Multidrug-resistant Corynebacterium striatum-induced severe pneumonia complicated with multiple organ failure: a diagnostic breakthrough guided by phagocytosis and therapeutic strategy

BACKGROUND: Corynebacterium striatum (C. striatum), a Gram-positive opportunistic pathogen, is increasingly linked to healthcare-associated pneumonia (HAP) in immunocompromised patients, but its nonspecific manifestations and multidrug resistance cause diagnostic delays. This case adds to literature by highlighting neutrophil phagocytosis in sputum smears as a pivotal clue for distinguishing C. striatum infection from contamination, especially in mixed infections. A 56-year-old female with uncontrolled diabetes, hypertension, and post-cerebral hemorrhage sequelae developed severe pneumonia, complicated by septic shock, CRRT-requiring acute kidney injury, and gastrointestinal bleeding. Initial therapy for Klebsiella pneumoniae and Pseudomonas aeruginosa failed. Sputum smear showed neutrophils phagocytosing Gram-positive rods; culture confirmed multidrug-resistant C. striatum. Therapy with ceftazidime-avibactam, vancomycin, and caspofungin improved outcomes. CONCLUSION: Microscopic detection of phagocytosis aids early C. striatum identification; dynamic etiological monitoring and individualized combination therapy are critical for refractory HAP in immunocompromised patients.