Respiratory viruses in bronchoalveolar lavage: A Retrospective study of clinical and laboratory features in immunocompromised children

<title>Abstract</title> <p>Background Immunocompromised children are at high risk for pulmonary infections caused by a broad spectrum of pathogens. Although bronchoalveolar lavage (BAL) combined with multiplex polymerase chain reaction (PCR) facilitates detection of respiratory viruses in the lower respiratory tract, pediatric data remain limited. Objectives To determine the prevalence of respiratory viruses detected in BAL fluid and to describe the associated clinical, radiologic, and laboratory characteristics in immunocompromised children. Methods We conducted a retrospective observational study of immunocompromised patients aged 1–20 years who underwent flexible bronchoscopy with BAL for evaluation of new pulmonary infiltrates at a tertiary care center between January 2016 and June 2025. Respiratory viruses were identified using multiplex real-time PCR. Patients were categorized into virus-positive and virus-negative groups for comparative analysis. Results Among 94 patients included in the analysis, respiratory viruses were detected in 27 cases (28.7%). Rhino/Enterovirus was the predominant pathogen (59.2%), followed by adenovirus, human metapneumovirus, and bocavirus. Patients in the virus-positive group were more likely to receive trimethoprim-sulfamethoxazole (Bactrim) prophylaxis (96.3% vs 71.6%, p = 0.010). Clinical features including cough (74.1% vs 40.3%, p = 0.003), sputum production (61.5% vs 29.9%, p = 0.005), and crepitations on chest examination (37.0% vs 13.4%, p = 0.010) were significantly more common in the virus-positive group. However, chest radiographic and computed tomography findings did not differ significantly between groups. Clinical outcomes, including pediatric intensive care unit admission, respiratory failure, and length of hospital stay, were also comparable. BAL galactomannan positivity was more frequent in virus-positive patients (50.0% vs 15.6%, p = 0.005), suggesting possible fungal co-infection. Conclusions Respiratory viruses are frequently detected in BAL fluid from immunocompromised children with pulmonary infiltrates, with Rhino/Enterovirus being the predominant virus identified. Patients with viral detection were more likely to receive trimethoprim-sulfamethoxazole prophylaxis and to present with cough, sputum production, and crepitations on chest examination. Radiologic features and clinical outcomes did not differ significantly between virus-positive and virus-negative groups. The higher prevalence of BAL galactomannan positivity in virus-positive patients raises the possibility of fungal co-infection.</p>