Acute nitrofurantoin toxicity - case description

Abstract

An 82-year-old woman came to the emergency room with a dry cough, fever and dyspnea for two days. She had been receiving prophylactic treatment with nitrofurantoin for six months due to recurrent urinary tract infections. On examination, a severe respiratory failure and a chest computed tomography (CT) scan with an organizing pneumonia pattern stood out (Figure 1A). As a result, the intensive care unit admitted the patient. There, she underwent bronchofibroscopy with bronchial aspiration and bronchoalveolar lavage without identifying microbiological agents on cultures, and the cytology was also negative. The remaining investigations also revealed negative results, such as those related to sputum culture, autoimmune investigation, and viral serology studies.
No eosinophilia was detected. 
There was no evidence of another disease justifying this case, so nitrofurantoin-induced organizing pneumonia was presumed. Nitrofurantoin was suspended, and corticosteroids were initiated. The patient responded excellently to the treatment and entirely resolved the complaints. Two months later, a new CT showed notable improvement compared to the previously identified alterations (Figure 1B). 
Several studies have shown that continuous prophylaxis with nitrofurantoin decreases the recurrence of urinary tract infections. However, it may be associated with pulmonary toxicity. The most common symptoms are dyspnea, dry cough, and fatigue; fever is rare with chronic exposure. Severe respiratory failure may also occur. Early diagnosis and discontinuation of the drug are usually associated with a good prognosis, with recovery within two weeks to three months. Once we can exclude infection, corticosteroids should be immediately initiated (methylprednisolone 1 mg/kg intravenously followed by oral prednisolone in a tapering regimen) as the cornerstone of treatment.