Mobilized Colistin Resistance (mcr) Genes, Resistotyping and Virulence Markers in Escherichia coli from Clinical and Water Samples

Abstract

Pathogenic Escherichia coli are responsible for a diverse range of human infections and diseases, causing a significant increase
in morbidity and mortality rates. This study determined the antibiotic resistance, virulence markers, and mobilized Colistin
resistance genes in E. coli using the disc diffusion method and the Vitek 2 automated system, bacteriological media, and multiplex
polymerase chain reaction, respectively. The results showed that 40.0%, 23.1%, and 30.0% of urine, blood, and wound samples
had E. coli, while 29.4% of water samples contained E. coli. The E. coli were highly sensitive (˃ 68.4%) to Ampicillin and
Ofloxacin, but ˃ 47.4% were resistant to Augmentin, Pefloxacin, and Nalidixic Acid. Of the 19 E. coli isolates, 9 (47.4%) and 8
(42.1%) exhibited intermediate resistance to Streptomycin, and Ciprofloxacin, respectively. All E. coli were resistant to
Cefalexin, and 84.2% were resistant to Nalidixic Acid, while E. coli (Ec-B3) was sensitive to Ciprofloxacin. The results showed
that E. coli (Ec-W1 and Ec-U5) and ExPEC (Ec-B1 and Ec-B2) shared 97.5% and 92% similarity, respectively. Of the 19 E. coli
strains obtained, 69.4%, 57.9%, and 52.6% were gelatinase-, lipase-, and caseinase-producing strains, respectively. The results
revealed that 57.9% of the E. coli strains were mobilized Colistin-resistant (COR), with 31.6%, 5.3%, and 21.1% having the mcr1, mcr-2, and mcr-3 genes, respectively. The E. coli harboured some virulence markers and were highly resistant to Cefalexin,
Nalidixic Acid, Augmentin, Pefloxacin, and Colistin, with mcr-1 as the predominant mcr gene. Thus, regular monitoring of
antibiotic susceptibility of bacterial isolates in both the community and hospital settings is recommended.