CHROMagar COL-APSE medium as a screening method for fecal carriage of Colistin resistant Enterobacteriaceae among patients in Mansoura university hospitals, Egypt

N A Mahmoud ,Samah Sabry El-Kazzaz

doi:10.21608/nrmj.2021.204801

Abstract

Colistin resistance (Col-R) has been rising worldwide with high rate of morbidity and mortality. The emergence of mobile colistin resistance (mcr) harboring microorganisms become of a health concern. Hence, screening for fecal carriage of Col-R Enterobacteriaceae could aid in the prevention and control efforts of Col-R. This study aimed to screen for Col-R Enterobacteriaceae in the stool specimens of the hospitalized patients; explore for colistin minimal inhibitory concentrations (MIC) and the genetic determinants of these isolates, and to predict the risk factors among the studied patients' groups. Stool specimens from 290 hospitalized adult patients were screened for the presence of Col-R bacterial isolates using CHROMagar COL-APSE medium. Colistin MIC was estimated for Col-R Enterobacteriaceae using the broth microdilution (BMD) assay. Bacterial isolates were screened through the Polymerase chain reaction (PCR) for the existence of mcr-1 and mcr-2 genes. The fecal carriage of Col-R among the studied patients was 16.8 %. About 72 Col-R bacterial isolates were recovered. Col-R Enterobacteriaceae were predominant and were detected in 89.7 % of the bacterial isolates. Using the BMD, Col-R was confirmed and most of the isolates showed low resistance MIC titer (4 μg/ ml; 55.7 %). In addition, mcr-1 gene was the most frequent Col-R gene detected (69.2 %), while mcr-2 gene was less prevalent (11.5 %). The current study reported high prevalence of the Col-R and mcr-1 gene harbored by the fecal flora; with the risk to be easily transmitted inside the hospitals and within the different communities. This highlights the need for active surveillance in addition to the infection control programs.

Highlights

Colistin is a polymyxin antimicrobial agent, which is important in curing infections triggered by the multiple drug-resistant (MDR) Gram negative rods (GNRs)
The objectives of the current study were to screen for Colistin resistance (Col-R) Enterobacteriaceae in the stool specimens of the hospitalized patients; explore for colistin minimal inhibitory concentrations (MIC) and genetic determinants of these isolates, and to predict the risk factors associated with Col-R among the studied patients' groups
About 290 stool samples were collected during this study; where 49 samples showed growth (Colistin resistant) on CHROMagar COL-APSE medium, 241 plates showed no growth (Colistin sensitive) and were excluded from further analysis

Summary

Introduction

Colistin is a polymyxin antimicrobial agent, which is important in curing infections triggered by the multiple drug-resistant (MDR) Gram negative rods (GNRs). Colistin interacts with the outer membrane of the Gram-negative bacterial cell wall; causing its damage as a bactericidal effect (Magiorakos et al, 2013). Ilsan et al, (2021) recently reported that Col-R has been rising worldwide mainly in Asia and in the Mediterranean region; with high morbidity and mortality rates. Bacterial resistance to colistin is either acquired or intrinsically originated. Acquired Col-R is either encoded on the bacterial chromosome through untransferable two-component systems PmrAB and PhoPQ; or more frequently be plasmid-borne through mcr genes, which encodes for Lipid A phosphoethanolamine transferase enzyme. The emergence of mcr harboring microorganisms become of health concern, which could be transferred between the different species (Nordmann et al, 2016; Grégoire et al, 2017)

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