Retapamulin is a semisynthetic pleuromutilin compound with in vitroactivity 
against Gram-positive bacteria, no cross-resistance to other classes of 
antimicrobial agents in current use and a low potential for development of 
resistance. A 1% ointment formulation has been developed for clinical use, and a 
placebo-controlled trial of impetigo in 210 patients produced significantly 
higher rates of clinical and microbiological success compared with placebo - 
85.6 versus 52.1% and 91.2 versus 50.9%, respectively. Additional comparative 
studies in over 1900 patients showed noninferiority to topical fusidic acid and 
oral cephalexin and a low frequency of adverse events. In 2007, retapamulin was 
approved in the USA for topical treatment of impetigo caused by Streptococcus 
pyogenes and methicillin-susceptible Staphylococcus aureus, and in the EU for 
topical treatment of impetigo and infected wounds caused by S. pyogenes and S. 
aureus, with approvals including adults and children over 9 months of age.