# Molecular Assessment Using the MASTDISCS® Combi D72C Set for the Phenotypic Detection of Extended-Spectrum Beta-Lactamases, AmpC Beta-Lactamases, and Carbapenemase Enzymes in Escherichia coli and Klebsiella pneumoniae

## TL;DR

This study evaluates the MASTDISCS® Combi D72C test for detecting antibiotic resistance enzymes in E. coli and K. pneumoniae, finding high rates of resistance genes in clinical isolates.

## Contribution

The study validates the MASTDISCS® Combi D72C set for phenotypic detection of β-lactamase enzymes and identifies co-expression of resistance genes in clinical isolates.

## Key findings

- 90.6% of E. coli and 100% of K. pneumoniae isolates showed ESBL and AmpC enzyme production.
- blaCTX-M and blaSHV genes were most common ESBL genes in the isolates.
- blaOXA was the most prevalent carbapenemase gene across both pathogens.

## Abstract

Beta-lactam resistance poses a global issue and a considerable challenge to effective antimicrobial therapy. The study aimed to ascertain the phenotypic and genotype traits of carbapenemase, extended-spectrum beta (β)-lactamases (ESBL), and AmpC β-lactamase-producing isolates collected from hospitals. A range of clinical samples consisted of 63 Escherichia coli
(E. coli) and 30 Klebsiella pneumoniae (K. pneumoniae) isolates. Phenotypic characterization was carried out utilizing the MASTDISCS® Combi ESBL, AmpC, and carbapenemase detection set-D72C (Mast Group Ltd, Bootle, United Kingdom). Molecular assays were used to detect carbapenemase, ESBL, and AmpC genes. Both E. coli and K. pneumoniae clinical isolates exhibited noticeably enhanced resistance to β-lactam antibiotics. MASTDISCS® Combi D72C phenotype detection tests revealed that 57 (90.6%) E. coli and 30 (100%) K. pneumoniae isolates produced ESBL and AmpC enzymes, with evidence of carbapenemase activity. The majority of isolates had at least one β-lactamase-related gene. Based on molecular findings, the majority of ESBL-producing isolates in both pathogens had 17 (56.6%) of the blaCTX-M gene in K. pneumoniae and 16 (53.3%) of the blaSHV gene in both pathogens. The AmpC-associated genes, both blaCMY1, and blaCMY2, were exposed in five (16.6%) K. pneumoniae isolates and nine (30%) and 10 (33.3%) among E. coli, respectively. In terms of the carbapenemase gene, blaOXA was the most prevalent gene, appearing in 20 (66.6%) of the two pathogens.This study demonstrated that K. pneumoniae and E. coli that produceβ-lactamases have emergedas pathogens linked to infections in healthcare settings. Accurate identification of β-lactamase-producing bacterial pathogens is essential for patient treatment. We observed co-expression of AmpC, carbapenemase, and ESBL genes in most isolates, indicating a need to implement modern plans against these pathogens.