The Role of Calprotectin and Alpha-Defensin in the Diagnosis of Pneumonia in Ventilated Patients

Abstract

Introduction: Hospital-acquired pneumonia and ventilator-associated pneumonia are the major causes of death in hospitalized patients, particularly in the intensive care unit, and early diagnosis may contribute to the survival of the patients. Our aim in this study was to contribute to the rapid treatment of ventilator-associated pneumonia by providing an early diagnosis of pneumonia with alfa-defensin, and calprotectin as inflammation biomarkers. Materials and Methods: The study was designed as a single-center, prospective observational study involving mechanically ventilated patients who were admitted to the Internal Medicine Intensive Care Unit at cukurova University Hospital between May 2018 and July 2019 and were above 18 years of age. Patients' demographics and clinical parameters were noted. Serum alpha-defensin levels were measured with the Human Alpha-defensin ELISA kit (Bioassay Technology Laboratory, Jiaxing, China). Serum calprotectin levels were measured with the Human Calprotectin ELISA kit (Bioassay Technology Laboratory, Jiaxing, China). Deep tracheal aspirates (DTA) and blood specimens were collected on the day of ventilation, as well as on the first, third, and seventh days, prospectively. The patients were monitored for the development of ventilator-associated pneumonia (VAP). Infections other than ventilator-associated pneumonia were also noted. Results: During the study period, 822 patients were admitted to the intensive care unit, accumulating 5101 patient days and 1966 ventilator days. Of the included 88 patients who were intubated and mechanically ventilated, 59.1% were male and the mean age was 59.9 +/- 18.4. Mean alpha defensin levels were higher in patients with pneumonia than those without (1679.21 +/- 3398.17 vs 552.32 +/- 243.67 respectively, p= 0.012). As for the ROC curve analysis, the area under the curve for alpha-defensin in pneumonia patients was 0.583 (p= 0.239). Mean calprotectin levels were higher in patients with pneumonia than those without (230.40 +/- 150.6819 ng/ mL vs 163.80 +/- 73.5819 ng/mL, p= 0.001). As for the ROC curve analysis, the area under the curve for calprotectin in pneumonia patients was 0.621 (p= 0.086). Conclusion: Serum and bronchoalveolar fluid levels of alpha defensin and calprotectin exhibited higher values in patients with pneumonia compared to those without pneumonia. However, due to the absence of statistical significance, larger-scale studies are necessaryto ascertain the clinical utility and benefits. In conclusion, it is recommended to plan a study with a larger number of patients, in which serum and bronchoalveolar fluid alpha defensin levels are measured simultaneously and molecular methods are used for more accurate diagnosis.