Diversity, antimicrobial characterization and biofilm formation of Enterococci isolated from aquaculture and slaughterhouse sources in Benin City, Nigeria

Abstract

The present study was designed to characterize Enterococci isolates obtained from water samples at aquaculture and slaughterhouse facilities in Benin City, Nigeria. A total of 144 water samples were collected from aquaculture and slaughterhouse facilities. All samples were analyzed using classical microbiological and molecular-based methods. Enterococci were identified using specific primer sets (genus and species specific primers) and are as follows: E. faecalis 36 (25.5%); E. faecium 39 (27.7%); E. durans 19 (13.4%); E. casseliflavus 13 (9.2%); E. hirae 14 (9.9%) and other Enterococcus species 20 (14.2%). The resistance profile of the bacterial strains to antibiotics was as follows: [tetracycline (n=67, 47%)]; [vancomycin (n=74, 52%)]; [erythromycin (n=91, 64%)] and [penicillin (n=141, 100%)]. Enterococci virulence genes detected include: [gelE (n=120, 85.1%)]; [cylA (n= 52, 36.9%)]; [hyl (n=96, 68.1%)]; [esp (n=135, 95.8%)]; [ace (n= 127, 90.1%)] and [agg n=118, 83.7%)]. Antibiotic-resistant gene detected from the phenotypic resistant isolates were 55/74 (74.3%) vanA; 61/67 (91.1%) tetC; 122/141 (86.5%) blapse1 and 62/91 (68.1%) ermA. Antibiotic-resistant coupled with biofilm formation potential of Enterococcus species include penicillin+biofilm 116 (82.3%); erythromycin+biofilm 85 (60.3%); and vancomycin+biofilm 74 (52.3%). Findings from this study reveal that strains with the ability of forming biofilms have enhanced antimicrobial resistance. Continuous monitoring of slaughterhouses and aquaculture facilities is necessary to guarantee food safety.

Key Words: Aquaculture, Biofilm,Enterococcus, Environments, Resistance, Slaughterhouse