Prevention of secondary household transmission during Shiga toxin-producing Escherichia coli outbreaks

Detection of plasma anti-lipopolysaccharide (LPS) antibodies against enterohemorrhagic Escherichia coli (EHEC) in asymptomatic kindergarten teachers from Buenos Aires province

In Argentina, hemolytic uremic syndrome (HUS) caused by EHEC has the highest incidence in the world. EHEC infection has an endemo-epidemic behavior, causing 20-30% of acute bloody diarrhea syndrome in children under 5 years old. In the period 2016-2020, 272 new cases per year were notified to the National Health Surveillance System. Multiple factors are responsible for HUS incidence in Argentina including person-to-person transmission. In order to detect possible EHEC carriers, we carried out a preliminary study of the frequency of kindergarten teachers with anti-LPS antibodies against the most prevalent EHEC serotypes in Argentina. We analyzed 61 kindergarten teachers from 26 institutions from José C. Paz district, located in the suburban area of Buenos Aires province, Argentina. Fifty-one percent of the plasma samples had antibodies against O157, O145, O121 and O103 LPS: 6.4% of the positive samples had IgM isotype (n=2), 61.3% IgG isotype (n=19) and 32.3% IgM and IgG (n=10). Given that antibodies against LPS antigens are usually short-lived specific IgM detection may indicate a recent infection. In addition, the high percentage of positive samples may indicate a frequent exposure to EHEC strains in the cohort studied, as well as the existence of a large non-symptomatic population of adults carrying pathogenic strains that could contribute to the endemic behavior through person-to-person transmission. The improvement of continuous educational programs in kindergarten institutions could be a mandatory measure to reduce HUS cases not only in Argentina but also globally.

Etiological diagnosis of post-diarrheal hemolytic uremic syndrome (HUS): humoral response contribution

BACKGROUND

Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolysis, thrombocytopenia, and thrombus formation leading to tissue injury. HUS is classified according to its etiology as post-diarrheal or atypical HUS. Differential diagnosis of both entities continues to be a challenge for pediatric physicians.

METHODS

The aim was to improve the rapid etiological diagnosis of post-diarrheal HUS cases based on the detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) infection by screening of stx_1/stx₂ and rfb_O157 in cultured stools by multiplex PCR, and the additional detection of anti-lipopolysaccharide (anti-LPS) O157, O145, and O121 antibodies by Glyco-iELISA test. In addition, we studied patients' relatives to detect circulating pathogenic strains that could contribute to HUS diagnosis and/or lead to the implementation of measures to prevent dissemination of familial outbreaks. This study describes the diagnosis of 31 HUS patients admitted to Hospital Municipal de Niños Prof Dr Ramón Exeni during the 2017-2020 period.

RESULTS

Stool PCR confirmed the diagnosis of STEC associated with HUS in 38.7% of patients (12/31), while anti-LPS serology did in 88.9% (24/27). In those patients in which both methods were carried out (n = 27), a strong association between the results obtained was found. We found that 30.4% of HUS patients had at least one relative positive for STEC.

CONCLUSIONS

We could identify 96.3% (26/27) of HUS cases as secondary to STEC infections when both methods (genotyping and serology) were used. The results demonstrated a high circulation of STEC in HUS families and the prevalence of the STEC O157 serotype (83%) in our pediatric cohort. A higher-resolution version of the Graphical abstract is available as Supplementary information.

Family Clusters of Shiga Toxin-producing Escherichia coli Infection: An Overlooked Source of Transmission. Data From the ItalKid-Hus Network

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.