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Mycobacterium fortuitum epidemics after open-heart surgery
Mycobacterium fortuitum epidemics after
open-heart surgery We present the clinical and epidemiological features of Mycobacterium fortuitum epidemics involving 19 patients who underwent open-heart surgery. The source of the infection could not be identified. However, bone wax and homografts utilized at that time have been suspected. The infected patients responded poorly to antibiotic management and their courses in most cases were influenced benefically by total sternectomy and transplantation of the omentum into the mediastinum. The emergence of M. fortuitum may represent an aggressive bacterial strain resistant to presently used broad-spectrum antibiotic drugs.
F. Robicsek, M.D., H. K. Daugherty, M.D., J. W. Cook, M.D., 1. G. Selle, M.D., T. N. Masters, Ph.D., P. R. O'Bar, M.D., C. R. Fernandez, M.D., C. U. Mauney, M.D., and D. M. Calhoun, M.D., Charlotte, N. C.
Since Julian I first described the median sternal incision as an approach to the mediastinal structures in open-heart surgery, sternomediastinitis has remained a dreaded, but fortunately infrequent, complication of cardiotomies. 2-10 In a number of published reports, the incidence of sternal infections has ranged from 0.5 to 5 percent.v 6. 7, 11 In a review of 2,594 cases, Culliford P' reported 39 sternal or costochondral infections. To forestall the occurrence of this disease, most surgeons utilize, heavy antibiotic coverage along with strict aseptic technique. 5, 10, 13. 14 Although antibiotics probably prevent a number of infections in these patients whose mediastinum and heart are open for hours and whose blood is pumped through yards of plastic pipelines during the operation, it may also contribute to the emergence of new, aggressive bacterial and fungal strains resistant to our presently used broadspectrum antibiotic drugs. L 10. 14-16 In the month of March, 1976, our cardiovascular unit was invaded by an unusual strain of bacteria, Mycobacterium fortuitum (chelonei), which caused severe sternal osteomyelitis in 19 of our patients. Since then, a similar outbreak occurred in two other large centers, and it is our belief that our profession has not From the Department of Thoracic and Cardiovascular Surgery, Charlotte Memorial Hospital and Medical Center, and The Heineman Medical Research Center, Charlotte, N. C. Received for publication May 19, 1977. Accepted for publication Aug. 5,1977. Address for reprints: Francis Robicsek, M.D., The Sanger Clinic, 1960 Randolph Rd., Charlotte, N. C. 28207.
heard the last of this new enemy. Because there was no precedence for such an epidemic, and because of several unusual clinical and microbiological features of this type of infection, we had considerable difficulties with both its recognition and treatment. For the same reasons, we thought it worthwhile to present our experiences to the profession.
The location Charlotte Memorial Hospital of Charlotte, North Caroline, is a teaching community hospital of 850 beds. Its Department of Thoracic and Cardiovascular Surgery has an average daily bed census of 60 and performs an average of two open-heart operations each day in two operating rooms. In these procedures, four attending surgeons, an identical number of residents, and (if we include the staff of the cardiac recovery unit) 72 auxiliary personnel are involved. The facilities are modern, and the rules of asepsis are enforced.
The beginning During the last 2 weeks of March and in early April, 1976, a larger than usual number of patients were observed with and treated for draining sternal wounds. These cases were characterized by the following features: The wound drainage appeared late, usually 2 to 3 weeks after the operation and in most cases several weeks after the patient had been discharged from the hospital. The patients in general did not appear ill. They had 91
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Fig. 1. A, The mediastinum after excision of the sternum and costal cartilages. B, The pedicle omental graft in place. no, or only minimal, elevation of temperature and there was only slight redness and moderate tenderness in the area of the surgical incision. The drainage was watery rather than purulent and resembled that of fat necrosis sometimes seen in abdominal incisions. The infection occurred exclusively in patients who underwent heart surgery with cardiopulmonary bypass. It was limited to the anterior chest wound only and did not involve the groin or leg incisions. Most of these patients were followed by the different surgeons in their offices, with treatment generally consisting of wound care and in some cases administration of broad-range antibiotics. The general condition of these patients remained good, their number relatively small (a total of eight on April 15) compared to the large number of patients who had had open-heart surgery (and even those were about equally distributed among four surgeons seeing patients on different occasions), and the cultures taken from the wounds were negative. The problem was noted but was not regarded as serious. Because of the unusually large number of "draining" wounds, however, simultaneous cultures were taken from the hands of the operating room personnel and the surgeons. They did not show the
presence of pathogens. Some minor changes in the surgical technique were introduced, such as limiting the use of cautery and prolonged scrubbing of the patients' skin with iodine preparations.
