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Nosocomial infections in a Brazilian Burn Unit
Burns 32 (2006) 477–481 www.elsevier.com/locate/burns
Nosocomial infections in a Brazilian Burn Unit Jefferson Lessa Soares de Macedo a,*, Joa˜o Barberino Santos b a
Hospital Regional da Asa Norte, Secretaria de Sau´de do Distrito Federal, SMHN, AE 1, Bloco A, 70000-000, Brası´lia, DF, Brasil b Nu´cleo de Medicina Tropical, Unıversidade de Brası´lia, Brası´lia, DF, Brasil
Abstract In 1-year prospective study, bacterial and fungal infections presenting in burned patients were registered. Two-hundred and seventy-eight patients were included. The median total body surface area burned was 14% (range 1–100%). The median length of hospital stay was 12 days (range 1–86 days). Eighty-six patients had in all 148 infections. Seventy-two bloodstream infections (BSI) occurred in 57 patients; most common microorganisms were coagulase-negative staphylococci and methicillin-sensitive Staphylococcus aureus. Forty-nine (17.6%) patients had burn wound infections and 18 (6.5%) had pneumonia. Antibiotics were given to only 30% of the burn patients. Overall mortality rate was 5.0% (14/278). The database can be used to evaluate the effects of changes in burn treatment, staffing and design of burn units, and antimicrobial resistance development in relation to antibiotic usage. # 2005 Elsevier Ltd and ISBI. All rights reserved. Keywords: Nosocomial infections; Bloodstream infection; Burns
1. Introduction Infection is the most common cause of death following burn. Burn victims are obviously at high risk for nosocomial infection due to the nature of the burn injury itself. The burn wound consisting of moist necrotic tissue represents an ideal culture medium for a wide variety of microorganisms. Furthermore, immunocompromising effects of burns, prolonged hospital stays, and intensive diagnostic and therapeutic procedures contribute significantly to nosocomial infections in these patients. Bacterial infections in burn patients are widely known. The time-related changes in the predominant flora of the burn wound from gram-positive to gram-negative recapitulate the history of burn wound infection [1,2]. Infection rates in burn patients have been rarely reported [3–7]. A study conducted in Brazil which included a considerable number of infections occurring over 7 years showed that bloodstream infection was the most common infection in contrast to other countries in which there * Corresponding author. Tel.: +55 61 3245 6974; fax: +55 61 327 8415. E-mail address: [email protected] (J.L.S. de Macedo). 0305-4179/$30.00 # 2005 Elsevier Ltd and ISBI. All rights reserved. doi:10.1016/j.burns.2005.11.012
was a predominance of pneumonia [4,7] or wound infection [3,6]. The gains of established infection control measures are now being felt in the developed countries with a purposebuilt burns unit. However, in developing countries, establishing such measures is hindered by poverty, ignorance, poor management and lack of personnel [8]. In this prospective study, we describe the results from one year of registration of infection in a consecutive series of burn patients.
2. Materials and methods Burn patients consecutively admitted to the Burn Unit of Hospital Regional da Asa Norte during 2004 were included in this prospective study. The patients were followed to discharge or death. The total body surface area burned (TBSAB) was calculated by Lund & Bowder chart, adding percentages of dermal and subdermal burns [9]. Since 1980, patients having partial skin thickness burns covering less than 25% of the body surface area, were not
478
J.L.S. de Macedo, J.B. Santos / Burns 32 (2006) 477–481
generally admitted to the Burns Unit if they were adults, or less than 10% if they were children. Patients with full skin thickness burns of small extent (5% of the body surface area), were also treated as outpatients until the wound was ready for excision and grafting by members of plastic surgery team. Commonly admission to the Burns Unit only occurred with severely burned patients (>25–30% of the body surface area). At direct patient contact a protective gown and disposable gloves were used. Hands were washed with conventional soap when necessary, and disinfected with 70% ethanol/ glycerol before and after patient contact. Fluid replacement was given according to a modified Parkland formula [8]. Plasma was given from the second day. Central venous catheters were placed in the subclavian or femoral vein at the discretion of the anesthetist. The catheters were removed on clinical grounds: no further indication, mechanical failure or suspected catheter infection. Catheters were not