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Rapid diagnosis of pneumococcal meningitis using Binax NOW Urinary Antigen Kit

Abstract number: r2080

Ebnoether  C., Schlaberg  R., Bregenzer  T., Zbinden  R.

Objectives: 

The Binax NOW Streptococcus pneumoniae urinary antigen assay (Binax NOW test) was developed to detect S. pneumoniae antigens in urine samples in patients with suspected pneumococcal pneumonia. Sensitivity and specifity are 65.9–70.4% and 89.7–100% respectively in adults with community-acquired pneumonia. Maria A. Marcos used Binax NOW test for the diagnosis of pneumococcal meningitis in CSF samples and urine. Sensitivity and specificity were 100% in specimen from eight patients. Cross-reactivity of rapid antigen tests are well known for S. pneumoniae and Streptococcus spp. of the oralis Group, i.e. S. oralis and S. mitis. Cross-reativity results from the fact that all three species share the C-polysaccharide, which is detected by Binax NOW. However, bacterial meningitis with oral streptoccoci are rare and usually iatrogenic.

Methods: 

We used the Binax Now test manufactured by Binax, Maine 04103 USA to test CSF-samples from 77 patients with suspected bacterial meningitis: 14 CSF-samples with Gram-positive cocci in the Gram-stain, 4 with Gram-negative rods (3) or Gram-negative cocci (1), 7 CSF-samples with negative direct stain but positive CSF culture. In addition, 52 CSF-samples with negative direct stain and negative CSF culture were tested.

Results: 

In 6 out of 14 CSF-samples with Gram-positive cocci in the direct stain culture grew S. pneumoniae, 4 grew coagulase negative Staph., 1 S. haemolyticus and 1 S. milleri and anaerobic flora, 1 Enterococci, 1 S. oralis/mitis. Binax Now test was positive for all CSF-samples growing S. pneumoniae and weakly positive in one sample with S. milleri. In 4 direct stain positive CSF (3 rods, 1 Gram-negative cocci) the Binax Now test was negative. In 7 Gram-stain negative CSF-samples cultures grew other species (5 coagulase negative Staph., 1 Enterobactercloacae, 1 Propioni bacterium) and Binax Now test was negative. It was negative too in the 52 CSF-samples with negative direct stain and negative culture. (ppV 86 %, npV 100 %). The patient with the false positive Binax Now test had a brain abscess (S.milleri and anaerobic flora).

Conclusion: 

Binax NOW antigen test on CSF revealed positive results in all culture positive pneumococcal meningitis. There was no false negative result and only one false positive (weak) reaction. In patients with suspected bacterial meningitis Binax NOW test seems to be a reliable, rapid diagnostic tool to identify patients with pneumococcal meningitis.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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