P-1284. Phenotypic Mapping of Carbapenem-Resistant Gram-Negative Bacteria among Clinical Isolates in Nepal: High Prevalence of Combination NDM and OXA-48-like Carbapenemases, Absence of Plasmid-Mediated Colistin Resistance (mcr-1)

TL;DR

This study found high rates of carbapenem-resistant bacteria in Nepal, with common NDM and OXA-48-like enzymes, but no colistin resistance gene mcr-1 in clinical isolates.

Contribution

The study reports the first phenotypic mapping of CR-GNB in Nepal, highlighting NDM + OXA-48-like co-production and absence of mcr-1 in clinical isolates.

Findings

75% of isolates produced carbapenemases, with NDM + OXA-48-like being more common than NDM alone.

No mcr-1 gene was detected in the 14 tested isolates, despite its presence in regional poultry.

K. pneumoniae was the most prevalent species, and one Acinetobacter isolate showed resistance without carbapenemase production.

Abstract

Carbapenem-resistant Gram-negative bacteria (CR-GNB) threaten global health, especially in South Asia, where multidrug resistance (MDR) is driven by antibiotic overuse and poor infection control. Previous studies have reported a high prevalence of multidrug-resistant Gram-negative bacilli in Nepal, with widespread carbapenemase genes. The mcr-1 gene, conferring colistin resistance, is reported in 1–21% of global samples and 20–60% of South Asian poultry, posing a pandrug-resistance risk. This study characterizes meropenem-resistant gram-negative bacteria in Nepal, assessing carbapenemase profiles, mcr-1 status, and the possibility of other resistance mechanisms.Distribution of Bacterial SpeciesCarbapenemase Production

Distribution of Bacterial Species

Carbapenemase Production

A retrospective study at the Center for American Medical Specialists (CAMS) clinic, Nepal, analyzed 24 meropenem-resistant gram-negative bacteria from human clinical samples (blood, urine, sputum, wound swabs) collected May 2024–April 2025 from local tertiary hospitals. Carbapenemase production was tested using the FDA-approved NG Biotech CARBA 5 assay (KPC, OXA-48-like, NDM, VIM, IMP). 14 isolates were tested for mcr-1 using NG Biotech’s MCR-1 assay.Distribution of Carbapenemase Types Among ProducersPhenotypic mapping of Carbapenem-Resistant Gram-Negative Bacteria

Distribution of Carbapenemase Types Among Producers

Phenotypic mapping of Carbapenem-Resistant Gram-Negative Bacteria

K. pneumoniae (58.3%) was the most prevalent CR-GNB. Carbapenemases occurred in 75% of isolates, with NDM being the dominant one at 94.4%; surprisingly, NDM + OXA-48-like (41.7%) was more prevalent than NDM alone (20.8%). One Acinetobacter isolate was meropenem-resistant, imipenem-sensitive, and carbapenemase-negative, suggesting efflux pumps or porin loss. All 14 tested isolates were mcr-1-negative. Details are shown in the tables.

This study's 75% carbapenemase rate and 41.7% NDM + OXA-48-like co-production reflect South Asia’s MDR crisis, surpassing USA/Europe rates. Although a small sample size, the low E. coli prevalence (4.2%) in this study is atypical for South Asia. The absence of mcr-1 in clinical isolates, despite its prevalence in regional poultry, may preserve colistin’s efficacy. Point-of-care diagnostics are vital for Nepal’s resource-limited setting, aiding targeted therapy, infection control, and antimicrobial stewardship.

Prabhat Adhikari, MD (Infectious Diseases & Critical Care), Novala Biotech Pvt Ltd, Nepal: Advisor/Consultant|Novala Biotech Pvt Ltd, Nepal: Board Member Sunita Gautam, PhD (Molecular Biotechnology), Novala Biotech Pvt Ltd, Nepal: Advisor/Consultant|Novala Biotech Pvt Ltd, Nepal: Board Member Kabin Maleku, Pharmacist (MPharm), Novala Biotech Pvt Ltd, Nepal: Advisor/Consultant|Novala Biotech Pvt Ltd, Nepal: Board Member Ravindra m. Sapkota, PhD (Immunology), Novala Biotech Pvt Ltd, Nepal: Advisor/Consultant|Novala Biotech Pvt Ltd, Nepal: Board Member

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