Secondary benefits of residential treatment camp for parents of adolescents with problematic internet use.

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy defined by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury [, ]. It occurs predominantly in young children and is the most common cause of acute intrarenal kidney injury in childhood. In most cases, HUS is triggered by infection with enterohemorrhagic , a highly pathogenic subgroup of Shiga toxin–producing (STEC), with O157:H7 (sequence type (ST) 11 and related STs) being the most extensively studied serotype [, ]. STEC infections usually occur sporadically, but larger outbreaks can cause substantial morbidity and mortality also in adolescents and adults, as highlighted by the 2011 European outbreak []. In August 2025, an outbreak caused by the STEC serotype O45:H2 originated in the northeastern German state of Mecklenburg-Western Pomerania and subsequently spread to North Rhine-Westphalia, with additional sporadic cases reported in other regions [, ]. This outbreak, the largest of its kind in Germany since 2011, currently has an unidentified source, and epidemiological investigations are ongoing [, ]. As of 17 November 2025, 199 laboratory-confirmed cases had been attributed to the outbreak, including 53 HUS cases and 145 STEC cases without HUS; disease classification was unknown in 1 case []. The median age was 4 years, and all HUS cases occurred in children []. Before this outbreak, the STEC causing serotype O45:H2 had been rarely detected in Germany. Between January 2015 and June 2025, the National Reference Centre for Salmonella and Other Bacterial Enteric Pathogens identified only 13 O45:H2 isolates, 4 of them associated with HUS; none were genetically closely related to the O45:H2 outbreak strain [, , ]. Given the rarity of this serotype and the unusually high number of associated HUS cases, this outbreak provides a unique opportunity to clinically characterize STEC O45:H2-associated HUS and to compare it with non-O45:H2 STEC-HUS cases from the same region and time period. Hemolytic uremic syndrome was defined by the concurrent presence of microangiopathic hemolytic anemia, reflected by hemoglobin concentrations below 10 g/dL (or below local standard values for age) with evidence of erythrocyte fragmentation, thrombocytopenia with platelet counts under 150 × 10/L (or local standard values for age), and acute kidney injury, defined according to the KDIGO pediatric criteria (≥stage 1) [], with assessment based on age-adjusted reference values in the absence of baseline creatinine measurements. Estimated glomerular filtration rate (eGFR) was calculated using the bedside Schwartz formula (2009), with age- and height-adjusted parameters applied via the PED(z) calculator [, ]. Arterial hypertension was defined as blood pressure exceeding the 95th percentile for age and height [, ]. Mild neurological symptoms included irritability, lethargy, headache, or mild alterations in mental status, whereas severe neurological involvement comprised seizures, markedly reduced level of consciousness (eg, somnolence or coma), focal neurological deficits, or neurological deterioration requiring intensive care. Fluid management was categorized as infusion, restriction, or monitoring. Infusion was defined as intravenous fluids administered according to weight-based maintenance requirements, calculated using the Holliday–Segar method, with the aim of volume expansion (∼3%–5% weight gain) [, ]. Baseline weight was obtained from parental report or health records; if unavailable, volume status was assessed clinically. Restriction was defined as fluid intake below calculated maintenance requirements. Monitoring was defined as observation without active intervention, with oral intake determined by the family.