Abstract Introduction Eosinophilic pneumonia is an uncommon but potentially serious side effect of daptomycin, with an incidence of approximately 1.7%. The nonspecific presentation of daptomycin-induced eosinophilic pneumonia (DIEP) makes diagnosis particularly challenging. Here, we present a case of DIEP, highlighting the diagnostic difficulties in differentiating it from amiodarone-induced lung injury and discussing the treatment approach. Case Presentation A 78-year-old male with a past medical history of vancomycin-resistant Enterococcus urinary tract infection (VRE UTI), for which he had completed a 3-week course of daptomycin, presented to the hospital with shortness of breath and gross hematuria. On presentation, he had mild leukocytosis, and a CT scan showed bilateral patchy airspace disease (figure 1). Daptomycin was restarted due to concern for recurrent VRE UTI. He received an additional 3 days of daptomycin before being switched to vancomycin and piperacillin-tazobactam due to progression of pneumonia on chest X-ray. A recent CBC revealed profound eosinophilia, with an absolute eosinophil count as high as 2900 × 109 cells/L. Daptomycin was subsequently discontinued due to concern for drug-induced pneumonitis. The patient was started on IV methylprednisolone 40 mg twice daily, which was gradually tapered. He responded dramatically to steroids, with significant improvement in breathing. His oxygen requirement decreased from heated high-flow nasal cannula to 5 L via nasal cannula, and his eosinophil count dropped to 1200 × 109 cells/L. Discussion Eosinophilic pneumonia is defined by peripheral blood eosinophilia (500 × 109 cells/L), increased eosinophils in bronchoalveolar lavage fluid (5% in the differential cell count), or eosinophilic infiltration of lung parenchyma on lung biopsy. Our patient had a blood eosinophil count of 2900 × 109 cells/L. He was also on chronic amiodarone therapy for atrial fibrillation, making differentiation necessary. However, the patient’s symptoms had a rapid onset with high-grade fever and cough. CT imaging did not show fibrosis or ground-glass opacities, making amiodarone-induced pneumonitis less likely. All bacterial and viral workups, including blood and respiratory cultures, were negative. The patient’s condition improved rapidly after discontinuation of daptomycin and initiation of corticosteroids, further supporting the diagnosis of daptomycin-induced pneumonitis. Conclusion DIEP is a rare complication of daptomycin. Distinguishing it from infectious, cardiogenic, or amiodarone-induced pneumonitis is challenging due to overlapping symptoms, variable onset, and the absence of specific biomarkers. Maintaining a high index of suspicion is essential, as prompt discontinuation of daptomycin and initiation of corticosteroids typically result in rapid recovery. This abstract is funded by: None
Akter et al. (Fri,) studied this question.