1727. Rifampin combined with cefazolin or vancomycin has increased efficacy than single agent prophylactic therapy against a Staphylococcus epidermidis surgical implant infection in mice
Session: Poster Abstract Session: Studies of the Interface of Host-Microbial Interaction
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • ID Week 2013 Stavrakis Poster.pdf (2.5 MB)
  • Background: Vancomycin and Cefazolin are both widely used for intravenous prophylaxis against surgical implant infections. The aim of this study was to compare the efficacy of low and high dose intravenous vancomycin or cefazolin alone and in combination with subcutaneous rifampin given as prophylactic therapy against a Staphylococcus epidermidis surgical implant infection model in mice.

    Methods: S. epidermidis was used to inoculate titaninum discs which were subsequently implanted subcutaneously. The efficacies of low versus high dose vancomycin (10 and 110mg/kg) and cefazolin (50 and 200mg/kg) intravenous prophylaxis plus/minus rifampin (25mg/kg) combination therapy were evaluated. Thesegroups were compared using in vivo bioluminescence imaging and ex vivo bacterial counts.

    Results: Low dose cefazolin resulted in decreased in vivo bioluminescent signals and lower CFUs harvested from both capsules and implants compared with sham treated mice (p<0.01). Low dose vancomycin had bioluminescent signals that did not differ from sham treated mice. However, low dose vancomycin resulted in decreased CFUs harvested from the capsules and implants (p<0.05). The addition of rifampin to low dose vancomycin had a marked therapeutic benefit; this combination resulted in bioluminescent signals that approached background levels and virtually undetectable CFUs harvested from capsules and implants (p<0.01). The addition of rifampin to low dose cefazolin resulted in lower bioluminescent signals than cefazolin alone and decreased CFUs harvested from the implants (p<0.01). However, the combination of rifampin to low dose cefazolin did not have an added benefit in reducing CFUs in the capsules. Finally, high dose cefazolin and vancomycin were effective as single agents as both resulted in bioluminescent signals that approached background levels and had almost undetectable CFUs obtained from the capsule and implants (p<0.01).

    Conclusion: These results suggest that rifampin has an added benefit to cefazolin and vancomycin and the rifampin plus vancomycin group was the most effective combination. Additionally, both high dose cefazolin and vancomycin were effective as single agent prophylactic therapy in this mouse model of S. epidermidis implant infection.

    Alexandra Stavrakis, MD1, Jared Niska, MD1, Jonathan Shahbazian, BS2, Amanda Loftin, BS1, Romela Ramos, BS, MS3, Lloyd Miller, MD, PhD2 and Daniel Z. Uslan, MD, MS4, (1)Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, (2)Dermatology, Johns Hopkins University School of Medicine, Baltimore, MD, (3)Dermatology, David Geffen School of Medicine at UCLA, Los Angeles, CA, (4)Infectious Diseases, David Geffen School of Medicine/University of California, Los Angeles, Los Angeles, CA

    Disclosures:

    A. Stavrakis, None

    J. Niska, None

    J. Shahbazian, None

    A. Loftin, None

    R. Ramos, None

    L. Miller, None

    D. Z. Uslan, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.