Bacterial resistance after short-term exposure to antibiotics.

PURPOSE To determine if there is a difference in antibiotic sensitivity to coagulase-negative Staphylococcus (CNS) cultured from the host versus the donor cornea at the time of corneal transplantation. Then to apply this knowledge to preoperative preparation of patients undergoing eye surgery. METHOD A total of 923 donor corneas stored in Optisol and 895 host corneas with no preoperative antibiotic exposure were cultured. Forty-two CNS positive cultures grew from the donor corneas and 40 from the host corneas (P = .5). RESULTS There was an increase in resistance in the bacteria cultured from the donor compared with the host. The most striking changes occurred in host versus donor to: ciprofloxacin 27.5% (P = .0033); gentamicin 27% (P = .0113); tobramycin 31.6% (P = .059). The combination of polymixin, bacitracin, and neomycin (P/B/N) was significantly better than ciprofloxacin, gentamicin, and tobramycin or the combination of ciprofloxacin, gentamicin, and tobramycin (C/G/T) (P = .0007). CONCLUSION The combination of C/G/T exhibited the highest change to resistant bacteria. P/B/N was the most effective commercially available preparation. These results should be considered when making the decision about which preoperative antibiotic to use, if any.