Assessing the diversity of the virulence potential of Escherichia coli isolated from bacteremia in São Paulo, Brazil

Most of the knowledge of the virulence determinants of extraintestinal pathogenic Escherichia coli (ExPEC) comes from studies with human strains causing urinary tract infections and neonatal meningitis and animal strains causing avian colibacillosis. In this research, we analyzed the phylogenetic ba...

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Bibliographic Details
Published in:	Brazilian journal of medical and biological research Vol. 46; no. 11; pp. 968 - 973
Main Authors:	Santos, A C M, Zidko, A C M, Pignatari, A C, Silva, R M
Format:	Journal Article
Language:	English
Published:	Brazil Associacao Brasileira de Divulgacao Cientifica (ABDC) 01-11-2013 Associação Brasileira de Divulgação Científica
Subjects:	Bacteremia Biological diversity Clinical Investigation Escherichia coli Extraintestinal pathogenic Escherichia coli Health aspects Intrinsic virulence potential Phylogenetic background Virulence (Microbiology) Virulence factors Brazil
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Summary:	Most of the knowledge of the virulence determinants of extraintestinal pathogenic Escherichia coli (ExPEC) comes from studies with human strains causing urinary tract infections and neonatal meningitis and animal strains causing avian colibacillosis. In this research, we analyzed the phylogenetic background, the presence of 20 ExPEC virulence factors, and the intrinsic virulence potential of 74 E. coli strains isolated in São Paulo, Brazil, from 74 hospitalized patients (43 males and 31 females) with unknown-source bacteremia. Unlike other places in the world, the bacteremic strains originated equally from phylogroups B2 (35%) and D (30%). A great variability in the profiles of virulence factors was noted in this survey. Nevertheless, 61% of the strains were classified as ExPEC, meaning that they possessed intrinsic virulent potential. Accordingly, these strains presented high virulence factor scores (average of 8.7), and were positively associated with 12 of 17 virulence factors detected. On the contrary, the non-ExPEC strains, isolated from 39% of the patients, presented a generally low virulence capacity (medium virulence factor score of 3.1), and were positively associated with only the colicin cvaC gene. These results show the importance of discriminating E. coli isolates that possess characteristics of true pathogens from those that may be merely opportunistic in order to better understand the virulence mechanisms involved in extraintestinal E. coli infections. Such knowledge is essential for epidemiological purposes as well as for development of control measures aimed to minimize the incidence of these life-threatening and costly infections.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0100-879X 1414-431X 1414-431X
DOI:	10.1590/1414-431X20133184