European Journal of Biomedical and Pharmaceutical Sciences

PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF CARBAPENEM RESISTANCE KLEBSIELLA PNEUMONIAE, PSEUDOMONAS AERUGINOSA AND ESCHERICHIA COLI: FROM A TERTIARY CARE HOSPITAL IN DHAKA, BANGLADESH

*Mst. Junnatul Ferdus, Sanjida Khondakar Setu, Abu Naser Ibne Sattar, Sadika Sarmin,
Sharmin Shanjana

ABSTRACT

Background: Gram-negative bacteria, particularly Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa, have become increasingly resistant to β-lactam antibiotics, particularly carbapenems, posing a significant global health risk. Resistance is largely driven by carbapenemases, but many strains exhibit resistance via overproduction of cephalosporinases, extended-spectrum β-lactamases (ESBLs), reduced outer membrane permeability, and enhanced efflux pump activity, complicating treatment options. Objectives: This study aims to characterize carbapenem-resistant Gram-negative bacteria phenotypically and molecularly to identify the mechanisms driving resistance, guiding appropriate antibiotic use, and informing drug development strategies. Materials and Methods: A total of 75 carbapenem-resistant isolates were collected from various clinical specimens. Identification was performed using MacConkey and chromogenic agars, standard biochemical testing, and the Vitek-2 compact (Biomerieux France). Carbapenemase production was screened using the mCIM and eCIM per CLSI guidelines, and PCR was employed to detect carbapenemase and efflux pump genes. Results: Of the 75 isolates, 34 (45.33%) were phenotypically carbapenemase producers. Molecular analysis identified resistance genes in 67 (89.33%) isolates, with 28 (37.33%) carrying carbapenemase genes, 20 (26.66%) carrying efflux pump genes, and 19 (25.33%) carrying both. KPC and OXA-48 were the predominant carbapenemases, while MexB and AcrAB were the most common efflux pump genes. A significant association was also determined between efflux pump genes and carbapenem resistance (p < 0.001). Conclusion: The co-existence of carbapenemase and efflux pump genes reflects the complexity of resistance mechanisms, emphasizing the need for ongoing surveillance and novel antimicrobial strategies.

Keywords: Carbapenemase, KPC, OXA-48, Efflux pump, Bangladesh, Vitek 2.