Virulence characteristics and genetic background of ESBL-producing Klebsiella pneumoniae isolates from wastewater

Resumen

Klebsiellapneumoniae is an opportunistic pathogen frequently multidrug-resistant, responsible for nosocomial and community infections. Pathogenicity of extended-spectrum P-lactamase (ESBL)-producing K. pneumoniae isolates recovered from wastewater, 52 from hospital effluents and 32 from municipal wastewater-treatment-plant, was assessed by screening for 25 virulence factors, comparing results with those of 43 ESBL-positive K. pneumoniae clinical isolates. In hospital effluents/wastewater-treatmentplant/clinical isolates, rates of types 1 and 3 adhesins genes were of 100%/100%/100% and 100%/96.9%/100%, respectively, while non-fimbrialadhesin gene cf9awas absent. Rates of enterobactin, yersiniabactin, salmochelinand aerobactin genes were of 98.1%/100%/100%, 15.4%/12.5%/39.5%, 0%/3.1%/2.3% and 0%/0%/4.6%, respectively. No wastewater isolates had hypermucoviscosity phenotype and associated genes magA and rmpA, while a clinical isolate had hypermucoviscosity phenotype and rmpA. All isolates had a capsule and capsule/lipopolysaccharide-associated genes wabG and uge, and showed biofilm formation and serum resistance. Urease, colibactin and hemolysin a genes were at rates of 100%/100%/100%, 0%/3.1%/4.6% and 0%/0%/0%. Overall, prevalences of virulence factors in wastewater and clinical isolates were close. Yersiniabactin, wabG and ESBL genes were located on IncFII plasmid, in a wastewater isolate. Combination of virulence factors allowed to distinguish 6 virulence profiles among wastewater isolates, whose pathogenicity was confirmed in mice. Molecular typing showed genetic diversity and no direct epidemiological relatedness between wastewater and clinical isolates; however, phylogroups and sequence-types previously reported in clinical isolates were detected in wastewater isolates. The study highlighted the pathogenicity of wastewater K. pneumoniae, comparable to clinical isolates and potential role of wastewater as reservoir of virulent Klebsiella and virulence genes into natural environments.