the modern control of surgical infections. The selection may necessarily be made blindly in a patient with a severe systemic infection on the basis of a presumptive diagnosis, until the nature of the causative organism and its sensitivity to the antibiotics are determined. Preferable to the blind selection is a choice of one or more agents suggested by the results of studies of the gram-stained smears of
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exudates. However, the probability of effectiveness of agents chosen in this manner is limited and subject to chance, since there is considerable variation in natural bacterial resistance within strains of infecting microorganisms. Whenever possible, it is advisable to obtain representative cultures of the etiologic agents and to perform susceptibility tests upon the various available antibiotic agents as soon as possible in order to assure the proper selection of the antibiotic agent. In the majority of instances, there has been a close correlation between the in vitro sensitivity tests and the clinical results obtained with the indicated antibiotic. For mixed infections produced by a variety of bacteria, it is recommended that two or rarely three antibacterial agents be selected for treatment if such condition as acute septic peritonitis, intra-abdominal abscess, perinephritic abscess, urinary tract infections, and various types of wound infections are present. Usually aqueous penicillin and tetracycline, Chloromycetin, Aureomycin or Terramycin are selected on the basis of the sensitivity tests for mixed infections. It is also advisable to repeat both cultures and sensitivity tests at weekly intervals in severe or prolonged infections because of the possible acquisition of resistance by the organisms to the antibacterial agent, or to the development of secondary or superimposed infections. Acquired resistance may be developed by bacteria in varying degrees to all of the antibiotic agents except polymyxin B and neomycin. Unfortunately, inincreasing numbers of bacterial strains are acquiring resistance to all of the available antibiotics. Occasionally, suppression of sensitive bacteria in mixed infections by antibiotics may permit other bacteria, normally of lesser virulence, to become invasive and to invade the blood stream, meninges or some other tissue. Infections produced in this manner are known as superimposed infections. Adequate Dosage. The evidence indicates that the dosage of the antibiotic agent should be large enough to produce an antibacterial concentration in the blood, intercellular fluids, and tissues. The duration of therapy should generally be extended for at least four to seven days after the return of normal temperature. Since the majority of antibiotic agents exerts a bacteriostatic action, treatment should be long enough to permit the natural defenses of the body to dispose of the inhibited but often still viable bacteria. Timed Surgical Intervention. The proper timing of operative procedures in relation to the nature and stage of the surgical infection, as well as the onset and duration of antibiotic therapy, is an important factor which is largely dependent upon the experience and the vigilance of the surgeon. Supportive Treatment. It must be remembered that the full therapeutic effect of the antibiotics used will not be obtained if local and systemic alterations in physiology are not corrected. Toxic or hypersensitive reactions produced by the antibacterial agents may cause varying degrees
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of physiological disturbances. For these and other reasons, supportive treatment remains an important aspect of management. A great host of bacterial species may be present as contaminants of surgical lesions, but fortunately the types producing surgical infections are more limited. Those of greatest importance are the pyogenic bacteria, the term usually applied to the staphylococci, the streptococci, the pneumococci, the gonococci and the meningococci. It is occasionally also applied to the colon bacilli and B. pyocyaneus. Infections encountered in surgical practice may be monomicrobic or polymicrobic, depending upon whether they are caused by one etiologic agent or are mixed infections. It is impossible to discuss all of the infections encountered in surgery and only the more important will be considered. STAPHYLOCOCCAL INFECTIONS
Staphylococcal infections tend to be localized, and are usually characterized by an area of cellulitis and erythema which subsequently undergoes central necrosis and abscess formation. An appreciable quantity of thick, creamy, odorless and yellowish pus is usually formed. From distributing foci, these organisms of staphylococcal infections may invade the blood stream and produce a bacteremia. In the great majority of instances, the responsible agent is the hemolytic Staph. aureus, which coagulates human plasma, liquefies fibrin and gelatin, and produces a locally necrotizing toxin. Its ability to coagulate plasma favors the development of thrombosis and thrombophlebitis in the adjacent veins, thereby facilitating bacteremia or metastatic abscess. The symptoms of staphylococcal infection consist of swelling, adjacent erythema, and increasing local pain which is throbbing in character and often synchronous with the pulse beat. The temperature usually is elevated and leukocytosis is generally present. In open wounds, the principal evidence of infection is a creamy purulent discharge associated with pain, redness and swelling of the contiguous tissues. In staphylococcal infections of wounds in soft tissues, the increase in pulse rate may not be as great as that in the temperature. If the process becomes invasive, malaise, higher fever, lymphangitis, lymphadenitis, chills and sweats usually occur (Fig. 444). Treatlllent
Management of staphylococcal lesions is based upon early diagnosis, the application of rest and heat, elevation, adequate drainage when pus has formed, and antibiotic therapy. Each lesion should be considered and treated individually. Acute spreading infections should not be incised or traumatized until the invasive qualities of the process have been overcome. The removal of pus or necrotic tissue in localized infections
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by adequate drainage is important, for once removed, healing usually follows rapidly. Sutured wounds, complicated by infection, should be opened with a hemostat at the point of maximum swelling, pain and fluctuation. The sutures are removed and the opening is enlarged to the size of the cavity, irrigated gently with saline, and packed loosely with gauze. The antibiotic agents effective for staphylococcal infections include penicillin, erythromycin, Chloromycetin, Achromycin, Terramycin,
Fig. 444. A, Photograph showing staphylococcal infection of the skin of the upper lip with adjacent cellulitis, resulting in swelling of the entire right side of the face. B, Closer view showing area of central necrosis containing pus about the site of origin and the zone of erythema peripherally. C & D, Complete resolution following local drainage of abscess and treatment with parenteral penicillin.
