Distribution of the Escherichia coli Common Pilus among Diverse Strains of Human Enterotoxigenic E. coli

Abstract

The Escherichia coli common pilus (ECP) is produced by commensal and pathogenic E. coli strains. This pilus is unrelated to any of the known colonization factors (CFs) of enterotoxigenic E. coli (ETEC). In this study, we investigated the distribution and production of ECP among a collection of 136 human CF-positive and CF-negative ETEC strains of different geographic origins. The major pilus subunit gene, ecpA, was found in 109 (80%) of these strains, suggesting that it is widely distributed among ETEC strains. Phenotypic analysis of a subset of 43 strains chosen randomly showed that 58% of them produced ECP independently of the presence or absence of CFs, a percentage even higher than that of the most prevalent CFs. These data suggest an important role for ECP in the biology of ETEC, particularly in CF-negative strains, and in human infection.Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease and mortality for children living in developing countries (11). The presence of ETEC in these areas is associated with a lack of sanitation or poor sanitation and the consumption of contaminated water or food. The main virulence factors of ETEC are a heat-labile (LT) and/or a heat-stable (ST) enterotoxin and multiple adhesive pili called colonization factors (CFs) (1, 7), which are produced in the small intestine and can cause life-threatening, cholera-like watery diarrhea (7). Since the early 1970s, more than 25 different CFs have been reported in ETEC strains of diverse geographic origins, and the prevalence of these pili differs by geographic region (7, 11). Studies of the prevalence and distribution of CFs among ETEC strains worldwide have shown that the most common CFs are CFA/I and combinations of E. coli surface antigens CS1, CS2, and CS3 or of antigens CS4, CS5, and CS6. Approximately 50% of ETEC strains contain at least one of these CFs (7), leaving 50% of strains that do not produce any of the CFs known or characterized so far. The presence of type IV pili, which are associated with host colonization and virulence in many gram-negative bacteria, has also been demonstrated in a significant number (30 to 50%, depending on the geographic source) of ETEC strains, including strains that do not harbor any of the known CFs. These pili provide a mechanism for the organisms to colonize the human gut and establish gastrointestinal disease. Epidemiological studies have shown that protective immunity, attributed to the antigenic variety of the CFs produced, can be achieved through multiple infections. Thus, it is believed that vaccines aimed at preventing ETEC infections, particularly in the young population and travelers, should contain the immunogenic B subunit of the LT and a combination of the most common CFs (7, 9, 10).Previously, it was reported that meningitis-associated E. coli strains, and not other E. coli pathogroups, were able to assemble a "meningitis-associated temperature-dependent pilus" (Mat) after growth at 20°C in Luria-Bertani (LB) medium. The major pilus subunit of the Mat...

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

“…Several reports have previously shown that this gene is highly conserved among the different intestinal and extraintestinal E. coli pathotypes, including commensal strains (4,5,35,36). A recent gene search study with Brazilian aEPEC strains showed that ecpA was present in all strains displaying an LAL pattern on HEp-2 cells (42).…”

“…The ECP, in association with BFP and other adhesins, contributes to the complex multifactorial interaction of EPEC with host epithelial cells (40). The recent demonstrations that ECP is as frequent as the most common colonization factors of ETEC (5), that the majority of EAEC strains produce ECP (4), and that meningitis-causing E. coli strains also elaborate ECP (called Mat in this pathogroup) to form biofilms (24) reinforce the notion that ECP plays a significant role in the biology of this organism and in its interaction with the host.…”

“…Likewise, NMEC strains with deletion of the ecp operon are incapable of producing biofilms (24). ECP is composed of a 21-kDa pilin subunit, and antibodies against the pilus have been used as a probe to detect the presence of ECP on diarrheagenic E. coli strains adhering to cultured epithelial cells (5,36,40). Recently, Scaletsky et al (42) showed that the major pilin ecpA gene was present in all of the 29 aEPEC strains belonging to different serotypes tested, but no information is available regarding the actual production of the pili in this group.…”

Presence of virulence genes and pathogenicity islands in extraintestinal pathogenic Escherichia coli isolates from Brazil

“…Susceptibility to the following antimicrobials was determined by microdilution on the automated Phoenix system: amikacin, aztreonam, cefazolin, cefepime, cefotaxime, ceftazidime, ciprofloxacin, ertapenem, gentamicin, imipenem, levofloxacin, meropenem, nitrofunrantoin, piperacillin + tazobactam, and trimethoprim-sulfamethoxazole. Detecting virulence genes using PCR Primers used for amplification of DNA fragments corresponding to virulence genes iroN, ompTp, hlyF, iss, iutA [4], tsh [17], hlyA, fyuA, papG [14], papC [18] and ecpA [19] are shown in Table 1. Bacterial DNA was amplified using 2.5 µl of supernatant in 12.5 µl of reaction mixture, which contained 1.5 U Taq polymerase (Invitrogen, Carlsbad, USA), 0.2 mM of each deoxynucleotide triphosphate (dNTP, Invitrogen), 2.5 mM MgCl 2 , PCR Buffer 10X (Invitrogen) and the appropriate primers (20 pmol/ µl).…”

The fimbriae activator MatA switches off motility in Escherichia coli by repression of the flagellar master operon flhDC

“…Proteus mirabilis, Salmonella enterica and E. coli, harbour regulatory systems for reciprocal regulation of these traits (Clegg & Hughes, 2002;Li et al, 2001;Ogasawara et al, 2011;Pesavento et al, 2008;Saini et al, 2010;Simm et al, 2004). We have previously described the common and conserved Mat (meningitis-associated and temperatureregulated) fimbria (Pouttu et al, 2001) [also called ECP (E. coli common pilus); Rendó n et al., 2007], which has host cell-adhesive (Avelino et al, 2010;Blackburn et al, 2009;Lasaro et al, 2009;Rendó n et al, 2007;Saldaña et al, 2009) and biofilm-promoting (Lehti et al, 2010) properties, and is a critical colonization determinant for a probiotic E. coli strain in the intestine of the infant mouse (Lasaro et al, 2009). The fimbrillin subunit MatB is an abundant surface protein on meningitis-associated IHE 3034 cells from a biofilm (Lehti et al, 2010).…”