Chlamydia trachomatis: a major agent of respiratory infections in infants from low-income families

To determine the prevalence of lower respiratory tract infection (LRTI) due to Chlamydia trachomatis in newborn infants and to describe the clinical, laboratory, and radiological characteristics of the disease. A cross-sectional study carried out over a 12-month period. All infants up to 6 months of age admitted consecutively at the Centro Pediátrico Professor Hosannah de Oliveira of the Universidade Federal da Bahia in Salvador, Brazil, and diagnosed with LRTI according to clinical and/or radiological criteria were included in the study. C. trachomatis infection was diagnosed by the enzyme-linked immunosorbent assay (ELISA) for the detection of IgM-class antibodies. The prevalence of LRTI by C. trachomatis was determined and the prevalence ratios for the infection and clinical or laboratory variables were calculated. One hundred and fifty-one infants were submitted to serology for C. trachomatis and 15 (9.9%) tested positive. Chlamydial infection was found only in infants under 5 months of age, mainly in those aged under 2 months. Three of the infants with C. trachomatis infection were born by cesarean section. Conjunctivitis and eosinophilia had occurred in 33.3% of the cases. Chest X rays were abnormal in 92.0% of cases. There was an association between C. trachomatis infection and the duration of hospitalization exceeding 15 days (p = 0.0398) and oxygen therapy (p = 0.0484). There was a high prevalence of C. trachomatis respiratory infection in the population studied. The infection was associated with a more severe form of the disease, emphasizing the importance of testing pregnant women for this infection to avoid infection in the newborn infant.