Clinical Features and Treatment Outcomes of Severe Versus Non-severe Psittacosis Pneumonia

Abstract

Background: Comparative data on clinical presentations, radiologic and laboratory profiles, antimicrobial management, and patient outcomes between severe and non-severe psittacosis pneumonia remain limited. Objectives: This study aimed to investigate these differences and provide practical insights for clinical management. Methods: Clinical data from patients diagnosed with psittacosis pneumonia by metagenomic or targeted next-generation sequencing (mNGS/tNGS) were retrospectively collected from three hospitals. Patients were classified as having severe or non-severe disease according to established criteria for severe pneumonia. Baseline characteristics, clinical presentations, radiologic and laboratory findings, antibiotic regimens, and clinical outcomes were compared between the two groups. Results: A total of 53 patients were analyzed. The male-to-female ratio was 1.12:1.0, and the mean age was 58.57 ± 11.48 years. Underlying diseases were present in 67.9% of patients, and 35.8% had a history of avian exposure. Common clinical manifestations included fever (94.30%), cough (67.90%), and myalgia (47.20%). There were 24 cases in the severe group and 29 in the non-severe group. The incidence of dyspnea was significantly higher in the severe group than in the non-severe group (15 (62.50%) vs. 3 (10.34%), P < 0.01). Laboratory tests showed that the white blood cell count, neutrophil count, C-reactive protein level, procalcitonin level, lactate dehydrogenase level, and creatine kinase level were significantly higher in the severe group (P < 0.05), whereas albumin levels and the oxygenation index were significantly lower (P < 0.05). Radiologically, the severe group had higher proportions of bilateral lung involvement (12 (50.00%) vs. 5 (17.20%), P = 0.01) and pleural effusion (17 (70.80%) vs. 7 (24.10%), P < 0.01). Regarding treatment, the severe group more frequently received combination antibiotic therapy with quinolones and tetracyclines. Compared with the non-severe group, the severe group had a significantly longer time to clinical stability (10.00 (8.00 - 14.25) vs. 7.00 (6.00 - 9.00), P < 0.01) and a significantly longer length of stay (14.00 (11.25 - 23.00) vs. 11.00 (9.00 - 15.00), P < 0.01). Conclusions: Severe psittacosis pneumonia is characterized by a higher frequency of dyspnea, more intense inflammatory and tissue-damage responses, greater respiratory dysfunction, more frequent use of combination antibiotic therapy, and a slower clinical recovery.