A case of necrotic pneumonia caused by Streptococcus pneumoniae was diagnosed using a pneumonia antigen test in BALF: A case report

Rationale: Streptococcus pneumoniae is a common cause of community-acquired pneumonia. Currently, it is believed that many cases of pulmonary infection with negative results on pathogenic testing are caused by S. pneumoniae. There have been no reports of the detection of S. pneumoniae antigen in lung lavage fluid. Patient concerns: An elderly male patient with suboptimal fasting blood glucose control and a history of liver abscess. Diagnosis: Chest computed tomography (CT) revealed inflammatory lesions in both lungs with consolidation in the middle lobe of the right lung. Interventions: After admission, we collected alveolar lavage fluid in a timely manner and performed pneumococcal antigen detection and etiological testing. Outcomes: Prompt testing for pneumococcal antigen in bronchoalveolar lavage fluid yielded a positive clinical outcome. Subsequent analysis via bacterial culture of sputum and next-generation sequencing (mNGS) of BALF definitively identified S. pneumoniae as the etiological agent. Following the analysis of drug sensitivity test results from the identified pathogens, adjustments were made to the antibiotic regimen, and appropriate pus puncture drainage was performed. Subsequently, the patient's condition improved, leading to discharge. Conclusion: The identification of S. pneumoniae antigen in bronchoalveolar lavage fluid may facilitate earlier and more precise diagnosis of pneumonia attributed to S. pneumoniae.