Abstract

Presence of antibiotic-resistant bacteria in fishponds could pose significant threat to public health worldwide. The aim of this study was to determine the chloramphenicol-resistant bacteria (CRB) proportion among total heterotrophic bacteria (THB) in fishponds and their antibiotic susceptibility. The study area was Rumuolumeni in Obio-Akpor Local Government Area of Rivers State in Nigeria. Water samples were collected from fishponds used for rearing African Catfish, and analyzed for pH, turbidity, Nitrate, Phosphate, and populations of THB and CRB. Populations of THB and CRB were used to calculate CRB proportion in the fishponds. CRB were identified through morphological/biochemical means and were subjected to antibiotic susceptibility testing. Zones of inhibition obtained from the susceptibility testing were compared to standard values. The results obtained showed that the pH of water columns in the fishponds ranged from 6.4 to 7.0, turbidity: 7.5 to 28.0 NTU, Nitrate concentration: 6.1 to 22.4 mg/L, phosphate concentration: 0.06 to 3.82 mg/L, THB population: 7.3±0.8 × 10¹⁰ to 4.7±3.2 × 10¹⁴ CFU/ml, and CRB population: 4.5±0.6 × 10¹ to 7.6±0.9 × 10³CFU/ml. CRB proportion among the THB in the fishponds was very low (1×10^-10 to 3×10^-7 %). Identified CRB included Vibrio species, Pseudomonas fluorescens, Staphylococcus species, Streptococcus species, Bacillus species, and Proteus hauseri. Susceptibility results revealed that Gentamicin was the most effective antibiotic against the CRB. It is concluded that though CRB are present in the fishponds, they are of relatively low population and are susceptible to gentamicin.