Escherichia coli from Human Wounds: Analysis of Resistance to β-Lactams and Expression of RND Efflux Pumps

Martin Rihacek; Michaela Kuthanova; Zbynek Splichal; Vojtech Adam; Kristyna Hrazdilova; Radek Vesely; Ludek Zurek; Kristyna Cihalova

doi:10.2147/IDR.S435622

Escherichia coli from Human Wounds: Analysis of Resistance to β-Lactams and Expression of RND Efflux Pumps

Infect Drug Resist. 2023 Nov 29:16:7365-7375. doi: 10.2147/IDR.S435622. eCollection 2023.

Authors

Martin Rihacek¹, Michaela Kuthanova¹, Zbynek Splichal¹, Vojtech Adam¹, Kristyna Hrazdilova¹, Radek Vesely^{2

3}, Ludek Zurek¹, Kristyna Cihalova¹

Affiliations

¹ Department of Chemistry and Biochemistry, Mendel University in Brno, Brno, Czech Republic.
² Department of Traumatology at the Medical Faculty, Masaryk University and Trauma Hospital Brno, Brno, Czech Republic.
³ Department of Traumatology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.

Abstract

Purpose: Resistance of pathogenic strains of Escherichia coli to β-lactams, particularly to ampicillin, is on the rise and it is attributed to intrinsic and acquired mechanisms. One important factor contributing to resistance, together with primarily resistance mechanisms, is a mutation and/or an over-expression of the intrinsic efflux pumps in the resistance-nodulation-division (RND) superfamily. Among these efflux pumps, AcrA, AcrB, TolC, and AcrD play an important role in antimicrobial co-resistance, including resistance to β-lactams.

Materials and methods: Twelve E. coli isolates obtained from patients' wounds and the control strain of E. coli ATCC 25922 were analyzed. The phenotypic resistance of these isolates to selected β-lactams was assessed by determination of the minimal inhibitory concentration. Additionally, the prevalence of β-lactamase genes (bla_TEM, bla_CTX-M, bla_SHV, and bla_AmpC) was screened by PCR. Real-time qPCR was used to determine the expression of the selected efflux pumps acrA, acrB, tolC, and acrD and the repressor acrR after the exposure of E. coli to ampicillin.

Results: Phenotypic resistance to β-lactams was detected in seven isolates, mainly to ampicillin and piperacillin. This was corroborated by the presence of at least one acquired bla gene in each of these isolates. Although E. coli strains varied in the expression of RND-family efflux pumps after the ampicillin exposure, their gene expression indicated that these pumps did not play a major role in the phenotypic resistance to ampicillin.

Conclusion: Each E. coli isolate displayed unique characteristics, differing in minimum inhibitory concentration (MIC) values, prevalence of acquired blaTEM and blaCTX-M genes, and expression of the RND-family pumps. This together demonstrates that these clinical isolates employed distinct intrinsic or acquired resistance pathways for their defense against ampicillin. The prevalence and spread of ampicillin resistant E. coli has to be monitored and the search for ampicillin alternatives is needed.

Keywords: ampicillin resistance; antibiotics; clinical isolates; resistance mechanisms.

Grants and funding

The study was financially supported by EDRF “Multidisciplinary research to increase application potential of nanomaterials in agricultural practise” (No. CZ.03.1.01/0.0/0.0/16_025/0007314).