Abstract
BackgroundBacillus cereus is one of the pathogens causing nosocomial bloodstream infections (BSIs). However, few reports have documented the antimicrobial susceptibility and clinical characteristics of Bacillus cereus BSI and the importance of empirical therapy. The aim of this study was to investigate the clinical characteristics and antimicrobial susceptibility of B. cereus isolates from patients with BSI and to analyze the impact of appropriate empirical therapy on the outcome of patients with B. cereus BSI.MethodsAll adult cases of bacteremia between April 2003 and March 2012 in a teaching hospital in Tokyo, Japan were reviewed retrospectively. Clinical data were collected from the patients’ medical records and charts. Antimicrobial susceptibility testing was performed by broth microdilution method. The patients with B. cereus BSI were divided into an appropriate empirical therapy group and an inappropriate empirical therapy group. The primary outcome was all-cause mortality at 4 weeks after the start of BSI. The secondary outcome was early defervescence within 2 days after starting empirical therapy.ResultsThere were 29 B. cereus bloodstream infection cases. No vancomycin, gentamicin, and imipenem-resistant isolates were found. However, 65.5 % were resistant to clindamycin and 10.3 % were resistant to levofloxacin. The main etiology was venous catheter-related (69 %). All-cause mortality at 4 weeks was not significantly different between the appropriate empirical therapy group (9 cases) and the inappropriate group (20 cases) in this study. However, early defervescence within 2 days after starting empirical therapy was significantly different (p = 0.032).ConclusionsThe BSI of B.cereus is mostly caused by venous catheter-related infections. Appropriate empirical therapy is important to achieve early clinical resolution in B. cereus BSI. Vancomycin is one of the appropriate selections of empirical therapy for B. cereus BSI.
Highlights
Bacillus cereus is one of the pathogens causing nosocomial bloodstream infections (BSIs)
The present data show that the BSI of B. cereus was mostly caused by venous catheter-related infections and that appropriate empirical therapy is important to achieve early clinical resolution in B. cereus bloodstream infection, the appropriateness of therapy does not affect mortality
B. cereus bacteremia was reported to be underestimated as contamination [24, 25], and it has recently been increasingly recognized that some cases of B. cereus bacteremia are definite BSIs [15, 17]
Summary
Bacillus cereus is one of the pathogens causing nosocomial bloodstream infections (BSIs). Few reports have documented the antimicrobial susceptibility and clinical characteristics of Bacillus cereus BSI and the importance of empirical therapy. The aim of this study was to investigate the clinical characteristics and antimicrobial susceptibility of B. cereus isolates from patients with BSI and to analyze the impact of appropriate empirical therapy on the outcome of patients with B. cereus BSI. The Bacillus cereus group contains six species, B. cereus, B. thuringiensis, B. weihenstephanensis, B. mycoides, B. pseudomycoides, and B. anthracis [1]. The most prevalent human pathogen in the B. cereus group is B. cereus [1]. B. cereus is a spore-forming Gram-positive bacillus that exists ubiquitously in soil, marine environments, vegetables, the intestinal tracts of invertebrates, and human skin [3].
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