Rapid emergence of resistant coagulase-negative staphylococci on the skin after antibiotic prophylaxis

One approach for prosthetic vascular surgery is to continue antimicrobial p rophylaxis while intravascular lines and catheters are in place. However th is may give rise to antimicrobial resistance in the colonizing bacterial fl ora. We studied 37 patients undergoing vascular surgery, who received eithe r co-amoxyclav for three days (group 1), ofloxacin plus metronidazole for t hree days (group 2) or for one day (group 3), respectively Seventeen hospit alized patients not undergoing surgery or receiving antibiotics were studie d as controls. In groups I and II there was a significant decline in suscep tibility to cloxacillin (12.8% respectively 23.6%) and ofloxacin (0.5% and 85% respectively) in skin staphylococci. The results from group 3 were inte rmediate. Molecular typing showed that the patient's susceptible community- derived strains were replaced by genetically unrelated resistant strains, p robably hospital derived. Long-term prophylaxis should be avoided as coloni zation occurs with resistant strains. (C) 1999 The Hospital Infection Socie ty.