Detection of blaNDM-1 and blaIMP-1 Metallo-β-Lactamases in Meropenem-Resistant Clinical Escherichia coli Isolates Using Modified Carbapenem Inactivation Method (mCIM) and PCR Techniques.

INTRODUCTION: Escherichia coli, a member of the Enterobacteriaceae family, is a leading cause of various infections. Carbapenems, a potent class of β-lactam antibiotics, serve as the last line of defense against multidrug-resistant bacteria. However, the global rise of carbapenemase-producing E. coli (CP-Ec), particularly metallo-β-lactamases (MBLs), poses a significant public health concern. This study aimed to determine the prevalence of blaNDM-1 and blaIMP-1 genes in E. coli strains isolated from clinical samples. METHODS: A cross-sectional study was conducted on 80 meropenem-resistant E. coli strains isolated from clinical samples. Bacterial identification was performed using biochemical tests, including IMViC. Carbapenemase production was assessed using the modified carbapenem inactivation method (mCIM). Genotypic analysis of carbapenem-resistant strains was conducted via polymerase chain reaction (PCR) to detect blaNDM-1 and blaIMP-1 genes. RESULTS: The mCIM phenotypic test identified 46.25% (37/80) of isolates as carbapenemase producers. PCR analysis revealed that blaNDM-1 was more prevalent than blaIMP-1 (48.65% vs. 16.22%). Four isolates (10.81%) carried both genes. Notably, 35.14% (13/37) of meropenem-resistant E. coli isolates tested negative for both blaNDM-1 and blaIMP-1, indicating the possible involvement of other carbapenemase genes such as blaVIM or non-carbapenemase mechanisms. CONCLUSION: The detection of blaNDM-1 and blaIMP-1 genes in E. coli highlights the alarming spread of carbapenem resistance. The presence of resistant strains lacking these genes suggests additional resistance mechanisms, warranting further investigation.