Aureomycin and bacitracin in average dosage. Because of the increasing number of strains acquiring resistance to these agents, sensitivity tests are advisable. However, about 96 per cent of staphylococci remain sensitive to Chloromycetin. The systemic use of the antibiotics is preferable to local use. STREPTOCOCCAL INFECTIONS
The majority of streptococcal infections are produced by the aerobic hemolytic streptococci, although some are caused by the nonhemolytic streptococci, the green streptococci, the anaerobic streptococci, or the micro-aerophilic streptococci. The source of wound contamination is
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usually from human sources, such as the upper respiratory tract, airborne dust, or cross contamination with other infected wounds. Lesions produced by the aerobic hemolytic streptococci tend to be invasive and to run a rapid course during the initial phase. They may occur as early as 12 to 48 hours after injury, or later. In older wounds which have been treated surgically and left open, the incidence of infection with these organisms increases with the duration of the wound as a result of secondary contamination. The early processes are usually ones of diffuse cellulitis with lymphangitis or lymphadenitis which show little tendency to form abscesses. Septicemia or rapid extension from such early lesions may follow imprudent surgical manipulation. Extension along fascial planes in deep wounds is prone to occur. When breakdown of tissue occurs, it is characterized either by gangrene of the overlying skin or development of thin watery pus. Invasion of the blood stream by bacteria from this primary focus is frequent, and it is important to recognize this complication early in order to minimize the distribution of virulent bacteria and subsequent development of metastatic abscesses. Such septicemia or bacteremia is suggested by clinical signs of chills, high fever, rapid thready pulse, prostration and other signs of toxemia. Hemolytic Streptococcal Gangrene. This type of infectious gangrene is essentially an epifascial, spreading, subcutaneous gangrene with thrombosis of the nutrient vessels and resultant slough of the overlying skin, frequently following contamination of a relatively minor wound with virulent streptococci (Fig. 445). It usually develops in the extremities, . although other parts of the body may be involved. It is characterized by the onset of severe pain and marked swelling at the site of the wound, chills, elevation of the temperature to 101 0 to 104°F., rapid pulse, toxemia and marked prostration. The overlying skin develops a spreading cellulitis with vesiculation and a peculiar patchy, purplish and expanding necrosis. Hemolytic streptococci, often in pure culture, are found in the fluid aspirated from the bullae or areas of subcutaneous gangrene. Anaerobic Streptococcal Infections. Anaerobic streptococci may produce acute and severe infections, particularly in wounds which involve or penetrate the genital, intestinal or respiratory tracts. Bacteremia may develop and result in metastatic abscesses in distant regions, such as the lung or brain. These infections, developing and progressing more slowly than other streptococcal infections, are characterized by marked induration, thick foul-smelling pus, and necrosis of the involved tissues extending progressively along fascial planes or muscle. ANAEROBIC STREPTOCOCCAL MYOSITIS may occur, characterized by massive inf~ction of muscle, local pain, and generalized toxemia. Established lesions show discoloration of the muscle, edema, crepitation, and fetid odor. The chief points of differentiation between it and clostridial myositis are the former's more pronounced cutaneous erythema, its discolored muscle which is still alive and reactive to stimuli, its different
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odor, and its gram-stained smears which reveal vast numbers of streptococci among masses of pus cells, but which show no presence of grampositive rods. Chronic Progressive Cutaneous Gangrene. This lesion,otherwise known as Meleney's synergistic gangrene, may complicate operations for puru-
Fig. 445. A, Photograph showing Gxten&iYl} involvement of left arm of a patient who developed aerobic hemolytic streptococcal gangrene following trivial injury. Note patchy purplish necrosis of dorsum of wrist and forearm. B, Closer view of area of streptococcal gangrene overlying elbow. Treatment consisted of parenteral penicillin and debridement of area of necrosis. A resulting defect in the skin over the elbow required skin grafting.
lent infections of the chest or peritoneal cavity. It is produced by the synergistic action of a micro-aerophilic nonhemolytic streptococcus and an aerobic hemolytic staphylococcus, or occasionally B. proteus. Seven to 14 days after operation for a lesion involving the gastrointestinal, genitourinary or respiratory tracts, an area of the surrounding skin be-
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comes tender, red and edematous, especially about any stay sutures that have been used. Within a few days, a carbuncular infection develops about the wound margins or stay-suture holes, and the central area assumes a purplish or purplish-black color. A wide area of bright red cellulitis develops peripherally, while the central purplish spots widen, become gangrenous, and finally slough. The central area of ulceration, bordered by a purplish-black narrow margin of gangrenous skin and a
Fig. 446. Photograph showing chronic progressive cutaneous gangrene of the skin of the lower leg. Note in the upper half of the lesion the area of ulceration periphera to which is a margin of black gangrenous skin which borders an area of erythema signifying underlying cellulitis. Definitive treatment required block excision of the entire area involved by ulceration, gangrene and cellulitis, with adjunctive treatment of large doses of the appropriate antibiotic shown by in vitro sensitivity tests.
large area of spreading cellulitis, is characteristic (Fig. 446). The gangrenous margin is slightly undermined, exquisitely tender, and very painful. This infection is slowly progressive. Large areas of the body may be denuded as a result of its progress. Systemic manifestations at first are slight, but in neglected cases, profound derangements in physiology may occur. Chronic Burrowing Ulcer. This lesion is another streptococcal infection described by Meleney and caused by micro-aerophilic hemolytic streptococci. It usually occurs in the cervical, axillary, perineal or popliteal regions, and is characterized by ulceration of the skin and burrowing sinus tracts which may extend through muscle, fascia and even bone.
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The lesion is very indolent, showing no signs of healing for many months, or longer. TreatInent
Management of streptococcal infections varies with the type of lesion and the type of streptococci. For aerobic hemolytic streptococcal infections, treatment consists primarily in the control of their invasive characteristics by rest, elevation, warm applications, and specific antibacterial therapy. Secondarily, it consists of adequate drainage for the removal of pus or necrotic tissue after it has formed. Incisions or manipulations should never be made in these infections until the invasive characteristics have been overcome, except in instances of acute hemolytic streptococcal gangrene, when radical longitudinal incisions are indicated through the skin and subcutaneous tissues to points just beyond the lesion's extent. Aerobic hemolytic streptococcal infections still respond very well, in the great majority of instances, to penicillin, the agent of choice. For resistant strains, sulfadiazine, erythromycin or one of the broad-spectrum antibiotics should be investigated as an effective agent by in vitro sensitivity tests. Active supportive therapy for patients with these infections is often mandatory. A naerobic streptococcal infections are more resistant to therapy than the aerobic ones, and they tend to become chronically active. In some ways they resemble staphylococcal lesions. They are relatively more resistant to the antibiotics, requiring larger doses and more prolonged treatment. Early incision and drainage of pus formed in the course of these infections is important. Septic thrombophlebitis and embolization are apt to occur and should be treated as indicated. Aqueous penicillin G is still the agent of choice, but the dosage recommended is 200,000 to 500,000 units intramuscularly, every six hours. In patients with chronic progressive cutaneous gangrene, radical excision of the ulcerated lesion and its gangrenous borders is indicated, along with systemic antibiotic treatment with aqueous penicillin G or erythromycin. There is some evidence to suggest that bacitracin is particularly valuable in this lesion. Its systemic use, however, should be controlled by the usual safety measures. Skin grafting is always necessary to cover the defect, and this is done by the authors approximately ten days after the radical excision. The sinus tracts produced by chronic burrowing ulcers require careful dissection, with their complete excision, if possible. Otherwise, the tracts should be incised throughout their extent. The resultant wounds are packed open, loosely, and healing is allowed to progress from the depths outward. If all of the tract is not excised, recurrence is the rule. Supportive antibiotic therapy should be on the basis of in vitro sensitivity
