Antibiotic ointments disrupt the skin microbiota


Eliminating some of the commensal skin bacteria with topical antibiotics and antiseptics may promote the development of skin infections.

Although oral antibiotics have been blamed for their side effects leading to a disruption in the intestinal flora, the consequences of topically applying antibiotic creams and antiseptic gels to the skin are much less well known. A University of Pennsylvania study has now confirmed that topical antibiotics disrupt the composition of the skin microbiota as well, to the extent that the skin is exposed to an increased risk of colonization by pathogenic bacteria.

In their study, researchers applied different antibiotics (mupirocin or a broad-spectrum mixture of three antibiotics) and antiseptics (80% alcohol or Betadine) to the skin of mice. The changes observed in the composition of the microbiota (more significant following the application of broad-spectrum antibiotics and relatively minor following the application of antiseptics), persisted for several days after treatment, to the point of increasing the risk of Staphylococcus aureus infection. This phenomenon is caused primarily by the reduction in populations of commensal staphylococci  -when these natural populations were reinforced, the risk of infection was cut 100-fold.

As such, the study authors call for the “judicious” use of antibiotic and antiseptic ointments.


SanMiguel AJ et al. Topical antimicrobial treatments can elicit shifts to resident skin bacterial communities and reduce colonization by Staphylococcus aureus competitors. Antimicrob Agents Chemother. 2017 Jun 19.