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 bla_NDM-1 and bla_IMP-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 bla_NDM-1 and bla_IMP-1 genes.

Results: The mCIM phenotypic test identified 46.25% (37/80) of isolates as carbapenemase producers. PCR analysis revealed that bla_NDM-1 was more prevalent than bla_IMP-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 bla_NDM-1 and bla_IMP-1, indicating the possible involvement of other carbapenemase genes such as bla_VIM or non-carbapenemase mechanisms.

Conclusion: The detection of bla_NDM-1 and bla_IMP-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.