The goal of this prospective and observatory study is to learn about the pathogen, clinical manifestations, prognosis, treatment and antibiotic resistance of bacteria in hospital-acquired pneumonia patients in China.

The main purposes of this study are:

1. clarify the regional differences and changes over time in the pathogen spectrum and antibiotic resistance rate among HAP patients in China;
2. build a continuously optimized nationwide HAP pathogen and antibiotic resistance surveillance network;
3. identify the molecular epidemiology of common pathogens

Inclusion Criteria:

1. Age ≥ 18 years old.
2. Meets the clinical diagnostic criteria for HAP in the 2018 HAP/VAP guidelines. Chest X-ray or CT shows new or progressive infiltrative shadows, consolidation shadows, or ground glass shadows, combined with 2 or more of the following 3 clinical symptoms, to establish a clinical diagnosis: 1) Fever, body temperature>38 ℃; 2) Purulent airway secretions; 3) Peripheral blood white blood cell count >10 × 10^9/L or <4 × 10^9/L.
3. Having qualified evidence of responsible pathogen. On the basis of clinical diagnosis, one of the following conditions should be met simultaneously: 1) Qualified lower respiratory tract secretions (neutrophil count >25/low magnification field, epithelial cell count <10/low magnification field, or a ratio of the two >2.5:1), pathogenic bacteria cultured through bronchoscopy anti pollution brush (PSB), bronchoalveolar lavage fluid (BALF), lung tissue or sterile body fluid, and consistent with clinical manifestations; 2) Pathology, cytopathology, or direct microscopic examination of lung tissue specimens showing fungi and evidence of tissue damage; 3) The serum IgM antibodies of atypical pathogens or viruses change from negative to positive, or the titers of specific IgG antibodies in both acute and recovery phases show a 4-fold or more change. During the outbreak of respiratory viruses and with a history of epidemiological contact, respiratory secretions were tested positive for corresponding virus antigens, nucleic acid tests, or virus culture.
4. obtained informed consent

Exclusion Criteria:

1. Those who cannot understand and execute the investigation plan.
2. Active pulmonary tuberculosis;
3. Severely immunosuppressed patients: absolute neutrophil count <0.5× 10^9/L, CD4<200/ml.

hospital-acquired pneumonia adult patients with qualified evidence of responsible pathogen in China