Abstract:

In this study, it was aimed to investigate the role of cattle slaughterhouse wastewater (SWW) as a possible source of the antibiotic-resistant Enterococcus faecalis and Enterococcus faecium strains that pose a significant public health risk. For this purpose, Enterococcus spp. strains isolated by conventional method from 106 SWW samples ob-tained from cattle slaughterhouses were confirmed by quantitative real-time polymerase chain reaction (Q-PCR) and characterized by conventional PCR. Their antimicrobial susceptibilities were determined with disc diffusion method. Out of the 95 (89.6%) enterococci isolates, 33 (34.7%) were identified as E. faecalis and 10 (10.5%) as E. faecium. While E. faecalis isolates were resistant to Quinupristin-dalfopristin, rifampin, tetracycline and erythromycin at the rates of 90%, 88%, 75% and 63%, respectively; the resistance rates of E. faecium isolates to the relevant antibiotics were determined as 90%, 100%, 80% and 80%, respectively. However, linezolid (90%), vancomycin (≥70%), and penicillin (>90%) showed high efficacy against E. faecalis and E. faecium isolates. Additionally, 26 (79%) of the E. faecalis isolates and all (100%) E. faecium isolates exhibited multiple drug resistance (MDR) and their multiple antibiotic resistance (MAR) indexes were greater than 0.2 for 84% and 100% of these isolates, respectively. In conclusion, the analyzed SWWs can serve as a reservoir for E. feacium and E. faecalis isolates that exhibit high resistance to medically significant antimicrobials, and they can play a critical role in colonization on the environment and humans. Therefore, appropriate treatment strategies should be applied to minimize the negative effects of SWWs with rich microbiota on public health and environment.