VEROTOXIGENIC ESCHERICHIA COLI INFECTION AND RELATED RISK FACTORS IN CHILDREN WITH ACUTE DIARRHEA IN ARGENTINA

MA RIVERO, JA PASSUCCI, EM RODRÍGUEZ, AE PARMA

Buenos Aires

Simposio; 7th International Symposium on Shiga Toxin (Verocytotoxin) Producing Escherichia coli Infections; 2009

Asociación Argentina de Microbiología.

The purpose of the study:             To identify different risk and protective factors for VTEC infections in children with acute diarrhea from Argentina, and for HUS development once the children are infected. The methods used             In a prospective study, we collected 417 stool samples from children up to 6 years old with acute diarrhea. A multiplex PCR was performed to detect virulence genes of VTEC. Then, we processed the VTEC positive samples for the isolation of individual strains. The isolates were genotyped and serogrouped. The patients enrolled had attended to health care institutions in Tandil city and its surroundings (76.4%), Bahía Blanca city (14.4%), Morón city (7.9%) and Río Cuarto city (1.2%). A questionnaire was performed to collect information about some exposures that could be related to VTEC infection. The questionnaire was processed using Epi-info version 3.3. 2004. We estimated the incidence of VTEC in fecal samples of children with acute diarrhea. In an univariate analysis, the risk and protective factors for VTEC infection were determinate through the relative risk (RR) and 95% confidence interval (CI). For the multivariable analysis we performed a logistic regression included all the factors that were significant (p value less than 0.05). Fisher exact test was applied. We choose the Stepwise method. Model fit was assessed by the Hosmer and Lemeshow goodness of-fit test, with PROC LOGISTIC of SAS V9.1.3. A summary of the results             The incidence of VTEC infections in fecal samples from children with acute diarrhea was 9.11%. Serogroups O157, O145, O26, O121, O111 and O118 were implicated in different types of diarrhea, and among them O157 and O145 were isolated from HUS cases. The consumption of products stored in freezer was found as a novel risk factor related to this infection (RR=3.6045; CI 1.8490-7.0268). The service of garbage collection was found as a protective factor (RR=0.4197; CI 0.1909-0.9229). Both factors remained statistically significant after the multivariable analysis (p=0.0002; p=0.0162 respectively). The goodness of-fit test gave a p=0.5959. We also found that, once infected, the children who had received antibiotic treatment presented a higher rate of HUS (66.67%) than the ones that did not were treated (27.78%). But we cannot consider yet antibiotic treatment as a risk factor (RR=2.4; CI 0.9989-5.7661). The conclusion reached             It is unclear why the consumption of products stored in freezer has relationship with VTEC infection. It may be due to a wrong management of this kind of food during thawing and cooking. It has been demonstrated that freezing preserves the viability of some pathogenic microorganisms, including some VTEC. The service of garbage collection as a protective factor may be explain by itself or it might be that the ones that do not have this service live in rural areas and could be exposed to VTEC more frequently than the ones that have the service. We believe that our results are relevant since they contribute with the prevention of this infection, the key to diminish the incidence of HUS.