Respiratory-tract colonization and a distinctive pneumonia syndrome in infants infected with Chlamydia trachomatis.

To learn if Chlamydia trachomatis causes in young infants a distinctive penumonia characterized by chronic, afebrile course, diffuse lung involvement and elevated serum immunoglobulins G and M, 47 black infants four to 24 weeks of age were examined for nasopharyngeal shedding of C. trachomatis and serum immunofluorescent antibody to lymphogranuloma venereum Type I. Nasopharyngeal C. trachomatis was found in 18 of 20 with the pneumonia syndrome, two of 15 with various other illnesses and 10 of 12 with inclusion conjunctivitis but without lower respiratory illness. Chlamydial antibody titers of infants with the pneumonia syndrome were significantly elevated (geometric mean-1, pneumonia vs. conjunctivitis = 24,833 vs. 1024 P less than 0.001). No other commonly recognized respiratory pathogens were consistently associated with the pneumonia syndrome. We believe these findings demonstrate an association between the distinctive pneumonia syndrome and C. trachomatis. This, in turn, is a particular facet of a more general event consisting of frequent colonization of the respiratory tract by C. trachomatis in natally acquired infection.