Association between hemolytic uremic syndrome and verotoxin-producing strains of E. coli

One of the most frequent etiologic agents of Hemolytic Uremic Syndrome (HUS) is Escherichia coli O157H7, a microorganism that possesses virulence factors (Shiga-like Toxins I and II and adhesion fimbriae). The present study was set up to determine the relationship between HUS and the presence of Verotoxin in patients of "Niño Jesús" Children's Hospital. Tucumán, Argentina. 19 Children between 0 and 4 years old suffering from HUS (typical and atypical symptoms) and 15 control children of similar sex and age were selected. Presence of enterohemorrhagic E. coli was studied in both groups using molecular hybridization techniques. Free Verotoxin and Verotoxin-producing E. coli were analyzed in Vero cells. The following results were obtained: 1) The cytotoxic effect on Vero cells from fecal filtrates was observed in all children suffering from HUS 2) Verotoxin-producing E. coli was detected in only 12 of them 3) None of the filtrates of feces from control children presented a cytotoxic effect on Vero cells 4) In 8 of the patients suffering from HUS serotype O157H7 was isolated, in one O55K59 and in 3 typification of E. coli was not possible with the serums assayed 5) 77.5% of the strains isolated from HUS patients gave a positive molecular hybridization reaction, showing the following: Adhesion Fimbriae (AF) (25%); AF + Shiga-like Toxin I (13.75%); AF + Shiga-like Toxin II (20%); AF + Shiga-like Toxins I and II (41.25%). In patients suffering from atypical HUS a combination of AF + Shiga-like Toxins I and II was found. The 15 control children did not hybridize to the probes assayed. From the results obtained we may conclude that there exists a relationship between HUS and the presence of Verotoxin in the children suffering from HUS studied. The predominant serotype in our cases was O157H7 and Shiga-like Toxin II was found with highest frequency.