Etiology and cytokine expression in patients requiring mechanical ventilation due to severe community-acquired pneumonia.
BACKGROUND
The relationship between bacterial etiology and serum cytokine levels in patients with severe community-acquired pneumonia (CAP) without response to initial empiric treatment remains unclear. This study investigated the bacterial etiology, outcomes, and bronchoalveolar and systemic cytokines (interleukin [IL]-1beta, IL-8, IL-10) in these patients.


METHODS
This hospital-based study enrolled 47 consecutive patients without response to initial empiric treatment and requiring mechanical ventilation due to severe CAP between July 1, 2000 and October 31, 2001, in a respiratory intensive care unit of a 1200-bed teaching hospital in central Taiwan. Bronchoalveolar lavage (BAL) was performed within 3 days after hospitalization. BAL fluid was processed for quantitative bacterial cultures. Blood samples were taken just before BAL, and the levels of both BAL and serum cytokines were measured.


RESULTS
The most common pathogens isolated were Pseudomonas aeruginosa (22.5%) and Klebsiella pneumoniae (25%). Patients with a K. pneumoniae isolate (n = 10) had significantly higher levels of IL-1beta in BAL fluid and significantly higher levels of IL-10 in serum and BAL fluid than patients with other etiologies. Non-survivors had higher levels of serum IL-8 (p = 0.001), serum IL-10 (p < 0.001) and BAL IL-10 (p = 0.039) than survivors. Marked increases in local and systemic cytokine expression (IL-8 and IL-10) were noted in rapidly fatal cases.


CONCLUSIONS
P. aeruginosa and K. pneumoniae are the most common causes of CAP requiring mechanical ventilation in Taiwan. Cytokine patterns in the BAL fluid and serum of patients with severe CAP due to K. pneumoniae showed significant elevations compared to other pathogens. Bronchoalveolar and systemic cytokine levels (especially IL-10) predicted mortality. These findings suggest the need for a clinical trial to determine how immunomodulating therapy might affect cytokine profiles and clinical outcome.
Wu
Chieh-Liang
CL
Division of Chest Medicine, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, National Yang-Ming University School of Medicine, Taipei, Taiwan, R.O.C.
Chan
Ming-Cheng
MC
Chang
Gee-Chen
GC
Lee
Yao-Ling
YL
Chin
Chung-Shih
CS
Chang
Kai-Ming
KM
Hsu
Jeng-Yuan
JY
D000368:Aged; D000369:Aged, 80 and over; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D017714:Community-Acquired Infections / Q000097:blood / Q000382:microbiology / Q000628:therapy; D016207:Cytokines / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000382:microbiology* / Q000628:therapy; D012121:Respiration, Artificial
D016207:Cytokines