What antibiotic is a common cause of eosinophilic pneumonia?

Nitrofurantoin is the Most Common Antibiotic Causing Eosinophilic Pneumonia

Nitrofurantoin is a well-established cause of drug-induced eosinophilic pneumonia, along with beta-lactam antibiotics, and should be considered first when evaluating antibiotic-related eosinophilic lung disease. 1

Primary Antibiotic Culprits

The most common antibiotics associated with eosinophilic pneumonia include:

• Nitrofurantoin - Consistently identified as a leading cause of drug-induced eosinophilic pneumonia in guideline literature 1
• Beta-lactam antibiotics - Recognized as a common drug class causing eosinophilia and eosinophilic pneumonia 1
• Daptomycin - Multiple case reports document daptomycin-induced eosinophilic pneumonia, with symptoms typically appearing after 2.8 ± 1.6 weeks of therapy 1, 2, 3

Clinical Presentation and Recognition

When evaluating for antibiotic-induced eosinophilic pneumonia, look for:

• Dyspnea (present in 94% of daptomycin cases) and fever (57% of cases) developing during or shortly after antibiotic therapy 3
• Peripheral eosinophilia (>0.5 × 10⁹/L) occurs in approximately 77% of cases, though its absence does not exclude the diagnosis 1, 3
• Infiltrates or ground-glass opacities on chest imaging (86% of cases) 3
• Symptom onset typically occurs within 2-4 weeks of antibiotic initiation 3

Daptomycin-Specific Considerations

Daptomycin deserves special mention as it should not be used for pneumonia treatment because its activity is inhibited by pulmonary surfactant, yet paradoxically causes eosinophilic pneumonia as an adverse effect. 1

Key features of daptomycin-induced eosinophilic pneumonia:

• Predominantly affects elderly males (mean age 65.4 ± 15 years, 83% male) 3
• Higher risk in patients with renal dysfunction receiving doses of 4-10 mg/kg/day 3
• Rapid symptom improvement (24 hours to 1 week) after discontinuation 3

Other Antibiotics Implicated

Less commonly reported but documented causes include:

• Imipenem/cilastatin - Case reports demonstrate acute eosinophilic pneumonia with recurrence upon rechallenge 4
• Minocycline - Recognized as a cause of acute eosinophilic pneumonia 4
• Mesalamine (technically an anti-inflammatory, not antibiotic) - Rare cause with documented cases 5

Diagnostic Approach

When antibiotic-induced eosinophilic pneumonia is suspected:

1. Review medication history focusing on nitrofurantoin, beta-lactams, and daptomycin exposure within the past 2-4 weeks 1, 3
2. Check peripheral eosinophil count (>0.5 × 10⁹/L supports diagnosis, but normal count doesn't exclude it) 1, 3
3. Obtain chest imaging looking for infiltrates or ground-glass opacities 3
4. Consider bronchoscopy with bronchoalveolar lavage if diagnosis is uncertain - eosinophils >10% of differential count is diagnostic 4

Management Strategy

Immediate discontinuation of the offending antibiotic is the cornerstone of treatment, with corticosteroids used in 66% of cases to accelerate recovery. 3

• Discontinue the suspected antibiotic immediately - symptom improvement typically occurs within 24 hours to 1 week 3
• Initiate corticosteroid therapy (prednisolone 60 mg daily for 14 days, then taper) for moderate to severe cases 1, 3
• Monitor for rapid clinical improvement - lack of improvement should prompt reconsideration of the diagnosis 3

Critical Pitfalls to Avoid

• Do not continue the antibiotic while investigating - delayed discontinuation can lead to fatal lung disease, particularly in acute eosinophilic pneumonia 6
• Do not assume peripheral eosinophilia must be present - 23% of daptomycin-induced cases lack peripheral eosinophilia 3
• Do not rechallenge with the same antibiotic - recurrence of symptoms is well-documented and can be more severe 4
• Remember that daptomycin is contraindicated for pneumonia treatment due to surfactant inactivation, making its association with eosinophilic pneumonia particularly ironic 1