Pathogenicity Island O-122 in enteropathogenic Escherichia coli strains is associated with diarrhea severity in children from Lima Peru

Abstract

EPEC is an attaching and effacing diarrheal pathogen that carries a large pathogenicity island, locus for enterocyte effacement (LEE). Recently, the pathogenicity island PAI O-122 was described among non-LEE effectors and found to be associated with diarrhea among atypical EPEC strains. It is unknown if incomplete PAI O-122 could be associated with diarrhea duration and severity. To identify these virulence determinants we analyzed 379 EPEC strains isolated from Peruvian children. EPEC was diagnosed by PCR(eae+, stx−) and classified as typical(t-EPEC) or atypical(a-EPEC). To characterize PAI O-122 we amplified three modules by PCR: Module 1(pagC), Module 2(senA, nleB and nleE) and Module 3(lifA/efa-1). To characterize the large ORF lifA/efa-1 we amplified the regions known as efa-N, efa-M and efa-C. Clinical information was obtained from the cohort study. A total of 379 EPEC strains were able to analyze PAI O-122 genes, 128 (10.4%) EPEC strains were isolated from 1235 diarrhea episodes and 251(9.2%) from 2734 healthy controls. t-EPEC strains were isolated from 14.8% (19/128) of children with diarrhea and 25/251(10.0%) from healthy controls. The most frequent PAI O-122 genes were nleE(37.7%), senA(34.6%) and nleB(37.5%), with similar prevalence among diarrhea and control samples. However, lifA/efa-1 was more common among diarrhea cases than healthy control cases (30.5% vs. 21.1%, p<0.05). The presence of complete PAI O-122 was associated with diarrhea episodes of higher severity among single pathogen infection (33.3% vs. 1.8%, p<0.05) mainly due to the presence of a complete lifA/efa-1 gene. In summary, the gene lifA/efa-1 is significantly associated with diarrheal episodes of higher severity, suggesting to be an important virulent factor.

Virulence Profiling and Molecular Typing of Shiga Toxin-Producing E. coli (STEC) from Human Sources in Brazil

“…The last serotype has been of particular interest and should receive attention in future studies, because in addition to the fact that it has been isolated as STEC, it has also been occurring in Brazil as aEPEC [IAL unpublished data]. Interestingly, the three strains of serotype O123:H2 analyzed in this study showed evidence of carrying a complete form of OI-122, which is a hallmark in terms of virulence and outbreak potential [42]. The exception in the group of eae-positive strains with a large number of virulence markers was observed in the two stx2f O145:H34 strains, which had very few markers indicating a low potential to cause more serious disease, as suggested previously [58].…”

“…Genes estA (ETEC thermo stable toxin), ehxA (pO157 marker), toxB (pO157 marker), katP (pO157 marker), espP (pO157 marker), iha (OI-48) efa-1 (OI-122 marker), nleB (OI-122 marker), nleE (OI-122 marker), sen (OI-122 marker), pagC (OI-122 marker), etpD (pO157 marker), cdt-V (cytolethal distending toxin -V), astA (EAST-1 toxin) subAB (pO113 marker), saa (pO113 marker), sab (STEC pO113 marker) and hes (pO113 marker) were searched by conventional PCR, while genes Z2098 (OI-57 marker), Z2099 (OI-57 marker), Z2121 (OI-57 marker), espK (OI-50 marker), ureD (OI-43/48 marker), espM1 (OI-71 marker), espN (OI-50 marker), terE (chromosomal gene associated with tellurite resistance) and espV (OI-44 marker) were investigated by real-time PCR. Primers and probes employed in these assays were as previously described [29,[35][36][37][38][39][40][41][42].…”

High Prevalence of Virulence Genes in Specific Genotypes of Atypical Enteropathogenic Escherichia coli

“…This PAI harbors genes efa1 (lifA) that encodes lymphocyte inhibitory factor (LifA) (Abu-Median et al, 2006), set/ent that encodes a homologous Shigella flexneri enterotoxin (Nataro et al, 1995), and nleB and nleE genes that encode proteins, which inhibit pro-inflammatory signaling (Newton et al, 2010). The simultaneous presence of all the OI-122 genes i.e., efa1 ( lifA ), set/ent, nleB , and nleE , is statistically associated with diarrhea compared to healthy controls (Afset et al, 2006; Mercado et al, 2016). …”

Identification and characterization of atypical enteropathogenic and Shiga toxin-producing Escherichia coli isolated from ground beef and poultry breast purchased in Botucatu, Brazil

“…Besides the LEE region, we found that aEPEC 11-1 (O105:H7) harbored the nleB and nleE genes (Table 2), which are located in a PAI known as OI-122, in contrast with the other five aEPEC isolates, which lacked all the additional virulence factorencoding genes investigated here ( Table 2). PAI OI-122 has been identified more frequently in aEPEC isolates obtained from diarrheic patients than from healthy subjects [36,37], and more recently, this PAI was statistically associated with diarrheal episodes of higher severity [38]. STEC 20-1 (ONT:H46), which lacked the LEE region, harbored the iha and saa genes, encoding proteins associated with the adherence of STEC isolates to epithelial cells and the ehxA and espP genes from the O157-EHEC plasmid (pO157), encoding for a EHEC-hemolysin and a serine protease with adhesive capability, respectively (Table 2).…”