Characterization of antibiotic-resistant Staphylococcus aureus from gills and gastro-intestinal tracts of catfish (Clarias gariepinus), and water samples from Jabi Lake, Abuja, Nigeria

Abstract

Background: The isolation of antibiotic resistant Staphylococcus aureus in freshwater fish poses a threat to public health because of the risk of human infections from consumption of such contaminated fish. Studies assessing antibiotic resistance of bacteria from body parts of fish and freshwater in Nigeria are sparse in the literature. This study therefore characterized S. aureus isolates from gills and gastrointestinal tract (GIT) of catfish (Clarias gariepinus), and water samples from Jabi Lake, Nigeria

Methodology: Over a period of three months (April to June 2018), gills and GIT samples of 30 fish, and water samples randomly collected from 6 sites of the Lake, were cultured on Mannitol Salt Agar (MSA) for the isolation of S. aureus. Standard biochemical tests were used for bacteria identification, and antibiogram of the isolates was determined by the disc diffusion method

Results: The bacterial colony count in the gills (54.6±1.41 x 10⁵ CFU/ml) and GIT (54.3±1.31 x 10⁵ CFU/ml) was significantly higher (p<0.05) than the count from water sample (27.7±2.85 x 10⁵ CFU/mL). S. aureus was isolated from 53% (16 of 30) of the gills, 57% (17 of 30) of the GIT, and 33% (2 of 6) of the water samples (p<0.05). Ninety four point one percent of S. aureus recovered from gills were resistant to ampicillin while 53.3% from the GIT were resistant to levofloxacin. S. aureus from water samples were resistant (100%) to ciprofloxacin, norfloxacin, gentamycin, amoxicillin, rifampicin, erythromycin, ampicillin and levofloxacin, and 50% were resistant to streptomycin and chloramphenicol

Conclusion: The presence of antibiotic resistant S. aureus in this study may be the result of selective antimicrobial pressure from anthropogenic activities as a result of abuse and overuse of antimicrobials leading to residual antibiotics in the aquatic environment

Keywords: Clarias gariepinus; gill, gastrointestinal tract; antibiotic; Staphylococcus