Further developments During the last 2 weeks of April, because of lack of healing , several patients were readmitted to the hospital. The number reached six on April 28. The wound cultures, with one exception, which showed Staphylococcus aureus, still were reported as showing "no growth" or "normal ski n flora." At that date , the entire prevailing situation was reevaluated . Without coming to any definite conclusion with regard to the causative agent , and despite negative wound cultures, we decided to isolate all patients with draining wounds, suspend surgery for 4 days, and conduct a general "clean-up" of the operating and cardiac recovery areas. The walls were repainted, all sutures and disposable material were cultured (and found to be sterile) and discarded , and the floors were scrubbed with disinfectants. In this process, besides the surgeons, the operating room personnel, and the Hospital Infection Control Committee, already active in managing the problem, two specialists in infectious disease,
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members of the Hospital staff, also were asked to participate . They also contributed thereafter in further studies and patient management. From that date, May I, no new cases of draining wounds were observed.
The full evolution of the epidemic Although after this' 'clean-up" no new infections occurred, I3 patients, in addition to the six already in the hospital, were readmitted. Their wounds drained material which was thin, watery, and nonodorous. The exposed tissue was edematous and covered with pale, unhealthy looking granulation. The infection in all cases involved the sternum itself. All patients were isolated and were treated with opening of the incisions, debridement , Chlorpactin irrigation, and broadspectrum antibiotics. They all remained in relatively good condition with the exception of one patient who was in heart failure, but their wounds showed little , if any, healing tendency . On May 3 , in a sample obtained from an unopened wound , the bacteriologist was able to identify a strain of acid-fast bacillus, which on further study proved to be Mycobacteriumfortuitum (chelonei). During the following 48 hours, the same pathogen was identified in three additional patients, and during the upcoming week, in all 19. All heart surgical procedures were discontinued , and the two operating rooms used for these operations and the cardiac recovery unit were quarantined. Patients awaiting heart surgery either were sent home or referred to other institutions. Assistance was requested from the Department of Epidemiology, North Carolina School of Public Health , and from the Federal Communicable Disease Center in Atlanta, Georgia.
Further clinical course The detailed epidemiological investigation and the bacteriolog ical aspects of these patients will be provided in a separate publication." The clinical management of the 19 patients, who filled an entire isolated floor of the hospital, became a formidable task. In only three of them was the wound problem regarded as "moderate," in 12 it was considered " severe," and in four, " critical. " The local treatment of the wounds consisted of repeated, extensive debridement and irrigation with Chlorpactin and later with hydrogen peroxide. Erythromycin , kanamycin, and rifampin, the antibiotics toward which the invading bacillus showed partial in vitro sensitivity, were administered and general supportive management was given. Three of the patients were on the respirator for pro-
Fig. 2. M. fortuitum abscess in the mediastinum.
longed periods , and one of them required dialy sis. Nine were returned to the operating room one or more times to remove bone sequestra and to open pockets of infection . Of the 19 patients, four died in the first 3 months after operation. One, a 40-year old man who had undergone triple valve surgery, died of cardiorespiratory failure after separation and nonunion of the sternal suture line. The second patient, a middle-aged woman who had had the mitral valve replaced, died of generalized Mycobacterium septicemia and bilateral bronchopneumonia. Two patients, both of them middleaged men who had had aortic valve surgery, died because of secondary hemorrhage from the aortic cannulation site and from the aortotomy suture line , respectively. These two patients were reoperated upon: One died on the operating table because of uncontrollable hemorrhage; the other survived the operation only to die of exsanguination several days later.
Surgical management The 15 survivors (14 patients with coronary artery grafts and one with a ventricular septal defect) were treated with antibiotics and repeated wound debridements . In three of the patients the wound healed completely, and they became asymptomatic. They are now regarded as cured.
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Fig. 3. Patient 4 months after total sternectomy. The wound also healed in a fourth patient (the one with an interventricular septal defect); however, she continued to exhibit temperature elevation, malaise, weight loss , and bilateral pulmonary infiltrates. Blood culture revealed invasion of M . fortuitum. The incision was explored , the sternum, which contained several "cold" abscesses ," was removed, and the mediastinum was drained . Despite these measures, she continued to be in a septic condition and died of uncontrollable Mycobacterium septicemia 3 weeks later. Six of the remaining II patients underwent total sternectomy . The operation was performed in the following manner: The incision was made in the axis of the sternum and the fistulous skin scar of the previous heart operation was excised. The pectoralis muscles were detached from the sternum on both sides, dissected off the bony chest wall and, in continuity with the skin, retracted laterally. The sternum was slowly and very carefully dissected free from the underlying mediastinal structures and, piece-by-piece, completely removed together with the medial half of the costal cartilages. All patients had cold abscesses in the sternum and the retrosternal area . The dissection was carried as close to the sternum as possible, and no efforts were made to identify the mediastinal structures underneath. Similarly, no effort was made to remove radically the base of some of the retrosternal abscesses, which was com-
posed of aortic wall, saphenous grafts, and other structures. The exposed mediastinum was covered with an omental flap brought up through a small midline laparotomy incision as recommended by Lee and associates.!" For the sternum to be removed safely, one or both of the pleural cavities had to be entered during the procedure. They were drained through intercostal tubes. Additional silicone tubes were inserted under the adequately mobilized muscle-skin flaps and were connected to suction. The incision then was closed in two layers with interrupted sutures of catgut and silk . The postoperative course of the six surgically treated patients was unexpected smooth. Neither a flail chest nor any other respiratory difficulty developed in any of them, and except for some moderate serous discharge from the upper corner of some of the incisions, their wound healing was smooth. All were discharged within 2 weeks after the procedure. In about 6 to 8 weeks the anterior chest wall became firm, and now all have resumed normal activities. Only one required additional excision of a postoperative fistula because of persisting infection. The remaining five patients are still being treated conservatively for the sternum infection. Two of them are in such poor general condition that an extensive surgical procedure is inadvisable at the present time , and two are scheduled for sternectomy in the near future. One patient refuses any further surgical procedure .
