Plasmid Carriage and Antibiotics Susceptibility of Cultivable Bacteria Isolated from Hospital Wastewater
M. P. Uko *
Department of Biological Sciences, Akwa Ibom State University, Nigeria.
S. C. U. Nwachukwu
Department of Microbiology, University of Lagos, Akoka, Lagos, Nigeria.
S. I. Umana
Department of Biological Sciences, Akwa Ibom State University, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Careless discharge of wastewater is another source of which the environmental health is continuously being threatened. Hospital wastewater contains clinically relevant strains. Study was undertaken on the prevalence of antibiotics resistant bacteria (ARB) in hospital wastewater and to determine the presence of plasmid and its association with antibiotic resistance expression among the bacteria using standard microbiological techniques and alkaline lysis method, respectively. Antibiotic susceptibility was determined by use of the disk diffusion method. Total heterotrophic count of 1.36 x 107 and 2.0 x 106 CFU/mL were obtained, Escherichia coli count gave 2.1 x 105 and 1.6 x 106 CFU/mL and Staphylococcal count gave 1.4 x 106 and 1.2 x 105 CFU/mL. Species of Staphylococcus, Pseudomonas, Klebsiella, Bacillus, Escherichia, Acinetobacter and Salmonella, were identified. Based on a differential staining process, the bacteria were tested against some commonly used antibiotics. A high profile of multi-antibiotics resistance was displayed among the bacteria. The percentage of resistance to the antibiotics were COT - 15%, AUG - 15%, GEN - 11%, TET - 10%, OFL - 3%, AMX - 10%, NIT - 5%, NAL - 6%, CXC - 10%, CHL - 6%, ERY - 3% and STR - 6%. Approximately 58% of the bacteria carried plasmids. Plasmid band size of 23.1 kbp was common among the bacteria. Resistance was observed in bacteria with plasmids as well as in those without plasmids. On curing, the organisms showed reduced resistance to the antibiotics while Pseudomonas aeruginosa and Bacillus sp. maintained their resistant pattern. Hospital wastewater contains loads of antibiotic resistant bacteria whose resistance in part are carried in plasmid. It contributes to environmental contamination with clinically important strains of microorganisms. The practice of releasing hospital wastewater into the environments should be strongly monitored and prohibited as the environment has a lot to do in our functioning and metabolic efficiency and therefore should be kept clean.
Keywords: Hospital wastewater, antibiotics susceptibility, microbial resistance, plasmid carriage