Prevalence and Antimicrobial Resistance of Bacteria Isolated from Marine and Freshwater Fish in Tanzania

Abstract

This study aimed to determine the prevalence and antimicrobial resistance of bacteria isolated from retail fish and shrimp in Tanzania. A total of 92 fish and 20 shrimp samples were analyzed. Fish samples consisted of 24 Nile tilapia, 24 Nile perch, and 24 red snapper. The isolates were identified by their morphological characteristics, conventional biochemical tests, and analytical profile index test kits. The antibiotic susceptibility of selected bacteria was determined by the disc diffusion method. Out of the 92 samples analyzed, 96.7% were contaminated with 7 different bacterial species. <i>E. coli</i> was the most prevalent bacteria (39%), followed by <i>Klebsiella</i> spp. (28%) and <i>Salmonella</i> spp. (16%). Other species isolated from this study were <i>Staphylococcus</i> spp. (8%), <i>Citrobacter</i> (4%), <i>Shigella</i> spp. (3%), and <i>Pseudomona</i>s spp. (1%). All samples were analyzed for <i>Campylobacter</i> spp.; however, none of the samples tested were positive for <i>Campylobacter</i> spp. Fish from the open-air market were contaminated by six bacterial species: <i>E. coli</i> (40%), <i>Klebsiella</i> spp. (26%), <i>Salmonella</i> spp. (24%), <i>Shigella</i> spp. (6.7%), <i>Citrobacter</i> spp. (6.5%), and <i>Pseudomonas</i> spp. (2%), while <i>E. coli</i> (37%), <i>Klebsiella</i> spp. (33%), <i>Staphylococcus</i> spp. (23%), and <i>Shigella</i> spp. (2%) were isolated in supermarket samples. According to the International Commission on Microbiological Specifications for Foods criteria, 54 (58.7%) and 38 (41.3%) samples were good and marginally acceptable, respectively. <i>E. coli</i> isolates were resistant to penicillin (PEN), erythromycin (ERY), gentamicin (GEN), azithromycin (AZM), and tetracycline (TET), while <i>Salmonella</i> spp. isolates exhibited resistance to gentamicin (CN), tetracycline (TET), penicillin (PEN), and erythromycin (ERY). These results suggest that the presence of these bacteria might cause a health risk/hazard to human beings and may cause disease to susceptible individuals, especially immune-compromised consumers.