Diagnostic importance of pulmonary interleukin-1beta and interleukin-8 in ventilator-associated pneumonia.
BACKGROUND
Ventilator-associated pneumonia (VAP) is the most commonly fatal nosocomial infection. Clinical diagnosis of VAP remains notoriously inaccurate. The hypothesis was tested that significantly augmented inflammatory markers distinguish VAP from conditions closely mimicking VAP.


METHODS
A prospective, observational cohort study was carried out in two university hospital intensive care units recruiting 73 patients with clinically suspected VAP, and a semi-urban primary care practice recruiting a reference group of 21 age- and sex-matched volunteers. Growth of pathogens at >10(4) colony-forming units (cfu)/ml of bronchoalveolar lavage fluid (BALF) distinguished VAP from "non-VAP". Inflammatory mediators were quantified in BALF and serum. Mediators showing significant differences between patients with and without VAP were analysed for diagnostic utility by receiver operator characteristic (ROC) curves.


RESULTS
Seventy-two patients had recoverable lavage-24% had VAP. BALF interleukin-1beta (IL-1beta), IL-8, granulocyte colony-stimulating factor and macrophage inflammatory protein-1alpha were significantly higher in the VAP group (all p<0.005). Using a cut-off of 10 pg/ml, BALF IL-1beta generated negative likelihood ratios for VAP of 0.09. In patients with BALF IL-1beta <10 pg/ml the post-test probability of VAP was 2.8%. Using a cut-off value for IL-8 of 2 ng/ml, the positive likelihood ratio was 5.03. There was no difference in cytokine levels between patients with sterile BALF and those with growth of <10(4) cfu/ml.


CONCLUSIONS
BALF IL-1beta and IL-8 are amongst the strongest markers yet identified for accurately demarcating VAP within the larger population of patients with suspected VAP. These findings have potential implications for reduction in unnecessary antibiotic use but require further validation in larger populations.
Conway Morris
Andrew
A
MRC Centre for Inflammation Research, Room C2.17, University of Edinburgh, Edinburgh EH16 4TJ, UK. mozza@doctors.org.uk
Kefala
Kallirroi
K
Wilkinson
Thomas S
TS
Moncayo-Nieto
Olga Lucia
OL
Dhaliwal
Kevin
K
Farrell
Lesley
L
Walsh
Timothy S
TS
Mackenzie
Simon J
SJ
Swann
David G
DG
Andrews
Peter J D
PJ
Anderson
Niall
N
Govan
John R W
JR
Laurenson
Ian F
IF
Reid
Hamish
H
Davidson
Donald J
DJ
Haslett
Christopher
C
Sallenave
Jean-Michel
JM
Simpson
A John
AJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000382:microbiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis; D053583:Interleukin-1beta / Q000032:analysis*; D016209:Interleukin-8 / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult
D015415:Biomarkers; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D016209:Interleukin-8