Latex agglutination test for the diagnosis of Haemophilus influenzae meningitis.

Abstract

Abstract Capsular antigens of Haemophilus influenzae were detected in cerebrospinal fluid (CSF) from 28 of 30 (93.3 per cent) clinically diagnosed or suspected cases of H. influenzae meningitis with the use of a rapid, sensitive slide test with antibody-coated latex particles. Two specimens were nonreactive. In one of these, no organisms were found on direct microscopic examination of the CSF, and growth in culture was delayed. No cross-reactions occurred among antigens of H. influenzae types a through f, with type 6 pneumococcal antigen, or with CSF specimens from patients with other bacterial meningitides. Heat-labile factors were responsible for low-titered nonspecific reactions in 2.3 per cent of control CSF specimens. This non-specific reactivity was destroyed by heating the specimens at 100 °C. for 15 minutes. Conversely, the reactivity in CSF specimens from cases of H. influenzae meningitis was not altered by heat. Results of this study indicate that the latex agglutination technique is a valuable diagnostic aid. It provides a rapid and reliable indication of H. influenzae infection, even in some cases where organisms are scarce or not found in the CSF and growth in culture is delayed or absent.