Prevalence of asymptomatic infection with Chlamydia pneumoniae in subjectively healthy adults

Study objective: To investigate the prevalence of asymptomatic infection wi th Chlamydia pneumoniae in subjectively healthy adults. Design: Prospective study. Setting: Kawasaki Medical School Hospital in Kurashiki, Japan. Participants : Total of 1,018 asymptomatic healthy adults (age range, 22 to 50 years; me an age, 32.4 years; 482 men and 536 women). Measurements and results: Nasopharyngeal swab specimens were obtained from ah subjects and analyzed by isolation in cell cultures and polymerase chain reaction (PCR) test for C pneumoniae. Serum samples were also obtained and tested for C pneumoniae-specific antibodies by the microimmunofluorescence test, Of 1,018 specimens tested, 14 specimens (1.4%) were judged positive by culture and/or the PCR, Thirteen specimens were PCR positive, and 4 spec imens were culture positive, There were three specimens positive by both te sts and II specimens positive with discrepancies in culture and PCR results . None of the individuals met the serologic criteria for acute infection. O f 1,018 sera tested, 64.1% of men and 58.0% of women had antibody to C pneu moniae, The overall prevalence of antibody was 60.9%, Forty individuals (3. 9%) had an IgG titer of greater than or equal to 1:512 or IgM titer of grea ter than or equal to 1:16, Conclusions: Our data suggest that asymptomatic infection with C pneumoniae may occur in subjectively healthy adults.