To identify pneumococcal antigen in exhaled breath condensate (EBC) from subjects with documented or highly suspected pneumococcal pneumonia.
Within 48 hours of starting antibiotics, EBC samples were obtained using the R- tube collection system from five cases with documented or supected pneumococcal pneumonia and five normal, healthy controls. Documented pneumococcal infection was defined as positive blood, CSF or sputum culture or a positive urine pneumococcal antigen. Highly suspected pneumococcal infection was defined by blood, CSF, or sputum sample with gram positive cocci in pairs and chains on gram stain. Inclusion criteria included age greater than 18, fever > 38 or < 36 degrees centigrade, leukocyte count > 12.0 × 103 cells/L or < 4.0 × 103 cells/L with bands > 10%, new infiltrate on chest radiograph, and documented or highly suspected pneumococcal infection. The EBC and urine samples were tested for the Streptococcus pneumoniae antigen using the Binax NOW® kit, an in vitro immunochromatographic assay.
Two of five cases had documented pneumococcal infection with positive blood cultures for streptococcus pneumoniae, with one having positive urine test. The remaining three highly suspucted cases demonstrated gram positive cocci in the sputum. The pneumococcal antigen was not identified in the EBC in any of the cases or controls. (Table 1).
In this pilot study, pneumococcal antigen was not identified in the exhaled breath condensate of patients with documented or highly suspected pneumococcal pneumonia. This maybe a result of failure to entrain bacterial antigens in EBC or entrainment at a concentration below the threshold of detection by the immunochromographic assay.
The demonstration of bacterial biomarkers in EBC would facilitate defining a pathogen directly from the tissue of interest in pulmonary infections. To our knowledge, a bacterial antigen has not been identified in the EBC. Further work is required to optimize recovery of bacterial biomarkers in EBC.
Mandip Rawla, No Financial Disclosure Information; No Product/Research Disclosure Information