Antibiogram fingerprinting of <i>Vibrio</i> species recovered from commercial fish specimens collected from key retailers in the Eastern Cape Region of South Africa

Abstract

Antimicrobial resistance (AMR) is a major global public health threat that compromises the effective treatment of infectious diseases. This study investigated the antimicrobial resistance patterns and resistance genes of <i>Vibrio</i> species isolated from fresh-frozen commercial fish obtained from major retail outlets in the Eastern Cape Province, South Africa. Identification of isolates was confirmed using polymerase chain reaction (PCR). A total of 190 presumptive isolates were recovered, of which 92 were confirmed as <i>Vibrio</i> species and subjected to antimicrobial susceptibility testing. Multidrug resistance was observed among the isolates, with resistance to erythromycin (79%), nitrofurantoin (40.2%), colistin (34.8%), ampicillin (31.5%), cefotaxime and oxytetracycline (17.4% each), azithromycin and ceftazidime (15.2% each), trimethoprim (5.4%), ciprofloxacin (3.3%), and imipenem (4%).The Multiple Antibiotic Resistance Index (MARI) ranged from 0.25 to 0.50, exceeding the threshold of 0.2 and indicating exposure to high-risk contamination sources. Among resistance determinants, the blaTEM gene was detected in 12% of resistant isolates, while plasmid-mediated colistin resistance genes (mcr-1 to mcr-4) were identified in 30.8% of resistant isolates. Tetracycline resistance (tet) genes were detected in 17.4% of resistant isolates. These findings demonstrate the presence of multidrug-resistant <i>Vibrio</i> species in commercially sold fish in the study region, posing a potential risk to food safety and public health. Strengthened surveillance and improved regulation of antimicrobial use in aquaculture and healthcare settings are urgently required.<br>