The use of oral washes to diagnose Pneumocystis carinii pneumonia: A blinded prospective study using a polymerase chain reaction-based detection system

Pneumocystis carinii pneumonia (PCP) can be diagnosed by direct microscopic examination of induced sputum or by bronchoalveolar lavage (BAL). However, many institutions have little diagnostic success with induced sputum, and BAL is invasive and expensive. This prospective, blinded study assessed ora l washes as a more convenient specimen than either sputum or BAL fluid and used a dissociation-enhanced lanthanide fluoroimmunoassay time-resolved flu orescent hybridization polymerase chain reaction (PCR) detection system tha t is feasible for clinical laboratories. The study assessed 175 oral washes , each paired with either an induced sputum that was positive for Pneumocys tis or a BAL sample. The PCR test based on the Pneumocystis major surface g lycoprotein primers had a sensitivity of 91% and a specificity of 94%, comp ared with a test based on mitochondrial large subunit rRNA primers, which h ad a sensitivity of 75% and a specificity of 96%. These results suggest tha t oral washes can provide a useful sample for diagnosis of PCP when a sensi tive PCR detection system is used.