The effects of nonclassic pediatric bacterial pathogens on the usefulness of the Directigen latex agglutination test.

Haemophilus influenzae type b, Escherichia coli, Neisseria meningitis, Streptococcus agalactiae, and Streptococcus pneumoniae are classically the predominant meningeal pathogens of children. The Directigen latex agglutination test identifies these pathogens by detecting specific antigens in cerebrospinal fluid (CSF) and urine. The authors tested 1151 specimens from 791 children with suspected meningeal infections. They found that the sensitivity of the Directigen test for detecting the five classic CSF pathogens of children was 83.3% with CSF and 60% with urine specimens. In detecting all pathogens, however, the sensitivity was only 50% with CSF and 37.5% with urine. Thus, an increased prevalence of nonclassic pathogens in a pediatric population adversely affects the efficacy of the Directigen test for confirming a diagnosis of meningitis and emphasizes the diagnostic importance of the clinical history and other routine CSF tests.