The Role of Interferon Gamma in the Diagnosis of <i>Chlamydia psittaci</i> and Viral Pneumonia: A Single-Center Retrospective Study

Abstract

Background: Chlamydia psittaci and viral pneumonia are significant respiratory infections that pose a diagnostic challenge due to overlapping clinical features. Objectives: This study aimed to investigate the role of interferon-gamma (IFN-γ) as a potential biomarker for the differential diagnosis of C. psittaci and viral pneumonia. Methods: We conducted a single-center retrospective study involving patients presenting with respiratory symptoms suggestive of C. psittaci or viral pneumonia. Clinical data, including demographic information, medical history, laboratory findings, radiological imaging, and microbiological results, were collected. Statistical analyses were performed to determine the diagnostic accuracy of IFN-γ in differentiating C. psittaci from viral pneumonia. Results: A total of 44 patients were included in the study, comprising 22 patients diagnosed with C. psittaci and 22 patients diagnosed with viral pneumonia. The mean age was 70 ± 13.5 years, and 59% of the participants were male. Serum IFN-γ levels were significantly elevated in patients with C. psittaci compared to those with viral pneumonia (P < 0.001). The receiver operating characteristic (ROC) curve analysis demonstrated good diagnostic accuracy of IFN-γ in differentiating C. psittaci from viral pneumonia, with an area under the curve (AUC) of 0.766 (95% CI, 0.606 - 0.885). Using the optimal cutoff value of 16.26, the sensitivity and specificity of IFN-γ were determined to be 68.18% and 95.45%, respectively. Conclusions: Our findings demonstrate that serum IFN-γ levels are significantly elevated in patients with C. psittaci compared to viral pneumonia. The diagnostic accuracy of IFN-γ suggests its potential as a valuable biomarker for differentiating between these two respiratory infections.