Bacterial resistance after short-term exposure to antibiotics

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. 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). 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). 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.