Objective:To investigate the similarities and differences of etiology and clinical characteristics in the elderly health care associated pneumonia(HCAP)and community-acquired pneumonia(CAP)and hospital-acquired pneumonia(HAP). Methods:The clinical data and sputum culture data of 152 cases of CAP and 102 cases of HCAP and 78 cases of HAP in our hospital were retrospectively analyzed. Data were analyzed using SPSS 17.0 statistical software and using analysis of variance and chi square test. Results:There was ...