ANTIBIOTIC RESISTANCE PATTERN, PLASMID CURING AND EXTENDED SPECTRUM BETA-LACTAMASE PRODUCTION BY BACTERIAL ISOLATES FROM HOSPITAL LABORATORY WASTEWATER

Abstract

Antibiotic resistance pattern, plasmid curing and extended spectrum beta-lactamase production in bacteria isolated from hospital wastewater collected from three Local Government Areas (Offa, Oyun and Ifelodun) of Kwara State, Nigeria, were carried out in this study. The hospital laboratory wastewater samples were collected during wet season and the dry season periods. The bacteria isolated from the samples were identified using conventional and molecular methods. Theses microbes were then subjected to antibiotic susceptibility test on Muller-Hinton agar using disk diffusion methods. The plasmids of the resistant bacteria were cured using 0.1mg/ml acridine orange. The production of extended beta-lactamase of bacteria was investigated using starch paper strip and double disc synergy test respectively. Also the types of beta-lactamase in the genome of isolates were detected using conventional and multiplex polymerase chain reaction (PCR) techniques. The findings from this study confirmed that hospital wastewaters had higher bacterial loads during dry season than in wet season. The bacterial isolates from hospital wastewater samples included Alcaligenes faecalis, A. aquatilis, Staphylococcus saprophyticus, Providencia rettgeri and Streptomyces nodosus. The study also confirmed A. faecalis as the most predominant and prevailing bacteria inhabiting hospital wastewater. The findings from invitro antibiotic susceptibility pattern on both the wet and dry seasons isolates of the three Local Government Areas indicated that ofloxacin (OFL) demonstrated highest antimicrobial potency against the test isolates, with diameter zone of inhibition (mm) (resistant ≤12, intermediate 13-15 and susceptible ≥ 16), while cefixime (CXM) has the least potency with diameter zone of inhibition diameters (mm) (resistant ≤15, intermediate 16-18 and susceptible ≥ 19), among the selected antibiotics. The study of in vitro antibiotic suceptibiity pattern of bacteria isolated from hospital wastewaters collected from Offa Local Government Area of Kwara State, after curing of plasmid revealed that the resistance of Alcaligenes faecalis JF3 and A. aquatilis YFMCD4 to ceftazidine (CAZ) were plasmid mediated, while the resistance of Staphylococcus saprophyticus FELA049, A. faecalis M453B1 and A. faecalis ISJI28 to ceftazidine (CAZ) were chromosomal

mediated. More so, the investigations on tests for production of beta lactamases among the hospital wastewaters’ bacteria in the three Local Government Areas revealed that A. faecalis M453B, S. nodosus N562010, A. faecalis HSC25S18 and A. faecalis SY1 were positive for beta-lactamase production while, A. aquatilis YFMCD4 and S. saprophyticus FELA049 were negative for betalactamase production. Finally, the detection of beta-lactamases possessed by the resistant isolates confirmed that the most frequently encountered mechanisms of resistance to beta-lactams found in this study were the productions of TEM and CTX-M beta-lactamases. This study also confirmed that isolates; Streptomyces sp. N562010, A. faecalis M453BI and A. faecalis KWW84 possessed genes for enzymes TEM and CTX-M at the same time. Thus, hospital wastewater must be avoided from getting into municipal water supply to prevent infections associated with A. faecalis, A. aquatilis, P. rettgeri and S. nodosus. The populace should be educated on the risk of self-medication and misuse of antibiotics in order to prevent the prevalence and emergence of resistant strains thereby reducing the spread of plasmid-mediated ESBL resistance in hospitals.