[Adult hospital acquired pneumonia: a multicenter study on microbiology and clinical characteristics of patients from 9 Chinese cities].

OBJECTIVE: To investigate the etiology and clinical characteristics of hospital-acquired pneumonia (HAP) in China and to provide evidence for appropriate therapy.

METHODS: We performed a prospective multicenter study in 13 Chinese urban tertiary hospitals. All HAP cases diagnosed at respiratory general ward and respiratory intensive care unit (RICU) from August 2008 to December 2010 were studied. Epidemiological data, etiology and clinical characteristics of enrolled patients were collected. Sputum or tracheal aspirate and blood cultures, Legionella antibodies and Streptococcus pneumoniae urinary antigen tests were performed. Bacteria to antimicrobial susceptibility test was performed.

RESULTS: A total of 610 cases of HAP were diagnosed during the study, with an overall incidence of 1.4% among 42 877 hospitalized patients, while the incidence was 0.9% (362/41 261) in respiratory general ward and 15.4% (248/1616) in RICU. 93.9% (573 cases) of patients had at least one underlying disease, and 91.0% (555 cases) had exposure to at least one antimicrobial agent within 90 days prior to HAP diagnosis. Pathogens were identified in 487 patients, with Acinetobacter baumannii [30.0% (183/610)], Pseudomonas aeruginosa [22.0% (134/610)], Staphylococcus aureus [13.4% (82/610)] and Klebsiella pneumonia [9.7% (59/610)] being the most common pathogens. Eighteen patients (3.0%) had infection with fastidious bacteria. A. baumannii and S. aureus were the more frequent pathogens in the ventilator-associated pneumonia (VAP) cases [50.5% (97/192) and 21.4% (41/192)] as compared to non-VAP cases [20.6% (86/418) and 9.8% (41/418), P < 0.01]. A. baumannii and S. aureus were also frequent pathogens in cases with a score of more than 20 by the acute physiology and chronic health evaluation II (APACHEII) scoring [45.7% (69/151) and 20.5% (31/151)], as compared to cases with a score of less than 20 of APACHE II [24.8% (114/459) and 11.1% (51/459), P < 0.01]. A. baumannii showed high resistance rates to carbapenems [more than 70% (109/142)], and the susceptibility to cefoperazone/sulbactam, polymyxin B and tigecycline were 40.8% (58/142), 99.3% (141/142) and 95.8% (136/142) respectively. Resistance rates of P. aeruginosa to meropenem and imipenem were 48.8% (40/82) and 70.7% (58/82) respectively. Methicillin-resistant S. aureus (MRSA) accounted for 87.8% (43/49) in all strains of S. aureus. Mortality rate of VAP cases was 34.5% (61/177), significantly more than that of HAP patients [22.3% (135/605), P < 0.05]. The average hospital stay of patients with HAP was (23.8 ± 20.5) days, significantly more than that of the average for inpatients [(13.2 ± 13.6) days, P < 0.01] during the study period. Mean costs of HAP were (108 950 ± 116 608) yuan, significantly higher than the average hospital costs of respiratory inpatients (17 999 ± 33 364) yuan.

CONCLUSIONS: Among Chinese patients hospitalized in urban tertiary medical centers, HAP incidence and mortality rate were high, which increased the patients' hospital stay and the medical costs. Common pathogens were A. baumannii, P. aeruginosa, S. aureus and K. pneumonia. The common bacteria of HAP in China showed high resistance rates to antibiotics.