Trends in microbial profile of burn patients following an event of dust explosion at a tertiary medical center.

BACKGROUND: Microbial infection is the main cause of increased morbidity and mortality in burn patients, especially infections caused by multiple drug-resistant organisms (MDRO). The purpose of this study was to explore major microbial trends in burn patients. METHODS: This retrospective study was conducted at burn wards and intensive care units, where burn patients were admitted following an event of dust explosion. Data were collected for a number of variables including severity of burns, demographic and clinical characteristics, laboratory data, and therapeutic devices. RESULTS: A total of 1132 specimens were collected from 37 hospitalized burn patients with mean TBSA of 46.1%.The most commonly isolated species were Staphylococcus spp. (22.4%). The highest rate of antibiotic resistance was observed in carbapenem-resistant A. baumannii (14.6%), followed by methicillin-resistant S. aureus (11.3%). For each additional 10% TBSA, the isolation of MDRO increased 2.58-17.57 times (p < 0.05); for each additional 10% of the third-degree burn severity, the risk of MDRO significantly decreased by 47% (95% CI, 0.38-0.73, p < 0.001) by Cox model. CONCLUSIONS: The proportion of overall microbial isolates increased with the increase in TBSA and duration of time after burns. The extent of TBSA was the most important factor affecting MDRO.

Alterations in airway microbiota in patients with PaO2/FiO2 ratio ≤ 300 after burn and inhalation injury.

BACKGROUND: Injury to the airways after smoke inhalation is a major mortality risk factor in victims of burn injuries, resulting in a 15-45% increase in patient deaths. Damage to the airways by smoke may induce acute respiratory distress syndrome (ARDS), which is partly characterized by hypoxemia in the airways. While ARDS has been associated with bacterial infection, the impact of hypoxemia on airway microbiota is unknown. Our objective was to identify differences in microbiota within the airways of burn patients who develop hypoxemia early after inhalation injury and those that do not using next-generation sequencing of bacterial 16S rRNA genes. RESULTS: DNA was extracted from therapeutic bronchial washings of 48 patients performed within 72 hours of hospitalization for burn and inhalation injury at the North Carolina Jaycee Burn Center. DNA was prepared for sequencing using a novel molecule tagging method and sequenced on the Illumina MiSeq platform. Bacterial species were identified using the MTToolbox pipeline. Patients with hypoxemia, as indicated by a PaO2/FiO2 ratio ≤ 300, had a 30% increase in abundance of Streptococcaceae and Enterobacteriaceae and 84% increase in Staphylococcaceae as compared to patients with a PaO2/FiO2 ratio > 300. Wilcoxon rank-sum test identified significant enrichment in abundance of OTUs identified as Prevotella melaninogenica (p = 0.042), Corynebacterium (p = 0.037) and Mogibacterium (p = 0.048). Linear discriminant effect size analysis (LefSe) confirmed significant enrichment of Prevotella melaninognica among patients with a PaO2/FiO2 ratio ≤ 300 (p<0.05). These results could not be explained by differences in antibiotic treatment. CONCLUSIONS: The airway microbiota following burn and inhalation injury is altered in patients with a PaO2/FiO2 ratio ≤ 300 early after injury. Enrichment of specific taxa in patients with a PaO2/FiO2 ratio ≤ 300 may indicate airway environment and patient changes that favor these microbes. Longitudinal studies are necessary to identify stably colonizing taxa that play roles in hypoxemia and ARDS pathogenesis.

Airway obstruction and bacterial invasion in autopsy tissue of pediatric burn victims.

This study measured airway obstruction and bacterial invasion in systematically sampled lung tissue of burn victims at autopsy. Lung tissue from victims of combined smoke inhalation and burn injury (n = 5) and burn injury alone (n = 9) was examined histologically and the degree of bronchial and bronchiolar obstruction was measured. The walls of both bronchi and bronchioles were examined for bacterial invasion. Correlation analysis was performed for the association of airway obstruction with TBSA burn, number of ventilatory days, maximum inspiratory pressure, and days after injury. There was no significant difference in the mean degree of airway obstruction in smoke inhalation and burn victims compared with victims of burn-only injury (P > .05). Increased bronchiolar obstruction scores were detected in victims with pneumonia (55.3 ± 24.2%) compared with victims without pneumonia (9.3 ± 0.2%; P = .03). Bacterial invasion of the bronchial wall was present in one case, and invasion into the walls of bronchioles was seen in five cases. Burned children who died had extensive bronchiolar obstruction whether or not they had smoke inhalation injury. There was bacterial invasion into the airway wall in six of 14 cases (43%). Improved understanding of the mechanisms of airway obstruction is important for improved care of burned children.

