RESUMO
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 percent) had seroreactivity to TWAR antigens, from which 23 (39.6 percent) had previous infection; 3 patients (5.2 percent) were diagnosed with CAP by TWAR and got cured. The incidence of TWAR CAP in our hospital by seroconversion was 5.2 percent. Our incidence of 5.2 percent 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.