Approximately one in five adults has chronic bronchitis. Acute bacterial exacerbation of this pulmonary disease is a common cause of hospitalization. Clinical manifestations of acute disease include increased daily cough and increased sputum production and purulence. About 50 to 60 percent of exacerbations are believed to be bacterial in origin (most commonly related to Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae). However, many physicians advocate the use of empiric antibiotic therapy in all patients with acute exacerbations of chronic bronchitis because of the potential for significant morbidity. Chodosh and colleagues performed a double-blind study comparing ciprofloxacin and clarithromycin to determine clinical and bacteriologic efficacy and safety of the two therapies. They also sought to compare the length of the infection-free interval between one acute exacerbation of chronic bronchitis and the next exacerbation.

Patients enrolled in the study included adults at least 18 years of age who had a history of chronic bronchitis associated with chronic asthma, chronic obstructive pulmonary disease (COPD), or both, as defined by the American Thoracic Society. The patients had to present with an increase in dyspnea, sputum volume and purulence, and they had to have a documented fever (temperature higher than 38.0°C [100.4°F]), increased wheezing or increased cough compared with baseline. Bacterial infection was documented by the presence of 25 or more leukocytes per low-power field and the presence of a likely bacterial pathogen on Gram stain. Patients who were more severely ill, including those with an infiltrate present on chest radiograph, a history of immunodeficiency or a need for parenteral antibiotics were excluded from the study. Patients were randomized to receive two 250-mg tablets of either ciprofloxacin or clarithromycin, which were identical in appearance. The antibiotics were administered twice daily for 14 days. The use of expectorants and bronchodilators was permitted. The effectiveness of the antimicrobial agents was assessed by patient clinical response and laboratory measurements, with a physical examination at two, 12, 24 and 36 weeks post-treatment—or when a treatment failure or a new exacerbation ocurred.

A total of 376 patients were initially randomized into the study. Approximately one-third of the patients were smokers; otherwise no significant differences existed between the two groups. Two hundred and eleven patients completed the study (the efficacy-valid population); however, the other 162 patients were included in the intention-to-treat analysis arm of the study. In the efficacy-valid population, 90 percent of the ciprofloxacin patients and 82 percent of the clarithromycin patients had clinical resolution of symptoms by day 14. Throughout the 36-week follow-up period, 55 percent of the ciprofloxacin patients and 59 percent of the clarithromycin patients experienced a relapse or a new exacerbation. The median length of infection-free interval was 142 days in the ciprofloxacin group and 51 days in the clarithromycin group. Bacterial eradication at the end of therapy was 91 percent in the ciprofloxacin group but only 77 percent in the clarithromycin patients.

The authors conclude from this study that patients taking ciprofloxacin showed a longer infection-free interval than did those treated with clarithromycin. In addition, ciprofloxacin is more effective at producing bacterial eradication than clarithromycin and appears to be favored as first-line therapy for treatment of chronic bronchitis.

editor's note: This study, although performed in a select group of high-risk patients, is consistent with a trend in the literature showing that the quinolones may be a good alternative as first-line treatment for acute lower respiratory infections. In the same issue of this journal, a second study shows similar results in the same subtype of patients treated with either ciprofloxacin or cefuroxime axetil, a second-generation cephalosporin. Also of note, several of the newer quinolone antibiotics have better efficacy against Streptococcus pneumoniae, compared with ciprofloxacin. These antibiotics also cover Chlamydia species and Mycoplasma species. The most recent guidelines from the Infectious Diseases Society of American list this class of drugs as a second-line choice for treating community-acquired pneumonia. The concern of many physicians remains the cost of these agents and their potential for promoting bacterial resistance.—j.t.k.