Study objective: To study the usefulness of a diagnostic multiplex PCR (mPCR) for Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, and Chlamydophila pneumoniae applied to bronchoalveolar lavage (BAL) in lower respiratmy tract infection (LRTI).
Design: Prospective diagnostic study.
Setting: Silkeborg County Hospital, Silkeborg, Denmark.
Patients and participants: Hospitalized adult LRTI patients (n=I56) and adult controls investigated on suspicion of malignancy (n=36).
Interventions: After fiberoptic bronchoscopy (FOB) BAL fluid was analysed with bacterial culture and mPCR. S. pneumoniae and H. influenzae etiologies were established by cultures from blood, BAL and sputum, and urinary antigen test for S. pneumoniae. M. pneumoniae etiology was established by singleplex PCR on BAL and throat swab, and C. pneumoniae etiology by singleplex PCR and culture on BAL and throat swab.
Measurements and Results: S. pneumoniae, H. influenzae, M. pneumoniae, and C. pneumoniae were etiologies in 14%, 21%, 3.2%, and 0, of the LRTI patients, respectively. These pathogens were identified by BAL mPCR in 28%, 47%, 3.2%, and 0.6%, respectively. The sensitivities of BAL mPCR were 0.86 for S. pneumoniae, 0.88 for H. influenzae, 1.0 for M. pneumoniae, and 0/0 for C. pneumoniae. The specificities were 0.81 for S. pneumoniae, 0.64 for H. influenzae, 1.0 for M. pneumoniae, and 0.99 for C. pneumoniae. In 103 patients with antibiotics taken prior to FOB, BAL culture and BAL mPCR identified S. pneumoniae in 2.9% and 31%, respectively, and H. influenzae in 20% and 50%, respectively. Among the controls, BAL culture and mPCR identified S. pneumoniae in 8.3% and 11%, respectively, and H. influenzae in 11% and 39%, respectively. No M. pneumoniae or C. pneumoniae was identified among the controls.
Conclusions: In LRTI patients, BAL mPCR can be useful for identification of S. pneumoniae, M. pneumoniae, and C. pneumoniae. The method appears particularly useful in patients treated with antibiotics.