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tests, since many of the strains of bacteria in our experience have acquired resistance to most of the antibiotics as a result of previous and unsuccessful treatment. GRAM-NEGATIVE BACILLARY INFECTIONS
Infections caused only by gram-negative bacilli of the gastrointestinal tract, such as B. coli, B. pyocyaneus, B. proteus or B. typhosus are relatively infrequent. However, they may occur, particularly in the genitourinary tract or in postoperative wounds. Invasive infection with bacteremia may arise from areas of cutaneous burns. Under ordinary circumstances, many of these bacteria are relatively nonvirulent, but under conditions of general debility, cortisone therapy, or the presence of necrotic tissue within a wound, they may produce invasive infections. In some instances, local infection of an operative wound produced by one of these organisms may become manifest as an abscess many weeks or months postoperatively. Treatlllent
The treatment of gram-negative bacillary infections consists of incision and drainage of abscesses, surgical excision of necrotic tissue, antibiotic treatment based upon results of in vitro sensitivity tests, and supportive treatment. Chloromycetin has been the most effective antibiotic for these infections in our experience. For those infections caused by B. pyocyaneus, polymyxin B is recommended. MIXED OR SYNERGISTIC INFECTIONS
There is a larger and miscellaneous group of infections of polymicrobic etiology that may occur spontaneously or as posttraumatic or postoperative complications. They are prone to occur in association with injuries or lesions of the gastrointestinal, respiratory or genitourinary tracts. The symbiosis of aerobes and anaerobes determines the nature of these lesions. They are characterized by the development of slough in the subcutaneous tissues, fascia, retroperitoneal tissues, and areolar tissue of the intermuscular planes. Abscess formation or dissecting cellulitis may occur. Examples of mixed or synergistic infections include deep infections of the neck, human bite infections, postoperative peritonitis, putrid empyema and phlegmonous cellulitis of the abdominal wall. Space does not permit our discussion of all of these lesions, and the one singled out for discussion is anaerobic nonclostridial cellulitis. Anaerobic nonclostridial cellulitis is a mixed infection which begins characteristically as a rapidly spreading, necrotizing infection of the areolar connective tissues adjacent to the wound or in the retroperitoneal area. Wounds of the perineum, abdominal wall, buttocks, thorax or neck, which have been contaminated by discharges from the intestinal, genitourinary or respiratory tracts, may be complicated by an infection of this
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nature. Its spread is often rapid by direct extension beneath Scarpa's fascia into the abdominal wall and flank, when it occurs in the region of the perineum or inguinal area. No single type of etiologic agent is consistently found, the various types of organisms associated with this process being strains of the coliform group, particularly E. coli, the anaerobic gram-negative bacilli of the Bacteroides group, such as B. melaninogenicum and B. thetoides, and the anaerobic streptococci.
Fig. 447. Photograph showing anaerobic nonclostridial cellulitis which developed postoperatively. Note discoloration and necrosis of subcutaneous fat, fascia and rectus muscles. Erythema of a wide zone of skin overlying these areas of infection can also be seen. This infection responded to wide incision and drainage of the wound, large doses of penicillin and local application of zinc peroxide ointment.
The essential pathology is a wet inflammation of the subcutaneous tissues which progresses to necrosis and crepitation within two to five days after the onset (Fig. 447). In those cases in which B. melaninogenicum is found, areolar and fascial tissues usually present a grayish-black color, and a characteristic odor similar to that of putrid material from a lung abscess or an appendiceal abscess is noted. Thrombosis of the nutrient vessels to the skin is a prominent finding histologically, and this is responsible for progressive gangrenous changes in the skin. Treatment
Successful management of this lesion depends upon early diagnosis, prompt surgical decompression by radical incision and drainage, active
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antibiotic therapy, and supportive therapy. The diagnosis may be very difficult in the early stages. Later, it may become obvious through the development of spreading cellulitis, crepitation, fever, rapid thready pulse, high leukocytosis, prostration, and episodes of hypotension from septic shock. Discoloration and gangrene of the skin may develop. There is too little time for selection of antibiotics on the basis of in vitro tests in these infections, once they are established. The choice is, therefore, an empirical one during the initial stages of treatment. Aqueous penicillin G in large intravenous or intramuscular doses is recommended, along with Chloromycetin or Achromycin or one of its derivatives. CLOSTRIDIAL MYOSITIS (TRUE GAS GANGRENE)
Clostridial myositis is a spreading or localized infection of muscle caused by one or more of the Clostridia. It is usually a mixed infection which primarily involves muscle tissue and which is characterized by spreading infectious gangrene of the muscle, profound toxemia, and a rapidly fatal course unless treated early and adequately. The infection may be confined within a muscle, but as a rule it spreads rapidly to involve a group of muscles, an entire limb, or the torso. Crepitation of the tissues produced by gas formation occurs in most cases, particularly in those produced by Cl. welchii and Cl. septique. A great variety of anaerobic bacteria, chiefly Cl. welchii, Cl. sordelli, Cl. oedematiens, Cl. histolyticus, and Cl. septique, have been found repeatedly in association with this condition, the individual case usually having a mixed bacterial flora of aerobes as well as anaerobes. With certain of the bacteria, gaseous infiltration and edema may develop; with others, edema without gas; and with still others, rapid digestion and dissolution of tissue with moderate edema but no gas. At times, gaseous infiltration, edema and rapid destruction of the tissues exist in the same wound. The production of gas and edema increases the pressure beneath the deep fascia and acts as an expanding tourniquet, favoring further devitalization of muscle by compression of the smaller vessels and linear spread through the tissue planes. Powerful soluble toxins are produced, which diffuse into adjacent tissues to cause further destruction and thrombosis of the vessels, or which are absorbed into the circulation to produce marked toxemia, profound anemia, shock, damage of the liver, heart and kidneys, prostration and death. The incubation period between injury and the onset of clostridial myositis varies between a few hours and four or more days, depending upon the nature of the wound and the virulence and type of causal Clostridium. Clostridial myositis may be spreading and diffuse or it may be localized. In the spreading type, involvement of the areolar connective tissue follows that of the muscles. Because of its milder and self-limiting
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nature, localized clostridial myositis should not be considered as gas gangrene. Pain is the earliest symptom of clostridial myositis. It is caused principally by the distention of the tissues by fluid or gas, and usually appears within the first 24 hours after injury. Later, the pain may disappear, and in the overwhelming toxemic forms, complete absence of pain may be seen. An alarmingly rapid and feeble pulse may follow the onset of pain and it usually is out of proportion to the temperature level.
Fig. 448. A & B, Photographs of far-advanced gas gangrene of the lower leg following compound fracture of the tibia and fibula. Note the marked swelling with tension on the suture lines, the brownish-red watery discharge and the herniation of muscle through the open incision. Emergency treatment required supracondylar amputation as a life-saving measure. Penicillin was given adjunctively in massive doses.
