Molecular analysis of typical and atypical enteropathogenic Escherichia coli (EPEC) isolated from children with diarrhoea

Abstract

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested. INTRODUCTIONEnteropathogenic Escherichia coli (EPEC) is one of the major causes of diarrhoea among children in developing countries (Hernandes et al., 2009;Moura et al., 2009). The pathogenesis of EPEC depends on the locus of enterocyte effacement (LEE), a chromosomal pathogenicity island. The LEE contains a number of different genes, including eae, which has an essential role in inducing a characteristic lesion formation in the intestinal epithelium, termed an attaching and effacing (A/E) lesion (Elliott et al., 1998;Vallance & Finlay 2000;Kaper et al., 2004). The eae gene encodes intimin, a 94 kDa outer-membrane protein that is responsible for the intimate adherence between bacterial and enterocyte membranes (Vallance & Finlay, 2000;Trabulsi et al., 2002). EPEC strains are classified as typical or atypical, according to the presence or absence of the E. coli adherence factor plasmid (EAF) that carries the bfpA gene, which encodes the bundle-forming pili (Hernandes et al., 2009). The most typical EPEC strains belong to the classic O : H serotypes and are eae-and bfpA-positive (Ochoa et al., 2008). The atypical EPEC isolates are eaepositive and bfpA-and stx (the gene encoding shiga-like toxin)-negative. EPEC are among the most important pathogens infecting children under 2 years of age in the developing world (Ochoa et al., 2008). Recent studies indicate that atypical EPEC is more prevalent than typical Abbreviations: EPEC, enteropathogenic Escherichia coli; LEE, locus of enterocyte effacement; PFGE, pulsed-field gel electrophore...

Expression of Enteropathogenic Escherichia coli Map Is Significantly Different than That of Other Type III Secreted Effectors In Vivo

“…pCM17 (the plasmid carrying an outer membrane OmpC promoter) and pfliC served as positive controls. Luciferase expression of all tested promoters was significantly reduced 10 to 25% in the presence of NH 4 Cl at 1 h postinoculation, in both PBS and DMEM, confirming that the expression of these constructs was regulated. In addition, gene expression was 20 times higher in DMEM than in PBS, confirming known regulatory patterns for the genes.…”

“…Bacteria were grown O/N in LB medium in the presence of appropriate antibiotics and then inoculated at 1:500 into different types of media: LB medium, LB medium with 18.4 mM NH 4 Cl, DMEM, DMEM with 18.4 mM NH 4 Cl, PBS, and PBS with 18.4 mM NH 4 Cl. At 1 h postinfection, triplicate samples of 100 l of each culture were pipetted into 96-well dark-walled, clear-bottom plates (Corning Incorporated, Corning, NY).…”

“…Strains carrying different EPEC effector protein promoters were inoculated into PBS or DMEM, and then the luciferase signal was measured by an IVIS (see Fig. S1A and B in the supplemental material) in the presence and absence of NH 4 Cl. The promoterless pCM10 plasmid carrying luxCDABE was used as a negative control.…”

“…nteropathogenic Escherichia coli (EPEC) is a human pathogen that causes infantile diarrhea in developing countries (1)(2)(3)(4)(5)(6)(7). EPEC adheres to host intestinal epithelium and induces attaching and effacing (A/E) lesions, which are characterized by intimate attachment of the organisms to host epithelial cells and effacement of the surrounding enterocyte microvilli (8).…”

Surveillance of Diarrheagenic Escherichia coli Strains Isolated from Diarrhea Cases from Children, Adults and Elderly at Northwest of Mexico

“…On the other hand, EPEC was the second most frequently isolated pathotype. Generally, EPEC are among the most important pathogens infecting children under 2 years of age in the developing world (Trabulsi et al, 2002; Nguyen et al, 2006; Nakhjavani et al, 2013). …”