Detection of Streptococcus pneumoniae and Haemophilus influenzae type b antigens in the serum and urine of patients with pneumonia in Papua New Guinea: comparison of latex agglutination and counterimmunoelectrophoresis.

Latex agglutination (LA) was compared with counterimmunoelectrophoresis (CIE) for the diagnosis of pneumonia due to Streptococcus pneumoniae or Haemophilus influenzae type b in children less than 6 years old in Papua New Guinea. Neither LA nor CIE was sufficiently sensitive for the detection of pneumococcal antigens. CIE was superior to LA but had a sensitivity of only 60% (six of 10) in concentrated urine and a specificity of 90% (54 of 60). LA for the detection of H. influenzae type b had a sensitivity of 100% (eight of eight) relative to that of blood culture and a specificity of 99% (112 of 113) when urine diluted fivefold was tested, as compared with a sensitivity of 100% (nine of nine) and a specificity of 92% (56 of 61) in undiluted urine. Undiluted and concentrated urine specimens were unsuitable for LA because of the many false-positive reactions that resulted from nasal carriage of H. influenzae type b and nasal carriage of the cross-reactive S. pneumoniae type 6. CIE for the detection of H. influenzae type b had a sensitivity of only 44% (four of nine) in concentrated urine.