Microbiological analyses Sputum samples and blood samples were collected, cultured and evaluated following standard procedures. Micro-organisms cultured in blood or sputum were recorded. In addition, Binax NOW-tests were used to detect urinary antigen for Legionella pneumophila and S. pneumoniae. Acute and convalescent serology samples were collected and evaluated for Mycoplasma pneumoniae, L. pneumophila and Chlamydia pneumonia. Any non-contaminating micro-organism cultured from a blood or sputum sample or detected by urinary antigen testing was considered a cause for the episode of pneumonia. For Mycoplasma pneumoniae, a fourfold or greater increase in titer in paired sera or a single titer of greater than or equal to 1:40 was considered indicative of infection. 23 (Immune fluorescence agglutination, Serodia-MycoII ®, Fujirebio, inc.) For Legionella pneumophila, a fourfold increase in the antibody titer to 1:128 or greater, or single titers of 1:256 or more were considered suggestive of Legionella pneumonia.24 For Chlamydia pneumoniae, detection of IgM above established values, seroconversion of IgG between acute and convalescence samples, high amounts of IgG in single titers or a combination of these factors were considered serological evidence of infection, according to the manufacturers instructions. (ELISA, Savyon Diagnostics Ltd)