The blood pressure may be normal or even slightly elevated early, but later it becomes significantly low. The degree of fever varies considerably, but frequently it is less than 101°F., a far from reliable index of the severity of the infectious process. A low temperature with a very rapid pulse suggests a grave outlook. TreatInent
,
The treatment of clostridial myositis depends particularly on early diagnosis, radical and prompt surgical intervention, antibiotic treatment, and vigorous supportive treatment. Unfortunately, the early diagnosis of gas gangrene may be difficult, and it may be unrecognized until the lesion is far advanced. Continued pain at the site of a wound containing devitalized muscle, a rapid and easily compressible pulse, varying degrees
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of fever, toxemia in association with spreading edema, a thin, brown, watery, malodorous discharge, crepitation, herniation of discolored muscle which does not bleed or contract, and typical discolorations of the skin in the regions of the wound are relatively late signs which are indicative of a far-advanced and often irreversible process (Fig. 448). The old principle of promptly inspecting the wound in the presence of unexplained pain or fever is particularly valuable in the early recognition of the process. Infiltrating gas may be detected early by the experienced observer through ausculatory percussion or by serial roentgenograms. In suspicious cases, films taken at intervals of from two to twelve hours may aid in the differentiation of gas due to the Clostridia from that due to mechanical causes, and may permit a positive diagnosis 24 or more hours earlier than possible by the clinical findings alone. It must be kept in mind that, in awaiting the results of various diagnostic tests, valuable time may be lost during which irreversible changes may occur in the tissues. For this reason it is important to explore surgically, and without delay, any wound in which the presence of clostridial myositis is suspected. The operative procedure recommended may be radical incision and drainage to decompress the muscular and fascial compartments, excision of infected or devitalized groups of musales, or open amputation, depending upon the state and severity of the infection. Aureomycin, Terramycin or Achromycin is the antibiotic of choice for this infection and should be given intravenously or intramuscularly as indicated. If penicillin is used, aqueous penicillin G is recommended in doses of 1,000,000 units every three hours. SUMMARY
Knowledge contributed to surgery from bacteriology and immunology has resulted in significant advances in the prevention, diagnosis and control of infections seen in surgical practice. Although bacteria are the ultimate cause of infections, other important factors often determine the actual development of the infection and contribute to its progress. These factors are known and have been discussed. The principal advances in the control of infections made in the past 12 years have resulted from our acquired knowledge of the antibiotic agents, which knowledge has permitted their safe clinical use. Experience has shown that antibiotic agents are used most effectively in conjunction with indicated surgical procedures, and that the success of their use depends upon the surgeon's observance of certain established principles. These, also, have been discussed. The outlook of surgical patients with established infections or operations performed through contaminated fields is now greatly improved. Many of the infections commonly seen in practice can now be controlled by the antibiotics used in conjunction with timed surgical intervention.
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However, the management of individual cases has not been simplified from the surgeon's viewpoint because of the introduction of a large number of problems associated with the use of the newer antibiotic agents. Unfortunately, there are still many surgical infections which have an unknown etiology or which are resistant to any known form of antibacterial therapy.
A. ALTEMEIER, M.D., F.A.C.S. W. R. CULBERTSON, M.D.
THE prevention of surgical infections, as well as their diagnosis, proper treatment and prognosis, depends upon a thorough understanding of various basic sciences dealt with in medicine. A working knowledge of bacteriology and immunology and a complete familiarity with the physiologic responses of the body to bacterial invasion and growth are particularly essential. To prevent infection in wounds, the surgeon uses knowledge gained from bacteriology and immunology for the most effective methods of aseptic and antiseptic techniques, for ways of improving the resistance of his patient to infecting bacteria, and for means of inhibiting or attenuating the growth of contaminating micro-organisms. To minimize morbidity and mortality in treating established surgical infections, he employs bacteriologic information for accurate diagnosis, for anticipating routes of spread, for antibiotic or other antibacterial treatment, for timing of necessary operative procedures, for localization of the process, and for supportive treatment. Until the studies of Pasteur and their surgical application by Lister, it was universally thought that a part of the natural process of the healing of wounds was the development of pus and other signs of the process now recognized as infection. Methods of treatment prior to Pasteur were, of necessity, completely blind and directed toward symptomatic relief rather than an attack upon the etiologic agent or its source of spread. Any elective surgical procedure was approached with great reluctance because of the feared development of "hospital gangrene" rather than the occurrence of "laudable pus." Consequently, most elective surgical operations were minor or superficial until 60 years ago. Today it is possible routinely to prevent infection in planned operative wounds, an achievement which is one of the great milestones of surgery. In addition, great progress has been made in preventing or attenuating From the Department of Surgery, University of Cincinnati, and the Cincinnati General Hospital, Cincinnati, Ohio.
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infection in accidental wounds or wounds of violence. Because of this success, many surgeons believe that the control of infection is no longer a prominent problem in surgery. This belief is treacherously incorrect. Most of the old problems continue to exist, and the complexity of the new methods of diagnosis and treatment requires more thought and care than ever before. GENERAL CONSIDERATIONS
Factors in the Developll1ent of Infection
The bacteriologist's premise that infection is the unfavorable result of the equation expressed as "dose mUltiplied by virulence and divided by resistance" is still applicable to both surgical and medical infections. Nearly all surgical infections are the result of the entry of pathogenic bacteria into the tissues of the body through a site of injury, which may be large or small and accidentally or intentionally produced. Most bacteria cannot invade the physiologic interior of the body through the intact mucous membrane or skin. Pathogenic bacterial invasion may also be prevented by the local or humeral defenses of the body after the entrance of bacteria has been provided by trauma. On the other hand, certain micro-organisms, such as spirochetes, E. typhosus and M. tuberculosis, have the ability to penetrate mucous membranes without preexisting trauma. Fortunately, these are all of minor surgical importance. Time Lapse. The lapse of time between the entry of organisms and the development of signs of infection is the incubation period which is of great importance to the surgeon in dealing with accidental wounds. It is the "Golden Period," during which, the greatest effects toward prevention of the establishment of infection can be obtained by means of proper debridement, establishment of passive immunologic states against specific organisms, and development of body resistance by general measures as well as specific antibacterial treatment. The bacteria in wounds of less than four hours' duration are generally considered to be relatively inactive, while they may be growing actively on the surface of the wound during the four to eight hour period. In wounds older than eight hours, the bacteria have usually invaded the adjacent tissues and may have started their spread along the lymphatics, in fascial planes or the blood stream. It must be remembered that bacteria of low virulence or saphrophytes can cause infections in the presence of devitalized avascular tissues. Invasiveness of the Infection. Infections limited to the area of the wound are considered to be local, and those spreading beyond the wound are invasive. Lesions spreading along fascial planes or lymphatics are designated as regionally invasive; those extending through the blood stream are systemically invasive, being either a bacteremia or a septicemia. In a bacteremia the area of infection distributes bacteria into the blood stream
