Study objective: To investigate the clinical presentation of community-acquired Chlamydia pneumoniae pneumonia in adults.
Design: Prospective study.
Setting: Kawasaki Medical School Hospital, Kawasaki Medical School Kawasaki Hospital, and Kurashiki Daiichi Hospital in Japan.
Participants: Forty patients with community-acquired pneumonia with C pneumoniae as the only pathogen identified admitted to three hospitals between April 1996 and March 2001 and their clinical presentations were compared to patients with Streptococcus pneumoniae and Mycoplasma pneumoniae pneumonia.
Measurements: The diagnosis of C pneumoniae infection was based on isolation and serologic testing of antibodies by the microimmunofluorescence test.
Results: The clinical presentations, except for shortness of breath, were similar for the three major etiologic agents. The mean temperature of C pneumoniae patients on hospital admission was 37.9°C, which was lower than that of patients with S pneumoniae and M pneumoniae. The mean WBC count on hospital admission was lower in the patients with C pneumoniae (mean, 9,100/μL) than in those with S pneumoniae pneumonia but higher than in those with M pneumoniae pneumonia. No patients required respiratory support or admission to an ICU, and no deaths occurred among the C pneumoniae pneumonia patients.
Conclusions: Our results indicate that C pneumoniae pneumonia as a single etiologic agent is mild and that the underlying conditions and clinical symptoms closely resemble those of S pneumoniae pneumonia. However, the physical examinations, laboratory findings, and prognostic factors of the C pneumoniae patients resembled those of patients with M pneumoniae pneumonia.