Detection of pneumococcal capsular antigen in saliva of children with pneumonia

Abstract

The concentration of pneumococcal capsular antigen (PCA) in saliva was examined in 44 Thai children aged between 2 months and 2 years admitted with community-acquired pneumonia and in 52 healthy controls. None of the children with pneumonia had a positive blood culture. PCA was detected by latex agglutination in the saliva of 12/44 (27%) children with pneumonia compared with 9/52 (17%) of the controls. More cases than controls had a PCA titre ≥ 10 (9/44 (20%) vs 1/52 (2%), p < 0.01). Three of the five cases with a saliva PCA titre ≥ 1000 were urine PCA antigen-positive. The salivary PCA titres were higher, but not significantly, in children with heavier pneumococcal carriage. Quantitative measurement of PCA in the saliva may be valuable in helping to make an aetiological diagnosis in children with pneumonia.