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once or intermittently, while in a septicemia it distributes the microorganisms more or less constantly. Although bacteria are necessarily the basis of infection occurring within wounds, experience has shown that micro-organisms may be present in the wound without producing evidence of infection and that many other factors are of importance in the development of infection. Tissue Resistance. The resistance of normal healthy tissues to bacterial infection is well established. On the other hand, devitalized, irritated or unhealthy tissues are susceptible to bacterial growth and favor the development of local septic processes. It must be remembered that tissues can become devitalized early by the injury, and later as a result of factors which impair the blood supply, such as arterial thrombosis, subfascial hematoma, constricting bandages, tight casts or operative repair under tension. The importance of the thorough removal of all devitalized tissue and foreign bodies from wounds and the restoration of the local physiologic state of the wound to normalcy is obvious. The General Condition of the Patient. This may also be an important factor. Anemia, shock, malnutrition and dehydration are conditions which may lower the resistance and favor bacterial invasion. Metabolic diseases, such as diabetes mellitus and arteriosclerosis, may also decrease his local and general powers of resistance. Surgical infections may, therefore, subside spontaneously, remain localized, spread to regional or distant areas, become chronic, or result in death or prolonged disability. Principles of Successful Therapy
Great progress has been made during the past two years in the control or management of surgical infections through the co-ordinated use of antibiotic agents with indicated surgical procedures. Experience has emphasized the importance of observing certain factors and principles of therapy in the successful management of surgical infections, and, as a rule, these principles have remained essentially unchang;ed. In general, the use of the antibiotic agents is adjunctive to clinical application of the established surgical principles of treatment. The proper use of the antibiotic agent has produced profound effects on the prevention and control of infections, but improper use has resulted in limited, incomplete or absent clinical results. Among the various factors which are important in the control of surgical infections and which determine the effectiveness of antibiotic therapy are the following. Early Diagnosis. The influence of early diagnosis and early treatment upon morbidity, mortality and functional results cannot be overemphasized. Antibacterial treatment is most apt to produce a prompt and rapid control of the invasiveness of the infection, with its complete and spontaneous resolution when the diagnosis is established early. Local tissue destruction or other complications are likely to be minimal. Late
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diagnosis permits the process to become more established, with the development of local necrosis, abscess, or systemic invasion. Under these circumstances, treatment produces more limited and delayed results, and complications are usually more numerous. The invasive qualities of the infection are generally overcome and the process is localized, but extensive necrosis of tissue may occur. At times the use of early, specific antibacterial therapy will so control the invasive qualities of certain infections that emergency surgical decompression or excision of infected areas either becomes unnecessary or can be replaced by more conservative types of surgery done at a time when the patient's condition has been improved. When the infection has become disseminated, with the production of metastatic abscesses or other infectious complications in remote areas, its control is much more difficult. Accurate and Complete Diagnosis. The necessity of a correct clinical diagnosis, including the site of infection, the responsible bacteria, the patient's general condition, the existence and location of metastatic abscesses or other complications, and the contributing causes and the stage of the process is obvious. Failure of the elevated temperature and other general signs of infection to begin to recede within 72 hours of the start of treatment, including antibacterial therapy, suggests the coexistence of a neighboring abscess, metastatic infections, such as intraperitonea; abscess, embolic pneumonitis, meningitis, pericarditis and thrombophlebitis, or resistance of the infecting bacteria to the chemotherapeutic agent in use. Information regarding the infecting micro-organism can be obtained by the immediate examination of stained smears of infectious material and by culture of exudates obtained by incision and drainage or aspiration with needle and syringe from the actual site of infection. Biopsy of the lesion is often very helpful in establishing the nature of the infection, particularly in chronic infections of a specific nature, such as tuberculosis, syphilis and actinomycosis. It must be kept in mind that errors in diagnosis can be made by accepting the report of the laboratory from cultures made of surface lesions. Such positive cultures may actually represent secondary invasion and not the true pathogen. This error is being made more and more frequently. Selection of Proper Chemotherapeutic Agent. The choice of antibacterial agent effective for the particular etiologic agents in any given case is extremely important in the modern control of surgical infections. The selection may necessarily be made blindly in a patient with a severe systemic infection on the basis of a presumptive diagnosis, until the nature of the causative organism and its sensitivity to the antibiotics are determined. Preferable to the blind selection is a choice of one or more agents suggested by the results of studies of the gram-stained smears of
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exudates. However, the probability of effectiveness of agents chosen in this manner is limited and subject to chance, since there is considerable variation in natural bacterial resistance within strains of infecting microorganisms. Whenever possible, it is advisable to obtain representative cultures of the etiologic agents and to perform susceptibility tests upon the various available antibiotic agents as soon as possible in order to assure the proper selection of the antibiotic agent. In the majority of instances, there has been a close correlation between the in vitro sensitivity tests and the clinical results obtained with the indicated antibiotic. For mixed infections produced by a variety of bacteria, it is recommended that two or rarely three antibacterial agents be selected for treatment if such condition as acute septic peritonitis, intra-abdominal abscess, perinephritic abscess, urinary tract infections, and various types of wound infections are present. Usually aqueous penicillin and tetracycline, Chloromycetin, Aureomycin or Terramycin are selected on the basis of the sensitivity tests for mixed infections. It is also advisable to repeat both cultures and sensitivity tests at weekly intervals in severe or prolonged infections because of the possible acquisition of resistance by the organisms to the antibacterial agent, or to the development of secondary or superimposed infections. Acquired resistance may be developed by bacteria in varying degrees to all of the antibiotic agents except polymyxin B and neomycin. Unfortunately, inincreasing numbers of bacterial strains are acquiring resistance to all of the available antibiotics. Occasionally, suppression of sensitive bacteria in mixed infections by antibiotics may permit other bacteria, normally of lesser virulence, to become invasive and to invade the blood stream, meninges or some other tissue. Infections produced in this manner are known as superimposed infections. Adequate Dosage. The evidence indicates that the dosage of the antibiotic agent should be large enough to produce an antibacterial concentration in the blood, intercellular fluids, and tissues. The duration of therapy should generally be extended for at least four to seven days after the return of normal temperature. Since the majority of antibiotic agents exerts a bacteriostatic action, treatment should be long enough to permit the natural defenses of the body to dispose of the inhibited but often still viable bacteria. Timed Surgical Intervention. The proper timing of operative procedures in relation to the nature and stage of the surgical infection, as well as the onset and duration of antibiotic therapy, is an important factor which is largely dependent upon the experience and the vigilance of the surgeon. Supportive Treatment. It must be remembered that the full therapeutic effect of the antibiotics used will not be obtained if local and systemic alterations in physiology are not corrected. Toxic or hypersensitive reactions produced by the antibacterial agents may cause varying degrees
