Verotoxin variants in VTEC isolated from children with acute diarrhoea from Centrl-Eastern Argentina. Association with Clinical symptoms, seasonality and hamburger consumption

RIVERO, MARIANA ALEJANDRA; KRÜGER, ALEJANDRA; RODRÍGUEZ, EDGARDO MARIO; LUCCHESI, PAULA; PASSUCCI, JUAN ANTONIO; PARMA, ALBERTO ERNESTO

Amsterdam

Simposio; 8th Intenational Symposium on Shiga Toxin (Verocytotoxin) Producins Escherichia coli Infections; 2012

Objetives - To estimate the verotoxin variants in VTEC isolated from children with acute diarrhoea from Central-Eastern Argentina. - To assess the association between vt gene variants and clinical symptoms, seasonality and hamburger consumption. Methods The vt variants present in 32 verotoxin-producing Escherichia coli (VTEC) strains were investigated. These strains were isolated from 437 children up to 6 years old with acute diarrhoea attended at Hospitals from Tandil and Bahía Blanca cities, 8% of whom progressed to Haemolytic Uraemic Syndrome (HUS). The associations among vt variants combinations and clinical symptoms, age, season, region and hamburger consumption were also assessed. The vt genes variants were identified by PCR-RFLP. An ordinal linear model for multinomial data was used considering as response variable the vt variants profile (in the order according to their pathogenicity: vt2EDL933+vt2vha; vt2EDL933; vt1EDL933), with cumulative logit as link function. Results Sixteen of the 32 isolates (50%) carried vt2EDL933+vt2vha genes and belonged to the O157:H7 serotype, usually associated with severe disease. Thirteen strains (40.6%) carried vt2EDL933, and belonged to O145:H- (7), O157:H7 (3), O121:H19 (2) and O26:H11 (1). Three strains (9.4%) carried vt1 alone and belonged to the serotypes O111:H8 (1), O26:H11 (1) and O118:H2 (1), generally related with milder symptoms. Considering the order of the combination of the vt variants (vt2EDL933+vt2vha; vt2EDL933; and vt1EDL933) a significant difference and an association was found in the distribution frequency of the variants combinations with HUS development (Table 1); bloody diarrhoea (Table 2); warm season (Table 3) and Bahía Blanca city (Table 4). However, no differences were detected by age (p=0.6723) or hamburger consumption (p=0.3353). Conclusion In HUS patients, bloody diarrhoea, warm season, and attendees from Bahía Blanca city, there are more chances to detect the combination of vt variants in a frequency decreasing in the order vt2EDL933+vt2vha; vt2EDL933; and vt1EDL933. As an association exists between some serotypes and the presence of some of the vt variants, and also between serotypes and disease severity, it cannot be ruled out that the associations found in this work could be also dependent on the VTEC serotype or other factors.