Third generation cephalosporin-resistant Klebsiella pneumoniae thriving in patients and in wastewater: what do they have in common?

Background Klebsiella pneumoniae are ubiquitous bacteria and recognized multidrug-resistant opportunistic pathogens that can be released into the environment, mainly through sewage, where they can survive even after wastewater treatment. A major question is if once released into wastewater, the selection of lineages missing clinically-relevant traits may occur. Wastewater (n = 25) and clinical (n = 34) 3(rd) generation cephalosporin-resistant K. pneumoniae isolates were compared based on phenotypic, genotypic and genomic analyses. Results Clinical and wastewater isolates were indistinguishable based on phenotypic and genotypic characterization. The analysis of whole genome sequences of 22 isolates showed that antibiotic and metal resistance or virulence genes, were associated with mobile genetic elements, mostly transposons, insertion sequences or integrative and conjugative elements. These features were variable among isolates, according to the respective genetic lineage rather than the origin. Conclusions It is suggested that once acquired, clinically relevant features of K. pneumoniae may be preserved in wastewater, even after treatment. This evidence highlights the high capacity of K. pneumoniae for spreading through wastewater, enhancing the risks of transmission back to humans.

Automated summary

This study compared the phenotypic, genotypic, and genomic characteristics of clinical and wastewater isolates of Klebsiella pneumoniae and found that they cannot be distinguished based on these features. Whole genome sequence analysis revealed that antibiotic and metal resistance or virulence genes were associated with mobile genetic elements, and these features varied among isolates according to their genetic lineage rather than their origin. Therefore, this study suggests that clinically relevant features of K. pneumoniae can be preserved in wastewater, even after treatment, highlighting the high capacity of K. pneumoniae for spreading through wastewater and increasing the risks of transmission back to humans.