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of physiological disturbances. For these and other reasons, supportive treatment remains an important aspect of management. A great host of bacterial species may be present as contaminants of surgical lesions, but fortunately the types producing surgical infections are more limited. Those of greatest importance are the pyogenic bacteria, the term usually applied to the staphylococci, the streptococci, the pneumococci, the gonococci and the meningococci. It is occasionally also applied to the colon bacilli and B. pyocyaneus. Infections encountered in surgical practice may be monomicrobic or polymicrobic, depending upon whether they are caused by one etiologic agent or are mixed infections. It is impossible to discuss all of the infections encountered in surgery and only the more important will be considered. STAPHYLOCOCCAL INFECTIONS
Staphylococcal infections tend to be localized, and are usually characterized by an area of cellulitis and erythema which subsequently undergoes central necrosis and abscess formation. An appreciable quantity of thick, creamy, odorless and yellowish pus is usually formed. From distributing foci, these organisms of staphylococcal infections may invade the blood stream and produce a bacteremia. In the great majority of instances, the responsible agent is the hemolytic Staph. aureus, which coagulates human plasma, liquefies fibrin and gelatin, and produces a locally necrotizing toxin. Its ability to coagulate plasma favors the development of thrombosis and thrombophlebitis in the adjacent veins, thereby facilitating bacteremia or metastatic abscess. The symptoms of staphylococcal infection consist of swelling, adjacent erythema, and increasing local pain which is throbbing in character and often synchronous with the pulse beat. The temperature usually is elevated and leukocytosis is generally present. In open wounds, the principal evidence of infection is a creamy purulent discharge associated with pain, redness and swelling of the contiguous tissues. In staphylococcal infections of wounds in soft tissues, the increase in pulse rate may not be as great as that in the temperature. If the process becomes invasive, malaise, higher fever, lymphangitis, lymphadenitis, chills and sweats usually occur (Fig. 444). Treatlllent
Management of staphylococcal lesions is based upon early diagnosis, the application of rest and heat, elevation, adequate drainage when pus has formed, and antibiotic therapy. Each lesion should be considered and treated individually. Acute spreading infections should not be incised or traumatized until the invasive qualities of the process have been overcome. The removal of pus or necrotic tissue in localized infections
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by adequate drainage is important, for once removed, healing usually follows rapidly. Sutured wounds, complicated by infection, should be opened with a hemostat at the point of maximum swelling, pain and fluctuation. The sutures are removed and the opening is enlarged to the size of the cavity, irrigated gently with saline, and packed loosely with gauze. The antibiotic agents effective for staphylococcal infections include penicillin, erythromycin, Chloromycetin, Achromycin, Terramycin,
Fig. 444. A, Photograph showing staphylococcal infection of the skin of the upper lip with adjacent cellulitis, resulting in swelling of the entire right side of the face. B, Closer view showing area of central necrosis containing pus about the site of origin and the zone of erythema peripherally. C & D, Complete resolution following local drainage of abscess and treatment with parenteral penicillin.
Aureomycin and bacitracin in average dosage. Because of the increasing number of strains acquiring resistance to these agents, sensitivity tests are advisable. However, about 96 per cent of staphylococci remain sensitive to Chloromycetin. The systemic use of the antibiotics is preferable to local use. STREPTOCOCCAL INFECTIONS
The majority of streptococcal infections are produced by the aerobic hemolytic streptococci, although some are caused by the nonhemolytic streptococci, the green streptococci, the anaerobic streptococci, or the micro-aerophilic streptococci. The source of wound contamination is
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usually from human sources, such as the upper respiratory tract, airborne dust, or cross contamination with other infected wounds. Lesions produced by the aerobic hemolytic streptococci tend to be invasive and to run a rapid course during the initial phase. They may occur as early as 12 to 48 hours after injury, or later. In older wounds which have been treated surgically and left open, the incidence of infection with these organisms increases with the duration of the wound as a result of secondary contamination. The early processes are usually ones of diffuse cellulitis with lymphangitis or lymphadenitis which show little tendency to form abscesses. Septicemia or rapid extension from such early lesions may follow imprudent surgical manipulation. Extension along fascial planes in deep wounds is prone to occur. When breakdown of tissue occurs, it is characterized either by gangrene of the overlying skin or development of thin watery pus. Invasion of the blood stream by bacteria from this primary focus is frequent, and it is important to recognize this complication early in order to minimize the distribution of virulent bacteria and subsequent development of metastatic abscesses. Such septicemia or bacteremia is suggested by clinical signs of chills, high fever, rapid thready pulse, prostration and other signs of toxemia. Hemolytic Streptococcal Gangrene. This type of infectious gangrene is essentially an epifascial, spreading, subcutaneous gangrene with thrombosis of the nutrient vessels and resultant slough of the overlying skin, frequently following contamination of a relatively minor wound with virulent streptococci (Fig. 445). It usually develops in the extremities, . although other parts of the body may be involved. It is characterized by the onset of severe pain and marked swelling at the site of the wound, chills, elevation of the temperature to 101 0 to 104°F., rapid pulse, toxemia and marked prostration. The overlying skin develops a spreading cellulitis with vesiculation and a peculiar patchy, purplish and expanding necrosis. Hemolytic streptococci, often in pure culture, are found in the fluid aspirated from the bullae or areas of subcutaneous gangrene. Anaerobic Streptococcal Infections. Anaerobic streptococci may produce acute and severe infections, particularly in wounds which involve or penetrate the genital, intestinal or respiratory tracts. Bacteremia may develop and result in metastatic abscesses in distant regions, such as the lung or brain. These infections, developing and progressing more slowly than other streptococcal infections, are characterized by marked induration, thick foul-smelling pus, and necrosis of the involved tissues extending progressively along fascial planes or muscle. ANAEROBIC STREPTOCOCCAL MYOSITIS may occur, characterized by massive inf~ction of muscle, local pain, and generalized toxemia. Established lesions show discoloration of the muscle, edema, crepitation, and fetid odor. The chief points of differentiation between it and clostridial myositis are the former's more pronounced cutaneous erythema, its discolored muscle which is still alive and reactive to stimuli, its different
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odor, and its gram-stained smears which reveal vast numbers of streptococci among masses of pus cells, but which show no presence of grampositive rods. Chronic Progressive Cutaneous Gangrene. This lesion,otherwise known as Meleney's synergistic gangrene, may complicate operations for puru-
Fig. 445. A, Photograph showing Gxten&iYl} involvement of left arm of a patient who developed aerobic hemolytic streptococcal gangrene following trivial injury. Note patchy purplish necrosis of dorsum of wrist and forearm. B, Closer view of area of streptococcal gangrene overlying elbow. Treatment consisted of parenteral penicillin and debridement of area of necrosis. A resulting defect in the skin over the elbow required skin grafting.
