Although large-scale administrative databases may be useful for studies of infectious diseases, conventional databases lack microbiological data. To illustrate the applicability of the National Hospital Organization Clinical Data Archives, a novel database of electronic medical records in Japan, we conducted a descriptive study of the microbiological findings in patients with community-acquired pneumonia using the database. We identified patients aged ≥18 years who were hospitalized for community-acquired bacterial pneumonia between April 2016 and March 2019. We evaluated the results of bacterial culture and antibacterial susceptibility of specimens obtained on the first day of hospitalization, in addition to patient characteristics, diagnosis codes, and intravenous antibiotics administered. The analysis identified 2200 eligible patients from 15 hospitals. Sulbactam–ampicillin was the most frequently used initial antibiotic (32 %), followed by ceftriaxone (22 %) and tazobactam–piperacillin (19 %). Overall, 56 %, 95 %, 56 %, and 73 % of patients with pathogen-specific diagnosis codes in the database for Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, and Pseudomonas aeruginosa, respectively, also tested positive for the corresponding pathogen in their sputum or blood cultures. Antibacterial susceptibilities were consistent with a previous report from Japan; 81 % of S. pneumoniae cases were resistant to azithromycin, and 48 % of H. influenzae cases were resistant to ampicillin. These microbiological characteristics warrant the future use of this database for detailed real-world research on infectious diseases.