ABSTRACT
Mupirocin is a natural crotonic acid derivative and antibiotic extracted from a strain of Pseudomonas fluorescens. It inhibits bacterial protein synthesis by specific reversible binding to bacterial isoleucyl tRNA synthase. In the period 1990-2014, in Belgium, 188 patients suspected of iatrogenic contact dermatitis were patch tested with mupirocin 10% pet. Considering the unwillingness of the manufacturer to provide mupirocin for patch testing, certain that the patch test concentration and vehicle of 10% pet. A patch test was strongly positive to the mupirocin cream; she also had positive reactions to multiple other drugs and ingredients of topical pharmaceuticals. The manufacturer declined to provide the different ingredients of the mupirocin cream. Patch tests were positive on day 5 to 2 different mupirocin 2% ointments and pimecrolimus 1% cream. The mupirocin ointment formulations consisted of only mupirocin and polyethylene glycol; the patient did react to polyethylene glycol 100%.
