Synanthropic Rodents and Shrews Are Reservoirs of Zoonotic Bacterial Pathogens and Act as Sentinels for Antimicrobial Resistance Spillover in the Environment: A Study from Puducherry, India

Abstract

Antimicrobial resistance is a major public health concern. Rodents and shrews live in closer proximity to humans and animals and serve as reservoirs for the transmission of several diseases, including AMR pathogens. There is no data available from India on surveillance of AMR bacteria in rodents and shrews. In this study, bacterial pathogens viz, Staphylococcus sp, Escherichia coli and Salmonella sp were isolated from rodents and shrews and genetic elements conferring antimicrobial resistance in the pathogens were screened by PCR. Bacterial pathogens in the oropharyngeal and anal swabs collected from the rodents and shrews trapped (n=100) were cultured on selective media such as Mannitol salt, Mac Conkey and Xylose lysine deoxycholate media to isolate Staphylococcus sp., E. coli and Salmonella sp. respectively. A total of 76 (80%) S. aureus and 19 (20%) Staphylococcus non aureus were isolated. E. coli was isolated in 89 samples and among the Salmonella sp (n=59), 16 (27%) were S. enteritidis and 29 (49.1%) were S. typhimurium. In S. aureus isolates, mec A and mec C (MRSA) were detected in 40 (52.6%) and 6 (7.9%) isolates respectively. Also, 7 (36.84%) and 1 (5.3%) Staphylococcus non aureus isolates were tested to harbour mec A and mec C genes. A total of 77 (86.5%) E. coli isolates had genes encoding ESBL [TEM in 21 (23.59%), SHV in 45 (50.6%) and CTXM in 11 (12.4%)]. Among the 45 pathogenic Salmonella sp, 44 (97.78%) harboured AMR genes [tet in 13 (28.9%), sul3 & sul4 in 20 (44.4%) and qnrA in 11 (24.4%)]. Thirty-eight animals harboured more than one zoonotic pathogen and 21 with multi-drug resistant genes. Our findings signify that these rodents and shrews may serve as sentinels to screen environment spillover of AMR pathogens and also act as reservoir to transmit MRSA, ESBL, Salmonella sp. human/animals. Also these animals aid in the transfer of antimicrobial resistance genetic elements to non-pathogenic organisms.