# Detection of O25B-ST131 clone and blaCTX-M-15 gene in Escherichia coli isolated from patients with COVID-19

## TL;DR

The study found a high prevalence of antibiotic-resistant Escherichia coli, specifically the O25B-ST131 clone with the blaCTX-M-15 gene, in patients with COVID-19.

## Contribution

This study reports the detection of the O25B-ST131 clone and blaCTX-M-15 gene in E. coli from COVID-19 patients, highlighting a new clinical concern.

## Key findings

- Most E. coli isolates were ESBL producers with resistance to multiple cephalosporins.
- 68.4% of isolates carried the blaCTX-M-15 gene, and 75% of these were the O25B-ST131 clone.
- Combined disc test (CDT1) showed better agreement as a phenotypic screening test for ESBL.

## Abstract

Isolation of blaCTX-M family of extended-spectrum beta-lactamases (ESBL) is a challenge in the field of microbiology in our locality that makes treatment fail and disseminate quickly.

To determine the prevalence of blaCTX-M-15 ESBL gene in Escherichia coli clone O25B-ST131 isolated from COVID-19 patients with different infections.

This cross-sectional study was conducted on 528 patients hospitalized due to COVID-19 infection with various symptoms from April to September 2021. Using standard culturing techniques, E. coli were isolated from patients’ various samples (urine, catheter tip, sputum, blood, endotracheal tube aspiration, pleural/peritoneal fluids, and throat swab). After the antibiotic susceptibility test, E. coli isolates that were resistant to more than one of the three cephalosporins (cefotaxime, ceftriaxone and ceftazidime) were tested for ESBL production using the double disc synergy test and combined disc test, then confirmed by genotypic detection of blaCTX-M-15 gene among clones of O25B-ST131 E. coli. Finally, it was sequenced and its incision number was received from NCBI.

A total of 234 E. coli isolates were detected from various patients’ samples, and all isolates showed multiple degrees of antibiotic resistance, especially ceftriaxone, ceftazidime, and cefepime. The phenotypic test showed that 63.2% of E. coli isolates were positive for ESBL, of which 58.1% were confirmed by double disc synergy test (DDST) (p = 0.002), 83.8% by combined disc test (CDT1) (p < 0.001) and 60.1% by CDT2 (p < 0.001). However, CDT1 has a better agreement as a phenotypic screening test (72.5% with a kappa value of 0.24) than DDST and CDT2. Most E. coli isolates were positive for the blaCTX-M-15 gene (68.4%), of which 75% were positive for the O25B- ST131 clone.

Most E. coli isolates were ESBL producers, held blaCTX-M-15 gene and were positive for the O25B-ST131 clone.