changed routinely. Early excision and skin grafting was performed within the first 5 days in full thickness burns when the patients condition permitted. All catheter tips were cultured when removed. On suspicion of blood stream infection, two to three sets of blood cultures were drawn by syringe from a peripheral vein and one culture from any suspected focus of infection. Microbial cultures were processed according to current methods. The bacteriological isolation was carried out in the microbiology laboratory of the Hospital Regional da Asa Norte, Brası´lia. The swabs were dipped in Stuart´s transport medium then plated on blood agar, chocolate agar, MacConkey, and Sabouraud´s dextrose agar media (Difco). After incubation for 18–48 h at 37 8C, the isolates were identified using conventional protocol. Afterwards, the sensitivity to the antibiotics was accomplished by automated method bioMe`rieux Vitek. The confirmation of precision and accuracy of the procedures to evaluate the antimicrobial susceptibility was made using ATCC (American Type Culture Collection) standard strains. When isolated Staphylococcus aureus oxacillin resistant, Acinetobacter sp and Pseudomonas aeruginosa multiresistant were confirmed by disc, by agar diffusion method according to the rules established by NCCLS [10]. Fungal cultures were obtained on Sabouraud dextrose agar (Difco) and on ‘‘mycogel’’ agar (Oxoid) at 378 and observed daily for 20 days. The characterization of fungi was done by the germ tube test, morphological examination and automated method Vitek YBC yeast identification system (bioMe`rieux Vitek, Inc., MI, USA) [11]. However, antibiotic sensitivity of fungi can not be done due to technical problems. Infections in all patients, admitted and treated for burns, have been registered prospectively, according to previously defined criteria [3,12]. Prophylactic antimicrobial therapy was not given. All infections were registered, starting at the day of admittance. Any infections manifested during the
management of a burn victim are followed carefully. Only burn wound infections already present on admission were excluded. Infections were grouped in three major classes: bloodstream infection (BSI), pneumonia and burn wound infection. The diagnosis of infection in burn patients is based on clinical and laboratory parameters. The criteria for infections were mainly based on those given by the Center for Disease Control, Atlanta, USA [3,13]. Infection were suspected when a patient showed signs of disorientation, hyperpyrexia or hypothermia, circulatory embarrassment, petechial hemorrhages, black and dark discoloration in a previously clean appearing burn wound, early and rapid eschar separation, bleeding into the subcutaneous tissues, and increasing edema in surrounding areas or leukocytosis in white blood cells counts. If there was any doubt about the diagnosis, a final decision was reached by consensus between the infectious disease consultant (author) and the burn surgeon directly in charge of the patient. Whenever we found positive blood cultures a BSI was registered even if the patient at the same time had pneumonia and/or wound infection, which were also registered. The evaluation of lymphocyte population of patients was performed by the flow cytometer at seven days post burn. The FITC—stained (flouroescein isothiocyanate) lymphocytes emit yellow-green light (at 515 nm, CD4 surface antigen) while the PE—stained (phyoerytrin) lymphocytes emit red-orange light (at 580 nm, CD8 surface antigen). All data were processed with SimulTest IMK Plus software program. Statistical methods used were Fisher’s exact test, Chisquare analysis with Yates´correction and logistic regression analysis. This study was approved by the Ethical Committee of the Secretary of State for Health of Brası´lia, Federal District.
3. Results Two-hundred and seventy-eight patients with burns, consecutively admitted to the Burn Unit of Hospital Regional da Asa Norte during 2004, 86 female and 160 male patients were included in the study. Median age for the 278 patients was 24 years (range 1–82). Median TBSAB was 14% (range 1–100%). One-hundred and fifty-two (54.7%) of the patients had flame injuries, 96 (34.5%) were scald injuries, 25 (9%) electrical injuries and 5 (1.8%) chemical injuries. Seven (3.9%) patients had smoke inhalation injury. Two-hundred and forty-five patients stayed >72 h in the unit. The median length of stay was 12 days (range 1–86 days). Two-hundred and thirty-four patients were admitted on the day of injury and eight had been treated in another hospital before admission. Twenty-eight patients were infected on admission. Of these, all had wound infections.
