A single-blind comparison of three-day azithromycin and ten-day co-amoxiclav treatment of acute lower respiratory tract infections

The efficacy and safety of a three-day regimen of azithromycin (500 mg od) and a ten-day regimen of co-amoxiclav (625 mg tid) were compared in a single-blind study in 99 patients with acute lower respiratory tract infections. Of these, 70 (71%) suffered an infective exacerbation of their chronic obstructive pulmonary disease. Nine patients had pneumonia and 19 purulent bronchitis. Treatment success, defined as cure or improvement, occurred in 43 of 48 (90%) patients in the azithromycin group, compared with 45 of 51 (88%) patients in the co-amoxiclav group. The most common isolated pathogens were Haemophilus influenzae (25 cases; MIC range of azithromycin (A) ≤ 0.06–4 mg/L; for co-amoxiclav (CA) 0.25–4 mg/L; Streptococcus pneumoniae (10 cases; A: ≤ 0.06– > 128; CA: ≤ 0.06); and Moraxella catarrhalis (four cases; A: ≤ 0.06; CA: ≤ 0.06–0.25). Microbiological response rates were comparable in the two groups. In 5% of patients, serological evidence for virus or atypical pathogens was found. Thirteen (26%) patients treated with co-amoxiclav had gastrointestinal complaints (seven with diarrhoea), compared with five (10%) treated with azithromycin (P = 0.09). Additional complaints occurred in three patients treated with co-amoxiclav and in one patient treated with azithromycin. It was concluded that a three-day regimen of azithromycin was as effective, clinically and microbiologically, as a ten-day regimen of co-amoxiclav in the treatment of acute lower respiratory tract infections.