Antibiotic resistance and virulence genes profiling of Vibrio cholerae and Vibrio mimicus isolates from some seafood collected at the aquatic environment and wet markets in Eastern Cape Province, South Africa

The current study determines the density of Vibrio spp. and isolates V. cholerae and Vibrio mimicus from fish-anatomical-sites, prawn, crab and mussel samples recovered from fish markets, freshwater and brackish water. Virulence and antibiotic resistance profiling of isolates were carried out using standard molecular and microbiology techniques. Vibrio spp. was detected in more than 90% of samples [134/144] and its density was significantly more in fish than in other samples. Vibrio. cholerae and V. mimicus were isolated in at least one sample of each sample type with higher isolation frequency in fish samples. All the V. cholerae isolates belong to non-O1/non-O139 serogroup. One or more V. cholerae isolates exhibited intermediate or resistance against each of the eighteen panels of antibiotics used but 100% of the V. mimicus were susceptible to amikacin, gentamycin and chloramphenicol. Vibrio cholerae exhibited relatively high resistance against polymyxin, ampicillin and amoxicillin/clavulanate while V. mimicus isolates exhibited relatively high resistance against nitrofurantoin, ampicillin and polymixin. The multiple-antibiotic-resistance-index [MARI] for isolates ranges between 0 and 0.67 and 48% of the isolates have MARI that is >0.2 while 55% of the isolates exhibit MultiDrug Resistance Phenotypes. The percentage detection of acc, ant, drf18, sul1, mcr-1, blasvh, blaoxa, blatem, blaoxa48, gyrA, gyrB and parC resistance-associated genes were 2%, 9%, 14%, 7%, 2%, 25%, 7%, 2%, 2%, 32%, 25% and 27% respectively while that for virulence-associated genes in increasing other was ace [2%], tcp [11%], vpi [16%], ompU [34%], toxR [43%], rtxC [70%], rtxA [73%] and hyla [77%]. The study confirmed the potential of environmental non-O1/non-O139 V. cholerae and V. mimicus to cause cholera-like infection and other vibriosis which could be difficult to manage with commonly recommended antibiotics. Thus, regular monitoring of the environment to create necessary awareness for this kind of pathogens is important in the interest of public health.