Conclusions In evaluating the events connected with the M. fortuitum epidemics, we first shall address ourselves to the possible cause of the infection. It is most frustrating that even after months of painstaking investigation we could not identify with certainty the source or the cause . All we know for sure is that , whatever it was, it was eliminated on April 29 . However, we cannot help but speculate and be constantly reminded of several points: Despite the fact that the same people , often in the same rooms, operated upon a large number of patients with a multitude of clinical conditions, the infections developed only in patients who underwent heart surgery with cardiopulmonary bypass. The infection in all patients was initially or permanently localized to the sternum. Therefore, it is logical to suppose that (I) the source of infection was probably material used in surgery rather than personnel; (2) this material was used exclusively in heart operations; (3) considering the frequency of infected cases (during one week in April
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eight out of 10 operated patients later manifested M. fortuitum infection), the infection was massive; (4) the infectious material probably was introduced directly into the sternum itself, such as is done with bone wax. Another theory on how M. chelonei may have been introduced into the operating room rests on a recent report of Laskowski and associates;'? in which they describe retrieving the organism from porcine heterografts. The brand of heterografts which was implicated as the carrier was indeed used in our operating rooms during the time of the epidemics. Although only some of the patients with sternal infection had implanted heterografts, one may theorize that the organism was released in the operating room from the heterograft as the container and the preserving fluid were discarded, settled in some specific spot, and became thereafter the source of infection. Another possibility also exists, namely, that during the critical period all of our patients who were operated upon for a variety of cardiac, pulmonary, and vascular ailments were exposed to temporary bloodstream invasion by mycobacteria. However, the invading agent settled permanently only in patients having heart surgery, the ones in whom a large spongious bone was exposed as the locus minoris resistentiae. The theory of a contaminated batch of bone wax as the source appears to be more plausible. With regard to the treatment of infections, we may conclude the following: I. Antibiotic management of our patients proved to be rather ineffective and, as far as we can tell, influenced the clinical course of our patients little if any. 2. Contrary to this, local management of the wound in M. fortuitum infections appears to be of primary importance. It is mandatory that, after the establishment of the bacterial diagnosis, the sternotomy incision be opened in its entire length. After the sternum is stabilized, all wire sutures should be removed and all unhealthy looking granulation tissue should be curetted out. Irrigation with hydrogen peroxide proved especiall y useful. 3. It is important that the wound be kept open for prolonged periods; otherwise the infection either may extend into the depth of the mediastinum or it may invade the bloodstream. 4. These measures may keep the infection under control but in most patients will not eliminate it. In the majority of cases, total cure of M. fortuitum infection after open-heart surgery can be achieved only by complete excision of the sternum and the neighboring cartilages.
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Summary We have described the events surrounding the epidemics of M. fortuitum (chelonei) sternum osteomyelitis involving 19 patients who underwent open-heart surgery. The clinical course of these patients indicates that the disease is potentially lethal and that cure can be effected in most cases only by total removal of the sternum and the costal cartilages. We express our gratitude to Drs. Philip C. Hoffman and David W. Fraser from the Communicable Disease Center, Atlanta, Ga., for their valuable help in connection with the problem elaborated in this paper, and to Dr. Michael A. Ibrahim, School of Public Health, University of North Carolina, Chapel Hill, N. C.
