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Genomic insights into pigmented Serratia marcescens strains isolated from patients in northeast Mexico
Mishael Sánchez-Pérez1, Angel Andrade2, Orlando Flores-Maldonado2
1Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Morelos, Mexico; División de Materiales Avanzados, Grupo de Ciencia e Ingeniería Computacionales, Centro Nacional de Supercómputo, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosi, Mexico.
Abstract:
Serratia marcescens (SM) is an opportunistic pathogen associated with outbreaks in immunocompromised hosts. While SM is commonly isolated from clinical and environmental sources, prodigiosin production is typically associated with environmental strains rather than clinical isolates. Here, we report the genome sequences of three pigmented SM clinical isolates -HU1848, HU2225, and HU2228- and examine their genomic and phenotypic characteristics. Phylogenetic analysis using 1103 finished public SM genomes revealed that these isolates cluster more closely with environmental SM strains than with those typically associated with clinical settings. Notably, despite their environmental-like genomic background, these isolates harbor multiple virulence genes implicated in colonization and resistance to fertilizers, as well as antimicrobial resistance genes for chloramphenicol, fosfomycin, and tetracycline. MIC determination showed susceptibility to aminoglycosides and fluoroquinolones. Additionally, we observed that the phenolic compound methyl gallate modulates pigment production and motility. The absence of AHL biosynthetic genes in these pigmented strains challenges previous associations between quorum sensing and prodigiosin biosynthesis. These findings suggest that certain SM strains with environmental-like genetic features can persist in clinical settings, underscoring the need to further investigate their potential role in nosocomial infections.
Insights
This study sequenced pigmented Serratia marcescens clinical isolates, finding they possess environmental-like genomes with virulence and antibiotic resistance genes. These findings highlight potential risks for nosocomial infections.
Area of Science:
- Microbiology
- Genomics
- Pathogen research
Background:
- Serratia marcescens (SM) is an opportunistic pathogen often found in clinical and environmental settings.
- Prodigiosin production, a characteristic pigment, is typically linked to environmental SM strains, not clinical isolates.
Purpose of the Study:
- To sequence and characterize three pigmented SM clinical isolates.
- To investigate the genomic and phenotypic traits of these isolates and their relation to environmental strains.
Main Methods:
- Whole-genome sequencing of three pigmented SM clinical isolates (HU1848, HU2225, HU2228).
- Phylogenetic analysis comparing these isolates to 1103 public SM genomes.
- Phenotypic characterization including antimicrobial susceptibility testing (MIC determination) and analysis of pigment production and motility.
Main Results:
- Phylogenetic analysis showed the clinical isolates cluster with environmental SM strains.
- Isolates possess virulence genes for colonization and resistance, alongside antimicrobial resistance genes (chloramphenicol, fosfomycin, tetracycline).
- Methyl gallate influenced pigment production and motility; AHL biosynthetic genes were absent, challenging quorum sensing links to prodigiosin.
Conclusions:
- Pigmented SM clinical isolates can exhibit environmental-like genomic features.
- These strains carry virulence and antibiotic resistance genes, posing potential risks in clinical settings.
- Further research is needed to understand the role of these strains in nosocomial infections.
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