J.L.S. de Macedo, J.B. Santos / Burns 32 (2006) 477–481
479
Table 1 Comparison between infected and uninfected patients
Patient (no.) Age (years, median, standard deviation) Flame injuries (% patients) TBSAB % (median, standard deviation) total Self-damage (no patients) Length of stay (days, median, standard deviation) Three or more catheters (no patients) Necessity of transfusion (no patients) Multiresistant bacteria in the wound (no patients) Fungi in the wound (no patients) Hemoglobin 9 g/dl (no patients) Serum albumin 2.0 g/dl (no patients) Platelets 100.000 (no patients) Number of CD4+ cells (median, standard deviation) No operation (median, standard deviation) Mortality (no patients)
Fourteen (5.0%) patients died during their stay in the burns unit. Median age for those patients was 37.9 27.1 years. TBSAB was median 47.5 28.6%. Ten patients had signs of severe infections at the time of death. The main contributing factors to death in patients without infection were pulmonary and cardiac failure. Eighty-six patients had in total 148 infections, whereas 192 patients were not infected. Comparison between infected and not infected patients are given in Table 1. One-hundred and forty-eight infections in 278 burn patients is equivalent to an infection ratio of 53.2 infections per 100 patients. Patients with infection were significantly older and had larger burns. Infected patients were submitted to more procedures such as skin grafting. Patients with infections stayed longer in the unit. Furthermore, infected patients needed more frequently catheters and transfusion. The most common laboratory findings of the infected patients were anemia, hypoalbuminemia, thrombocytopenia and lower median number of CD4+ cells (lymphocytes) on first week of stay. The isolation of multiresistant bacteria or fungi in the wound were more likely in infected patients. Fifty-seven of 84 blood-cultured patients (67.9%) had 72 episodes of BSI. Their median age was 25.2 23.1 years. Their median TBSAB was 29.1 22.1%. Their median length of stay was 20.9 3.9 days. The microorganisms causing BSI are listed in Table 2. Coagulase-negative staphylococci (CoNS) were the most common microorganisms causing BSI, and next in frequency were oxacillin sensitive Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The mortality rate for patients with verified and strongly suspected BSI (21%, 12/57) was 20 times greater than for the non septic patients (0.9%, 2/221) (P < 0.0001). Eighteen patients developed pneumonia. Median age was 29 years (range 3–65). Median TBSAB was 27%. The
Infected
Uninfected
P
86 28.3 23.6 69.8 23.1 20.6 11 19.3 11.9 16 50 51 31 50 16 9 361 261 3.2 1.7 13
192 21.5 19.1 50.5 9.0 6.5 4 8.7 5.9 0 30 34 11 29 2 0 553 230 2.1 1.1 1
0.021 0.002 <0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Table 2 Number of micro-organisms that caused bloodstream, wound infection and pneumonia Micro-organisms
Bloodstream
Wound
Pneumonia
Coagulase-negative staphylococci Staphylococcus aureus Pseudomonas aeruginosa Klebsiella pneumoniae Acinetobacter baumannii Enterobacter cloacae Serratia marcescens Escherichia coli Aeromonas hydrophila Enterococcus faecalis Streptococcus pyogenes Cedecea sp. Candida sp.
19 14 5 5 4 3 1 1 1 1 1 0 5
10 12 8 6 2 5 1 1 1 1 0 0 1
2 5 4 3 1 2 1 0 0 0 0 1 0
median length of stay was 25 days. The most common microorganisms causing pneumonia were Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus. Seven of 14 patients died with pneumonia. Forty-nine patients had burn wound infections. Their median age was 30.3 23.8 years. TBSAB was median 17.6 15.6%. Their median length of stay was 21.6 13.1 days. Three hundred and sixty four sampling procedures (surface swabs) were performed from the burn wounds. The microorganisms causing burn wound infection are listed in Table 2. The most frequent organism causing wound infection was oxacillin sensitive Staphylococcus aureus, and next in frequency were Coagulase-negative staphylococci. Eighty-four of the 278 patients (30%) received antibiotics during their stay in the Burn Unit, with a median duration of 14 days. Cefepime amikacin and vancomycin amikacin were the most common antibacterial combinations in empirical therapy.
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4. Discussion Despite advances in the use of topical and parenteral antimicrobial therapy, and the practice of early tangential excision, bacterial infection remains a major problem in the management of burn victims today. Few patients are as susceptible to the development of infections as burn patients. Severe dysfunction of the immune system, a large cutaneous colonization, the possibility of gastrointestinal translocation, a prolonged hospitalization and invasive diagnostic and therapeutic procedures, all contribute to infections. Although any organism is a potential pathogen in burned patients, coagulase-negative staphylococci and S. aureus were the most common pathogens causing infection in our burn unit and was also most common in other reports [2–5]. This is in contrast to some other studies, which report P. aeruginosa as the most predominant organism in burn infection [6,14,15]. Most of the patients with BSI blood isolates were similar to those that colonized/infected the burn wound surface. Thus the main source of BSI in these patients appeared to be the burn wound itself [2]. Antimicrobial therapy can cause severe problems with resistance mainly against cephalosporins and other betalactams. This calls for an urgent institution of an antibiotic policy at local and national levels, amongst other measures to check antibiotic misuse. A strict antibiotic policy is of importance in the control of antibiotic