The Urinary Antigen Tests have High Sensitivity in Diagnosis of Pneumococcus Caused Community-Acquired Pneumonia Posterior to Antimicrobial Therapy

Antibiotic treatment before microbiological test significant reduces the positive rate of culture methods of Streptococcus pneumoniae. The Binax NOW S. pneumoniae immunochromatographic test (ICT) has become a more commonly used procedure to diagnose S. pneumoniae from community-acquired pneumonia in adults. However, performance of this test after empirical antimicrobial therapy is uncertain. Therefore, in this prospective study, we evaluate the impact of antimicrobial therapy on sensitivity of ICT test in 487 hospitalized adult patients. The results showed that 192 (39.4 %) and 295 (60.6 %) specimens were collected before (Group 1) or after antibiotic treatment (Group 2), respectively. S. pneumoniae was detected by ICT in 21 (10.9 %) patients in the Group 1 and 39 (13.2 %) in the Group 2 and their positive rates were not different (P > 0.05). However, The positive rate of blood and pleural fluid was declined from 5.7 to 2.7 % and sputum, from 9.9 to 4.7 % after the antibiotic treatment, respectively. This study confirmed that the ICT urinary antigen test remained to have a high sensitivity for diagnosis of pneumococcal infection after empiric antibiotic treatment was started. The ICT urinary antigen test would have a potential to guide the right choice of therapy for pneumonia in adults earlier.