Club Cell protein: a candidate diagnostic biomarker of Pseudomonas aeruginosa nosocomial pneumonia

Introduction

Early etiological diagnosis of nosocomial pneumonia (NP) determines prompt targeted treatment. The aim of this study was to investigate the role of Club Cell protein (CCP) as a candidate diagnostic biomarker of Pseudomonas aeruginosa (PA) NP.

Methods

The observational study in ICU ventilated septic patients with peritonitis (65%), pancreonecrosis (20%) and mediastinitis (15%) was performed in 2010 and 2013. Diagnosis of NP was made according to the standard clinical criteria. Associations of multiresistant Gram- negative bacteria were detected in sputum of all patients. PA was detected in 75% of patients. Plasma CCP was measured on the day of NP diagnosis (day 0) and days 3, 5 and 7 by the immunoenzyme essay (BioVendor, USA). Data were statistically analyzed by STATISTICA 7.0, ANOVA method, and presented as Me and 25 to 75 percentiles, ng/ml; P < 0.05 was considered significant. Areas under the receiver operating curves (ROC) were calculated.

Results

Ninety patients (out of 350 screened) were enrolled in the study according to the inclusion/exclusion criteria. Patients were assigned to groups: NP (n = 50, 45 ± 4.3 years old, M/F 36/14) and noNP (n = 40, 48 ± 7.2 years old, M/F 30/10). Groups were comparable in APACHE II and CPIS scores. In patients with PA NP (n = 30), plasma CCP was significantly lower at all points than in the patients with no PA detected (n = 20; Figure 1). Plasma CCP on day 0 had a good capacity for the diagnosis of PA NP: CCP on day 0 ≤ 17.5 ng/ml yielded a sensitivity of 86.5% and specificity of 66.7% (AUC 0.74; 95% CI 0.630 to 0.829; P = 0.0001; Figure 2).

Figure 1

Club Cell protein concentration in patients with Pseudomonas aeruginosa NP.

Figure 2

ROC curve for Club Cell protein (day 0) for the diagnosis of Pseudomonas aeruginosa NP.

Conclusion

Plasma CCP level ≤17.5 ng/ml is a sensitive and specific candidate diagnostic biomarker of PA NP.