Stray Dogs (Mongrels) Are Potent Reservoir of Drug-Resistant Pathogens: A Study in Peri-Urban Areas of Kolkata, India.

This study depicts the drug-resistance and phylogenomic characteristics of 365 Escherichia coli (EC) and 76 Klebsiella pneumoniae (KP) isolated from stray dogs (293) in and around Kolkata, India. Initial screening found 59 isolates, including 48 E. coli and 11 KP multidrug resistant, which included 33 extended-spectrum β-lactamase, 41 AmpC β-lactamase and 18 metallo-β-lactamase producers carrying bla NDM-1 (11) and bla NDM-5 (7) genes. Majority of them had the resistant genes such as bla CTX-M (33), bla TEM (18), bla SHV (4), bla OXA (17), bla FOX (2), bla DHA (2), bla CITM (15), bla CMY-2 (13), bla GES (2) and bla VEB (2), qnr S (15), qnr B (3), aac-6'-Ib-cr (14), tet A (26), tet B (14), sul -1 (25), arm A (2) and rmt B (6), in addition to adherence genes such as csg A (33), fim A (27), fli C (13), sdi A (33), rcs A (38), and rpo S (39). They also carried plasmid of diverse replicon types of which IncF IA and F IB were the most frequent. Phylogrouping categorized most of the MDR E. coli in phylogroup A (20), B1 (14), and B2 (6). Enterobacteriaceae repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) showed genetic diversity of multidrug resistant isolates irrespective of their origin, resistance, and virulence types, differentiating the EC in five clades (A-E) and KP in four clades (A-D). As these stray dogs, which had no history or scope of previous antimicrobial therapy, were found to have contracted potential antimicrobial resistance pathogens, the role of environment in spread of such pathogens and further possibility of human infections cannot be ruled out.