Detection of Mycoplasma pneumoniae by polymerase chain reaction in lung aspirates from patients with community-acquired pneumonia

Study objective: This study was designed to evaluate the usefulness of polymerase chain reaction (PCR) to detect Mycoplasma pneumoniae DNA in samples obtained by transthoracic needle aspiration (TNA). Design: Prospective study of cases. Setting: A university hospital in Lleida, Spain. Patients: A total 101 unselected patients, admitted between January 1993 and March 1994 in the emergency department, with a clinical and radiologic picture of community-acquired pneumonia, and without contraindications for TNA application. Interventions: Patients were studied with conventional diagnostic techniques for community-acquired pneumonia. In addition, a sample obtained by TNA was processed by the following methods: culture in standard media, culture in selective media for Legionella, detection of capsular antigens for Streptococcus pneumoniae and Haemophilus influenzae, and detection of M pneumoniae specific genome by PCR. Results: Serologic data were not available in eight patients and were excluded from this analysis. M pneumoniae PCR amplification was possible in eight cases, well correlated with serologic responses indicating current infection. Samples from ten additional patients, negative by PCR, were found to be demonstrative of recent M pneumoniae infection by serologic study. Finally, in all remaining 75 cases, including the 59 patients for whom a different microbial diagnosis was established, M pneumoniae PCR test gave negative results. Conclusion: This study indicates that PCR, applied to samples obtained by TNA, appears to be a moderately sensitive and highly specific method for rapid detection of M pneumoniae lung infection.