The Binax NOW 'Streptococcus pneumoniae' test for the diagnosis of pneumococcal meningitis in children

ABSTRACT

@#Background: Identifying the causes of childhood meningitis is difficult. Conventional diagnostic tests (culture, bacterial latex and Gram staining) have limitations, especially in settings where many children receive antibiotics prior to presentation. A point-of-care test called Binax NOW detects meningitis due to 'Streptococcus pneumoniae' in 15 minutes and is not affected by pre-test antibiotic use. <br /><br /> Methods: A prospective study was conducted among children with suspected bacterial meningitis at Angau Memorial General Hospital to evaluate the usefulness of the Binax NOW 'S. pneumoniae' test in comparison with conventional tests cerebrospinal fluid (CSF) bacterial culture, Gram stain and latex agglutination. Latex antigen testing was done for 'S. pneumoniae, Haemophilus influenzae and Neisseria meningitidis'. We analysed the CSF of all children who had a lumbar puncture done for clinical suspicion of meningitis. FINDINGS: 132 children were enrolled in the study, of which 3 were excluded because of insufficient CSF sample to do the Binax NOW test. 5 CSFs were culture positive, all for 'S. pneumoniae'. 13 (10%) of 129 CSF specimens had organisms seen with Gram staining; 7 had Gram-positive cocci and 6 showed Gram-negative bacteria. Latex antigens were positive in 20 cases for S. pneumoniae (11), 'H. influenzae' (8), 'N. meningitidis' (1). Using the 3 conventional tests combined (culture, Gram stain and antigens) 14 cases of 'S. pneumoniae' meningitis were detected. Binax NOW was positive for 'S. pneumoniae' in 19 cases (15% of meningitis cases) the 14 samples positive by conventional methods and a further 5 cases that were not detected by conventional methods. <br /><br /> Conclusion: The Binax NOW test increases the diagnostic yield for pneumococcal meningitis on CSF. This may be important in surveillance for the effectiveness of pneumococcal conjugate vaccine introduced in Papua New Guinea (PNG) in 2014, and in clinical diagnosis. 'H. influenzae' is rarely identified on culture in PNG provincial hospital laboratories, so latex antigen testing is still needed for the accurate diagnosis of 'Haemophilus' meningitis and monitoring of the effectiveness of 'Haemophilus influenzae' type b vaccine.