Affiliation:
1. Département de Microbiologie Médicale et Moléculaire, EA 3250, CHU Bretonneau, 37044 Tours Cedex
2. INRA, Centre de Recherche de Tours, URO 86, 37380 Nouzilly
3. Département de Microbiologie, CHU Morvan, 29609 Brest, France
Abstract
ABSTRACT
To determine the extent to which the vagina, endocervix, and amniotic fluid screen the
Escherichia coli
strains responsible for neonatal infections, we studied the genetic relationships among 105
E. coli
strains isolated from all of the ecosystems involved in this infectious process. Twenty-four strains were isolated from the intestinal flora, and 25 strains were isolated from the vaginas of pregnant women. Twenty-seven strains were isolated from the amniotic fluid, blood, and cerebrospinal fluid (CSF) of infected neonates. The intraspecies genetic characteristics of all of the isolates were determined by random amplified polymorphic DNA (RAPD) analysis, PCR ECOR (E. coli reference) grouping, and PCR virulence genotyping. A correlation was found between the intraspecies distributions of the strains in the A, B1, B2, and D ECOR groups and in the two major RAPD groups (I and II). Nevertheless, the distribution of the
E. coli
strains in the RAPD groups according to their anatomical origins was more significant than their distribution in the ECOR groups. This may be explained by the existence of an
E. coli
subpopulation, defined by the RAPD I group, within the ECOR B2 group. This RAPD I group presents a major risk for neonates: 75% of the strains isolated from patients with meningitis and 100% of the strains isolated from patients with bacteremia were in this group. The vagina and the amniotic fluid are two barriers that favor colonization by highly infectious strains. Indeed, only 17% of fecal strains belonged to the RAPD I group, whereas 52% of vaginal strains and 67% of amniotic fluid strains belonged to this subpopulation. The
ibeA
and
iucC
genes were significantly associated with CSF strains, whereas the
hly
and
sfa/foc
genes were more frequent in blood strains. These findings could serve as a basis for developing tools to recognize vaginal strains, which present a high risk for neonates, for use in prophylaxis programs.
Publisher
American Society for Microbiology
Cited by
89 articles.
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