Research Article SequentialMeasurementsofPentraxin3SerumLevelsin PatientswithVentilator-AssociatedPneumonia:ANested Case-Control Study HuseyinBilgin , 1 MuratHaliloglu, 2 AliYaman, 3 PinarAy, 4 BelizBilgili, 2 MustafaKemalArslantas , 2 FilizTureOzdemir, 5 GoncagulHaklar, 3 IsmailCinel, 2 andLutfiyeMulazimoglu 1 1 Infectious Diseases and Clinical Microbiology, Marmara University School of Medicine, Istanbul, Turkey 2 Department of Anesthesiology and Intensive Care, Marmara University School of Medicine, Istanbul, Turkey 3 Department of Biochemistry, Marmara University School of Medicine, Istanbul, Turkey 4 Department of Public Health, Marmara University School of Medicine, Istanbul, Turkey 5 Department of Immunology, Marmara University School of Medicine, Istanbul, Turkey Correspondence should be addressed to Huseyin Bilgin; husambilginer@gmail.com Received 7 January 2018; Revised 4 March 2018; Accepted 29 March 2018; Published 13 May 2018 Academic Editor: Jorge Garbino Copyright©2018HuseyinBilginetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. e main purpose of this study was to investigate the dynamics of pentraxin 3 (PTX3) compared with procalcitonin (PCT) and C-reactive protein (CRP) in patients with suspicion of ventilator-associated pneumonia (VAP). Materials and Methods. We designed a nested case-control study. is study was performed in the Surgical Intensive Care Unit of a tertiary care academic university and teaching hospital. Ninety-one adults who were mechanically ventilated for >48 hours were enrolled in the study. VAP diagnosis was established among 28 patients following the 2005 ATS/IDSA guidelines. Results. e median PTX3 plasma level was 2.66 ng/mL in VAP adults compared to 0.25 ng/mL in non-VAP adults (p < 0.05). Procalcitonin and CRP levels did not significantly differ. Pentraxin 3, with a 2.56 ng/mL breakpoint, had 85% sensitivity, 86% specificity, 75% positive predictive value, and 92.9% negative predictive value for VAP diagnosis (AUC � 0.78). Conclusions.WiththesuspicionofVAP,apentraxin3 plasma breakpoint of 2.56 ng/mL could contribute to the decision of whether to start antibiotics. 1.Introduction For patients with suspected ventilator-associated pneumo- nia (VAP), the 2016 ATS/IDSA guidelines [1] recommend using clinical criteria alone, rather than combining those criteria with procalcitonin (PCT) or C-reactive protein (CRP) to decide whether to start antibiotics. Besides, in- terobserver variability in interpreting subjective criteria, such as chest X-rays and respiratory secretions, is prob- lematic [2, 3], making the diagnosis of VAP controversial. Indeed, VAP is responsible for 50% of antibiotic consumption in critically ill patients [4, 5]. e lack of objectivity and of a consensus regarding clinical criteria causes overdiagnosis of VAP, excessive use of antibiotics, and difficulties in benchmarking [6]. Diagnosis of VAP is complicated by the potential overlap with tracheobronchitis [7]. Pentraxin 3 (PTX3) is an acute-phase inflammatory medi- ator whose levels increase rapidly in inflammatory and infectious conditions. Increased PTX3 levels are correlated with the severity of lung injury and infection [8, 9]. us, we hypothesized that plasma PTX3 levels may aid in VAP diagnosis. e purpose of this study was to investigate the potential role of pentraxin 3, PCT, and CRP in VAP diagnosis. A prospective nested case- control study was performed with sequential measurement of pentraxin 3, procalcitonin, and CRP levels in patients receiving mechanical ventilation in the Surgical Intensive Care Unit, with the aim of determining the utility of biomarker levels in the diagnosis of VAP and establishing a cutoff point. Hindawi Canadian Journal of Infectious Diseases and Medical Microbiology Volume 2018, Article ID 4074169, 8 pages https://doi.org/10.1155/2018/4074169