Community-acquired pneumonia by Chlamydophila pneumoniae: a clinical and incidence study in Brazil.

As there was not any data on Chlamydia pneumoniae (TWAR) infections in Brazil so far, a prospective cohort study of adult patients hospitalized due to CAP was carried out for one year in a Brazilian university general hospital to detect the incidence of CAP by Chlamydophila pneumoniae (TWAR) for one year. During a whole year 645 consecutive patients hospitalized due to an initial presumptive diagnosis of respiratory diseases by ICD-10 (J00-J99), excluding upper respiratory diseases, were screened; 59 consecutive patients with CAP were diagnosed. They had determinations of serum antibodies to C. pneumoniae by microimmunofluorescence at the Infectious Diseases Laboratory of University of Louisville (KY, USA); 37 patients (63.8%) had seroreactivity to TWAR antigens, from which 23 (39.6%) had previous infection; 3 patients (5.2%) were diagnosed with CAP by TWAR and got cured. The incidence of TWAR CAP in our hospital by seroconversion was 5.2%. Our incidence of 5.2% is probably underestimated since TWAR culture was not available; we suggest that Real-Time PCR be used along with other diagnostic methods in future studies to detect the actual incidence of TWAR CAP. We propose that the serological criterion of IgM >1:16 alone to the diagnosis of acute infection by TWAR are discontinued due a lack of specificity.