ABSTRACT
Tilapia fishes (Oreochromis niloticus) are commonly consumed and exported in Thailand. Bacterial isolation anddrug resistance from farmed tilapia fished in Thailand were previously reported. This study was purposed to studyon the distribution of human pathogenic bacteria in tilapia fishes, which were collected from Thai farms (n = 180)and fresh markets (n = 160) by identification, antibiotic susceptibility test; and conduct to identify virulence genesby molecular technique. Pathogen isolations were collected from internal organs of fish samples for identificationand test of antibiotic susceptibility according to Clinical and Laboratory Standards Institute (CLSI) criteria. blaCTX-Mand Int1 genes detection of antibiotic resistance bacteria was performed by molecular based techniques. Klebsiellapneumoniae, Edwardsiella tarda, and coagulase-negative Staphylococci were most frequent bacteria isolated fromfarming tilapia fishes, respectively. However, Escherichia coli, coagulase-negative Staphylococci, and K. pneumoniawere frequently distributed from tilapia fishes in markets of Bangkok area. Klebsiella pneumoniae, E. coli, and Proteusmirabilis were resisted to penicillin and ampicillin. Klebsiella pneumoniae is the most important isolated bacteria dueto the distribution in tilapia fishes and positive for blaCTX-M and Int1 gene detection. However, E. coli and P. mirabiliswere lack of blaCTX-M and Int1 genes, possibly there may reserve other antibiotic resistance genes