lent infections of the chest or peritoneal cavity. It is produced by the synergistic action of a micro-aerophilic nonhemolytic streptococcus and an aerobic hemolytic staphylococcus, or occasionally B. proteus. Seven to 14 days after operation for a lesion involving the gastrointestinal, genitourinary or respiratory tracts, an area of the surrounding skin be-
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comes tender, red and edematous, especially about any stay sutures that have been used. Within a few days, a carbuncular infection develops about the wound margins or stay-suture holes, and the central area assumes a purplish or purplish-black color. A wide area of bright red cellulitis develops peripherally, while the central purplish spots widen, become gangrenous, and finally slough. The central area of ulceration, bordered by a purplish-black narrow margin of gangrenous skin and a
Fig. 446. Photograph showing chronic progressive cutaneous gangrene of the skin of the lower leg. Note in the upper half of the lesion the area of ulceration periphera to which is a margin of black gangrenous skin which borders an area of erythema signifying underlying cellulitis. Definitive treatment required block excision of the entire area involved by ulceration, gangrene and cellulitis, with adjunctive treatment of large doses of the appropriate antibiotic shown by in vitro sensitivity tests.
large area of spreading cellulitis, is characteristic (Fig. 446). The gangrenous margin is slightly undermined, exquisitely tender, and very painful. This infection is slowly progressive. Large areas of the body may be denuded as a result of its progress. Systemic manifestations at first are slight, but in neglected cases, profound derangements in physiology may occur. Chronic Burrowing Ulcer. This lesion is another streptococcal infection described by Meleney and caused by micro-aerophilic hemolytic streptococci. It usually occurs in the cervical, axillary, perineal or popliteal regions, and is characterized by ulceration of the skin and burrowing sinus tracts which may extend through muscle, fascia and even bone.
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The lesion is very indolent, showing no signs of healing for many months, or longer. TreatInent
Management of streptococcal infections varies with the type of lesion and the type of streptococci. For aerobic hemolytic streptococcal infections, treatment consists primarily in the control of their invasive characteristics by rest, elevation, warm applications, and specific antibacterial therapy. Secondarily, it consists of adequate drainage for the removal of pus or necrotic tissue after it has formed. Incisions or manipulations should never be made in these infections until the invasive characteristics have been overcome, except in instances of acute hemolytic streptococcal gangrene, when radical longitudinal incisions are indicated through the skin and subcutaneous tissues to points just beyond the lesion's extent. Aerobic hemolytic streptococcal infections still respond very well, in the great majority of instances, to penicillin, the agent of choice. For resistant strains, sulfadiazine, erythromycin or one of the broad-spectrum antibiotics should be investigated as an effective agent by in vitro sensitivity tests. Active supportive therapy for patients with these infections is often mandatory. A naerobic streptococcal infections are more resistant to therapy than the aerobic ones, and they tend to become chronically active. In some ways they resemble staphylococcal lesions. They are relatively more resistant to the antibiotics, requiring larger doses and more prolonged treatment. Early incision and drainage of pus formed in the course of these infections is important. Septic thrombophlebitis and embolization are apt to occur and should be treated as indicated. Aqueous penicillin G is still the agent of choice, but the dosage recommended is 200,000 to 500,000 units intramuscularly, every six hours. In patients with chronic progressive cutaneous gangrene, radical excision of the ulcerated lesion and its gangrenous borders is indicated, along with systemic antibiotic treatment with aqueous penicillin G or erythromycin. There is some evidence to suggest that bacitracin is particularly valuable in this lesion. Its systemic use, however, should be controlled by the usual safety measures. Skin grafting is always necessary to cover the defect, and this is done by the authors approximately ten days after the radical excision. The sinus tracts produced by chronic burrowing ulcers require careful dissection, with their complete excision, if possible. Otherwise, the tracts should be incised throughout their extent. The resultant wounds are packed open, loosely, and healing is allowed to progress from the depths outward. If all of the tract is not excised, recurrence is the rule. Supportive antibiotic therapy should be on the basis of in vitro sensitivity
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tests, since many of the strains of bacteria in our experience have acquired resistance to most of the antibiotics as a result of previous and unsuccessful treatment. GRAM-NEGATIVE BACILLARY INFECTIONS
Infections caused only by gram-negative bacilli of the gastrointestinal tract, such as B. coli, B. pyocyaneus, B. proteus or B. typhosus are relatively infrequent. However, they may occur, particularly in the genitourinary tract or in postoperative wounds. Invasive infection with bacteremia may arise from areas of cutaneous burns. Under ordinary circumstances, many of these bacteria are relatively nonvirulent, but under conditions of general debility, cortisone therapy, or the presence of necrotic tissue within a wound, they may produce invasive infections. In some instances, local infection of an operative wound produced by one of these organisms may become manifest as an abscess many weeks or months postoperatively. Treatlllent
The treatment of gram-negative bacillary infections consists of incision and drainage of abscesses, surgical excision of necrotic tissue, antibiotic treatment based upon results of in vitro sensitivity tests, and supportive treatment. Chloromycetin has been the most effective antibiotic for these infections in our experience. For those infections caused by B. pyocyaneus, polymyxin B is recommended. MIXED OR SYNERGISTIC INFECTIONS
There is a larger and miscellaneous group of infections of polymicrobic etiology that may occur spontaneously or as posttraumatic or postoperative complications. They are prone to occur in association with injuries or lesions of the gastrointestinal, respiratory or genitourinary tracts. The symbiosis of aerobes and anaerobes determines the nature of these lesions. They are characterized by the development of slough in the subcutaneous tissues, fascia, retroperitoneal tissues, and areolar tissue of the intermuscular planes. Abscess formation or dissecting cellulitis may occur. Examples of mixed or synergistic infections include deep infections of the neck, human bite infections, postoperative peritonitis, putrid empyema and phlegmonous cellulitis of the abdominal wall. Space does not permit our discussion of all of these lesions, and the one singled out for discussion is anaerobic nonclostridial cellulitis. Anaerobic nonclostridial cellulitis is a mixed infection which begins characteristically as a rapidly spreading, necrotizing infection of the areolar connective tissues adjacent to the wound or in the retroperitoneal area. Wounds of the perineum, abdominal wall, buttocks, thorax or neck, which have been contaminated by discharges from the intestinal, genitourinary or respiratory tracts, may be complicated by an infection of this
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nature. Its spread is often rapid by direct extension beneath Scarpa's fascia into the abdominal wall and flank, when it occurs in the region of the perineum or inguinal area. No single type of etiologic agent is consistently found, the various types of organisms associated with this process being strains of the coliform group, particularly E. coli, the anaerobic gram-negative bacilli of the Bacteroides group, such as B. melaninogenicum and B. thetoides, and the anaerobic streptococci.
Fig. 447. Photograph showing anaerobic nonclostridial cellulitis which developed postoperatively. Note discoloration and necrosis of subcutaneous fat, fascia and rectus muscles. Erythema of a wide zone of skin overlying these areas of infection can also be seen. This infection responded to wide incision and drainage of the wound, large doses of penicillin and local application of zinc peroxide ointment.
