title: Staphylococcus epidermidis is cleared from biomaterial implants but persists in peri-implant tissue in mice despite rifampicin/vancomycin treatment.
abstract: Infections associated with implanted biomedical devices (BAI) are predominantly caused by Staphylococcus epidermidis. We previously observed in murine experimental BAI that S. epidermidis persists in peri-implant tissue rather than on the implanted biomaterial itself (Boelens et al., J Infect Dis 2000;181:1337-1349; Broekhuizen et al., Infect Immun 2007;75:1129-1136). To investigate the efficacy of rifampicin/vancomycin to clear S. epidermidis from implants and peri-implant tissues, mice with two implants were challenged with 10(7) cfu S. epidermidis per implant and received daily injections of rifampicin (25 mg/kg) and vancomycin (50 mg/kg). On the day of termination, implants and peri-implant tissue were collected and processed for culture and histology. After 1 and 8 days, implants of control mice were culture positive in 14/18 and 5/16 cases, respectively, and tissue biopsies were all culture positive. In the antibiotic-treated mice, bacteria were recovered from only 1/18 and 1/16 implants after 1 and 8 days, respectively, whereas the tissues were culture positive in 14/18 and 7/16 biopsies, respectively. In microscopy, bacteria were seen in the tissue at a distance of several cell layers from the tissue-implant interface, colocalized with host cells. Thus, although a regimen of rifampicin/vancomycin sterilized the implants, S. epidermidis persisted in peri-implant tissue, which might be an as yet unrecognized reservoir in the pathogenesis of BAI.
authors.affiliation: Department of Medical Microbiology, Center of Infection and Inflammation Amsterdam (CINIMA), Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Corine A N
authors.initials: CA
authors.lastname: Broekhuizen
authors.forename: Leonie
authors.initials: L
authors.lastname: de Boer
authors.forename: Kim
authors.initials: K
authors.lastname: Schipper
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Jones
authors.forename: Shan
authors.initials: S
authors.lastname: Quadir
authors.forename: Christina M J E
authors.initials: CM
authors.lastname: Vandenbroucke-Grauls
authors.forename: Sebastian A J
authors.initials: SA
authors.lastname: Zaat
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D001706:Biopsy; D015169:Colony Count, Microbial; D005260:Female; D051379:Mice; D019736:Prostheses and Implants / Q000382:microbiology*; D012293:Rifampin / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D013212:Staphylococcus epidermidis; D013997:Time Factors; D017211:Treatment Failure; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D012293:Rifampin