Daptomycin-Induced Eosinophilic Pneumonia Mimicking Multifocal Pneumonia

A 71-year-old female presented to the emergency department with worsening dyspnea, dry cough, malaise, weight loss, fever, chills, and diaphoresis for one week. The patient had been hospitalized four weeks prior with right knee methicillin-resistant Staphylococcus aureus (MRSA) bursitis and was initially treated with IV vancomycin but was switched to IV daptomycin at the time of discharge for convenience of dosing. On presentation to the ED, vitals were normal. Physical examination revealed bilateral scattered rhonchi and crepitations. Chest X-ray revealed new patchy bilateral interstitial and airspace opacities concerning for multifocal pneumonia. Labs were pertinent for mild peripheral eosinophilia. CT chest revealed moderate diffuse ground glass opacities involving both lungs, with subpleural predominance and some areas of septal thickening seen as well. Daptomycin-induced pneumonitis was suspected, and empiric antibiotics were discontinued. The patient subsequently underwent fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial lung biopsy. BAL fluid showed leukocytosis and eosinophilia of 25 mm³. Right upper lobe biopsy demonstrated foci of alveolar spaces with collections of eosinophils and histiocytes consistent with acute eosinophilic pneumonia. The patient was started on oral prednisone and albuterol breathing treatments with significant improvement after 48 hours from admission. She was discharged on albuterol inhalers and prednisone taper. Acute eosinophilic pneumonia (AEP) is a lung condition that can be rapidly progressive, leading to significant morbidity and mortality. Daptomycin-induced AEP can mimic community-acquired pneumonia, resulting in delayed diagnosis and management. Recognizing the temporal association between drug initiation and the development of symptoms is crucial in the diagnosis of drug-induced AEP. If it is recognized and treated in a timely manner, the prognosis is generally excellent, with rapid and complete clinical recovery as demonstrated by our case.