Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries

Blanco, Miguel; González, Enrique A.; Blanco, Jesús E.; Alonso, Marı́a Pilar; Garabal, J.I.; Jansen, W. H.

doi:10.1007/bf00209526

Cited by 25 publications

(18 citation statements)

References 42 publications

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“…The MLVA carried out in this work has a high discriminatory power which proved to be particularly useful in epidemiological studies (17). Serogroups O6, O153, O78, and O159 detected in our collection have been reported for ETEC isolates from other locations (3,4,36). However, strains reacting simultaneously with anti-O104 and anti-O127 sera are not commonly isolated and may represent a geographically confined group of strains.…”

Section: Discussionmentioning

confidence: 55%

Distribution of Classical and Nonclassical Virulence Genes in Enterotoxigenic Escherichia coli Isolates from Chilean Children and tRNA Gene Screening for Putative Insertion Sites for Genomic Islands

et al. 2011

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Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea. Three adhesins (Tia, TibA, EtpA), an iron acquisition system (Irp1, Irp2, and FyuA), a GTPase (LeoA), and an autotransporter (EatA) are ETEC virulence-related proteins that, in contrast to the classical virulence factors (enterotoxins and fimbrial colonization factors) have not heretofore been targets in characterizing isolates from epidemiological studies. Here, we determined the occurrence of these nonclassical virulence genes in 103 ETEC isolates from Chilean children with diarrhea and described their association with O serogroups and classical virulence determinants. Because tia, leoA, irp2, and fyuA are harbored by pathogenicity islands inserted into the selC and asnT tRNA genes (tDNAs), we analyzed the regions flanking these loci. Ten additional tDNAs were also screened to identify hot spots for genetic insertions. Associations between the most frequent serogroups and classical colonization factor (CF)-toxin profiles included O6/LT-STh/CS1-CS3-CS21 (i.e., O6 serogroup, heat-labile [LT] and human heat-stable [STh] enterotoxins, and CFs CS1, -3 and -21), O6/LT-STh/CS2-CS3-CS21, and O104-O127/STh/ CFAI-CS21. The eatA and etpA genes were detected in more than 70% of the collection, including diverse serogroups and virulence profiles. Sixteen percent of the ETEC strains were negative for classical and nonclassical adhesins, suggesting the presence of unknown determinants of adhesion. The leuX, thrW, and asnT tDNAs were disrupted in more than 65% of strains, suggesting they are hot spots for the insertion of mobile elements. Sequences similar to integrase genes were identified next to the thrW, asnT, pheV, and selC tDNAs. We propose that the eatA and etpA genes should be included in characterizations of ETEC isolates in future epidemiological studies to determine their prevalence in other geographical regions. Sequencing of tDNAassociated genetic insertions might identify new ETEC virulence determinants.Enterotoxigenic Escherichia coli (ETEC) causes nearly 400 million diarrhea episodes every year in children younger than 5 years of age and is responsible for approximately 50% of all traveler's diarrhea episodes (35). ETEC colonizes the smallbowel epithelium, producing heat-labile (LT) and/or heat-stable (ST) enterotoxins (7) that cause secretion of water and electrolytes. Toxin variants LT-I and STh are produced only by strains that infect humans. LT-II and STp are expressed by strains that infect mostly piglets, although they occasionally also infect humans (20).Other classical ETEC virulence determinants are the colonization factors (CFs), also referred to as coli surface antigens (20), adhesins that direct colonization of the small bowel epithelium. Currently, 22 different putative ETEC CFs have been identified, designated CS followed by a number depending on their order of discovery, with the exception of CFAI, which maintains its original denomination (10, 31). The most prevalent CFs associated with the occurrence of diarrhea worldwi...

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Section: Discussionmentioning

confidence: 55%

Distribution of Classical and Nonclassical Virulence Genes in Enterotoxigenic Escherichia coli Isolates from Chilean Children and tRNA Gene Screening for Putative Insertion Sites for Genomic Islands

et al. 2011

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“…In investigations conducted in Germany [181] and Brazil [100], STEC were isolated more frequently from diarrhoeic calves than from healthy calves. Conversely, other studies have reported higher rates of STEC faecal carriage in healthy than in diarrheic animals [9,141].…”

