Alveolar pentraxin 3 as an early marker of microbiologically confirmed pneumonia: a threshold-finding prospective observational studyReport as inadecuate

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Critical Care

, 18:562

First Online: 15 October 2014Received: 24 April 2014Accepted: 01 October 2014


IntroductionTimely diagnosis of pneumonia in intubated critically ill patients is rather challenging. Pentraxin 3 PTX3 is an acute-phase mediator produced by various cell types in the lungs. Animal studies have shown that, during pneumonia, PTX3 participates in fine-tuning of inflammation for example, microbial clearance and recruitment of neutrophils. We previously described an association between alveolar PTX3 and lung infection in a small group of intubated patients. The aim of the present study was to determine a threshold level of alveolar PTX3 with elevated sensitivity and specificity for microbiologically confirmed pneumonia.

MethodsWe recruited 82 intubated patients from two intensive care units San Gerardo Hospital, Monza, Italy, and Massachusetts General Hospital, Boston, MA, USA undergoing bronchoalveolar lavage BAL as per clinical decision. We collected BAL fluid and plasma samples, together with relevant clinical and microbiological data. We assayed PTX3 and soluble triggering receptor expressed on myeloid cells 1 sTREM-1 in BAL fluid and PTX3, sTREM-1, C-reactive protein CRP and procalcitonin PCT in plasma. Two blinded independent physicians reviewed patient data to confirm pneumonia. We determined the PTX3 threshold in BAL fluid for pneumonia and compared it to other biomarkers.

ResultsMicrobiologically confirmed pneumonia of bacterial n =12, viral n =4 or fungal n =8 etiology was diagnosed in 24 patients 29%. PTX3 levels in BAL fluid predicted pneumonia with an area under the receiving operator curve of 0.815 95% CI =0.710 to 0.921, P <0.0001, whereas none of the other biomarkers were effective. In particular, PTX3 levels ≥1 ng-ml in BAL fluid predicted pneumonia in univariate analysis β =2.784, SE =0.792, P <0.001 with elevated sensitivity 92%, specificity 60% and negative predictive value 95%. Net reclassification index PTX3 values ≥1 ng-ml in BAL fluid for pneumonia indicated gain in sensitivity and-or specificity vs. all other mediators. These results did not change when we limited our analyses only to confirmed cases of bacterial pneumonia. Moreover, when we considered only the 70 patients who fulfilled the clinical criteria for the diagnosis of pneumonia at BAL fluid sampling, the diagnostic accuracy of PTX levels was confirmed in univariate and ROC curve analysis.

ConclusionsIn this hypothesis-generating convenience sample, a PTX3 level ≥1 ng-ml in BAL fluid was discriminative of microbiologically confirmed pneumonia in mechanically ventilated patients.

AbbreviationsAUCArea under the receiving operating characteristic curve

BALBronchoalveolar lavage

CPISClinical Pulmonary Infection Score

CRPC-reactive protein

NPVNegative predictive value


PPVPositive predictive value

PTX3Pentraxin 3

sTREM-1Soluble triggering receptor expressed on myeloid cells 1

Electronic supplementary materialThe online version of this article doi:10.1186-s13054-014-0562-5 contains supplementary material, which is available to authorized users.

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Author: Tommaso Mauri - Andrea Coppadoro - Michela Bombino - Giacomo Bellani - Vanessa Zambelli - Carla Fornari - Lorenzo Berra - E


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