2 3
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REFERENCES Julian, O. c., Lopez-Belio, M., Dye, W. S., Javid, H., and Grove, W. J.: The Median Sternal Incision in Intracardiac Surgery With Extracorporeal Circulation: A General Evaluation of its Use in Heart Surgery, Surgery 42: 753, 1957. Amoury, R. A.: Sternal Infection, in Norman, J. C.; editor: Cardiac Surgery, New York, 1967, AppletonCentury-Crofts, p. 491. Bryant, L. R., Spencer, F. C., and Trinkle, 1. K.: Treatment of Median Sternotomy Infection by Mediastinal Irrigation With an Antibiotic Solution, Ann. Surg. 169: 914, 1969. Cheanvechai, c., Traviano, F., and Effler, D. B.: Treatment of Infected Sternal Wounds, Cleve. Clin. Q. 39: 43, 1972. Engelman, R. M., Williams, D., Gouge, T. H., Chase, R. M., Jr., Falk, E. A., Boyd, A. D., and Reed, G. E.: Mediastinitis Following Open-Heart Surgery, Arch. Surg. 107: 772, 1973. Hoffman, P. c., Fraser, D. W., Robicsek, F., Hattler, B. G., Jr., O'Bar, P., and Mauney, C. U.: Outbreaks of Wound Infections Due to the Mycobacterium fortuitum Complex. To be published. Jimenez-Martinez, M., Arguero-Sanchez, R., PerezAlvarez, J. 1., and Mina Castaneda, P.: Anterior Mediastinitis as a Complication of Median Sternotomy Incisions: Diagnosticand Surgical Considerations, Surgery 67: 929, 1970. Nelson, J. C.; and Nelson, R. M.: The Incidence of Hospital Wound Infection in Thoracotomies, J. THORAc. CARDIOVASC. SURG. 54: 586, 1967. Webb, W. R., and Burford, T. H.: Current Concepts of the Management of Acute Mediastinitis, Am. Surg. 28: 309, 1962. Williams, C. D., Cunningham, J. N., Falk, E. A., Isom, O. W., Chase, R. N., and Spencer, F. C.: Chronic Infection of the Costal Cartilages After Thoracic Surgical Procedures, 1. THORAc. CARDIOVASC. SURG. 66: 592, 1973. Murray, I. G., Buckley, H. R., and Turner, G. c. Pre-
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12
13
14
15
16
17
cipitins to Candida Species After Open-Heart Surgery, Antonie van Leeuwenhoek, 35: E 17, 1969. Culliford, A. T., Cunningham, 1. N., Jr., Zeff, R. H., Isom, O. W., Teiko, P., and Spencer, F. C.: Sternal and Costochondral Infections Following Open-Heart Surgery: A Review of 2,594 Cases, J. Thorac. Cardiovasc. Surg. 72: 714, 1976. Kittle, C. F., and Reed, W. A.: Antibiotics and Extracorporeal Circulation, J. THORAe. CARDIOVASe. SURG. 41: 63, 1960. Sanfelippo, P. M., and Danielson, G. K.: Complications Associated With Median Sternotomy, 1. THoRAe. CARDIOVASe. SURG. 63: 499, 1972. Blakemore, W. S., McGarrity, G. J., Thurer, R. J., Wallace, H. W., MacVaugh, H., III, and Coriell, L. L.: Infection by Air-Borne Bacteria With Cardiopulmonary Bypass, Surgery 70: 830, 1971. Firor, W. B.: Infection Following Open-Heart Surgery With Special Reference to the Role of Prophylactic Antibiotics, J. THORAe. CARDIOV ASe. SURG. 53: 371, 1967. Konig, F.: Die Tuberculose der Thoraxwand und Besonder Beriicksichtigung der Rippentuberculose auf Grund
Klinischer Beobachtung, Arch. Klin. Chir. 79: I, 1906. 18 Lee, A. B., Schimert, G., and Shotkin, S.: Total Excision of the Sternum and Thoracic Pedicle Transposition of the Greater Omentum; Useful Strategems in Managing Severe Mediastinal Infection Following Open-Heart Surgery, Surgery 80: 433, 1976. 19 Laskowski, L. F., Marr, 1. J., Spernoga, J. F., Frank, N. 1., Barner, H. B., Kaiser, G., and Tyras, D. H.: Fastidious Mycobacteria Grown From Porcine ProstheticHeart-Valve Cultures, N. Eng!. J. Med. 297: 101, 1977. 20 Hehrlein, F. W., Herrmann, H., and Kraus, J.: Complications of Median Sternotomy in Cardiovascular Surgery, J. THoRAe. CARDIOVASC. SURG. 13: 390, 1972. 21 Thurer, R. J., Bognalo, D., Vargas, A., Isch, 1. H., and Kaiser, G. A.: The Management of Mediastinal Infection Following Cardiac Surgery, J. THORAC. CARDIOV ASC. SURG. 68: 962, 1974. 22 Wray, T. M., Bryant, R. E., and Killen, D. A.: Sternal Osteomyelitis and Costochondritis After Median Sternotomy, J. THORAe. CARDlOVASe. SURG. 65: 227,1973. 23 Wilensky, A. 0., and Samuels, S. S.: Osteomyelitis of the Sternum, Ann. Surg. 83: 206, 1926.
