Antibiogram profiles of heterotrophic bacteria and coliforms isolated from Orogodo river in Agbor - Southern Nigeria

Abstract

This study examined selected bacteriological attributes as well as the antibiogram and plasmid profiling of identified surface water borne bacterial cultures. Several water samples were collected from 3 locations along the Orogodo River in Delta State, Nigeria. Using serial dilution and pour plate procedures, the mean total heterotrophic bacterial (THBC) and coliform counts (TCC) of the water samples were determined.  Tentative identification of the bacterial isolates was achieved by subjecting the respective isolates to several biochemical tests which included Gram staining and catalase production tests.  The overall mean THBC and TCC ranged from 3.59 ± 241 × 10⁵cfu/ml to 7.06 ± 177 × 10⁵ cfu/ml and 3.32 ± 79 × 10⁴ cfu/ml to 4.85 ± 186 × 10⁴cfu/ml respectively. The observed difference between the overall mean THBC and TCC were not insignificant (P> 0.05). The tentatively identified bacterial isolates were; Bacillus sp., Weisselasp., Pseudomonas sp., Corynebacterium sp., Micrococcussp., Pseudomonassp., Shigellasp., Serratia sp., Klebsiella sp., Eschericia coli and Citrobacter sp. respectively.  Antibiotic susceptibility/resistance testing of the bacterial isolates revealed that both Corynebacterium sp. and Serratia sp. Exhibited maximal multiple drug resistance index (MDRI) value of 0.6 respectively, while Citrobacter sp. showed the lowest MDRI value (0.1). Plasmid profiling indicated that Bacilllus sp, Weissela sp., Corynebacterium sp., Micrococcus sp. and Shigella spharbored plasmids while no   plasmid was detected in Klebsiella sp. And E. coli respectively.Findings from this study suggested an urgent need for continuous monitoring of the river as well as implementation of pollution control strategies to protect both public health and the Orogodo river aquatic ecosystem respectively.