[Rapid evaluation of the early pathogen of severe Chlamydophila psittaci pneumonia by diagnostic bronchoscopy]

To explore the rapid evaluation of the early pathogen of severe Chlamydophila psittaci pneumonia by bedside diagnostic bronchoscopy, so as to start effective anti-infection treatment before the results of macrogenome next generation sequencing (mNGS) test.

The clinical data of three patients with severe Chlamydophila psittaci pneumonia who were successfully treated in the First Affiliated Hospital of Xinjiang Medical University, the First People's Hospital of Aksu District, and the First Division Hospital of Xinjiang Production and Construction Corps from October 2020 to June 2021 were retrospectively analyzed, including the rapid assessment of early pathogens by bedside diagnostic bronchoscopy and the use of antibiotics to start anti-infection treatment. These patients were successfully treated.

The three patients were male, aged 63, 45 and 58 years old, respectively. Before the onset of the penumonia, they had a clear medical history of bird exposure. The clinical manifestations mainly included fever, dry cough, shortness of breath and dyspnea. One case had abdominal pain and lethargy. The results of laboratory examination indicated that the peripheral blood white blood cell count (WBC) of two patients were high [(10.2-11.9)×10⁹/L], the percentage of neutrophils increased (85.2%-94.6%) and the percentage of lymphocytes decreased (3.2%-7.7%) in all 3 patients after admission to hospital and entering into intensive care unit (ICU). The procalcitonin (PCT) of 3 patients increased after admission, and still increased when entering ICU (0.3-4.8 ng/L), so did C-reactive protein (CRP, 58.0-162.0 mg/L) and erythrocyte sedimentation rate (ESR, 36.0-90.0 mm/1 h). After admission, serum alanine transaminase (ALT) increased in 2 cases (136.7 U/L, 220.5 U/L), so did aspartate transaminase (AST) in 2 cases (249.6 U/L, 164.2 U/L). ALT (162.2-267.9 U/L) and AST (189.8-223.2 U/L) increased in 3 patients when they entered ICU. The level of serum creatinine (SCr) of 3 patients were normal after admission and entering ICU. The chest computed tomography (CT) findings of 3 patients were acute interstitial pneumonia, bronchopneumonia and lung consolidation, of which 2 cases were accompanied by a small amount of pleural effusion, and 1 case was accompanied by more regular small air sacs. Multiple lung lobes were involved, but mainly one lung lobe. The oxygenation index (PaO₂/FiO₂) of the 3 patients admitting to ICU were 100.0, 57.5 and 105.4 mmHg (1 mmHg ≈ 0.133 kPa), respectively, which met with the diagnostic criteria of moderate and severe acute respiratory distress syndrome (ARDS). All three patients received endotracheal intubation and mechanical ventilation. Under the bedside bronchoscope, the bronchial mucosa of 3 patients were obviously congested and edematous, without purulent secretion, and there was 1 case with mucosal hemorrhage. Three patients underwent bedside diagnostic bronchoscopy, and the evaluation result of the pathogen was that it might be atypical pathogen infection, so they were given moxifloxacin, cisromet and doxycycline intravenously, respectively, and combined with carbapenem antibiotics intravenously. After 3 days, the detection results of mNGS in bronchoalveolar lavage fluid (BALF) showed that only Chlamydia psittaci was infected. At this time, the condition was significantly improved, and PaO₂/FiO₂ was significantly increased. Therefore, the antibiotic treatment scheme remained unchanged, and mNGS only served to verify the initial diagnosis. Two patients were extubated on the 7th and 12th day of admission to the ICU, respectively, while one patient was extubated on the 16th day of admission to the ICU due to nosocomial infection. All 3 patients were transferred to the respiratory ward after the condition was stable.

The bedside diagnostic bronchoscopy based on clinical characteristics is conducive to not only the rapid assessment of the early pathogens of severe Chlamydia psittaci pneumonia, but also effective anti-infection treatment before the returning of mNGS test results, which can make up for the lag and uncertainty of the mNGS test results.