Evaluation of the Japanese Respiratory Society guidelines for the identification of Mycoplasma pneumoniae pneumonia.

Background And Objective: Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. Mycoplasma pneumoniae is one of the major causative pathogens of CAP. Early diagnosis of M. pneumoniae pneumonia is crucial for initiating appropriate antibiotic therapy. The aim of this study was to determine whether the Japanese Respiratory Society (JRS) guidelines on CAP are effective for diagnosing M. pneumoniae pneumonia.

Methods: Between August 2008 and July 2009, adult outpatients with CAP were consecutively enrolled. The aetiology of CAP was determined by culture and real-time polymerase chain reaction (PCR) methods to detect M. pneumoniae, urine antigen tests to detect Streptococcus pneumoniae and Legionella pneumoniae, blood and sputum culture for bacteria and real-time PCR for eight common respiratory viruses. The predictive value of the JRS guidelines for differentiating M. pneumoniae pneumonia from typical bacterial and viral pneumonias was determined.

Results: Data from 215 adult CAP outpatients was analyzed. An aetiological diagnosis was made for 105 patients (48.8%), including 62 patients with M. pneumoniae pneumonia, 17 patients with typical bacterial pneumonia and 23 patients with viral pneumonia. According to the JRS criteria for differential diagnosis of atypical pneumonia, 55 of 62 patients were correctly diagnosed with M. pneumoniae pneumonia (sensitivity 88.7%), and 31 of 40 patients with bacterial and viral pneumonia were correctly excluded (specificity 77.5%).

Conclusions: The JRS guidelines on CAP provide a useful tool for the identification of M. pneumoniae pneumonia cases and differentiating these from cases of typical bacterial or viral pneumonia.