Information for authors
Most of the provisions of the Copyright Act of 1976 became effective on January I, 1978. Therefore, all manuscripts must be accompanied by the following statement, signed by each author: "The undersigned author(s) transfers all copyright ownership of the manuscript entitled (title of article) to The C. V. Mosby Company in the event the work is published. The author(s) warrants that the article is original, is not under consideration by another journal, and has not been previously published. " Authors will be consulted, when possible, regarding republication of their material.
open-heart surgery We present the clinical and epidemiological features of Mycobacterium fortuitum epidemics involving 19 patients who underwent open-heart surgery. The source of the infection could not be identified. However, bone wax and homografts utilized at that time have been suspected. The infected patients responded poorly to antibiotic management and their courses in most cases were influenced benefically by total sternectomy and transplantation of the omentum into the mediastinum. The emergence of M. fortuitum may represent an aggressive bacterial strain resistant to presently used broad-spectrum antibiotic drugs.
F. Robicsek, M.D., H. K. Daugherty, M.D., J. W. Cook, M.D., 1. G. Selle, M.D., T. N. Masters, Ph.D., P. R. O'Bar, M.D., C. R. Fernandez, M.D., C. U. Mauney, M.D., and D. M. Calhoun, M.D., Charlotte, N. C.
Since Julian I first described the median sternal incision as an approach to the mediastinal structures in open-heart surgery, sternomediastinitis has remained a dreaded, but fortunately infrequent, complication of cardiotomies. 2-10 In a number of published reports, the incidence of sternal infections has ranged from 0.5 to 5 percent.v 6. 7, 11 In a review of 2,594 cases, Culliford P' reported 39 sternal or costochondral infections. To forestall the occurrence of this disease, most surgeons utilize, heavy antibiotic coverage along with strict aseptic technique. 5, 10, 13. 14 Although antibiotics probably prevent a number of infections in these patients whose mediastinum and heart are open for hours and whose blood is pumped through yards of plastic pipelines during the operation, it may also contribute to the emergence of new, aggressive bacterial and fungal strains resistant to our presently used broadspectrum antibiotic drugs. L 10. 14-16 In the month of March, 1976, our cardiovascular unit was invaded by an unusual strain of bacteria, Mycobacterium fortuitum (chelonei), which caused severe sternal osteomyelitis in 19 of our patients. Since then, a similar outbreak occurred in two other large centers, and it is our belief that our profession has not From the Department of Thoracic and Cardiovascular Surgery, Charlotte Memorial Hospital and Medical Center, and The Heineman Medical Research Center, Charlotte, N. C. Received for publication May 19, 1977. Accepted for publication Aug. 5,1977. Address for reprints: Francis Robicsek, M.D., The Sanger Clinic, 1960 Randolph Rd., Charlotte, N. C. 28207.
heard the last of this new enemy. Because there was no precedence for such an epidemic, and because of several unusual clinical and microbiological features of this type of infection, we had considerable difficulties with both its recognition and treatment. For the same reasons, we thought it worthwhile to present our experiences to the profession.
The location Charlotte Memorial Hospital of Charlotte, North Caroline, is a teaching community hospital of 850 beds. Its Department of Thoracic and Cardiovascular Surgery has an average daily bed census of 60 and performs an average of two open-heart operations each day in two operating rooms. In these procedures, four attending surgeons, an identical number of residents, and (if we include the staff of the cardiac recovery unit) 72 auxiliary personnel are involved. The facilities are modern, and the rules of asepsis are enforced.
The beginning During the last 2 weeks of March and in early April, 1976, a larger than usual number of patients were observed with and treated for draining sternal wounds. These cases were characterized by the following features: The wound drainage appeared late, usually 2 to 3 weeks after the operation and in most cases several weeks after the patient had been discharged from the hospital. The patients in general did not appear ill. They had 91
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Fig. 1. A, The mediastinum after excision of the sternum and costal cartilages. B, The pedicle omental graft in place. no, or only minimal, elevation of temperature and there was only slight redness and moderate tenderness in the area of the surgical incision. The drainage was watery rather than purulent and resembled that of fat necrosis sometimes seen in abdominal incisions. The infection occurred exclusively in patients who underwent heart surgery with cardiopulmonary bypass. It was limited to the anterior chest wound only and did not involve the groin or leg incisions. Most of these patients were followed by the different surgeons in their offices, with treatment generally consisting of wound care and in some cases administration of broad-range antibiotics. The general condition of these patients remained good, their number relatively small (a total of eight on April 15) compared to the large number of patients who had had open-heart surgery (and even those were about equally distributed among four surgeons seeing patients on different occasions), and the cultures taken from the wounds were negative. The problem was noted but was not regarded as serious. Because of the unusually large number of "draining" wounds, however, simultaneous cultures were taken from the hands of the operating room personnel and the surgeons. They did not show the
presence of pathogens. Some minor changes in the surgical technique were introduced, such as limiting the use of cautery and prolonged scrubbing of the patients' skin with iodine preparations.
