Hemolytic uremic syndrome associated with Shiga toxin-producing Escherichia coli infection in Argentina: update of serotypes and genotypes and their relationship with severity of the disease.

Background: Shiga toxin-producing Escherichia coli (STEC) infection is the most common cause of hemolytic uremic syndrome (HUS). Only few studies correlated serotypes and stx genotypes with disease severity. This study aimed to update STEC serotypes, stx genotypes, and virulence factors (eae and ehxA) in a cohort of patients with STEC-HUS and investigate whether they influence the severity of disease.
Methods: In this multicentric study, children hospitalized between 2005 and 2016 with STEC-HUS confirmed by the National Reference Laboratory were included. Serotypes (O157, O145, O121, and others), stx genotypes (stx _1a , stx _2a , stx _2c, stx _2d , and others), and virulence factors were analyzed, and their association with dialysis requirement (>10 days); severe neurological, cardiovascular, and/or bowel involvement; and death was assessed.
Results: The records of 280 patients were reviewed; 160 females, median age 21 months (IQR18m). STEC O157 was isolated in 206 (73.6%) patients, O145 in 47 (16.8%), O121 in 15 (5.4%), and other serotypes in 12 (4.2%). The stx _2a / _2c genotype was carried by 179 (63.9%) strains, stx _2a by 94 (33.6%), stx _1a /stx _2a by five (1.8%), and stx _1a only by two (0.7%). All strains except six harbored eae and ehxA genes. Fifty-nine (21.1%) patients had severe neurological involvement, 29 (10.4%) severe bowel injury, 14 (5%) cardiovascular involvement, 53 (18.9%) required > 10 days of dialysis, and 12 (4.3%) died. Neither serotypes nor stx genotypes detected were significantly linked to severity.
Conclusions: Serotype O157 and virulence stx _2a/2c , eae, ehxA genotype are prevalent in Argentina, and no relationship was found between severity and serotypes and genotypes of STEC detected.
(© 2021. IPNA.)