Asymptomatic infections by diarrheagenic Escherichia coli in children from Misiones, Argentina, during the first twenty months of their lives.

Diarrheagenics Escherichia coli are the major agents involved in diarrheal disease in developing countries. The aim of this study was to evaluate the time of appearance of the first asymptomatic infection by the different categories of diarrheagenic E. coli in 44 children since their birth and during the first 20 months of their lives. In all of the children studied, we detected at least one category of diarrheagenic E. coli through the 20 months of the study. 510 diarrheagenic E. coli (33.5%) were obtained from the 1,524 samples collected from the 44 children during the time of the study (31.4% EAggEC, 28.8% EPEC, 27.1% DAEC, and 12.7% ETEC). Neither EHEC nor EIEC were identified. The median age for diarrheagenic E. coli colonization was 7.5 months. The mean weaning period was 12.8 months and the mean age for introduction of mixed feeding (breast fed supplemented) was 3.8 months. A significantly lower incidence of diarrheal disease and asymptomatic infections was recorded among the exclusively breast-fed rather than in the supplemented and non breast-fed infants. For ETEC, EPEC and EAggEC the introduction of weaning foods and complete termination of breast-feeding were associated with an increase of asymptomatic infections.

Effects of subinhibitory concentrations of ciprofloxacin on enterotoxigenic Escherichia coli virulence factors.

Eight enterotoxigenic Escherichia coli were studied with the aim of investigating the effect of subinhibitory concentrations of ciprofloxacin on their adherence properties and on the expression of thermolabile enterotoxin. Our data showed that the hydrophobicity on the bacterial cell surface, the hemagglutination properties, and thermolabile enterotoxin production were considerably reduced after treatment with subinhibitory concentrations of ciprofloxacin, suggesting that ciprofloxacin may be capable of decreasing adhesiveness and expression of the thermolabile toxin of enterotoxigenic Escherichia coli. In conclusion, our study supports the concept that subinhibitory concentrations of ciprofloxacin interfere with the process of host-parasite interactions such as adherence and toxin production.