Distribution of Major Pilin Subunit Genes Among Atypical Enteropathogenic Escherichia coli and Influence of Growth Media on Expression of the ecp Operon

Abstract

Atypical enteropathogenic Escherichia coli (aEPEC) strains are unable to produce the bundle-forming pilus (BFP), which is responsible for the localized adherence pattern, a characteristic of the pathogenicity of typical EPEC strains. The lack of BFP in aEPEC strains suggests that other fimbrial or non-fimbrial adhesins are involved in their adhesion to the host cells. The aim of this study was to investigate the distribution of major subunit fimbrial genes known to be important adherence factors produced by several E. coli pathotypes in a collection of 72 aEPEC strains. Our results demonstrate that a high percentage (94–100%) of aEPEC strains harbored ecpA, fimA, hcpA, and lpfA fimbrial genes. Other fimbrial genes including pilS, pilV, sfpA, daaC, papA, and sfa were detected at lower frequencies (1–8%). Genes encoding fimbrial subunits, which are characteristic of enteroaggregative E. coli or enterotoxigenic E. coli were not found. No correlation was found between fimbrial gene profiles and adherence phenotypes. Since all aEPEC strains contained ecpA, the major pilin gene of the E. coli common pilus (ECP), a subset of ecpA+ strains was analyzed for transcription of ecpRABCDE and production of ECP upon growth in three different culture conditions at 37°C. Transcription of ecpRABCDE occurred in all conditions; however, ECP production was medium dependent. In all, the data suggest that aEPEC strains are highly heterogeneous in terms of their fimbrial gene profiles. Despite lacking BFP production, other mechanisms of cell adherence exist in aEPEC strains to ensure host colonization, e.g., mediated by other prevalent pili such as ECP. Moreover, the production of ECP by aEPEC strains might be influenced by yet unknown post-transcriptional factors.

<p>Diversity of Virulence Genes in Multidrug Resistant <em>Escherichia coli</em> from a Hospital in Western China</p>

“…Some E. coli strains, contain another type of fimbria, long polar fimbriae (LPF), encoded by the conserved gene lpfA 23,24. We found that 41.24% of the E. coli isolates carried lpfA , which is similar to the frequency (50%) reported in Mexico 25. Initial studies conducted on human biopsy samples have suggested that adherence and the attaching and effacing lesion caused by E. coli do not require LPF 24.…”

Etiology of acute gastroenteritis among children less than 5 years of age in Bucaramanga, Colombia: A case-control study

“…The mPCR was designed to detect genes found in six well-established pathogenic E. coli pathotypes as follows: gene daaE for diffusely adherent E. coli (DAEC); aaiC and aggR for enteroaggregative E. coli (EAEC); ipaH for enteroinvasive E. coli (EIEC); eae and/or bfpA for enteropathogenic E. coli (EPEC); lt and/or st for enterotoxigenic E. coli (ETEC); and stx and/or eae for Shiga-toxin producing E. coli (STEC), as described before [20]. We further categorized EPEC as typical EPEC (eaeA+ bfpA+) or atypical EPEC (eaeA+ bfpA-) [20,25]. Also, EAEC were further subtyped in typical EAEC (aggR+) or atypical EAEC (aggR-, aaiC+) [26].…”

“…coli (STEC), as described before [ 20 ]. We further categorized EPEC as typical EPEC ( eaeA + bfpA +) or atypical EPEC ( eaeA + bfpA -) [ 20 , 25 ]. Also, EAEC were further subtyped in typical EAEC ( aggR+ ) or atypical EAEC ( aggR- , aaiC+ ) [ 26 ].…”

An Assessment of the Viability of Lytic Phages and Their Potency against Multidrug Resistant Escherichia coli O177 Strains under Simulated Rumen Fermentation Conditions

“…Most farm animals, including ruminants, harbour foodborne pathogens [ 3 , 27 , 28 , 29 ]. In addition, intensively reared beef and dairy animals tend to be housed in large numbers and this may promote proliferation and dissemination of foodborne pathogens into the environment [ 30 ].…”