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Temporal study of the variability of virulence factors and phylogenetic groups of extraintestinal pathogenic Escherichia coli (ExPEC) isolated from bacteremia in patients of one Hospital in Sao Paulo: its relationship with ExPEC evolution


In spite of the progress in the handling of the bacterial infectious diseases in general, occurrence of bacteremia continues to be the cause of great morbidity and mortality all over the world. One of the pathogens more frequently involved is the extra intestinal pathogenic Escherichia coli (ExPEC) responsible for a variety of infections mainly in the urinary tract, meningites, pneumonias, and bacteremia of various origins, which affect both humans and animals. These strains are distributed mainly in four phylogenetic groups: A, B1, B2, and D. Many studies have been showing that ExPEC belongs most to the phygroup B2 and, in smaller frequency, to the phylogroup D, while the commensals are from groups A or B1. A vast number of virulence factors (VFs) have been described as important in the installation of those infections, which are located in mobile DNA elements, as plasmids and pathogenicity associated islands (PAIs) allowing its dissemination in an effective way. Being so, the literature is unanimous in considering ExPEC as a group that is still ongoing genetic remodeling. By the way, it was recently reported the emergency of the "clonal group A", composed of strains belonging to the phylogrupo D, and carrying several virulence factors. Concomitantly, on this year of 2008 it was reported in Europe and Africa, the emergency of super-virulent and multi-resistant clones originated from the phylogroup B2. A recent study carried out in our laboratory on the phylogeny of ExPEC strains isolated from bacteremia in São Paulo, despite of revealing the prevalence of groups B2 and D, it showed high frequency of the usually commensal groups B1 and A possessing various VFs. This result is accordance with the hypothesis that these isolates are also an example of ongoing genetic rearrangements which are turning them more virulent as detected in other geographical areas. This study has the purpose of testing this hypothesis by studying, along the time, the occurrence of variability in respect of both the virulence pattern and the phylogeny of strains isolated from bacteremia of inpatients of a unique hospital in São Paulo. The involvement of mobile DNA elements in this occurrence will also be addressed. In that way, we hoped to contribute for the knowledge on the plasticity of the ExPEC genome, as well as for the best understanding of its evolution. (AU)

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(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
A.C.M. SANTOS; A.C.M. ZIDKO; A.C. PIGNATARI; R.M. SILVA. Assessing the diversity of the virulence potential ofEscherichia coli isolated from bacteremia in São Paulo, Brazil. Brazilian Journal of Medical and Biological Research, v. 46, n. 11, p. 968-973, . (09/00402-6)
SANTOS, ANA CAROLINA M.; SILVA, ROSA M.; VALIATTI, TIAGO B.; SANTOS, FERNANDA E.; SANTOS-NETO, JOSE E.; CAYO, RODRIGO; STRELING, ANA P.; NODARI, CAROLINA S.; GALES, ANA C.; NISHIYAMA-JR, MILTON Y.; et al. Virulence Potential of a Multidrug-ResistantEscherichia coliStrain Belonging to the Emerging Clonal Group ST101-B1 Isolated from Bloodstream Infection. MICROORGANISMS, v. 8, n. 6, . (16/01656-5, 17/21947-7, 09/00402-6, 18/17353-7)
DE MELLO SANTOS, ANA CAROLINA; FUGA, BRUNA; ESPOSITO, FERNANDA; CARDOSO, BRENDA; SANTOS, FERNANDA FERNANDES; VALIATTI, TIAGO BARCELOS; SANTOS-NETO, JOSE FRANCISCO; GALES, ANA CRISTINA; LINCOPAN, NILTON; SILVA, ROSA MARIA; et al. Unveiling the Virulent Genotype and Unusual Biochemical Behavior of Escherichia coli ST59. Applied and Environmental Microbiology, v. 87, n. 16, . (19/15578-4, 09/00402-6, 18/17353-7)

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