Stenotrophomonas maltophilia bacteremia in burn patients

Abstract

Stenotrophomonas maltophilia has been increasingly reported as a nosocomial opportunistic pathogen in debilitated patients, including burn patients. There is, however, only one published report in English that discusses S. maltophilia bacteremia in burns. We performed a retrospective chart review and statistical analysis of the incidence, the duration of hospital stays before a diagnosis of bacteremia, antimicrobial susceptibility, prognosis, and mortality risk factors in burn patients. From January 1996 to December 2004, 14 episodes of S. maltophilia bacteremia in 13 of 666 patients admitted to the burn center at our hospital were identified. The patients, nine males and four females, ranged in age from 1 to 76 years (mean: 42.9 ± 24.4 years). Eleven injuries were from flame burns and two were from scald burns. The mean total burned surface area (TBSA) was 47 ± 30.2% and mean prognostic burn index (PBI) was 81.7 ± 31.3. The average annual incidence was 2.3 episodes per 1000 admissions, and no outbreak cluster was noticed. The mean hospital stay before bacteremia was 19.8 ± 11.9 days. Most isolates were susceptible to ticarcillin-clavulanate (87.5%) and moxalactam (85.7%). The overall mortality was 30.7% (4/13) and correlated significantly with TBSA (P < 0.01) and PBI (P < 0.05). The incidence of S. maltophilia bacteremia was higher in hospitalized burn patients than in hospitalized non-burn patients. Different antimicrobial susceptibility patterns may exist, especially in different geographic regions. Awareness of the possibility of infection by this opportunistic pathogen and commencement of adequate antibiotics treatment, especially after 3 weeks of intensive care, should be incorporated into the strategy of treatment in major burn patients.

Introduction

Systemic bacterial infections remain the leading cause of death in burn patients, despite the variety of available antibiotic treatments [1]. Stenotrophomonas maltophilia, formerly called Pseudomonas maltophilia and Xanthomonas maltophilia [2], is an aerobic ubiquitous, gram-negative bacillus that has been isolated from humans, animals, soil, food, and pharmaceuticals [3]. Because of its limited invasiveness and low level of pathogenicity, it is rarely responsible for community-acquired serious infections [4]. However, it has been increasingly reported as a cause of life-threatening infections in debilitated, immunocompromised patients [5], [6], theoretically including burn patients [7]. Although several published reports describe cases of S. maltophilia bacteremia, they include debilitated individuals with various underlying illness. Only a single case report but no published series describes S. maltophilia bacteremia in burn patients [7]. We conducted this retrospective study to determine the incidence of S. maltophilia bacteremia, duration of hospital stay before diagnosis of S. maltophilia bacteremia was confirmed, susceptibility to antimicrobial agents, and risk factors for prognosis and mortality, including age, gender, inhalation injury, and burn severity. Awareness of the possibility of S. maltophilia infection and choice of the appropriate antibiotic treatment for the geographical area should improve outcomes of burn patients.