Phenotypic And Genotypic Detection Of Carbapenemase-Producing Escherichia Coli And Klebsiella Pneumoniae In Accra, Ghana

Abstract

Background: Escherichia coli and Klebsiella pneumoniae belong to the Enterobacteriaceae family, and are pathogens of high clinical significance. They are prone to acquiring antibiotic resistance genes, including those encoding carbapenemases, which confer resistance to carbapenems (the current drugs of last resort against infections with multidrug-resistant [MDR] Enterobacteriaceae). However, little is known about carbapenemase-producing E. coli and K. pneumoniae in Ghana. Aim: To investigate the occurrence of carbapenem resistance among MDR E. coli and K. pneumoniae isolated from clinical specimens in Accra using phenotypic and genotypic methods. Methodology: The study was cross-sectional, involving 144 clinical MDR E. coli and K. pneumoniae isolates originating from 15 different sample types from the Central Microbiology Laboratory of the Korle Bu Teaching Hospital between the periods of December 2020 to March 2021. The isolates were re-cultured, subsequently identified using standard biochemical tests, and subjected to antibiotic susceptibility testing using the Kirby-Bauer method. Carbapenem resistance was determined based on imipenem, meropenem, and ertapenem zones of inhibition, as well as minimum inhibitory concentrations (MICs); carbapenemase production was confirmed phenotypically with the Modified Hodge test (MHT) and Modified Carbapenem Inactivation Method (mCIM) and genotypically with multiplex PCR targeting blaKPC, blaIMP, blaNDM, blaVIM, and blaOXA-48. Results: Of the 144 MDR isolates, 69.4% were E. coli, and 30.6% were K. pneumoniae. The distribution of antimicrobial resistance rates among them were ampicillin (97.2%), cefuroxime (93.1%), sulfamethoxazole-trimethoprim (86.8%), tetracycline (85.4%), cefotaxime and cefpodoxime (77.1% each), amoxicillin-clavulanate (75%), ceftriaxone (73.6%), ciprofloxacin (70.8%), levofloxacin (66.0%), cefepime (65.3%), ceftazidime (64.6%), gentamicin (48.6), piperacillin-tazobactam (40.3%), cefoxitin (14.6%), amikacin (13.9%), ertapenem and meropenem (5.6% each), and imipenem (2.8%). In total, 5.6% (8/144) of them were carbapenem-resistant (carbapenem MIC range = 0.094–32.0 μg/ml), with 75% (6/8) of these testing positive by the phenotypic tests and 62.5% (5/8) by the genotypic test (of which 80% [4/5] carried blaOXA-48 and 20% (1/5) blaNDM). The blaVIM, blaIMP, and blaKPC genes were not detected. Conclusion: Although the rates of antibiotic resistance among the isolates were high, the prevalence of carbapenemase producers were low. There is evidence that blaOXA-48 and blaNDM may be circulating in Ghana, warranting upscaling of antimicrobial resistance surveillance programmes and fortification of infection prevention and control programmes in the country.