Antimicrobial Resistance Profiles, Virulence Determinants, and Biofilm Formation in Enterococci Isolated from Rhesus Macaques (Macaca mulatta): A Potential Threat for Wildlife in Bangladesh?

SIMPLE SUMMARY: In this study, 67 rectal swab samples of rhesus macaques were screened to investigate the prevalence of antimicrobial resistance, virulence factors, and biofilm formation in enterococci found in rhesus macaques (Macaca mulatta) in Bangladesh. Enterococcus faecalis and E. faecium were detected in 65.7% and 22.4% of the samples; each of them was a biofilm former. The enterococci isolates showed phenotypic resistance to multiple antibiotics, including penicillin, rifampin, ampicillin, erythromycin, vancomycin, and linezolid. Moreover, multidrug resistance was exhibited in 88.63 % of E. faecalis and 100% of E. faecium isolates. The resistance bla(TEM) gene was harbored in 61.4% and 60% of E. faecalis and E. faecium isolates, respectively. Virulence genes, such as agg, fsrA, fsrB, fsrC, gelE, sprE, pil, and ace, were harbored in enterococci isolates. As we know, this is the first report on determining antimicrobial resistance, virulence factors, and biofilm formation in enterococci from rhesus macaques in Bangladesh. The findings of this study highlight the potential threat of enterococci in rhesus macaques and their potential transmission to other wildlife species and humans in Bangladesh. ABSTRACT: Enterococci are commensal bacteria that inhabit the digestive tracts of animals and humans. The transmission of antibiotic-resistant genes through human–animal contact poses a potential public health risk worldwide, as zoonoses from wildlife reservoirs can occur on every continent. The purpose of this study was to detect Enterococcus spp. in rhesus macaques (Macaca mulatta) and to investigate their resistance patterns, virulence profiles, and biofilm-forming ability. Conventional screening of rectal swabs (n = 67) from macaques was followed by polymerase chain reaction (PCR). The biofilm-forming enterococci were determined using the Congo red agar plate assay. Using the disk diffusion test (DDT), antibiogram profiles were determined, followed by resistance and virulence genes identification by PCR. PCR for bacterial species confirmation revealed that 65.7% (44/67) and 22.4% (15/67) of the samples tested positive for E. faecalis and E. faecium, respectively. All the isolated enterococci were biofilm formers. In the DDT, enterococcal isolates exhibited high to moderate resistance to penicillin, rifampin, ampicillin, erythromycin, vancomycin, and linezolid. In the PCR assays, the resistance gene bla(TEM) was detected in 61.4% (27/44) of E. faecalis and 60% (9/15) of E. faecium isolates. Interestingly, 88.63 % (39/44) of E. faecalis and 100% (15/15) of E. faecium isolates were phenotypically multidrug-resistant. Virulence genes (agg, fsrA, fsrB, fsrC, gelE, sprE, pil, and ace) were more frequent in E. faecalis compared to E. faecium; however, isolates of both Enterococcus spp. were found negative for the cyl gene. As far as we know, the present study has detected, for the first time in Bangladesh, the presence of virulence genes in MDR biofilm-forming enterococci isolated from rhesus macaques. The findings of this study suggest employing epidemiological surveillance along with the one-health approach to monitor these pathogens in wild animals in Bangladesh, which will aid in preventing their potential transmission to humans.