Gut Commensal Escherichia coli, a High-Risk Reservoir of Transferable Plasmid-Mediated Antimicrobial Resistance Traits

Mahmoud Mohamed Tawfick; Aliaa Ali Elshamy; Kareem Talaat Mohamed; Nagwan Galal El Menofy

doi:10.2147/IDR.S354884

Gut Commensal Escherichia coli, a High-Risk Reservoir of Transferable Plasmid-Mediated Antimicrobial Resistance Traits

Infect Drug Resist. 2022 Mar 16:15:1077-1091. doi: 10.2147/IDR.S354884. eCollection 2022.

Authors

Mahmoud Mohamed Tawfick^{1

2}, Aliaa Ali Elshamy², Kareem Talaat Mohamed³, Nagwan Galal El Menofy⁴

Affiliations

¹ Department of Microbiology and Immunology, Faculty of Pharmacy (For Boys), Al-Azhar University, Cairo, 11751, Egypt.
² Department of Microbiology and Immunology, Faculty of Pharmacy, Heliopolis University, Cairo, 11785, Egypt.
³ Department of Microbiology and Immunology, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), 6th October City, Giza, 11787, Egypt.
⁴ Department of Microbiology and Immunology, Faculty of Pharmacy (For Girls), Al-Azhar University, Cairo, 11751, Egypt.

Abstract

Background: Escherichia coli (E. coli), the main human gut microorganism, is one of the evolved superbugs because of acquiring antimicrobial resistance (AMR) determinants via horizontal gene transfer (HGT).

Purpose: This study aimed to screen isolates of gut commensal E. coli from healthy adult individuals for antimicrobial susceptibility and plasmid-mediated AMR encoding genes.

Methods: Gut commensal E. coli bacteria were isolated from fecal samples that were taken from healthy adult individuals and investigated phenotypically for their antimicrobial susceptibility against diverse classes of antimicrobials using the Kirby Bauer disc method. PCR-based molecular assays were carried out to detect diverse plasmid-carried AMR encoding genes and virulence genes of different E. coli pathotypes (eaeA, stx, ipaH, est, elt, aggR and pCVD432). The examined AMR genes were β-lactam resistance encoding genes (bla _CTX-M1, bla _TEM, bla _CMY-2), tetracycline resistance encoding genes (tetA, tetB), sulfonamides resistance encoding genes (sul1, sulII), aminoglycoside resistance encoding genes (aac(3)-II, aac(6')-Ib-cr) and quinolones resistance encoding genes (qnrA, qnrB, qnrS).

Results: PCR results revealed the absence of pathotypes genes in 56 isolates that were considered gut commensal isolates. E. coli isolates showed high resistance rates against tested antimicrobial agents belonging to both β-lactams and sulfonamides (42/56, 75%) followed by quinolones (35/56, 62.5%), tetracyclines (31/56, 55.4%), while the lowest resistance rate was to aminoglycosides (24/56, 42.9%). Antimicrobial susceptibility profiles revealed that 64.3% of isolates were multidrug-resistant (MDR). High prevalence frequencies of plasmid-carried AMR genes were detected including bla _TEM (64%) sulI (60.7%), qnrA (51.8%), aac(3)-II (37.5%), and tetA (46.4%). All isolates harbored more than one gene with the most frequent genetic profile among isolates was bla _TEM-bla _CTX-M1-like-qnrA-qnrB-tetA-sulI.

Conclusion: Results are significant in the evaluation of plasmid-carried AMR genes in the human gut commensal E. coli, suggesting a potential human health risk and the necessity of strict regulation of the use of antibiotics in Egypt. Commensal E. coli bacteria may constitute a potential reservoir of AMR genes that can be transferred to other bacterial species.

Keywords: MDR; antibiotic resistance; gut microorganisms; plasmid; resistance genes.

Grants and funding

This research is self-funded and received no external funding or any specific grant from funding agencies.