LAUSR

BACKGROUND The most severe form of pneumococcal disease is invasive pneumococcal disease (IPD), including empyema, sepsis and meningitis. Thomsen-Friedenreich antigen (TA; Galβ1-3GalNAc) activation is known to be a predictor of Streptococcus pneumoniae-associated hemolytic uremic syndrome (Sp-HUS). There have been limited data to correlate TA activation and overall disease severity of IPD in children. The study aimed to prove the positive correlation between TA activation and disease severity and to demonstrate the trend of TA level during the disease course. METHODS We retrospectively reviewed the medical records from 38 pediatric patients aged from 0 to 18 years with microbiologically-confirmed IPD between 2010 and 2015 at a medical center in Taiwan. All cases underwent TA activation testing by the fluorescence-labeled peanut lectin agglutination method. Medical information including demographic data, laboratory findings, co-morbidities, and outcome was collected and reviewed. We compared the clinical manifestations and associated co-morbidities between TA-positive and TA-negative patients. RESULTS Among the 38 patients, 25 (66%) showed TA activation. Compared to TA-negative patients, patients with TA activation had a statistically higher rate of prolonged anemia, thrombocytopenia, and acute kidney injury. TA-positive patients also had a longer intensive care unit stay and overall hospitalization days. The TA levels usually peaked 5-10 days after disease onset. Twenty-one pneumococcal isolates were recovered from the patients and serotyping was determined in 11 isolates: 10 serotype 19A and 1 serotype 3. CONCLUSIONS TA determination not only helps to diagnose Sp-HUS but also is a predictor for IPD severity. Among hospitalized patients with severe pneumococcal disease, the peak of TA level usually appeared 5-10 days after disease onset.