[Analysis of clinical features of 16 cases with Chlamydia psittaci pneumonia]

To analyze the clinical characteristics of Chlamydia psittaci pneumonia and to investigate the correlation between serum inflammatory biomarkers and severity of the disease.

Sixteen patients with Chlamydia psittaci pneumonia admitted to the Huizhou Municipal Central Hospital from January 2020 to July 2021 were selected as the study subjects, including 10 severe cases and 6 mild cases. Clinical data were collected and analyzed, such as baseline characteristics, clinical symptoms, laboratory inspection and chest imaging manifestations.

(1) Thirteen Chlamydia psittaci pneumonia were associated with a definite bird or poultry contact history. Common symptoms included high fever, chill, cough, fatigue, and anorexia (16 cases), dyspnoea (12 cases), and other systemic symptoms. (2) Laboratory test results showed normal white blood cell count (WBC, 10 cases), decreased lymphocyte count (LYM, 13 cases), increased high sensitive C-reactive protein (hs-CRP, 16 cases), D-dimer (15 cases), lactate dehydrogenase (LDH, 13 cases), aspartate aminotransferase (AST, 16 cases) and alanine aminotransferase (ALT, 12 cases) levels, however, the albumin (Alb, 15 cases) lever was decreased. The numbers of CD3⁺ T cells and CD4⁺ T cells decreased in 10 patients. (3) The levels of D-dimer, interleukins (IL-2, IL-6, IL-10) in severe Chlamydia psittaci pneumonia were significantly higher than those in mild Chlamydia psittaci pneumonia [D-dimer (μg/L): 10 257±4 203 vs. 1 085±642, IL-2 (ng/L): 1.1 (0.8, 1.7) vs. 0.3 (0.1, 0.7), IL-6 (ng/L): 315 (182, 505) vs. 75 (18, 131), IL-10 (ng/L): 7.0±4.1 vs. 2.3±0.7], but the LYM was lower (×10⁹/L: 0.4±0.1 vs. 1.1±0.4), with significant differences (all P < 0.05). (4) Chest imaging manifestations were exudative lesions and large consolidation of lungs. Large consolidation of both lungs can occur in some critically ill patients.

Chlamydia psittaci pneumonia is mainly associated with a bird or poultry contact history. The clinical manifestations usually present high fever, dyspnea, normal or slightly increased leucocytes, and lung consolidation. The levels of LYM, D-dimer, IL-2, IL-6 and IL-10 in serum are expected to predict the severity of the Chlamydia psittaci pneumonia.