Section: Cattlementioning

confidence: 67%

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission

et al. 2005

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-Enterohaemorrhagic Escherichia coli (EHEC) constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin (Stx)-producing E. coli (STEC) firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Stx production is essential but not sufficient for EHEC virulence. Most strains are capable of colonising the intestinal mucosa of the host with the "attaching and effacing" mechanism, genetically governed by a large pathogenicity island (PAI) defined as the Locus of Enterocyte Effacement. Other virulence factors carried by mobile genetic elements like PAI and plasmids have been recently described, and their role in the pathogenic process has not been fully elucidated. EHEC are zoonotic pathogens. They rarely cause disease in animals, and ruminants are recognised as their main natural reservoir. Cattle are considered to be the most important source of human infections with EHEC O157, and the ecology of the organism in cattle farming has been extensively studied. The organism has also been reported in sheep, goats, water buffalos, and deer. Pigs and poultry are not considered to be a source of EHEC and the sporadic reports may derive from accidental exposure to ruminant dejections. The epidemiology of EHEC infections has remarkably changed during the past ten years and an increasing number of unusual food vehicles have been associated with human infections. New routes of transmission have emerged, like contact with animals during farm visits and a wide variety of environment-related exposures. As for other zoonotic agents, having animals and raw products that are free from EHEC is not possible in practice. However, their occurrence can be minimised by applying high standards of hygiene in all the steps of the food production chain.

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“…Of these serogroups, O6, O8, O78, O114, O120, O148, O153 and O159 have frequently been associated with ETEC in previous studies [18][19][20] and these 8 O-groups were detected in 26 of the 43 ETEC strains. A small number of additional strains were of O serogroups that have infrequently been detected in ETEC strains, namely, O1, O41 and O21.…”

Section: Resultsmentioning

confidence: 99%

Enterotoxins, colonization factors, serotypes and antimicrobial resistance of enterotoxigenic Escherichia coli (ETEC) strains isolated from hospitalized children with diarrhea in Bolivia

Rodas¹,

Mamani²,

Blanco³

et al. 2011

Braz J Infect Dis

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Enterotoxigenic Escherichia coli (ETEC) is recognized as the main cause of bacterial diarrhoea among children in Asia, Africa and Latin America but less investigated in Bolivia. Objective: To determine the relation between enterotoxins, CFs and serotypes as well as the antimicrobial resistance patterns in a set of ETEC isolates collected from hospitalized children with acute diarrhea. In the present study we characterized 43 ETEC strains isolated from 2002 to 2006 from hospitalized children (0-5 years) with acute diarrhea in Bolivia. The strains were analyzed for heat-labile (LT) and heat-stable (ST) enterotoxins and colonization factor (CF) profiles, as well as for serogroups and antimicrobial resistance using phenotypic (ELISA, dot blot, slide agglutination and disc diffusion) and genotypic (Multiplex PCR) methods. Among the ETEC isolates tested, 30 were positive for LT, 3 for STh and 10 for LT/STh. Sixty-five percent (28/43) of the strains expressed one or more CF. The most common CFs were CS17 (n = 8) and CFA/I (n = 8). The phenotypical and genotypical results for toxins and CFs were congruent except for CS21 that was amplified in 10 of the strains by multiplex PCR, but CS21 pili was only detected phenotypically in four of these strains. The ETEC strains had diverse O and H antigens and the most common types were O8:H9 LT CS17 (n = 6; 14%) and O78:HNM LT-ST CFA/I (n = 4; 9%). The analysis of antibiotic resistance showed that 67% (n = 29/43) of the strains were resistant to one or several of the antimicrobial agents tested. Presence of CFs was associated with antibiotic resistance. Conclusion: The most common toxin profile was LT 70%, LT/STh 23% and STh 7%. High antimicrobial resistance to ampicillin among serogroups O6, O8 and O78 were the most common.

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Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries

Cited by 25 publications

References 42 publications

Distribution of Classical and Nonclassical Virulence Genes in Enterotoxigenic Escherichia coli Isolates from Chilean Children and tRNA Gene Screening for Putative Insertion Sites for Genomic Islands

Distribution of Classical and Nonclassical Virulence Genes in Enterotoxigenic Escherichia coli Isolates from Chilean Children and tRNA Gene Screening for Putative Insertion Sites for Genomic Islands

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission

Enterotoxins, colonization factors, serotypes and antimicrobial resistance of enterotoxigenic Escherichia coli (ETEC) strains isolated from hospitalized children with diarrhea in Bolivia

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