Antibiotic Resistance Profile of CTX-M-type Extended-Spectrum Beta-Lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Abstract

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. The most common ESBL types include CTX-M, TEM and SHV. This genetic diversity in the various ESBL-producing organisms may reflect characteristic differences in relation to pathogenesis, antibiotic resistance expression, response to therapy, transmission and infection control. This work sought to determine the characteristic antibiotic minimum inhibition concentrations (MICs) and antimicrobial sensitivity profile of CTX-M-type ESBLs in Accra. Hundred (100) DNA templates were extracted from ESBL-producing K. pneumoniae and E. coli isolates. The specific ESBL types were determined by polymerase chain reaction with specific primers and reaction conditions. The MICs of the antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France). The results showed that CTX-M-type ESBL have cefotaxime MIC in the resistant range of >64 µg/ml. The CTX-M-type ß-lactamases showed co-resistances to gentamicin (88.6%), tetracycline (71.4%), trimethoprim-sulphamethoxazole (98.6%).The resistance of CTX-M-type ESBL producing organisms to fluoroquinolones have been well established in this work with resistances in ciprofloxacin (71.4%) and norfloxacin (71.4%) with MIC₉₀ being >4 µg/ml and >16 µg/ml respectively. The beta-lactam-beta-lactamase inhibitor combination of piperacillin-tazobactam was more susceptible to CTX-M-type ESBL than amoxicillin-clavulanate. Imipenem and amikacin has been established as the in vitro drug of choice for the management of organisms producing CTX-M-type ESBL in this present work. Efforts should be made to control the increasing prevalence of CTX-M-type producing organisms in the communities and hospital settings in Accra with their adverse multiple-drug resistance.

Keywords: Extended spectrum beta-lactamase, CTX-M-type ESBL, Resistance, Antibiotics