Bacteriological Quality and Prevalence of Multidrug Resistant Gram-negative Bacteria from Surface and Underground Domestic Water Sources in Selected Locations in Ibadan, Oyo State, Nigeria

Aim: To examine the bacteriological quality and prevalence of multidrug resistant (MDR) Gram-negative bacteria in surface and underground domestic water sources in Ibadan.

Study Design: Descriptive cross-sectional study.

Place and Duration of Study: Collection of water samples was in Ibadan, Oyo State, Nigeria; Analysis of water samples and characterisation of bacterial isolates was at the laboratory of the Department of Pharmaceutical Microbiology, University of Ibadan, between September 2015 and November 2015.

Materials and Methods: Twenty six water samples involving 2 collections each at 2 weeks intervals, from 13 different selected sources (8 hand-dug wells, 3 flowing rivers and 2 dams) were collected sequentially within Ibadan. Determination of total viable bacteria count was by pour-plate method, presumptive coliform count was by broth-dilution method, Bacterial identification was by standard methods and antibiotic susceptibility testing was by disc-diffusion method.

Results: The mean values of the total viable counts for the first water sample collection ranged from 3.1×102 to 6.2×104 cfu/mL and 2.4×102 to 6.1×104 cfu/mL for the second collection with the mean difference statistically significant for samples from sites AJR, DDR, ADM, EDM, WW-B and WW-G (P > .05). Most Probable Number of Coliforms ranged from 20 to >180/100 mL. A total of 7 bacteria genera including E. coli, Klebsiella spp., Proteus spp., Pseudomonas spp., Serratia spp., Providencia spp. and Enterobacter spp. were isolated. Among the isolates, 100% showed resistance to ampicillin, over 80% to amoxicillin, amoxicillin-clavulanic acid, cefuroxime and cefotaxime, 60% to ceftazidime, over 50% to ciprofloxacin and aztreonam, <40% to ofloxacin, nitrofurantoin and gentamicin while 100% were susceptible to the carbapenems. A total of 90.9% exhibited MDR phenotype.

Conclusion: In this study, the presence of high level of coliforms with MDR phenotype in surface and underground water used domestically in Ibadan signifies a public health hazard that requires urgent attention.