# Carriage of multidrug-resistant bacteria and encoding genes among Vietnamese children with acute diarrhea

## TL;DR

This study found that nearly a third of Vietnamese children with acute diarrhea carried multidrug-resistant bacteria or resistance genes, highlighting the need for better antibiotic use and infection control.

## Contribution

The study provides new insights into the prevalence and genetic characteristics of multidrug-resistant bacteria in children with acute diarrhea in Vietnam.

## Key findings

- 33.2% of children carried at least one multidrug-resistant bacteria or colistin resistance gene.
- Extended-spectrum β-lactamase–producing Escherichia coli was the most common MDR pathogen.
- mcr-1 and mcr-3 colistin resistance genes were frequently detected in stool samples.

## Abstract

•This work investigated the phenotypic and genetic features of multidrug-resistant (MDR) bacteria.•A total of 33.2% children with acute diarrhea harbored at least one MDR bacteria and/or one colistin-resistance genes.•Extended-spectrum β-lactamase–producing Escherichia coli was the predominant MDR pathogen.•blaCTX-M-A was the most frequent resistance gene among Enterobacteriaceae.•Colistin resistance genes, especially mcr-1 and mcr-3, were commonly detected.

This work investigated the phenotypic and genetic features of multidrug-resistant (MDR) bacteria.

A total of 33.2% children with acute diarrhea harbored at least one MDR bacteria and/or one colistin-resistance genes.

Extended-spectrum β-lactamase–producing Escherichia coli was the predominant MDR pathogen.

blaCTX-M-A was the most frequent resistance gene among Enterobacteriaceae.

Colistin resistance genes, especially mcr-1 and mcr-3, were commonly detected.

This study aimed to assess the prevalence of multidrug-resistant (MDR) bacterial carriage and resistance-encoding genes in children with acute diarrhea.

A prospective study was conducted from July 2020 to July 2021 in hospitalized children aged under 5 years. Stool samples were collected at hospital admission. MDR bacteria were identified by culture, antimicrobial susceptibility patterns were assessed using the disk diffusion method, and resistance genes were investigated in isolates, using real-time polymerase chain reaction. Colistin resistance genes were also tested from stool samples.

A total of 451 children were included; 33.2% harbored at least one MDR bacteria and/or one colistin resistance genes. A total of 79 (17.6%) children were positive for at least one MDR pathogen by culture. A total of 100 isolates were identified, including 17 methicillin-resistant Staphylococcus aureus and 83 Enterobacteriaceae. Escherichia coli was the most common (11.8%), followed by S. aureus (3.8%) and Klebsiella pneumoniae (2.7%). High resistance levels were observed in tested isolates: 94.8% to ceftriaxone, 77.1% to cefepime, 42.2% to piperacillin–tazobactam, and 19.3% to ertapenem. Among methicillin-resistant S. aureus isolates, 15 of 17 (88.2%) carried the mecA gene. Among Enterobacteriaceae, 73/83 (88.0%) carried blaCTX-M-A, 49 (59.0%) had blaTEM, 19 (22.9%) had blaSHV, and six (7.2%) were positive for blaNDM. In addition, 87 (19.3%) of 451 children carried at least one colistin resistance gene, with 10.9% of mcr-1.

MDR bacterial carriage and resistance genes were frequently detected at hospital admission, reflecting community or previous health care–associated exposure rather than in-hospital antibiotic selection. These findings underscore the urgent need for strengthened antimicrobial stewardship, rational antibiotic use, improved infection control, and enhanced diagnostic capacity.