Further developments During the last 2 weeks of April, because of lack of healing , several patients were readmitted to the hospital. The number reached six on April 28. The wound cultures, with one exception, which showed Staphylococcus aureus, still were reported as showing "no growth" or "normal ski n flora." At that date , the entire prevailing situation was reevaluated . Without coming to any definite conclusion with regard to the causative agent , and despite negative wound cultures, we decided to isolate all patients with draining wounds, suspend surgery for 4 days, and conduct a general "clean-up" of the operating and cardiac recovery areas. The walls were repainted, all sutures and disposable material were cultured (and found to be sterile) and discarded , and the floors were scrubbed with disinfectants. In this process, besides the surgeons, the operating room personnel, and the Hospital Infection Control Committee, already active in managing the problem, two specialists in infectious disease,
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members of the Hospital staff, also were asked to participate . They also contributed thereafter in further studies and patient management. From that date, May I, no new cases of draining wounds were observed.
The full evolution of the epidemic Although after this' 'clean-up" no new infections occurred, I3 patients, in addition to the six already in the hospital, were readmitted. Their wounds drained material which was thin, watery, and nonodorous. The exposed tissue was edematous and covered with pale, unhealthy looking granulation. The infection in all cases involved the sternum itself. All patients were isolated and were treated with opening of the incisions, debridement , Chlorpactin irrigation, and broadspectrum antibiotics. They all remained in relatively good condition with the exception of one patient who was in heart failure, but their wounds showed little , if any, healing tendency . On May 3 , in a sample obtained from an unopened wound , the bacteriologist was able to identify a strain of acid-fast bacillus, which on further study proved to be Mycobacteriumfortuitum (chelonei). During the following 48 hours, the same pathogen was identified in three additional patients, and during the upcoming week, in all 19. All heart surgical procedures were discontinued , and the two operating rooms used for these operations and the cardiac recovery unit were quarantined. Patients awaiting heart surgery either were sent home or referred to other institutions. Assistance was requested from the Department of Epidemiology, North Carolina School of Public Health , and from the Federal Communicable Disease Center in Atlanta, Georgia.
Further clinical course The detailed epidemiological investigation and the bacteriolog ical aspects of these patients will be provided in a separate publication." The clinical management of the 19 patients, who filled an entire isolated floor of the hospital, became a formidable task. In only three of them was the wound problem regarded as "moderate," in 12 it was considered " severe," and in four, " critical. " The local treatment of the wounds consisted of repeated, extensive debridement and irrigation with Chlorpactin and later with hydrogen peroxide. Erythromycin , kanamycin, and rifampin, the antibiotics toward which the invading bacillus showed partial in vitro sensitivity, were administered and general supportive management was given. Three of the patients were on the respirator for pro-
Fig. 2. M. fortuitum abscess in the mediastinum.
longed periods , and one of them required dialy sis. Nine were returned to the operating room one or more times to remove bone sequestra and to open pockets of infection . Of the 19 patients, four died in the first 3 months after operation. One, a 40-year old man who had undergone triple valve surgery, died of cardiorespiratory failure after separation and nonunion of the sternal suture line. The second patient, a middle-aged woman who had had the mitral valve replaced, died of generalized Mycobacterium septicemia and bilateral bronchopneumonia. Two patients, both of them middleaged men who had had aortic valve surgery, died because of secondary hemorrhage from the aortic cannulation site and from the aortotomy suture line , respectively. These two patients were reoperated upon: One died on the operating table because of uncontrollable hemorrhage; the other survived the operation only to die of exsanguination several days later.
Surgical management The 15 survivors (14 patients with coronary artery grafts and one with a ventricular septal defect) were treated with antibiotics and repeated wound debridements . In three of the patients the wound healed completely, and they became asymptomatic. They are now regarded as cured.
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Fig. 3. Patient 4 months after total sternectomy. The wound also healed in a fourth patient (the one with an interventricular septal defect); however, she continued to exhibit temperature elevation, malaise, weight loss , and bilateral pulmonary infiltrates. Blood culture revealed invasion of M . fortuitum. The incision was explored , the sternum, which contained several "cold" abscesses ," was removed, and the mediastinum was drained . Despite these measures, she continued to be in a septic condition and died of uncontrollable Mycobacterium septicemia 3 weeks later. Six of the remaining II patients underwent total sternectomy . The operation was performed in the following manner: The incision was made in the axis of the sternum and the fistulous skin scar of the previous heart operation was excised. The pectoralis muscles were detached from the sternum on both sides, dissected off the bony chest wall and, in continuity with the skin, retracted laterally. The sternum was slowly and very carefully dissected free from the underlying mediastinal structures and, piece-by-piece, completely removed together with the medial half of the costal cartilages. All patients had cold abscesses in the sternum and the retrosternal area . The dissection was carried as close to the sternum as possible, and no efforts were made to identify the mediastinal structures underneath. Similarly, no effort was made to remove radically the base of some of the retrosternal abscesses, which was com-
posed of aortic wall, saphenous grafts, and other structures. The exposed mediastinum was covered with an omental flap brought up through a small midline laparotomy incision as recommended by Lee and associates.!" For the sternum to be removed safely, one or both of the pleural cavities had to be entered during the procedure. They were drained through intercostal tubes. Additional silicone tubes were inserted under the adequately mobilized muscle-skin flaps and were connected to suction. The incision then was closed in two layers with interrupted sutures of catgut and silk . The postoperative course of the six surgically treated patients was unexpected smooth. Neither a flail chest nor any other respiratory difficulty developed in any of them, and except for some moderate serous discharge from the upper corner of some of the incisions, their wound healing was smooth. All were discharged within 2 weeks after the procedure. In about 6 to 8 weeks the anterior chest wall became firm, and now all have resumed normal activities. Only one required additional excision of a postoperative fistula because of persisting infection. The remaining five patients are still being treated conservatively for the sternum infection. Two of them are in such poor general condition that an extensive surgical procedure is inadvisable at the present time , and two are scheduled for sternectomy in the near future. One patient refuses any further surgical procedure .
