New Delhi metallo-β-lactamases among extensively drug-resistant clinical isolates from Lahore, Pakistan

Aim: The study determines rates of carbapenem resistance (CR) and frequency of blaNDM in multidrug-resistance (MDR) or extensive drug resistance (XDR), and evaluates the potential of phenotypic tests for detecting NDM production. Materials & methods: Singleplex PCR was used to detect blaNDM. Phenotypic tests, including combination disc test (CDST) and modified Hodge test (MHT), were evaluated for NDM production. Results: Among 338 CR isolates, 47.63% were MDR, whereas 52.36% were XDR with 53.25% carrying blaNDM. MHT was found to be discriminative for detecting NDM production, whereas no significant association was observed for CDST. Conclusion: The high incidence of CR and MDR and XDR isolates possessing blaNDM presents an impending threat in therapeutics. Limitations of phenotypic tests suggest better testing, including molecular detection of the enzyme.
The study addresses the emergence of New Delhi Metallo-β-lactamases (NDM) as a cause of carbapenem resistance with its scope limited to Pakistan.
47.63% MDR and 52.36% XDR isolates among 338 carbapenem resistance isolates where 53.25% possessing blaNDM gene reflects the high prevalence of blaNDM in the region.
Phenotypic tests, including modified hodge test (MHT) and combination disc test (CDST), were evaluated for NDM detection accuracy where MHT demonstrated significant discriminative accuracy (p = 0.03) in detecting NDM production, while CDST did not show a significant association (p = 0.12).
Sequencing analysis revealed the dominance of NDM-1 and NDM-5 variants, underscoring their prevalence in the region.
The presence of NDM-1 and NDM-5 variants among in-patients and out-patients highlights the dissemination of blaNDM and poses challenges in therapeutic interventions.
Limitations of phenotypic tests emphasize the need for improved testing strategies, including molecular detection, to accurately identify carbapenemase-producing isolates.