Effect of Antimicrobial Prophylaxis on Infection and the Skin Microbiome of Immunodeficient Mice.

is an opportunistic pathogen of the skin of immunodeficient mice and is sensitive to oral antibiotics that reach therapeutic blood concentrations. However, prophylactic antibiotics are considered to be ineffective at preventing infection. In addition, the effect of on the skin microbiome (SM) of common immunodeficient mouse strains has yet to be characterized. Consequently, we evaluated whether oral prophylactic antibiotics prevent infection after inoculation. An infectious dose of was applied to the skin of Hsd:Athymic Nude (nude) and NOD. Cg-/SzJ (NSG) mice. Mice were then housed individually and assigned randomly to receive either untreated drinking water (+Abx-group) or prophylactic amoxicillin-clavulanic acid in the drinking water (0.375 mg/mL) for 14 d (+Abx+group). A third treatment group of each mouse strain was uninoculated and untreated (-Abx-group). Mice from all groups were serially sampled by using dermal swabs to monitor infection via quantitative real-time PCR and the SM via 16S rRNA sequence analysis. Fourteen days of prophylactic antibiotics prevented the perpetuation of skin infection in both strains. Only the combination of inoculation and oral antibiotics (+Abx+) significantly affected the SM of NSG mice at day 14; this effect resolved by the end of the study (day 70). In mice that did not receive antibiotics, significantly altered the SM of nude mice but not NSG mice at days 14 and 70. These findings demonstrate the potential benefit of prophylactic antibiotics for prevention of infection. However, indirect effect of antibiotics on commensal bacteria and potential effects on xenograft models must be considered.