Conclusions In evaluating the events connected with the M. fortuitum epidemics, we first shall address ourselves to the possible cause of the infection. It is most frustrating that even after months of painstaking investigation we could not identify with certainty the source or the cause . All we know for sure is that , whatever it was, it was eliminated on April 29 . However, we cannot help but speculate and be constantly reminded of several points: Despite the fact that the same people , often in the same rooms, operated upon a large number of patients with a multitude of clinical conditions, the infections developed only in patients who underwent heart surgery with cardiopulmonary bypass. The infection in all patients was initially or permanently localized to the sternum. Therefore, it is logical to suppose that (I) the source of infection was probably material used in surgery rather than personnel; (2) this material was used exclusively in heart operations; (3) considering the frequency of infected cases (during one week in April
Volume 75 Number 1
January, 1978
eight out of 10 operated patients later manifested M. fortuitum infection), the infection was massive; (4) the infectious material probably was introduced directly into the sternum itself, such as is done with bone wax. Another theory on how M. chelonei may have been introduced into the operating room rests on a recent report of Laskowski and associates;'? in which they describe retrieving the organism from porcine heterografts. The brand of heterografts which was implicated as the carrier was indeed used in our operating rooms during the time of the epidemics. Although only some of the patients with sternal infection had implanted heterografts, one may theorize that the organism was released in the operating room from the heterograft as the container and the preserving fluid were discarded, settled in some specific spot, and became thereafter the source of infection. Another possibility also exists, namely, that during the critical period all of our patients who were operated upon for a variety of cardiac, pulmonary, and vascular ailments were exposed to temporary bloodstream invasion by mycobacteria. However, the invading agent settled permanently only in patients having heart surgery, the ones in whom a large spongious bone was exposed as the locus minoris resistentiae. The theory of a contaminated batch of bone wax as the source appears to be more plausible. With regard to the treatment of infections, we may conclude the following: I. Antibiotic management of our patients proved to be rather ineffective and, as far as we can tell, influenced the clinical course of our patients little if any. 2. Contrary to this, local management of the wound in M. fortuitum infections appears to be of primary importance. It is mandatory that, after the establishment of the bacterial diagnosis, the sternotomy incision be opened in its entire length. After the sternum is stabilized, all wire sutures should be removed and all unhealthy looking granulation tissue should be curetted out. Irrigation with hydrogen peroxide proved especiall y useful. 3. It is important that the wound be kept open for prolonged periods; otherwise the infection either may extend into the depth of the mediastinum or it may invade the bloodstream. 4. These measures may keep the infection under control but in most patients will not eliminate it. In the majority of cases, total cure of M. fortuitum infection after open-heart surgery can be achieved only by complete excision of the sternum and the neighboring cartilages.
M. fortuitum epidemics after open-heart surgery
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Summary We have described the events surrounding the epidemics of M. fortuitum (chelonei) sternum osteomyelitis involving 19 patients who underwent open-heart surgery. The clinical course of these patients indicates that the disease is potentially lethal and that cure can be effected in most cases only by total removal of the sternum and the costal cartilages. We express our gratitude to Drs. Philip C. Hoffman and David W. Fraser from the Communicable Disease Center, Atlanta, Ga., for their valuable help in connection with the problem elaborated in this paper, and to Dr. Michael A. Ibrahim, School of Public Health, University of North Carolina, Chapel Hill, N. C.
