Pneumonia due to Chlamydia trachomatis in Japanese infants.

Sera from 109 Japanese infants with pneumonia were tested for antibody to Chlamydia trachomatis (C. trachomatis) L2 strain by an indirect immunofluorescence (IF) technique. Nasopharyngeal swabs were also collected to isolate C. trachomatis. Clinical specimens were inoculated onto cycloheximide-treated McCoy cells and DEAE-dextran-treated HeLa 229 cells. Of 109 patients, 32 (29%) were positive for IgM antibodies (titer, greater than or equal to 1:16) to C. trachomatis. C. trachomatis was isolated from 21 (66%) of 32 IgM antibody-positive infants as compared with 5 (7%) of 77 IgM antibody-negative infants. Detectable levels of IgM antibody were common in infants during the first four months of life. Clinical characteristics of pneumonia of these IgM antibody-positive patients were also described. This is the first report of serology and clinical characteristics of C. trachomatis pneumonitis from Asian countries including Japan.