A retrospective study of health care-associated pneumonia patients at Aichi Medical University hospital

Health care-associated pneumonia (HCAP) was defined in the American Thoracic Society/Infectious Disease Society of America guidelines on hospital-acquired pneumonia in 2005. However, little is known about the occurrence of HCAP in Japan. A retrospective review of background characteristics, pathological conditions, causative organisms, initial treatments, and risk factors for HCAP was conducted to determine the relationship of HCAP to community-acquired pneumonia and hospital-acquired pneumonia. Thirty-five patients who were admitted to our hospital for pneumonia acquired outside our hospital were included and were stratified by disease severity according to the Japanese Respiratory Society risk stratification guidelines (A-DROP [age, dehydration, respiratory failure, orientation disturbance, and shock blood pressure] criteria). All patients had an underlying disease. A total of 70 microbial strains (25 gram-positive, 37 gram-negative, 6 anaerobic, and 2 causative of atypical pneumonia) were isolated from sputum cultures, showing high isolation frequencies of Pseudomonas aeruginosa and Staphylococcus aureus and extremely low isolation frequencies of Streptococcus pneumoniae and Haemophilus influenzae. “History of hospitalization within 90 days before the onset of pneumonia” was the most common risk factor, and most of the patients had two or three risk factors. Initially, monotherapy [mainly tazobactam/piperacillin (TAZ/PIPC), sulbactam/ampicillin (SBT/ABPC), ceftriaxone (CTRX), cefepime (CPFM), carbapenems, or fluoroquinolones] or combination therapy (beta-lactam and fluoroquinolone) were administered and gave clinical effects in 63% (22/35) of cases. Bacteriological effects were seen in most strains (57%; 40/70). Since the causative organisms of HCAP were closely related to those of hospital-acquired pneumonia and not to community-acquired pneumonia, we believe that aggressive chemotherapy using broad-spectrum antimicrobials is needed in the initial treatment.