resistance. It is possible to reserve antibiotics for proven infection and to limit the use of broad-spectrum drugs. Therefore, only 30% of the patients admitted to the Burn Unit of Hospital Regional da Asa Norte received antibiotics. The pattern of bacterial sensitivities is subject to frequent modifications. As such frequent assessment and institution of other simple infection control measures like handwashing before and after attending to a patient and restriction of movements of personnel within a burns ward should be carried out. The mortality rate in our study of burn patients is consistent with those reported from other studies [2,3,6]. Infected patients were older, had larger burns, longer stay in hospital, more operations and a larger number of catheters compared to uninfected patients. In agreement, Appelgren et al. [3] showed equivalent comparisons. Furthermore, anemia, hypoalbuminemia, thrombocytopenia and lower median number of CD4+ cells (lymphocytes) on first week of stay were more likely in infected patients. Also, a strong correlation was determined between infectious complications and flame injuries, self-damage and necessity of transfusions. Infection after burns could be accompanied by anemia, thrombocytopenia and lower number of CD4+ T lymphocytes but the mechanisms responsible have not been clearly identified. The possible factors for those laboratory parameters in infected patients could de direct bone marrow
suppression, increased cells destruction, presence of endotoxins, production of autoantibodies, drugs used in the management of the burn patient (penicillin, vancomycin, diazepam morphine, tetanus toxoid), hypersplenism, haemophagocytosis and accelerated consumption [2]. The study showed a rate of infection of 53.2 per 100 patients, whereas other studies showed 38.1 [6], 64 [16], 77 [4] and 90 [7] infections per 100 discharges and deaths. In most of the studies, a higher nosocomial infection rate than observed in this study were found among burned patients. In bigger hospitals, a higher proportion of patients with severe underlying diseases are treated, and more invasive methods are applied. The majority of infections were bloodstream infections, followed by wound infections, which is consistent with other study in Brazil [5]. Otherwise, in Sweden, in a 3-year prospective study, Appelgren et al. [3] registered wound infection as the most common infection, followed by bloodstream infection. As well as, in Turkey, Oncul et al. [6], in 1-year prospective study, observed that the majority of infections were wound infections. Infection rates in burns have been reported to be high, compared to other intensive care units, which have ranged from 15 to 50% of the admissions [3,6]. The burn patient is infection-prone and very contagious when infected. Furthermore, one or more surgical procedures, might also allow burn patient to be colonized with multiresistant organisms. The isolation of multiresistant bacteria or fungi in the wound were more likely in infected patients (P < 0.001). The isolation care in general is important in the prevention of nosocomial transmission of infection. Cross-transmission of multiresistant microorganisms is common in intensive care units. This cross-transmission is an indicator of patient crowing and/or poor compliance with infection control guidelines by patient care personnel. Simple barrier precautions using gloves and gown at patient contact is more effective than elaborate isolation care. At present the main infection control measures in the burn unit are early excision and grafting, improved barrier nursing and regular microbiological analysis of the hospital’s environment and staff. Microbiological surveillance of burn patients when is routinely done helps in learning about the types of organisms and facilitates the choice of antibiotic. Each individual unit varies in its baseline population of microorganisms over time, and generalizations from one unit may have little applicability to others. Measures to prevent and treat infections are essential for the survival of patients with extensive burns and infection is correlated to mortality. Besides, in patients with less extensive burns, infections may increase morbidity and hospital stay. Infection is one indicator of outcome in the field of quality assurance in burn management. Careful surveillance of infection, good isolation techniques and procedure routines, and a restrictive antimicrobial
J.L.S. de Macedo, J.B. Santos / Burns 32 (2006) 477–481
policy can keep antimicrobial resistance rates and infection rates low in infection-prone burn patients.
References [1] Macedo JLS. Imunodepressa˜o no queimado: patogeˆnese e fator de risco para sepse. Revista Brasileira de Queimaduras 2003;3:26–35. [2] Macedo JLS, Rosa SC, Castro C. Sepsis in burned patients. Rev Soc Bras Med Trop 2003;36:647–52. [3] Appelgren P, Bjornhagen V, Bragderyd K, Jonsson CE, Ransjo U. A prospective study of infections in burn patients. Burns 2002;28:39–46. [4] Taylor GD, Kibsey P, Kirkland T, Burroughs E, Tredget E. Predominance of staphylococcal organisms in infections occurring in a burns intensive care unit. Burns 1992;18:332–5. [5] Santucci SG, Gobara S, Santos CR, Fontana C, Levin AS. Infections in a burn intensive care unit: experience of seven years. J Hosp Infect 2003;53:6–13. [6] Oncul O, Yuksel F, Altunay H, Ac¸ikel C, C ¸ eliko¨z B, C ¸ avuslu S. The evaluation of nosocomial infection during 1-year-period in the burn unit of a training hospital in Istanbul, Turkey. Burns 2002;28:738–44. [7] Wurtz R, Karajovic M, Dacumos E, Jovanovic B, Hanumadass M. Nosocomial infections in a burn intensive care unit. Burns 1995;21: 181–4.