The essential pathology is a wet inflammation of the subcutaneous tissues which progresses to necrosis and crepitation within two to five days after the onset (Fig. 447). In those cases in which B. melaninogenicum is found, areolar and fascial tissues usually present a grayish-black color, and a characteristic odor similar to that of putrid material from a lung abscess or an appendiceal abscess is noted. Thrombosis of the nutrient vessels to the skin is a prominent finding histologically, and this is responsible for progressive gangrenous changes in the skin. Treatment
Successful management of this lesion depends upon early diagnosis, prompt surgical decompression by radical incision and drainage, active
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antibiotic therapy, and supportive therapy. The diagnosis may be very difficult in the early stages. Later, it may become obvious through the development of spreading cellulitis, crepitation, fever, rapid thready pulse, high leukocytosis, prostration, and episodes of hypotension from septic shock. Discoloration and gangrene of the skin may develop. There is too little time for selection of antibiotics on the basis of in vitro tests in these infections, once they are established. The choice is, therefore, an empirical one during the initial stages of treatment. Aqueous penicillin G in large intravenous or intramuscular doses is recommended, along with Chloromycetin or Achromycin or one of its derivatives. CLOSTRIDIAL MYOSITIS (TRUE GAS GANGRENE)
Clostridial myositis is a spreading or localized infection of muscle caused by one or more of the Clostridia. It is usually a mixed infection which primarily involves muscle tissue and which is characterized by spreading infectious gangrene of the muscle, profound toxemia, and a rapidly fatal course unless treated early and adequately. The infection may be confined within a muscle, but as a rule it spreads rapidly to involve a group of muscles, an entire limb, or the torso. Crepitation of the tissues produced by gas formation occurs in most cases, particularly in those produced by Cl. welchii and Cl. septique. A great variety of anaerobic bacteria, chiefly Cl. welchii, Cl. sordelli, Cl. oedematiens, Cl. histolyticus, and Cl. septique, have been found repeatedly in association with this condition, the individual case usually having a mixed bacterial flora of aerobes as well as anaerobes. With certain of the bacteria, gaseous infiltration and edema may develop; with others, edema without gas; and with still others, rapid digestion and dissolution of tissue with moderate edema but no gas. At times, gaseous infiltration, edema and rapid destruction of the tissues exist in the same wound. The production of gas and edema increases the pressure beneath the deep fascia and acts as an expanding tourniquet, favoring further devitalization of muscle by compression of the smaller vessels and linear spread through the tissue planes. Powerful soluble toxins are produced, which diffuse into adjacent tissues to cause further destruction and thrombosis of the vessels, or which are absorbed into the circulation to produce marked toxemia, profound anemia, shock, damage of the liver, heart and kidneys, prostration and death. The incubation period between injury and the onset of clostridial myositis varies between a few hours and four or more days, depending upon the nature of the wound and the virulence and type of causal Clostridium. Clostridial myositis may be spreading and diffuse or it may be localized. In the spreading type, involvement of the areolar connective tissue follows that of the muscles. Because of its milder and self-limiting
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nature, localized clostridial myositis should not be considered as gas gangrene. Pain is the earliest symptom of clostridial myositis. It is caused principally by the distention of the tissues by fluid or gas, and usually appears within the first 24 hours after injury. Later, the pain may disappear, and in the overwhelming toxemic forms, complete absence of pain may be seen. An alarmingly rapid and feeble pulse may follow the onset of pain and it usually is out of proportion to the temperature level.
Fig. 448. A & B, Photographs of far-advanced gas gangrene of the lower leg following compound fracture of the tibia and fibula. Note the marked swelling with tension on the suture lines, the brownish-red watery discharge and the herniation of muscle through the open incision. Emergency treatment required supracondylar amputation as a life-saving measure. Penicillin was given adjunctively in massive doses.
The blood pressure may be normal or even slightly elevated early, but later it becomes significantly low. The degree of fever varies considerably, but frequently it is less than 101°F., a far from reliable index of the severity of the infectious process. A low temperature with a very rapid pulse suggests a grave outlook. TreatInent
,
The treatment of clostridial myositis depends particularly on early diagnosis, radical and prompt surgical intervention, antibiotic treatment, and vigorous supportive treatment. Unfortunately, the early diagnosis of gas gangrene may be difficult, and it may be unrecognized until the lesion is far advanced. Continued pain at the site of a wound containing devitalized muscle, a rapid and easily compressible pulse, varying degrees
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of fever, toxemia in association with spreading edema, a thin, brown, watery, malodorous discharge, crepitation, herniation of discolored muscle which does not bleed or contract, and typical discolorations of the skin in the regions of the wound are relatively late signs which are indicative of a far-advanced and often irreversible process (Fig. 448). The old principle of promptly inspecting the wound in the presence of unexplained pain or fever is particularly valuable in the early recognition of the process. Infiltrating gas may be detected early by the experienced observer through ausculatory percussion or by serial roentgenograms. In suspicious cases, films taken at intervals of from two to twelve hours may aid in the differentiation of gas due to the Clostridia from that due to mechanical causes, and may permit a positive diagnosis 24 or more hours earlier than possible by the clinical findings alone. It must be kept in mind that, in awaiting the results of various diagnostic tests, valuable time may be lost during which irreversible changes may occur in the tissues. For this reason it is important to explore surgically, and without delay, any wound in which the presence of clostridial myositis is suspected. The operative procedure recommended may be radical incision and drainage to decompress the muscular and fascial compartments, excision of infected or devitalized groups of musales, or open amputation, depending upon the state and severity of the infection. Aureomycin, Terramycin or Achromycin is the antibiotic of choice for this infection and should be given intravenously or intramuscularly as indicated. If penicillin is used, aqueous penicillin G is recommended in doses of 1,000,000 units every three hours. SUMMARY
Knowledge contributed to surgery from bacteriology and immunology has resulted in significant advances in the prevention, diagnosis and control of infections seen in surgical practice. Although bacteria are the ultimate cause of infections, other important factors often determine the actual development of the infection and contribute to its progress. These factors are known and have been discussed. The principal advances in the control of infections made in the past 12 years have resulted from our acquired knowledge of the antibiotic agents, which knowledge has permitted their safe clinical use. Experience has shown that antibiotic agents are used most effectively in conjunction with indicated surgical procedures, and that the success of their use depends upon the surgeon's observance of certain established principles. These, also, have been discussed. The outlook of surgical patients with established infections or operations performed through contaminated fields is now greatly improved. Many of the infections commonly seen in practice can now be controlled by the antibiotics used in conjunction with timed surgical intervention.
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However, the management of individual cases has not been simplified from the surgeon's viewpoint because of the introduction of a large number of problems associated with the use of the newer antibiotic agents. Unfortunately, there are still many surgical infections which have an unknown etiology or which are resistant to any known form of antibacterial therapy.