Analyse moléculaire et étude de la résistance aux antibiotiques des souches d’Escherichia coli productrices de β-lactamases à spectre étendu (BLSE) isolées au CHU de Constantine.

Abstract

The species Escherichia coli is among the bacteria responsible for nosocomial infections and epidemics. The resistance of E. coli to antibiotics is undergoing a worrying worldwide development due to the production of extended spectrum β-lactamases (ESBLs). These microorganisms, responsible for nosocomial infections, are found to be resistant to several families of antibiotics such as β-lactams and aminoglycosides. The increase and spread of antibiotic resistance in this species represents a major global public health problem. The aim of this study was to investigate the antibiotic resistance of strains of E. coli isolated at the University Hospital of Constantine between 2013-2015, and the characterization of AmpC genes as well as the study of the coexistence of 16S rRNA methylase genes and carbapenemases in ESBL-producing strains of Escherichia coli. 235 strains of E. coli were collected and identification was performed using standard biochemical galleries and confirmed by mass spectrometry (MALDI-TOF-MS). Then, the antibiotic sensitivity study (method of diffusion of discs on agar) was carried out according to the recommendations of CLSI. Phenotypic research of the production of extended spectrum β- lactamases (ESBL) and carbapenemases was also performed. In addition, the antibiotic resistance genes have been characterized by Molecular Biology techniques (PCR and sequencing). Next, the determination of the ST131 clone and the phylogenetic groups of the strains of ESBL E. coli was carried out using respectively the specific PCR targeting the papB gene according to the method of Clermont et al., 2009 for the detection of the ST131 clone and the PCR of phylogroups according to the revised method of Clermont et al., 2013. In this study, we report for the first time the description of E. coli strains co-expressing both the ArmA, OXA-48, CMY-16 and TEM-1 genes. These strains isolated at the University Hospital of Constantine were resistant to β-lactams and aminoglycosides by production of ESBLs, cephalosporinases, carbapenemases and 16S rRNA methylases. Which shows the increased frequency of multidrug-resistant strains of E. coli, and which requires establishing control measures in Algerian hospitals to prevent their spread.