title: Combination prophylactic therapy with rifampin increases efficacy against an experimental Staphylococcus epidermidis subcutaneous implant-related infection.
abstract: The incidence of infections related to cardiac devices (such as permanent pacemakers) has been increasing out of proportion to implantation rates. As management of device infections typically requires explantation of the device, optimal prophylactic strategies are needed. Cefazolin and vancomycin are widely used as single agents for surgical prophylaxis against cardiac device-related infections. However, combination antibiotic prophylaxis may further reduce infectious complications. To model a localized subcutaneous implant-related infection, a bioluminescent strain of Staphylococcus epidermidis was inoculated onto a medical-procedure-grade titanium disc, which was placed into a subcutaneous pocket in the backs of mice. In vivo bioluminescence imaging, quantification of ex vivo CFU from the capsules and implants, variable-pressure scanning electron microscopy (VP-SEM), and neutrophil enhanced green fluorescent protein (EGFP) fluorescence in LysEGFP mice were employed to monitor the infection. This model was used to evaluate the efficacies of low- and high-dose cefazolin (50 and 200 mg/kg of body weight) and vancomycin (10 and 110 mg/kg) intravenous prophylaxis with or without rifampin (25 mg/kg). High-dose cefazolin and high-dose vancomycin treatment resulted in almost complete bacterial clearance, whereas both low-dose cefazolin and low-dose vancomycin reduced the in vivo and ex vivo bacterial burden only moderately. The addition of rifampin to low-dose cefazolin and vancomycin was highly effective in further reducing the CFU harvested from the implants. However, vancomycin-rifampin was more effective than cefazolin-rifampin in further reducing the CFU harvested from the surrounding tissue capsules. Future studies in humans will be required to determine whether the addition of rifampin has improved efficacy in preventing device-related infections in clinical practice.
authors: Orthopaedic Hospital Research Center (OHRC), UCLA/Orthopaedic Hospital-Department of Orthopaedic Surgery, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California, USA.
authors: Alexandra I
authors: AI
authors: Stavrakis
authors: Jared A
authors: JA
authors: Niska
authors: Jonathan H
authors: JH
authors: Shahbazian
authors: Amanda H
authors: AH
authors: Loftin
authors: Romela Irene
authors: RI
authors: Ramos
authors: Fabrizio
authors: F
authors: Billi
authors: Kevin P
authors: KP
authors: Francis
authors: Michael
authors: M
authors: Otto
authors: Nicholas M
authors: NM
authors: Bernthal
authors: Daniel Z
authors: DZ
authors: Uslan
authors: Lloyd S
authors: LS
authors: Miller
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D002437:Cefazolin / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D051379:Mice; D016459:Prosthesis-Related Infections / Q000188:drug therapy*; D012293:Rifampin / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013212:Staphylococcus epidermidis / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology* / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D002437:Cefazolin; D012293:Rifampin