INVESTIGATION OF CAUSATIVE AGENTS IN COMMUNITY-ACQUIRED ATYPICAL PNEUMONIA CASES

To investigate the causative agents involved in atypical community-acquired pneumonia (CAP) patients with lower respiratory tract infections. This prospective study (October 2014-August 2016) included 92 adult patients with pre-existing CAP. Serum samples were analyzed for IgG and IgM antibodies using the indirect immunofluorescence antibody (IFA) method. Causative agents associated with typical pneumonia were evaluated in simultaneously obtained sputum cultures. The IgM antibodies and/or the cultures of typical agents exhibited positivity for atypical CAP causative agents in 26 (28%) of the patients. Positive IgM antibodies were found for influenza B virus in five patients, parainfluenza serotype 2 virus in four, echovirus in four, parainfluenza serotype 1 virus in two, parainfluenza serotype 3 virus in two, influenza A (H1N1) virus in two, C. pneumoniae in two and H. influenzae in one. Thirteen (50%) of these patients had typical bacterial growth, while more than one agent was detected in five (20%). The rate of atypical causative agents other than L. pneumophila was quite high. Viruses were the main agents in the atypical CAP patients. The high incidence of typical pneumonia agents found in these patients indicates the necessity of determining the etiologic agents prior to initiation of treatment.