An antibiotic for <4 days symptoms of acute upper respiratory tract infection (except: Bilateral acute otitis media in children younger than 2 years; Acute otitis media in children with otorrhoea; Acute sore throat/acute pharyngitis/acute tonsillitis when three or more CENTOR criteria are present; Significantly increasing CRP or the proportion of neutrophils; examinations of respiratory secretions suggesting bacterial infection). This evidence concerns the gene CRP and Acute otitis media.