Characteristics of pathogenic bacteria isolates associated with the gut and gill of molluscan shellfish, Eastern Cape, South Africa

Abstract

Introduction: Infectious diseases attributable to the consumption of raw and lightly cooked molluscan shellfish are caused by bacterial agents that are associated either with human waste disposed into the ocean or those of marine origin. This has led to the increase in prevalence of bacterial diseases and microbial resistance to antibiotics. Method: Samples of P. perna were dissected and homogenized for bacterial isolation. Six bacteria were isolated, identified and evaluated for their antimicrobial susceptibility profiling. Results: The microbial counts obtained revealed significant differences in the pathogenic bacteria populations found in the gut and gill of Perna perna. The morphological characteristics of the isolates were found to be of different shapes. All the isolates were catalase and oxidase positive except Vibrio spp. which was negative to the latter. Chloramphenicol and ciprofloxacillin were the most effective antibiotics against all the isolates, each exhibiting 100% efficacy. The highest resistance to ampicilin was observed in Salmonella spp., Shigella spp., Listeria monocytogenes and Staphylococcus xylosus. Conclusions: The results revealed that marine habitats are reservoirs of bacterial pathogens and there is increased resistance to antibiotic therapy, thereby constituting risks to public health. Therefore, appropriate surveillance measures to safeguard the health of shellfish consumers’ should be established.