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Phylogenetic analysis of Bacillus cereus isolates from severe systemic infections using multilocus sequence typing
Maria Vassileva1, Keizo Torii, Megumi Oshimoto
1Department of Bacteriology, Nagoya University Graduate School of Medicine, Aichi, Japan.
Microbiology and Immunology
|September 21, 2006
Summary
Severe Bacillus cereus infections, including respiratory cases, were analyzed. Genetic analysis revealed distinct clusters for pathogenic strains, with some respiratory strains being genetically distant from Bacillus anthracis.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Bacillus cereus is an opportunistic pathogen causing severe systemic infections.
- Understanding the genetic diversity of B. cereus is crucial for infection control and treatment.
- Previous studies have linked specific genetic lineages to clinical manifestations.
Purpose of the Study:
- To genetically characterize Bacillus cereus strains from severe and lethal systemic infections, particularly those with respiratory symptoms.
- To investigate the phylogenetic relationship of these strains to Bacillus anthracis and other known pathogenic B. cereus lineages.
- To determine if pathogenic B. cereus strains form distinct phylogenetic clusters.
Main Methods:
- Multilocus sequence typing (MLST) using the B. cereus MLST database.
- Phylogenetic analysis comparing novel isolates with existing database entries.
- Analysis of strains from severe/lethal systemic infections, including respiratory cases.
Main Results:
- Isolates were evenly distributed across two main phylogenetic clades.
- 60% of analyzed strains possessed novel allele profiles not previously in the database.
- Half of the strains clustered in a lineage near Bacillus anthracis.
- Strains causing respiratory symptoms were found in both major clades and were genetically distinct from B. anthracis.
- Clinical isolates from this study clustered with previously reported isolates from systemic infections, suggesting pathogenic strains form distinct phylogenetic groups.
Conclusions:
- Pathogenic Bacillus cereus strains appear to form distinct clusters within the phylogenetic tree.
- This study identifies B. cereus strains causing respiratory symptoms that are genetically distant from B. anthracis.
- The findings contribute to a better understanding of the genetic basis of B. cereus pathogenicity and host-pathogen interactions.
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