Detection of antipneumolysin in invasive childhood pneumococcal infections

Antibody levels against pneumolysin, a virulence factor in pneumococcal infections were evaluated by a neutralization test, using crude pneumolysin. A study population of 28 hospitalised children with culture proven pneumococcal meningitis and pneumonia were tested for detection of antipneumolysin antibodies in their serum. Results were compared with age and sex matched controls who were admitted with infections other than pneumococcal. Geometric mean titer (GMT) of antipneumolysin in serum of patients with pneumococcal infections showed a significant difference when compared with controls, GMT of 196.1 and 185.2 were noted in patients with meningitis and pneumonia respectively, in contrast to a titer of 40.32 among controls. A difference of more than 4-fold antibody titers between patients and controls was considered significant. Detection of antipneumolysin in serum can therefore be considered as a useful laboratory investigation in diagnosing invasive pneumococcal infections.