Polyphenol cytotoxicity induced by the bacterial toxin pyocyanin: role of NQO1.

Pyocyanin is an important bacterial redox-active toxin produced by the opportunistic human pathogen Pseudomonas aeruginosa. The bacterium is a cause of serious infections of the respiratory tract, particularly for those with cystic fibrosis and for those with burn injuries. Pyocyanin induces oxidative stress and causes cells to become prematurely senescent, which compromises tissue remodeling and wound repair. A diverse range of antioxidants have been found useful in preventing oxidant-induced cellular senescence, including quercetin, a common dietary polyphenol. This study evaluated the effectiveness of three common polyphenols (quercetin, (+)-catechin, and (-)-epicatechin) as potential inhibitors of pyocyanin-induced senescence. Whereas at the lowest concentration the polyphenols maintained cellular replicative capacity, in the presence of pyocyanin they unexpectedly displayed concentration-dependent cytotoxicity with a rank order of quercetin>epicatechin>>catechin. On oxidation, polyphenols with B-ring catechol functionality form toxic alkylating quinones that are normally inactivated by cellular antioxidant defense and redox maintenance systems, including reduction by ascorbate and NAD(P)H:quinone oxidoreductase 1 (NQO1). Pyocyanin inhibited cellular NQO1 activity at low micromolar concentrations, but the presence of exogenous ascorbate eliminated pyocyanin-induced polyphenol cytotoxicity. These data indicate that pyocyanin compromises cellular redox maintenance systems, leaving cells susceptible to the adverse effects of otherwise nontoxic redox-active compounds.

Septicaemia after burn injury: a comparative study.

Seventy-nine (8.4%) patients during June 1992-May 1996 (Group-1) and 68 (7.2%) patients from June 1996 to May 2000 (Group-2) who developed septicaemia at the burns unit of Al-Babtain Centre for Plastic Surgery and Burns, Kuwait, were retrospectively studied and compared. The mean age of 26 years, male predominance, flame burns as main aetiology and mean burn percentage of >or=40% was observed in both the groups. Both groups revealed extensive flame burn, inhalation injury, intubation and difficult resuscitation as the risk factors. The proportion of satisfactory resuscitation increased significantly (P<0.001) in Group-2. The septicaemia commonly occurred within 2 weeks postburn but the number of episodes during 5 days postburn was less in Group-2. The surface wound was found to be the likely source of entry of the organisms into the blood stream in both the groups. The gram positive organisms were dominant aetiologic factor in both groups but an increase frequency of Acnetobacter was found in Group-2. The proportion of MRSE and Pseudomonas septicaemia was significantly higher (P<0.01) in the Group-1. The rate of survivors, in both the groups was higher among operated patients but it was significantly higher (P<0.001) in the Group-1. A mortality rate 20.6% in Group-2 decreased against Group-1, which can be attributed to better resuscitation, nutritional care, early detection of septicaemia, appropriate antibiotics and early wound excision and skin grafting. MOF was the cause of death of 60.9% in Group-1 and 85.7% in Group-2. There was no role of prophylactic antibiotic in burn patients in the incidence of septicaemia and mortality.

Pneumonia in patients with severe burns : a classification according to the concept of the carrier state.

OBJECTIVE: To establish baseline values of pneumonia incidence and mortality and to distinguish primary endogenous from secondary endogenous and exogenous pneumonias in a homogeneous patient population with severe burns. DESIGN: Cohort study. SETTING: A six-bed burn ICU. PATIENTS: All patients of > or = 14 years admitted to the ICU between January 1995 and June 1996 with a total body surface area burn of > or = 20%. INTERVENTION: Collection of data on surveillance samples from throat and rectum on admission and twice weekly afterward, and pneumonias during the ICU stay. MEASUREMENTS AND RESULTS: Fifty-six patients fulfilled the criteria of the study. Mean age was 43 +/- 19.8 years; total body surface area burn, 41 +/- 18.2%; the area of full-thickness burn was 24 +/- 17.7%. Forty-one patients required mechanical ventilation. Twenty-seven patients (48%) experienced 37 episodes of pneumonia. Twenty-one pneumonias were of primary endogenous development, ie, caused by potential pathogens carried in the admission flora. There were 14 secondary endogenous and 2 exogenous infections caused by microorganisms acquired on the burn unit. Inhalation injury was identified in 26 patients. The pneumonia rate was two times higher in the subset of patients with inhalation injury compared with the group of patients without inhalation injury (p < 0.001). Overall mortality was 25%. CONCLUSIONS: This study shows that pneumonia in burn patients is mainly an endogenous problem. Interventions that prevent the development of endogenous infections deserve prospective evaluation in patients with severe burns.

