Evaluation of a latex kit reagent for the detection and identification of pneumococci.

The ability of a commercial latex kit to detect pneumococcal antigen in 50 CSF samples, 150 ear swabs and 80 sputum samples was investigated. Results were compared with microscopic and culture findings. 18/19 culture-positive specimens were latex-positive. 7 latex-positive specimens yielded organisms other than S. pneumoniae which agglutinated the latex, 4 Klebsiella spp, 2 Staphylococcus aureus and 1 Haemophilus influenzae. For 11 other specimens latex agglutination was positive and culture negative. S. pneumoniae was recovered from the blood of 1 of these patients and, in 2 further cases, microscopy showed poorly stained organisms which had some resemblance to S. pneumoniae. For 10 different strains of S. pneumoniae suspensions containing between 10(4) and 10(7) organisms per ml were required to agglutinate the latex.