# 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.

## Key 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