EFFECTS OF ANTIBIOTIC-TREATMENT IN THE SUBSET OF COMMON-COLD PATIENTSWHO HAVE BACTERIA IN NASOPHARYNGEAL SECRETIONS

Background Upper-respiratory-tract infection is one of the main causes of overuse of antibiotics. We have found previously that bacteria suc h as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae can be isolated from the nasopharyngeal secretions of a sub stantial proportion of adults with upper-respiratory-tract infections, We have assessed the efficacy of co-amoxiclav in patients with common colds but no clinical signs of sinusitis or other indications for ant ibiotics, Methods Between January, 1992, and March, 1994, 314 patients who presented to our outpatient clinic with common colds were enrolle d in the double-blind, placebo-controlled study. They were randomly as signed 5 days' treatment with co-amoxiclav (375 mg three times daily) or identical placebo. Clinical examinations were done at enrolment and on day 5-7 to assess outcome (cured, persistent symptoms, worse sympt oms). Seven patients were excluded after randomisation, seven did not have nasopharyngeal aspiration, and 12 did not return for followup ass essment. Findings Of 300 patients with nasopharyngeal aspirates, 72 ha d negative bacterial cultures, 167 had cultures positive only for bact eria unrelated to respiratory infections, and 61 had cultures positive for H influenzae, M catarrhalis, or S pneumoniae. At 5-day follow-up of these culture-positive patients, the distribution of outcome was si gnificantly better among co-amoxiclav-treated (n=30) than placebo-trea ted (n=28) patients (cured 27 vs 4%; persistent symptoms 70 vs 60%; wo rse symptoms 3 vs 36%; p=0.001). Patients on co-amoxiclav also scored their symptoms significantly lower than patients on placebo (p=0.008). Among culture-negative patients (n=230), the outcome distribution did not differ between the treatment groups(p=0.392). Interpretation The majority of patients with upper-respiratory-tract infection do not ben efit from antibiotics and side-effects are frequent. However, for the subgroup whose nasopharyngeal secretions contain H influenzae, M catar rhalis, or S pneumoniae, antibiotics are clinically beneficial.