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Escherichia coli colonizing healthy children in Tunisia: High prevalence of extra-intestinal pathovar and occurrence of non-extended-spectrum-β-lactamase-producing ST131 clone
- Ferjani, Sana, Saidani, Mabrouka, Maamar, Elaa, Harbaoui, Sarra, Hamzaoui, Zeineb, Hosni, Houda, Amine, Faouzi Slim, Boubaker, Ilhem Boutiba Ben
- International journal of antimicrobial agents 2018 v.52 no.6 pp. 878-885
- Escherichia coli, aminoglycosides, ampicillin, antibiotic resistance, carbapenems, cephalosporins, children, colistin, hygiene, intestinal microorganisms, mutation, pandemic, pathogenicity islands, pathogens, pathovars, phylogeny, plasmids, quinolones, replicon, resistance genes, sulfamethoxazole, ticarcillin, virulence, Tunisia
- This study was performed to investigate the distribution of antimicrobial resistance genes and extra-intestinal virulence determinants in a collection of 98 Escherichia coli strains isolated from rectal swabs of healthy children. Forty-six isolated strains were resistant to at least one of the tested antibiotics (usually active against enterobacteria). They were mainly resistant to ampicillin and ticarcillin (42.97%), tetracyclin (26.5%), and trimethoprim/sulfamethoxazole (18.4%). No resistance to the third generation of cephalosporins, carbapenems, aminoglycosides and colistin was found. Resistance to penicillins was encoded by blaTEM-1 (n=34) and blaSHV-1 genes (n=4). Tetracyclin resistance was encoded by tetB (n=12), tetA (n= 5), and tetC (n=1) genes. Amongst resistant quinolones isolated (n=5), chromosomal mutations in gyrA and parC genes were detected in four isolates and qnrS1 gene in two strains. Nine plasmid replicon types were detected; IncFIB (n=36) and IncI1 (n=7) were the most frequent ones. Isolates frequently belonged to phylogenetic groups A (51.1%) and D (27.5%). Extra-intestinal pathovar (n=38) occurred mainly in B2 phylogroup (P=0.0002). Amongst them, two isolates (non-extended-spectrum-β-lactamase (ESBL)-producers) belonged to the pandemic clone ST131. A significant distribution of virulence determinants and pathogenicity island marker was observed within strains belonging to B2 and D phylogroups. Interestingly, our results showed that ExPEC strains, including ST131 pandemic clone, are present within fecal isolates in healthy children. These findings highlight the importance of intestinal microbiota as a reservoir for virulent and resistant strains. Thus, reinforcing hand hygiene and antibiotic rational use is imperative to avoid the diffusion of these pathogens in the community.