Procalcitonin--a sepsis parameter in severe burn injuries.

Procalcitonin (PCT) levels increase in patients with systemic infections; the highest levels have been found in sepsis. This study tested whether plasma procalcitonin level was related to sepsis, CRP, burn size, inhalation injury or mortality in severely burned patients over the entire clinical course. In 27 patients with 51 (20-91)% TBSA, PCT was measured three times weekly from admission over the entire course of stay in a single ICU. Daily scoring by the "Baltimore Sepsis Scale" was performed. The patients were assigned to three groups depending on the clinical course and outcome: A = no septic complications, B = septic complications-survivors, C = septic complications non-survivors. PCT levels were elevated slightly at admission (mean 2.1 ng/ml) except in three patients who suffered electrical burns (mean 15.7 ng/ml). PCT peak levels correlated well with the Scoring values (r = 0.84) while CRP did not (r = 0.64). Peak PCT levels were significantly higher (p < 0.005) in septic patients (B and C) who averaged 49.8+/-76.9 ng/ml, than in non-septic patients (A) who averaged peak levels of 2.3+/-3.7 ng/ml. The highest PCT levels were found immediately before death (86.8+/-97 ng/ml). Seven patients had an inhalation injury 3rd degree. In these patients at 24 h postburn, there was no relationship between PCT levels and inhalation injury but during the later days postburn there were significant differences in PCT levels in patients with versus without inhalation injury. All patients with inhalation injury 3rd degree developed septic complications. There was no positive correlation between the PCT-admission-levels and the TBSA, but there was a positive correlation between the TBSA and the mean peak PCT levels during the later days postburn (r = 0.73; p < 0.05). The cut-off value of 3 ng/ ml we found reliable to indicate severe bacterial or fungal infection. PCT values over 10 ng/ml increasing over the following days were found only in life-threatening situations due to systemic infections. The individual course of PCT in one patient is more important than absolute values. PCT presented in this study as a useful diagnostic parameter in severely burned patients.

Emergence of a multiply-resistant strain of Acinetobacter in a burns unit.

Multiply-resistant Acinetobacter has emerged as an important organism in the Burns Unit of the Singapore General Hospital. From November 1990 onwards, a strain that was resistant to all antibiotics except Polymyxin B emerged in the Burns Unit. We present two cases where the Acinetobacter isolated was resistant to all antibiotics including Polymyxin B. These cases serve as an important reminder to adhere to strict infection control procedures.

[Bacteriologic study of lung infection in 47 cases of burns].

The culture results of sputum (SP), blood (BL) and wound secretions (WS) of 47 cases of burns with lung infection were analyzed. Symptoms of pneumonia within 5 days after burn were observed in 90.3% of inhalation injury patients (IIG, 31 cases) whereas only in 25.0% of noninhalation injury patients (NIIG, 16 cases). The isolation rates of Gr(-) bacteria from the 3 sources of culture were markedly higher than those of Gr(+) cocci. The same bacteria, mainly Ps. aeruginosa and Staph. aureus, were identified simultaneously from the 3 sources of culture in 12 cases (25.5%). Isolates from SP correlated well with those from WS, the coincidence rates of 4 main Gr(-) bacteria were over 58%. Ps. aeruginosa was the commonest pathogen of IIG but Staph. aureus was the commonest in SP and BL of NIIG. The isolation rate of fungi of SP in NIIG was about twice that in IIG. Ps. aeruginosa and E. coli were susceptible to Amikacin and Polymixin B, Ps. aeruginosa was more susceptible to Cefoperazone, while the Gr(+) cocci were susceptible to first generation Cephalosporins.

[Bacteria of the species Acinetobacter calcoaceticus as the possible etiological factor in infectious complications in burns]. / Bakterii vida Acinetobacter calcoaceticus kak vozmozhnyi étiologicheskii faktor infektsionnykh oslozhnenii pri ozhogakh.

The results of the study of the etiological role of Acinetobacter calcoaceticus in infectious complications of burning lesions are presented. These bacteria were shown to occur in 28% of burn wounds, quite frequently as a monoculture or association with diphtheroids. A. calcoaceticus were capable of persisting in the wounds during the whole period of treatment (up to 2-3 months). A high level of the contamination of burn wounds with these microorganisms, reaching 10(5)-10(6) cells per 1 g of tissue or 1 cm2 of the wound surface, was observed. The occurrence of A. calcoaceticus in the blood of the patients from whose burn wounds these microorganisms could be isolated was 36.3%. All isolated strains possessed multiple drug resistance.