Family Clusters of Shiga Toxin-producing Escherichia coli Infection

Abstract

Background: The aim of the present work was to investigate family clusters of Shiga toxin-producing Escherichia coli (STEC) infection among the household members of STEC positive patients, identified within a screening program of bloody diarrhea (BD) for STEC in Northern Italy. Methods: Stool samples from patients with BD or BD-associated-hemolytic uremic syndrome (HUS) and related households were investigated by molecular and bacteriologic methods to detect and characterize the virulence profile of STEC and Pulsed Field Gel Electrophoresis analysis were done on isolates. Results: Thirty-nine cases of STEC infection (isolated BD in 16, BD-associated-HUS in 23) were considered, and a total of 130 stool samples from 1 to 8 households of the index patient were analyzed. The prevalence of positivity was higher in siblings (34.8%, 8/23) than in mothers (20%, 7/35), grandparents (9.5%, 2/21), fathers (8.8%, 3/34) or other households. In 14 clusters (36%), one or more household shared a STEC with the same virulence profile (stx, eae, serogroup) as the index case. In 7 clusters, STEC strains isolated from at least 2 subjects also shared identical Pulsed Field Gel Electrophoresis profile. The frequency of household infection does not appear to be associated to the index case’s illness (HUS or BD), nor with the serotype or with the virulence profile of the involved STEC (stx2 or stx1-stx2). Conclusions: Our study shows that STEC infections, most likely related to human-to-human transmission, are common among households of patients with STEC BD or HUS and underlines the importance of extending the epidemiologic investigations to all family members, as the index case may not always be the primary infection in the family.

Shiga Toxin-Associated Hemolytic Uremic Syndrome: Specificities of Adult Patients and Implications for Critical Care Management

“…Human-to-human transmissions have been incriminated in secondary cases during outbreaks, including in Japan in 1996 and in Europe in 2011 [ 14 , 34 , 39 ] and among households [ 69 ].…”

Do asymptomatic STEC-long-term carriers need to be isolated or decolonized? New evidence from a community case study and concepts in favor of an individualized strategy

“…In childcare settings, secondary cases via human-to-human spread during active diarrhea are frequent and this is advocated as an important mechanism during outbreaks ( 33 ). During the acute diarrheal phase persons appear to be more likely to spread STEC than asymptomatic long-term shedders ( 6 , 7 ). In registries of STEC-O157 cases from England ( n = 225 children <6 yrs), Scotland ( n = 2.228 cases over 10 years) and the US secondary cases due to fecal-oral transmission occurred in 10–14% of all cases with confirmed acute enterocolitis.…”

“…Infection prevention measures like sanitary separation of patients during enterohemorrhagic diarrheal disease are undisputed and essential to prevent human-to-human spread. However, the role of asymptomatic STEC carriers as a potential source of new outbreaks is controversial (5)(6)(7)(8). Still, health authorities in most western countries are imposing far-reaching restrictions on STEC carriers.…”