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[8] Macedo JLS, Rosa SC. Estudo epidemiolo´gico dos pacientes internados na. Unidade de Queimados: Hospital Regional da Asa Norte, Brası´lia, 1992–1997. Brası´lia Med 2000;37:87–92. [9] Lund CC, Browder NC. The estimation of areas of burns. Surg Gynecol Obstet 1944;79:352–8. [10] National Committee for Clinical Laboratory Standards—Performance Standards for Antimicrobial Susceptibility Testing. National Committee for Clinical Laboratory Standards, Wayne (M100-S9, 1999). [11] Freydiere AM, Guinet R, Boiron P. Yeast identification in the clinical microbiology laboratory: phenotypical methods. Med Mycol 2001;39: 9–33. [12] Cal MA, Cerda E, Garcia-Hierro P, Lorente L, Sanchez-Concheiro M, Diaz C, et al. Pneumonia in patients with severe burns: a classification according to the concept of the carrier state. Chest 2001;119: 1160–5. [13] Garner JS, Jarvis WR, Emori TG, Horan TC, Hughes JM. CDC definitions for nosocomial infections. Am J Infect Control 1988;16:128–40. [14] Sharma S, Hans C. Bacterial infections in burns patients: a 3 year study at RML hospital, Dehli. J Commun Dis 1996;28:101–6. [15] Lari AR, Alaghenhandan R. Nosocomial infections in an Iranian burn care center. Burns 2000;26:737–40. [16] Wenzel RP, Thompson RI, Landry SM. Hospital acquired infections in intensive care units: an overview with emphasis on epidemics. Infect Control 1983;4:371–6.
Nosocomial infections in a Brazilian Burn Unit Jefferson Lessa Soares de Macedo a,*, Joa˜o Barberino Santos b a
Hospital Regional da Asa Norte, Secretaria de Sau´de do Distrito Federal, SMHN, AE 1, Bloco A, 70000-000, Brası´lia, DF, Brasil b Nu´cleo de Medicina Tropical, Unıversidade de Brası´lia, Brası´lia, DF, Brasil
Abstract In 1-year prospective study, bacterial and fungal infections presenting in burned patients were registered. Two-hundred and seventy-eight patients were included. The median total body surface area burned was 14% (range 1–100%). The median length of hospital stay was 12 days (range 1–86 days). Eighty-six patients had in all 148 infections. Seventy-two bloodstream infections (BSI) occurred in 57 patients; most common microorganisms were coagulase-negative staphylococci and methicillin-sensitive Staphylococcus aureus. Forty-nine (17.6%) patients had burn wound infections and 18 (6.5%) had pneumonia. Antibiotics were given to only 30% of the burn patients. Overall mortality rate was 5.0% (14/278). The database can be used to evaluate the effects of changes in burn treatment, staffing and design of burn units, and antimicrobial resistance development in relation to antibiotic usage. # 2005 Elsevier Ltd and ISBI. All rights reserved. Keywords: Nosocomial infections; Bloodstream infection; Burns
1. Introduction Infection is the most common cause of death following burn. Burn victims are obviously at high risk for nosocomial infection due to the nature of the burn injury itself. The burn wound consisting of moist necrotic tissue represents an ideal culture medium for a wide variety of microorganisms. Furthermore, immunocompromising effects of burns, prolonged hospital stays, and intensive diagnostic and therapeutic procedures contribute significantly to nosocomial infections in these patients. Bacterial infections in burn patients are widely known. The time-related changes in the predominant flora of the burn wound from gram-positive to gram-negative recapitulate the history of burn wound infection [1,2]. Infection rates in burn patients have been rarely reported [3–7]. A study conducted in Brazil which included a considerable number of infections occurring over 7 years showed that bloodstream infection was the most common infection in contrast to other countries in which there * Corresponding author. Tel.: +55 61 3245 6974; fax: +55 61 327 8415. E-mail address: [email protected] (J.L.S. de Macedo). 0305-4179/$30.00 # 2005 Elsevier Ltd and ISBI. All rights reserved. doi:10.1016/j.burns.2005.11.012
was a predominance of pneumonia [4,7] or wound infection [3,6]. The gains of established infection control measures are now being felt in the developed countries with a purposebuilt burns unit. However, in developing countries, establishing such measures is hindered by poverty, ignorance, poor management and lack of personnel [8]. In this prospective study, we describe the results from one year of registration of infection in a consecutive series of burn patients.
