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

RIVERO, M. A.; KRÜGER, A.; RODRÍGUEZ, E.M.; LUCCHESI, P. M. A.; PASSUCCI, J. A.; PARMA, A. E.

Simposio; 8th INTERNACIONAL SYMPOSIUM ON SHIGA TOXIN (VEROCYTOTOXIN) - PRODUCING Escherichia coli INFECTIONS; 2012

Introduction and Objectives: In this study, the vt genes variantspresent in 32 verotoxin-producing Escherichia coli (VTEC) strainswere investigated. These strains were isolated from 437 childrenup to 6 years old with acute diarrhoea attended at Hospitals fromTandil and Bahý´a Blanca cities, 8% of whom progressed to HaemolyticUraemic Syndrome (HUS). The associations among vt variantscombinations and clinical symptoms, age, season, region, and hamburgerconsumption were also assessed.Material and Methods: The vt genes variants were identified byPCR-RFLP. An ordinal linear model for multinomial data was usedconsidering as response variable the vt variants profile (in the order:vt2EDL933 + vt2vha; vt2EDL933; vt1EDL933), with cumulative logitas link function.Results: Sixteen of the 32 isolates (50%) carriedvt2EDL933 + vt2vha genes and belonged to the O157:H7 serotype,usually associated with severe disease. Thirteen strains (40.6%) carriedvt2EDL933, and belonged to O145:H-(7), O157:H7 (3),O121:H19 (2) and O26:H11 (1). Three strains (9.4%) carried vt1alone and belonged to the serotypes O111:H8 (1), O26:H11 (1) andO118:H2 (1), generally related with milder symptoms. Consideringthe order of the combination of the vt variants(vt2EDL933 + vt2vha; vt2EDL933; and vt1EDL933) a significant differenceand an association was found in the distribution frequencyof the variants combinations with HUS development (OR 6.04;CI95% 1.58?23.12; P = 0.0051); bloody diarrhoea (OR 2.97; CI95%1.23?7.80; P = 0.0252); warm season (OR 3.21; CI95% 1.03?10.07;P = 0.0418) and Bahý´a Blanca city (OR 11.94; CI95%:4.38?32.55;P < 0.0001). However, no differences were detected by age(P = 0.6723) or hamburger consumption (P = 0.3353).Conclusions: In conclusion, in HUS patients, bloody diarrhoea,warm season, and attendees from Bahý´a Blanca city, there are morechances to detect the combination of vt variants in a frequencydecreasing in the order vt2EDL933 + vt2vha; vt2EDL933; andvt1EDL933. As an association exists between some serotypes and thepresence of some of the vt variants, and also between serotypes anddisease severity, it cannot be ruled out that the associations found inthis work could be also dependent on the VTEC serotype or otherfactors.