Abstract

Antimicrobial resistance is an emerging global concern, as antibiotics are of major importance for human and animal health. As contact between wildlife, humans and domestic animals is increasing, resistant pathogens dissemination to wildlife through direct contact or environmental routes is also increasing.

We aimed to evaluate the potential of otters and their intestinal commensal bacteria as models of antimicrobial resistance dissemination in the environment. These free-ranging semi-aquatic predators are found in several aquatic environments, targeting aquatic prey including detritivores, and are more prone to the cumulative effects of antimicrobials in effluents.

We assessed the presence of antimicrobial-resistant commensal intestinal bacteria, namely Enterococcus spp., in 28 spraints from Eurasian (Lutra lutra) and 26 from Neotropical otters (Lontra longicaudis), collected in Portugal and Brazil during 2015 and 2016 in different climatic seasons. Isolates’ clonal diversity and antimicrobial resistance profiles were also determined.

Isolates from Lutra lutra and Lontra longicaudis presented different PCR fingerprinting profiles. The bacterial collection revealed high genomic diversity, representing the diversity of enterococci eliminated into the environment via otter spraints. Only one isolate was susceptible to all the antimicrobials tested, and the majority showed resistance to more than one antibiotic. Comparing the results with a previous work developed by our research team in 2013,¹ an increase in the resistance percentages to gentamicin, Clindamycin, penicillin, and tetracycline were observed, while resistance percentages regarding Chloramphenicol, enrofloxacin, and vancomycin were lower. The environmental persistence of vancomycin-resistant enterococci in Portugal is a significant concern for human health. These results also show the importance of the application of control measures to antibiotic administration, as the decrease in Vancomycin resistance may be associated with the banning of the use of avoparcin in animal production in Europe since 1997. Antimicrobial resistance was higher in enterococci from spraints collected in Brazil. However, statistically significant correlations between resistance to individual compounds and country were only observed for enrofloxacin and vancomycin.

Results confirm the otters’ and enterococci potential as models for monitoring antimicrobial resistance dissemination. Aquatic habitats occupied by otters may act as reservoirs of resistant bacteria, the presence of which could also impact human health through exposure to contaminated water during fishing or recreational activities.

Acknowledgments

The authors would like to thank CIISA - Centre for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon (Project UID/CVT/00276/2013). Teresa Semedo-Lemsaddek is financially supported by FCT-Portugal (SFRH/BPD/108123/2015). Nuno M. Pedroso was supported by grant #2014/08601–6, São Paulo Research Foundation (Fundação de Amparo à Pesquisa do Estado de São Paulo). Miguel Grilo holds a PhD fellowship (C10571K) from University of Lisbon. Luciano M. Verdade holds a Productivity Scholarship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Proc. No. 312049/2015–3)

Literature Cited

1.  Semedo-Lemsaddek T, Nóbrega CS, Ribeiro T, Pedroso NM, Sales-Luís T, Lemsaddek A, et al. Virulence traits and antibiotic resistance among enterococci isolated from Eurasian otter (Lutra lutra). Vet Microbiol. 2013;163(3–4):378–382.