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REFERENCES Julian, O. c., Lopez-Belio, M., Dye, W. S., Javid, H., and Grove, W. J.: The Median Sternal Incision in Intracardiac Surgery With Extracorporeal Circulation: A General Evaluation of its Use in Heart Surgery, Surgery 42: 753, 1957. Amoury, R. A.: Sternal Infection, in Norman, J. C.; editor: Cardiac Surgery, New York, 1967, AppletonCentury-Crofts, p. 491. Bryant, L. R., Spencer, F. C., and Trinkle, 1. K.: Treatment of Median Sternotomy Infection by Mediastinal Irrigation With an Antibiotic Solution, Ann. Surg. 169: 914, 1969. Cheanvechai, c., Traviano, F., and Effler, D. B.: Treatment of Infected Sternal Wounds, Cleve. Clin. Q. 39: 43, 1972. Engelman, R. M., Williams, D., Gouge, T. H., Chase, R. M., Jr., Falk, E. A., Boyd, A. D., and Reed, G. E.: Mediastinitis Following Open-Heart Surgery, Arch. Surg. 107: 772, 1973. Hoffman, P. c., Fraser, D. W., Robicsek, F., Hattler, B. G., Jr., O'Bar, P., and Mauney, C. U.: Outbreaks of Wound Infections Due to the Mycobacterium fortuitum Complex. To be published. Jimenez-Martinez, M., Arguero-Sanchez, R., PerezAlvarez, J. 1., and Mina Castaneda, P.: Anterior Mediastinitis as a Complication of Median Sternotomy Incisions: Diagnosticand Surgical Considerations, Surgery 67: 929, 1970. Nelson, J. C.; and Nelson, R. M.: The Incidence of Hospital Wound Infection in Thoracotomies, J. THORAc. CARDIOVASC. SURG. 54: 586, 1967. Webb, W. R., and Burford, T. H.: Current Concepts of the Management of Acute Mediastinitis, Am. Surg. 28: 309, 1962. Williams, C. D., Cunningham, J. N., Falk, E. A., Isom, O. W., Chase, R. N., and Spencer, F. C.: Chronic Infection of the Costal Cartilages After Thoracic Surgical Procedures, 1. THORAc. CARDIOVASC. SURG. 66: 592, 1973. Murray, I. G., Buckley, H. R., and Turner, G. c. Pre-
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cipitins to Candida Species After Open-Heart Surgery, Antonie van Leeuwenhoek, 35: E 17, 1969. Culliford, A. T., Cunningham, 1. N., Jr., Zeff, R. H., Isom, O. W., Teiko, P., and Spencer, F. C.: Sternal and Costochondral Infections Following Open-Heart Surgery: A Review of 2,594 Cases, J. Thorac. Cardiovasc. Surg. 72: 714, 1976. Kittle, C. F., and Reed, W. A.: Antibiotics and Extracorporeal Circulation, J. THORAe. CARDIOVASe. SURG. 41: 63, 1960. Sanfelippo, P. M., and Danielson, G. K.: Complications Associated With Median Sternotomy, 1. THoRAe. CARDIOVASe. SURG. 63: 499, 1972. Blakemore, W. S., McGarrity, G. J., Thurer, R. J., Wallace, H. W., MacVaugh, H., III, and Coriell, L. L.: Infection by Air-Borne Bacteria With Cardiopulmonary Bypass, Surgery 70: 830, 1971. Firor, W. B.: Infection Following Open-Heart Surgery With Special Reference to the Role of Prophylactic Antibiotics, J. THORAe. CARDIOV ASe. SURG. 53: 371, 1967. Konig, F.: Die Tuberculose der Thoraxwand und Besonder Beriicksichtigung der Rippentuberculose auf Grund
Klinischer Beobachtung, Arch. Klin. Chir. 79: I, 1906. 18 Lee, A. B., Schimert, G., and Shotkin, S.: Total Excision of the Sternum and Thoracic Pedicle Transposition of the Greater Omentum; Useful Strategems in Managing Severe Mediastinal Infection Following Open-Heart Surgery, Surgery 80: 433, 1976. 19 Laskowski, L. F., Marr, 1. J., Spernoga, J. F., Frank, N. 1., Barner, H. B., Kaiser, G., and Tyras, D. H.: Fastidious Mycobacteria Grown From Porcine ProstheticHeart-Valve Cultures, N. Eng!. J. Med. 297: 101, 1977. 20 Hehrlein, F. W., Herrmann, H., and Kraus, J.: Complications of Median Sternotomy in Cardiovascular Surgery, J. THoRAe. CARDIOVASC. SURG. 13: 390, 1972. 21 Thurer, R. J., Bognalo, D., Vargas, A., Isch, 1. H., and Kaiser, G. A.: The Management of Mediastinal Infection Following Cardiac Surgery, J. THORAC. CARDIOV ASC. SURG. 68: 962, 1974. 22 Wray, T. M., Bryant, R. E., and Killen, D. A.: Sternal Osteomyelitis and Costochondritis After Median Sternotomy, J. THORAe. CARDlOVASe. SURG. 65: 227,1973. 23 Wilensky, A. 0., and Samuels, S. S.: Osteomyelitis of the Sternum, Ann. Surg. 83: 206, 1926.
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Most of the provisions of the Copyright Act of 1976 became effective on January I, 1978. Therefore, all manuscripts must be accompanied by the following statement, signed by each author: "The undersigned author(s) transfers all copyright ownership of the manuscript entitled (title of article) to The C. V. Mosby Company in the event the work is published. The author(s) warrants that the article is original, is not under consideration by another journal, and has not been previously published. " Authors will be consulted, when possible, regarding republication of their material.