Phenotypic and molecular characterization of Klebsiella spp. isolates causing community-acquired infections

Area of Science:

• Microbiology
• Infectious Diseases
• Genetics

Background:

• Klebsiella species are significant pathogens causing community-acquired infections.
• Characterizing Klebsiella isolates is crucial for understanding antimicrobial resistance and virulence in different geographical settings.

Purpose of the Study:

• To characterize Klebsiella isolates from community-acquired infections in rural Mexico.
• To determine the species distribution, antimicrobial resistance profiles, virulence factors, and genetic diversity of these isolates.

Main Methods:

• Biochemical tests and multiplex-PCR for species identification.
• Phylogenetic analysis of rpoB and concatenated genes for precise classification.
• Antimicrobial susceptibility testing, extended-spectrum beta-lactamase (ESBL) gene detection (CTX-M-15).
• Assessment of biofilm production and hypermucoviscosity phenotype.
• Serotyping (K2, K5, K54) and multilocus sequence typing (MLST) for genetic diversity analysis.

Main Results:

• 39 Klebsiella isolates were identified: predominantly K. pneumoniae (92.4%), with K. variicola (2.5%) and K. quasipneumoniae/K. quasivariicola (5.1%) also detected.
• Most isolates were multidrug-resistant; 10.2% produced ESBLs, with the CTX-M-15 gene identified.
• High prevalence of biofilm production (92.3%) and moderate hypermucoviscosity (17.9%).
• ST29 was the most prevalent sequence type (19%), with two ST29 isolates exhibiting hypermucoviscosity.
• Fimbriae and siderophores were the most common virulence factors detected.

Conclusions:

• Community-acquired infections in this Mexican region are caused by diverse Klebsiella species, notably K. pneumoniae.
• Isolates exhibit significant multidrug resistance and varied virulence potential, including high rates of biofilm formation.
• Genetic diversity exists, but ST29 is a notable sequence type associated with hypermucoviscosity.