Multidrug-Resistant Serratia marcescens Cavitary Pneumonia in an HIV Patient: A Case Report

<i>Serratia marcescens</i> is an opportunistic gram-negative bacillus with both intrinsic and acquired resistance mechanisms, making it a challenging pathogen in immunocompromised individuals. We report a fatal case of cavitary pneumonia caused by multidrug-resistant <i>S. marcescens</i> in a 42-year-old HIV-positive man with chronic comorbidities, who presented with acute hypoxic respiratory failure and septic shock. Imaging revealed a large cavitary lesion in the right upper lobe, and cultures from blood, urine, and respiratory secretions confirmed <i>S. marcescens</i> with broad-spectrum antibiotic resistance. Despite aggressive medical management, including broad-spectrum antimicrobials, vasopressor support, bronchoscopy, and renal replacement therapy, the patient's condition deteriorated, resulting in death. This case underscores the rare but severe pulmonary manifestation of <i>S. marcescens</i> in immunocompromised hosts, emphasizing the importance of early recognition, infection control, and targeted antimicrobial therapy in managing such high-risk infections.