Although more than 10 million adults in the United States are treated each year for acute bronchitis, the use of antibiotics for this condition is highly controversial. Clinical trials and meta-analyses of antibiotics have not clearly demonstrated their benefit, and serious concerns have been raised about increasing bacterial resistance by indiscriminate use of antibiotics. Azithromycin has become a popular antibiotic choice, based on its broad spectrum and infrequent adverse effects. However, it is expensive and has not been extensively studied in the treatment of acute bronchitis. Evans and colleagues conducted a double-blind, randomized clinical trial of azithromycin as a treatment for acute bronchitis, using vitamin C as a control.

Adults were recruited from the ambulatory screening clinic of an inner-city county hospital if they had an acute cough of two to 14 days' duration and had been diagnosed with acute bronchitis. Exclusions were pregnancy, chronic lung disease, asthma, any clinical characteristic suggesting pneumonia, contraindications to the study medications, other infectious diseases requiring antimicrobial therapy, current use of bronchodilators or glucocorticoids, and recent use of antibiotics or angiotensin-converting enzyme inhibitors.

To increase consistency in their diagnoses, all treating physicians attended a two-hour training course on the diagnosis and management of acute bronchitis before the study. The researchers assigned 220 patients to treatment with either azithromycin (500 mg initially, then 250 mg daily for four days) or an identical capsule of vitamin C. All patients received aggressive symptomatic therapy, including dextromethorphan syrup (10 mL every six hours, plus 15 mLat night to suppress cough) and an albuterol inhaler with a spacer (two puffs every six hours). To establish symptoms and their effect on quality of life, interviewers surveyed patients on entry to the study, on the third day, and on the seventh day after starting treatment.

The symptom and quality-of-life scores on both days were not significantly different among the 112 patients treated with azithromycin and the 108 treated with vitamin C. The rate of improvement was also similar. Five patients treated with azithromycin and four treated with vitamin C made second visits before day seven because of persisting symptoms. No patient required hospital admission, but one patient (in the vitamin C treatment group) developed pneumonia. The most commonly reported adverse effects were diarrhea and nausea. By day seven, adverse effects were reported by 25 percent of patients taking azithromycin and 21 percent of patients receiving vitamin C. Most patients (81 percent) considered the albuterol to be effective, and on day seven, 44 percent of patients were still using it.

The authors conclude that azithromycin was no more effective than vitamin C in the treatment of acute bronchitis. They attribute much of the rapid improvement in their patients to the early and accurate diagnosis, plus aggressive symptomatic therapy and follow-up. They call for further studies to identify the optimal treatment for acute bronchitis, particularly the role of antibiotics, because many physicians perceive pressure to offer patients prescription medications.

editor's note: The good news is that we can care for patients who have mild acute bronchitis with good symptomatic care and follow-up. The bad news is that physicians will have to convince patients that they don't need antibiotics (especially patients who seek help by telephone), and that there will be the nagging worry about the occasional patient who may develop pneumonia. As one of my partners commented about the very similar situation of delaying antibiotic therapy for children with earache, “The first 100 patients are the most difficult, then the word gets out!”—a.d.w.