Comamonas resistens Co-Producing GES-5 and OXA-17 in Urban Wastewater as a Potential Novel Disseminator of Clinically Relevant β-Lactamases.

Comamonas species have been isolated from different sources, with Comamonas testosteroni and Comamonas resistens commonly related to human diseases and multidrug resistance, respectively. During a surveillance study to monitor carbapenem resistance in bacteria from wastewater samples in Brazil, a carbapenem-resistant strain, named M13, was obtained and identified as C. resistens (ANI 98.90%, dDDH 94.60%) by genomic analysis, being a species distinct from C. testosteroni. It exhibited multidrug resistance and presented small inhibition zones around disks containing novel β-lactams and β-lactam-β-lactamase inhibitor combinations. Comparative genomics showed significant single nucleotide polymorphism divergence between M13 and other C. resistens genomes, suggesting geographically driven genomic diversity. Strain M13 uniquely harbored genes related to antimicrobial resistance and metal tolerance as follows: bla (carbapenem resistance), bla (third-generation cephalosporin resistance), mer operon (mercury tolerance), and pco operon (copper tolerance). The bla and bla genes were located on distinct plasmids that lacked conjugative genes but contained mobilization elements, indicating the potential for horizontal transfer. Unlike C. resistens strains from China, M13 strain may have acquired clinically relevant antimicrobial resistance genes via interactions with Brazilian microbial communities. These findings highlight the relevance of monitoring Comamonas species as potential reservoirs and disseminators of clinically relevant antimicrobial resistance genes and underscore the need for environmental monitoring of carbapenem-resistant strains.