Lactobacillus paracasei-induced lung abscess in a splenectomized patient: A rare case report.

Rationale: Lactobacillus paracasei (LP), a probiotic species, is rarely associated with lung abscesses. This case highlights its role as an opportunistic pathogen in immunocompromised patients.

Patient concerns: A 65-year-old splenectomized man presented with persistent abdominal pain, fever, and respiratory symptoms. Imaging revealed a right lung abscess, mediastinal lymphadenopathy, and adrenal nodules. Next-generation sequencing (NGS) confirmed LP infection. Multidisciplinary management with tailored antibiotics (faropenem) led to clinical improvement.

Diagnoses: Comprehensive examination, including imaging studies, revealed a right lung abscess complicated by mediastinal lymphadenopathy, bilateral pleural effusion, and adrenal nodules. Subsequent lung puncture biopsy and NGS testing confirmed LP infection and the presence of an accessory spleen.

Interventions: In collaboration with a multi-disciplinary treatment, the patient's antibiotic treatment plan was adjusted based on the confirmed diagnosis of LP infection. Management included targeted antibiotic therapy (faropenem) tailored to the identified pathogen.

Outcomes: The patient's condition gradually improved following the adjusted treatment plan, leading to a reduction in symptoms and successful discharge from the hospital, with favorable follow-up results.

Lessons: This case highlights LP as an emerging opportunistic pathogen causing severe lung abscesses in splenectomized patients. Early diagnosis via NGS and targeted antibiotic therapy guided by multidisciplinary collaboration were pivotal in achieving clinical resolution. Our findings underscore the importance of pathogen-specific management in immunocompromised hosts.