2. Materials and methods Burn patients consecutively admitted to the Burn Unit of Hospital Regional da Asa Norte during 2004 were included in this prospective study. The patients were followed to discharge or death. The total body surface area burned (TBSAB) was calculated by Lund & Bowder chart, adding percentages of dermal and subdermal burns [9]. Since 1980, patients having partial skin thickness burns covering less than 25% of the body surface area, were not
478
J.L.S. de Macedo, J.B. Santos / Burns 32 (2006) 477–481
generally admitted to the Burns Unit if they were adults, or less than 10% if they were children. Patients with full skin thickness burns of small extent (5% of the body surface area), were also treated as outpatients until the wound was ready for excision and grafting by members of plastic surgery team. Commonly admission to the Burns Unit only occurred with severely burned patients (>25–30% of the body surface area). At direct patient contact a protective gown and disposable gloves were used. Hands were washed with conventional soap when necessary, and disinfected with 70% ethanol/ glycerol before and after patient contact. Fluid replacement was given according to a modified Parkland formula [8]. Plasma was given from the second day. Central venous catheters were placed in the subclavian or femoral vein at the discretion of the anesthetist. The catheters were removed on clinical grounds: no further indication, mechanical failure or suspected catheter infection. Catheters were not changed routinely. Early excision and skin grafting was performed within the first 5 days in full thickness burns when the patients condition permitted. All catheter tips were cultured when removed. On suspicion of blood stream infection, two to three sets of blood cultures were drawn by syringe from a peripheral vein and one culture from any suspected focus of infection. Microbial cultures were processed according to current methods. The bacteriological isolation was carried out in the microbiology laboratory of the Hospital Regional da Asa Norte, Brası´lia. The swabs were dipped in Stuart´s transport medium then plated on blood agar, chocolate agar, MacConkey, and Sabouraud´s dextrose agar media (Difco). After incubation for 18–48 h at 37 8C, the isolates were identified using conventional protocol. Afterwards, the sensitivity to the antibiotics was accomplished by automated method bioMe`rieux Vitek. The confirmation of precision and accuracy of the procedures to evaluate the antimicrobial susceptibility was made using ATCC (American Type Culture Collection) standard strains. When isolated Staphylococcus aureus oxacillin resistant, Acinetobacter sp and Pseudomonas aeruginosa multiresistant were confirmed by disc, by agar diffusion method according to the rules established by NCCLS [10]. Fungal cultures were obtained on Sabouraud dextrose agar (Difco) and on ‘‘mycogel’’ agar (Oxoid) at 378 and observed daily for 20 days. The characterization of fungi was done by the germ tube test, morphological examination and automated method Vitek YBC yeast identification system (bioMe`rieux Vitek, Inc., MI, USA) [11]. However, antibiotic sensitivity of fungi can not be done due to technical problems. Infections in all patients, admitted and treated for burns, have been registered prospectively, according to previously defined criteria [3,12]. Prophylactic antimicrobial therapy was not given. All infections were registered, starting at the day of admittance. Any infections manifested during the
management of a burn victim are followed carefully. Only burn wound infections already present on admission were excluded. Infections were grouped in three major classes: bloodstream infection (BSI), pneumonia and burn wound infection. The diagnosis of infection in burn patients is based on clinical and laboratory parameters. The criteria for infections were mainly based on those given by the Center for Disease Control, Atlanta, USA [3,13]. Infection were suspected when a patient showed signs of disorientation, hyperpyrexia or hypothermia, circulatory embarrassment, petechial hemorrhages, black and dark discoloration in a previously clean appearing burn wound, early and rapid eschar separation, bleeding into the subcutaneous tissues, and increasing edema in surrounding areas or leukocytosis in white blood cells counts. If there was any doubt about the diagnosis, a final decision was reached by consensus between the infectious disease consultant (author) and the burn surgeon directly in charge of the patient. Whenever we found positive blood cultures a BSI was registered even if the patient at the same time had pneumonia and/or wound infection, which were also registered. The evaluation of lymphocyte population of patients was performed by the flow cytometer at seven days post burn. The FITC—stained (flouroescein isothiocyanate) lymphocytes emit yellow-green light (at 515 nm, CD4 surface antigen) while the PE—stained (phyoerytrin) lymphocytes emit red-orange light (at 580 nm, CD8 surface antigen). All data were processed with SimulTest IMK Plus software program. Statistical methods used were Fisher’s exact test, Chisquare analysis with Yates´correction and logistic regression analysis. This study was approved by the Ethical Committee of the Secretary of State for Health of Brası´lia, Federal District.
