RT Journal Article SR Electronic T1 Acute otitis media: antibiotics are moderately effective and mildly increase the risk of adverse effects; prevalence of different causative bacteria changed after introduction of the heptavalent pneumococcal conjugate vaccine JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 181 OP 182 DO 10.1136/ebm1407 VO 16 IS 6 A1 Sox, Colin YR 2011 UL http://ebm.bmj.com/content/16/6/181.abstract AB