Molecular detection of extended-spectrum β-lactamase- and carbapenemase-producing Klebsiella pneumoniae isolates in southwest Iran.

Abstract

Objective: The global emergence of carbapenem-resistant Klebsiella pneumoniae is considered a significant contemporary concern., as carbapenems are the last resort for treating infections caused by multidrug-resistant Gram-negative bacteria. This study aimed to investigate the carbapenem-resistance genes in extended-spectrum β-lactamase producing K. pneumoniae isolates.

Methods: Seventy-five non-duplicate clinical K. pneumoniae strains were isolated from urine, blood, sputum, and wound samples. Antimicrobial susceptibility tests for 12 different antibiotics were performed using the disk diffusion method, followed by determining minimum inhibitory concentrations of imipenem and meropenem. Phenotypic detection of extended-spectrum β-lactamase and carbapenemase enzymes was performed by double-disc synergy test and modified Hodge test, respectively. PCR assay further investigated resistant isolates for extended-spectrum β-lactamase and carbapenemase-encoding genes.

Results: The highest and lowest resistance rates were observed against ampicillin (93.3%) and tigecycline (9.3%). According to phenotypic tests, 46.7% of isolates were positive for extended-spectrum β-lactamase enzymes and 52.8% for carbapenemase. A total of 11 isolates contained carbapenemase genes, with bla_OXA-48 (19.4%; 7/36) being the predominant gene, followed by bla_NDM (8.3%; 3/36).

Conclusion: The study's findings reveal the alarming prevalence of beta-lactamase enzymes in K. pneumoniae strains. Early detection of carbapenem-resistant isolates and effective infection control measures are necessary to minimise further spread, as carbapenem resistance has become a public health concern.