3. Results Two-hundred and seventy-eight patients with burns, consecutively admitted to the Burn Unit of Hospital Regional da Asa Norte during 2004, 86 female and 160 male patients were included in the study. Median age for the 278 patients was 24 years (range 1–82). Median TBSAB was 14% (range 1–100%). One-hundred and fifty-two (54.7%) of the patients had flame injuries, 96 (34.5%) were scald injuries, 25 (9%) electrical injuries and 5 (1.8%) chemical injuries. Seven (3.9%) patients had smoke inhalation injury. Two-hundred and forty-five patients stayed >72 h in the unit. The median length of stay was 12 days (range 1–86 days). Two-hundred and thirty-four patients were admitted on the day of injury and eight had been treated in another hospital before admission. Twenty-eight patients were infected on admission. Of these, all had wound infections.
J.L.S. de Macedo, J.B. Santos / Burns 32 (2006) 477–481
479
Table 1 Comparison between infected and uninfected patients
Patient (no.) Age (years, median, standard deviation) Flame injuries (% patients) TBSAB % (median, standard deviation) total Self-damage (no patients) Length of stay (days, median, standard deviation) Three or more catheters (no patients) Necessity of transfusion (no patients) Multiresistant bacteria in the wound (no patients) Fungi in the wound (no patients) Hemoglobin 9 g/dl (no patients) Serum albumin 2.0 g/dl (no patients) Platelets 100.000 (no patients) Number of CD4+ cells (median, standard deviation) No operation (median, standard deviation) Mortality (no patients)
Fourteen (5.0%) patients died during their stay in the burns unit. Median age for those patients was 37.9 27.1 years. TBSAB was median 47.5 28.6%. Ten patients had signs of severe infections at the time of death. The main contributing factors to death in patients without infection were pulmonary and cardiac failure. Eighty-six patients had in total 148 infections, whereas 192 patients were not infected. Comparison between infected and not infected patients are given in Table 1. One-hundred and forty-eight infections in 278 burn patients is equivalent to an infection ratio of 53.2 infections per 100 patients. Patients with infection were significantly older and had larger burns. Infected patients were submitted to more procedures such as skin grafting. Patients with infections stayed longer in the unit. Furthermore, infected patients needed more frequently catheters and transfusion. The most common laboratory findings of the infected patients were anemia, hypoalbuminemia, thrombocytopenia and lower median number of CD4+ cells (lymphocytes) on first week of stay. The isolation of multiresistant bacteria or fungi in the wound were more likely in infected patients. Fifty-seven of 84 blood-cultured patients (67.9%) had 72 episodes of BSI. Their median age was 25.2 23.1 years. Their median TBSAB was 29.1 22.1%. Their median length of stay was 20.9 3.9 days. The microorganisms causing BSI are listed in Table 2. Coagulase-negative staphylococci (CoNS) were the most common microorganisms causing BSI, and next in frequency were oxacillin sensitive Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The mortality rate for patients with verified and strongly suspected BSI (21%, 12/57) was 20 times greater than for the non septic patients (0.9%, 2/221) (P < 0.0001). Eighteen patients developed pneumonia. Median age was 29 years (range 3–65). Median TBSAB was 27%. The
Infected
Uninfected
P
86 28.3 23.6 69.8 23.1 20.6 11 19.3 11.9 16 50 51 31 50 16 9 361 261 3.2 1.7 13
192 21.5 19.1 50.5 9.0 6.5 4 8.7 5.9 0 30 34 11 29 2 0 553 230 2.1 1.1 1
0.021 0.002 <0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
Table 2 Number of micro-organisms that caused bloodstream, wound infection and pneumonia Micro-organisms
Bloodstream
Wound
Pneumonia
Coagulase-negative staphylococci Staphylococcus aureus Pseudomonas aeruginosa Klebsiella pneumoniae Acinetobacter baumannii Enterobacter cloacae Serratia marcescens Escherichia coli Aeromonas hydrophila Enterococcus faecalis Streptococcus pyogenes Cedecea sp. Candida sp.
19 14 5 5 4 3 1 1 1 1 1 0 5
10 12 8 6 2 5 1 1 1 1 0 0 1
2 5 4 3 1 2 1 0 0 0 0 1 0
median length of stay was 25 days. The most common microorganisms causing pneumonia were Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus. Seven of 14 patients died with pneumonia. Forty-nine patients had burn wound infections. Their median age was 30.3 23.8 years. TBSAB was median 17.6 15.6%. Their median length of stay was 21.6 13.1 days. Three hundred and sixty four sampling procedures (surface swabs) were performed from the burn wounds. The microorganisms causing burn wound infection are listed in Table 2. The most frequent organism causing wound infection was oxacillin sensitive Staphylococcus aureus, and next in frequency were Coagulase-negative staphylococci. Eighty-four of the 278 patients (30%) received antibiotics during their stay in the Burn Unit, with a median duration of 14 days. Cefepime amikacin and vancomycin amikacin were the most common antibacterial combinations in empirical therapy.
