Lower respiratory tract sampling in COVID-19 acute respiratory distress syndrome: A focus on microbiology, cellular morphology, cytology, and management impact.

Background: Lower respiratory tract (LRT) sampling through bronchoscopy has been done sparingly in COVID-19 acute respiratory distress syndrome (ARDS) due to the high aerosol risk for the health-care workers (HCWs). Valuable information can be gained by a detailed evaluation of bronchoscopic LRT samples.

Methods: LRT samples were obtained by bedside bronchoscopy severe COVID-19 ARDS patients on mechanical ventilation. Microbiological, cellular, and cytological studies including LRT COVID-19 reverse transcription-polymerase chain reaction were analyzed.

Results: A total of 100 samples were collected from 63 patients, 53 were males (84%). Forty-three patients (68%) had at least 1 comorbidity. 55% of cases had a secondary bacterial infection, commonly with multidrug-resistant organisms (94.5%). The most common organisms were Klebsiella pneumoniae and Acinetobacter baumannii in 56.3% and 14.5% of cases, respectively. Fungal superinfection was observed in 9 patients (14.3%). Bronchoscopy helped confirm COVID-19 diagnosis in 1 patient and helped rule out COVID-19 in 3 patients. The median bronchoalveolar lavage fluid (BALF) white blood cell (WBC) count was 953 (inter quartile range; 400-2717), with mean neutrophil count 85.2% (±13.9) and mean lymphocyte count 14.8% (±13.9). Repeat sampling done in some patients showed a progressive increase in the total WBC count in BALF, an increase in neutrophil percentage, and a higher chance of isolating an organism on the culture. Rate of superinfection increased with a longer duration of illness. Bronchoscopic LRT sampling contributed significantly to modifying antibiotic coverage and discontinuing steroids in 37% of cases.

Conclusions: Our study provides a detailed analysis of bronchoscopic LRT sampling in critically ill COVID-19 patients, augmenting disease understanding and contributing to clinical management.