Antibiogram profiles and virulence factors associated with water-borne gram-negative bacteria from Ogbese river, Edo State, Nigeria

Abstract

Surface waters such as flowing rivers, fresh water lakes and hand dug wells are the major sources of water for most rural dwellers in Nigeria. These are often consumed without testing their potability. This study was conducted to assess the bacteriological quality of surface water sampled from five (5) sampling locations on Ogbese river in Ogbese and Olumoye towns, Ovia North East Local Government Area, Edo State. Water samples were collected in duplicates from the sampling locations during the months of June 2018 to February 2019. Bacteriological analysis of the water samples was conducted using the membrane filtration technique and isolates identified by standard cultural and genomic procedures. Disc diffusion technique was utilized to determine the antibiotic sensitivity profiles of the identified bacteria. Other microbiological analysis which comprised of screening for enterotoxin production, invasiveness, hemolysin production and serum resistance, which are all virulence factors were performed using relevant methods. The total heterotrophic bacterial count varied from 1.0 ± 32.0 ×104𝑐𝑓𝑢/𝑚𝑙 and 1.0 ±0.12 ×104𝑐𝑓𝑢/𝑚𝑙 to 9.7 ± 2.23 ×104𝑐𝑓𝑢/𝑚𝑙. The total coliform count ranged from 0.1 ± 0.02 ×102𝑐𝑓𝑢/𝑚𝑙 to 5.5 ± 0.05 ×102𝑐𝑓𝑢/𝑚𝑙. The observed differences between the mean heterotrophic bacterial and coliform counts recorded for Ogbese and Olumoye sampling points was significant (P< 0.05). The identified bacterial isolates included; Escherichia coli, Enterobacter cloacae, Shigella flexneri, Salmonella enterica, Vibrio cholerae, Klebsiella pneumoniae and Pseudomonas aeruginosa Both E. coli (60.0%) and E. cloacae (60.0%) were the most frequently isolated water borne isolates cultured from Ogbese sampling point. All E. coli and S. enterica isolates exhibited sensitivity towards ciprofloxacin and streptomycin. All S. flexneri isolates were invasive and serum resistant. There is an urgent need by relevant Governmental and Non –Governmental agencies to conduct advocacy programs targeted at these communities on the necessity of treating and disinfecting abstracted water sourced directly from the water body prior to drinking.