A Stenotrophomonas maltophilia multilocus sequence typing scheme for inferring population structure

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Stenotrophomonas maltophilia is a resilient, opportunistic pathogen found globally.
• Existing genogrouping methods like amplified fragment length polymorphism (AFLP) show distinct environmental and clinical isolate distributions.
• Understanding the population structure is crucial for managing this pathogen.

Purpose of the Study:

• To develop and validate a multilocus sequence typing (MLST) scheme for Stenotrophomonas maltophilia.
• To analyze the population structure and genetic diversity of S. maltophilia strains from diverse ecological origins.
• To correlate genogroups with clinical and environmental sources.

Main Methods:

• A novel MLST scheme was designed using seven loci from 70 diverse S. maltophilia strains across seven countries.
• Sequence data were analyzed to define sequence types (STs) and assess genetic diversity and recombination.
• Phylogenetic analysis and comparison with existing genogroups were performed.

Main Results:

• Fifty-four unique sequence types (STs) were identified among the 70 strains.
• Significant linkage disequilibrium and evidence of recombination were observed.
• The MLST scheme confirmed previously defined genogroups and identified five new ones, with distinct clustering of environmental and clinical isolates.
• Respiratory and cystic fibrosis isolates predominantly belonged to genogroup 6, while invasive blood isolates were more diverse.

Conclusions:

• The developed MLST scheme provides a robust method for genotypic classification of S. maltophilia.
• The study elucidates the population structure, highlighting specific genogroups associated with clinical (e.g., respiratory, CF) and environmental origins.
• This classification aids in further research into the epidemiology and distribution of S. maltophilia.