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4. Discussion Despite advances in the use of topical and parenteral antimicrobial therapy, and the practice of early tangential excision, bacterial infection remains a major problem in the management of burn victims today. Few patients are as susceptible to the development of infections as burn patients. Severe dysfunction of the immune system, a large cutaneous colonization, the possibility of gastrointestinal translocation, a prolonged hospitalization and invasive diagnostic and therapeutic procedures, all contribute to infections. Although any organism is a potential pathogen in burned patients, coagulase-negative staphylococci and S. aureus were the most common pathogens causing infection in our burn unit and was also most common in other reports [2–5]. This is in contrast to some other studies, which report P. aeruginosa as the most predominant organism in burn infection [6,14,15]. Most of the patients with BSI blood isolates were similar to those that colonized/infected the burn wound surface. Thus the main source of BSI in these patients appeared to be the burn wound itself [2]. Antimicrobial therapy can cause severe problems with resistance mainly against cephalosporins and other betalactams. This calls for an urgent institution of an antibiotic policy at local and national levels, amongst other measures to check antibiotic misuse. A strict antibiotic policy is of importance in the control of antibiotic resistance. It is possible to reserve antibiotics for proven infection and to limit the use of broad-spectrum drugs. Therefore, only 30% of the patients admitted to the Burn Unit of Hospital Regional da Asa Norte received antibiotics. The pattern of bacterial sensitivities is subject to frequent modifications. As such frequent assessment and institution of other simple infection control measures like handwashing before and after attending to a patient and restriction of movements of personnel within a burns ward should be carried out. The mortality rate in our study of burn patients is consistent with those reported from other studies [2,3,6]. Infected patients were older, had larger burns, longer stay in hospital, more operations and a larger number of catheters compared to uninfected patients. In agreement, Appelgren et al. [3] showed equivalent comparisons. Furthermore, anemia, hypoalbuminemia, thrombocytopenia and lower median number of CD4+ cells (lymphocytes) on first week of stay were more likely in infected patients. Also, a strong correlation was determined between infectious complications and flame injuries, self-damage and necessity of transfusions. Infection after burns could be accompanied by anemia, thrombocytopenia and lower number of CD4+ T lymphocytes but the mechanisms responsible have not been clearly identified. The possible factors for those laboratory parameters in infected patients could de direct bone marrow
suppression, increased cells destruction, presence of endotoxins, production of autoantibodies, drugs used in the management of the burn patient (penicillin, vancomycin, diazepam morphine, tetanus toxoid), hypersplenism, haemophagocytosis and accelerated consumption [2]. The study showed a rate of infection of 53.2 per 100 patients, whereas other studies showed 38.1 [6], 64 [16], 77 [4] and 90 [7] infections per 100 discharges and deaths. In most of the studies, a higher nosocomial infection rate than observed in this study were found among burned patients. In bigger hospitals, a higher proportion of patients with severe underlying diseases are treated, and more invasive methods are applied. The majority of infections were bloodstream infections, followed by wound infections, which is consistent with other study in Brazil [5]. Otherwise, in Sweden, in a 3-year prospective study, Appelgren et al. [3] registered wound infection as the most common infection, followed by bloodstream infection. As well as, in Turkey, Oncul et al. [6], in 1-year prospective study, observed that the majority of infections were wound infections. Infection rates in burns have been reported to be high, compared to other intensive care units, which have ranged from 15 to 50% of the admissions [3,6]. The burn patient is infection-prone and very contagious when infected. Furthermore, one or more surgical procedures, might also allow burn patient to be colonized with multiresistant organisms. The isolation of multiresistant bacteria or fungi in the wound were more likely in infected patients (P < 0.001). The isolation care in general is important in the prevention of nosocomial transmission of infection. Cross-transmission of multiresistant microorganisms is common in intensive care units. This cross-transmission is an indicator of patient crowing and/or poor compliance with infection control guidelines by patient care personnel. Simple barrier precautions using gloves and gown at patient contact is more effective than elaborate isolation care. At present the main infection control measures in the burn unit are early excision and grafting, improved barrier nursing and regular microbiological analysis of the hospital’s environment and staff. Microbiological surveillance of burn patients when is routinely done helps in learning about the types of organisms and facilitates the choice of antibiotic. Each individual unit varies in its baseline population of microorganisms over time, and generalizations from one unit may have little applicability to others. Measures to prevent and treat infections are essential for the survival of patients with extensive burns and infection is correlated to mortality. Besides, in patients with less extensive burns, infections may increase morbidity and hospital stay. Infection is one indicator of outcome in the field of quality assurance in burn management. Careful surveillance of infection, good isolation techniques and procedure routines, and a restrictive antimicrobial
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policy can keep antimicrobial resistance rates and infection rates low in infection-prone burn patients.
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