EPIDEMIOLOGY OF ANTIMICROBIAL RESISTANCE OF SALMONELLA SPP., STAPHYLOCOCCUS SPP. AND ESCHERICHIA COLI IN FREE RANGING BATS

Abstract

Antimicrobial resistance (AMR) is currently one of the greatest challenges to the global health. The prevalence of resistant microbes in wildlife are poorly understood. Bats are a diverse and highly mobile taxon that often lives in close proximity to people and livestock. Bats use of shared environments may contribute to their exposure to AMR enteric pathogens. The identification of zoonotic and anthropozoonotic agents carried by bats is critical for understanding the ecology of zoonotic pathogens. A cross-sectional study was conducted to determine the epidemiology of AMR in Salmonella spp., Staphylococcus spp. and Escherichia coli (E. coli) isolated from bats and test the hypothesis that drinking behavior of bats may result in their infection with AMR bacteria. We collected fecal samples (N=369) from free-ranging bats and 21 water samples from different water bodies in Dhaka city between December 2016 and June 2017. Pre-enrichment was done in buffered peptone water for Salmonella spp. & E. coli and in Mueller Hinton broth for Staphylococcus spp. Samples were cultured on selective media; biochemical test and PCR were done to confirm bacterial isolates. Culture sensitivity test was determined using Kirby-Bauer disc diffusion technique of 12 antibiotics for each organism on selective media. Overall prevalence of Salmonella spp., Staphylococcus spp and E. coli in Pteropus medius & Rousettus leschenaulti bats was found 10.04-2.86%, 19.65-40.71% & 31.85-25.71%, respectively. Analysis showed 7.32% (27/369; 95% CI: 5-11) of fecal samples of bats positive for resistant Salmonella spp., 26.29% (97/369; 95% CI: 22-31) for resistant Staphylococcus spp. and E. coli resistant to 28.18% (104/369; 95% CI: 24-33). Around 4% (n=21, 95 % CI: 18-62) of water samples were positive for Salmonella spp. The final multivariate model revealed that odds of having resistant Staphylococcus spp. and E. coli were significantly higher in Faridpur (OR=3.1; CI: 2-6, P=0.00) and Dhaka (OR=2.3; CI: 1-5, P=0.03), compared than other locations. In case of Salmonella spp., prevalence was significantly higher in summer season (OR=8.9; CI: 4-24, P=0.00). Results of the present study exposed that all isolates had developed resistance to multiple antibiotics. Salmonella spp. were resistant to Tetracycline (93%), Sulphamethoxazoal-Trimethoprime (80%), Azithromycin (76%), Chloramphenicol (62%), Amoxicillin-Clavulanic acid (42%) & Cefotaxime (41%). Staphylococcus sp. showed high resistance to Ampicillin (55%) and Methicillin, Oxacillin, Streptomycin & Tigecycline (by 12% on average). E. coli showed resistance against Cefepime (16%) followed by Ampicillin (13%). Page | xvi Furthermore, water samples showed remarkable resistance to Tetracycline (86%), Amoxicillin-Clavulanic acid (75%), Ceftriaxone (72%), Ciprofloxacin (71%) followed by Chloramphenicol (57%) & Sulphamethoxazoal-Trimethoprime (58%). The study results indicate presence of AMR Salmonella spp., Staphylococcus spp. and E.coli in bats. It is unclear how bats were infected with AMR bacteria, however water contaminated by people and/or livestock may be a source of infection. Screening people and livestock for similar resistant bacterial species will improve our understanding of pathogen transmission among wildlife, livestock and people interface.