Human pathogenic bacteria isolation from tilapia fishes (Oreochromis niloticus), a possible reservoir for zoonotic transmission

Context: Rare report of bacterial isolation and drug resistance from farmed tilapia fishes in Thailand where high yield of tilapia fish products and export. Aims: 1) To isolated and identified of human pathogens in Tilapia fishes (Oreochromis niloticus) from seven aquacultures at Surat Thani, Thailand, including 4 of well-typed fish ponds, 2 of floating baskets and 1 of nursery fish pond 2) To determine water quality of each fish farm. Materials and Methods: The internal organs from 210 of fish samples were collected for pathogen isolation and identification, and then, tested for antibiotic susceptibility. All microbiological laboratory techniques were performed by Clinical and laboratory standards institute (CLSI) criteria. Water quality was evaluated and compared with standard of water quality criteria. Results and Discussion: The three of most bacterial isolations in Tilapia fish from well-typed fish ponds were Klebsiella pneumoniae, Edwardsiella tarda and coagulase negative Staphylococci. While, K. pneumoniae, Proteus mirabilis, and Streptococcus group D non enterococci were isolated from Tilapia fish, which feeding on river floating baskets. Therefore, only K. pneumoniae and C. albicans were isolated from fry in nursery fish pond. Penicillin and ampicillin resistance were occurred in K. pneumoniae and P. mirabilis. Water qualities of fish water farms were evaluated and almost of water parameters were to water standard quality, except ammonia and alkaline values were higher and lower than reference values, respectively. Conclusions: We were deduced that growing of pathogens in fishes, especially K. pneumoniae may relate to water environment. However, antibiotic resistance of isolated bacteria may concern as zoonotic pathogens.