Extended Spectrum Beta Lactamase (ESBL), blaTEM,blaSHV and blaCTX-M, Resistance Genes in Community and Healthcare Associated Gram Negative Bacteria from Osun State, Nigeria.

Abstract

Extended Spectrum Beta Lactamase (ESBL) production in gram negative bacteria confers multiple antibiotic resistance, adversely affecting antimicrobial therapy in infected individuals. ESBLs result from mutations in β-lactamases encoded mainly by the blaTEM,blaSHV and blaCTX-M genes. The prevalence of ESBL producing bacteria has been on the increase globally, especially its upsurge among isolates from community-acquired infections has been observed. To determine ESBL prevalence and identify ESBL genes among clinical isolates in Osun State, Nigeria. A cross-sectional study was carried out from August 2016 - July 2017 in Osun State, Nigeria. Three hundred and sixty Gram-negative bacteria recovered from clinical samples obtained from both community and healthcare-associated infections were tested. They included 147 Escherichia coli (40.8%), 116 Klebsiella spp (32.2%), 44 Pseudomonas aeruginosa (12.2%) and 23 Proteus vulgaris (6.4%) isolates. Others were Acinetobacter baumannii, Serratia rubidae, Citrobacter spp, Enterobacter spp and Salmonella typhi. Disk diffusion antibiotic susceptibility testing was carried out, isolates were screened for ESBL production and confirmed using standard laboratory procedures. ESBLs resistance genes were identified by Polymerase Chain Reaction (PCR). All isolates demonstrated multiple antibiotic resistance. Resistance to ampicillin, amoxicillin with clavulanate and erythromycin was 100%, whereas resistance to Imipenem was very low (5.0%). The overall prevalence of ESBL producers was 41.4% with Klebsiella spp as the highest ESBL producing Enterobacteriacaea. ESBL producers were more prevalent among the hospital pathogens than community pathogens, 58% vs. 29.5% (p=0.003). ESBL genes were detected in all ESBL producers with the blaCTX-M gene predominating (47.0%) followed by blaTEM (30.9%) and blaSHV gene was the least, 22.1%. The blaCTX-M gene was also the most prevalent in the healthcare pathogens (62%) but it accounted for only 25% in those of community origin. A high prevalence of ESBL producing gram-negative organisms occurs both in healthcare and in the community in our environment with the CTX-M variant predominating. Efforts to control the spread of these pathogens should be addressed.