Detection of Streptococcus pneumoniae Antigen in Bronchoalveolar Lavage Fluid Samples by a Rapid Immunochromatographic Membrane Assay

Abstract

Streptococcus pneumoniae prevails as a leading cause of community-acquired pneumonia (CAP), and it ranks as one of the organisms most commonly involved as the cause of severe CAP requiring intensive care admission (1, 9). Recently, an immunochromatographic membrane test (ICT) for rapid detection of S. pneumoniae antigen (NOW Streptococcus pneumoniae test; Binax, Portland, Maine) has been marketed. Till now, the test has been validated for urine and cerebrospinal fluid samples only. According to the package leaflet of the NOW Streptococcus pneumoniae test, the detection limit of the test in cerebrospinal fluid is 5.10 4 CFU/ml. In our hospital, bronchoscopy with bronchoalveolar lavage (BAL) is used in the diagnosis of severe or nonresolving CAP, ventilator-associated pneumonia (VAP), and pneumonia in immunocompromised patients (7). As the BAL procedure dilutes the lung secretions 10-to 100-fold, a BAL fluid colony count of Ն10 4 CFU/ml represents a bacterial load of Ն10 5 to 10 6 /ml at the collection site, which is indicative of pneumonia (2). As this 10 4 CFU/ml threshold is within reach of the ICT, we were interested in evaluating its performance characteristics when applied on BAL fluid samples obtained in patients with suspected pneumonia. MATERIALS AND METHODSSetting and samples. This retrospective study was conducted at the University Hospital of Maastricht, a 600-bed tertiary care hospital. Bronchoscopy with BAL was performed in patients with suspected pneumonia, including severe or nonresolving CAP, VAP, and pneumonia in immunocompromised patients. To test the sensitivity of the ICT, a group of BAL fluid samples obtained from patients diagnosed as having pneumococcal pneumonia was elected: diagnosis was made by microbiological culture, i.e., growth of S. pneumoniae in blood cultures drawn within 24 h before or after bronchoscopy and/or growth in BAL fluid samples in quantities of Ն10 4 CFU/ml. Specificity and cross-reactions were tested in samples of patients with nonpneumococcal pneumonia, i.e., BAL fluid samples with a clear respiratory pathogen demonstrated (influenza virus, respiratory syncytial virus, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila) or with microorganisms other than S. pneumoniae in quantities of Ն10 4 CFU/ml. Furthermore, a group of BAL fluid samples in which pneumonia was suspected but not microbiologically confirmed were included: in these samples, no respiratory pathogen was detected, and quantitative cultures did not reach the 10 4 CFU/ml threshold level. In some samples belonging to the latter two groups, S. pneumoniae was cultured, although in amounts less than 10 4 CFU/ml. Sampling technique. A fiber-optic bronchoscope (Pentax FB-15H/FB-15X; Pentax Medicals, Tokyo, Japan) was introduced and "wedged" into the affected segmental or subsegmental bronchus. Four aliquots of 50 ml sterile saline (0.9% NaCl, room temperature) were instilled and immediately aspirated and recovered. The BAL fluid samples were transported to the laboratory within 15 min after c...

The Binax NOW Test as a Tool for Diagnosis of Severe Acute Otitis Media and Associated Complications

“…However, studies have been performed on nasopharyngeal secretions (10), middle ear effusions (11), cerebrospinal fluids (36), bronchoalveolar lavage fluids (17), pleural fluids (30), and blood cultures (29). The present study included the first three of these sample types, and the test was further successfully adapted to bone tissue.…”

British Thoracic Society guideline for diagnostic flexible bronchoscopy in adults: accredited by NICE

“…Performing the pneumococcal antigen test on BAL is reported to have a sensitivity of 54–95% and a specificity of 86.8–100% for pneumococcal pneumonia 215 216. When available, use of PCR on BAL has been shown to be useful in the detection of legionella,217 218 with reported sensitivity and specificity approaching 100% 218.…”

Clinical impact of combined viral and bacterial infection in patients with community-acquired pneumonia

“…Moreover, risk of contamination from the upper airways has also been reported with this method. Some studies have indicated promising results regarding immune-chromatographic membrane test for S. pneumoniae applied on BAL (Jacobs et al 2005). Bronchoscopy has mostly been used in the intensive care of patients treated with mechanical ventilation.…”