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Updated: May 11, 2026
In Vivo Mouse Model of Spinal Implant Infection
Published on: June 23, 2020
Efficacy of a synthetic antimicrobial peptidomimetic versus vancomycin in a Staphylococcus epidermidis device-related
Jorunn Pauline Cavanagh1, Hildegunn Norbakken Granslo, Elizabeth Aarag Fredheim
1Paediatric Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. pauline.cavanagh@uit.no
Objectives:
Biofilm-forming Staphylococcus epidermidis is a prevalent cause of peritonitis during peritoneal dialysis. We compared the efficacy of a synthetic antimicrobial peptidomimetic (Ltx21) versus vancomycin in a murine model mimicking a device-related peritonitis.
Methods:
Silicone implants, pre-colonized with an S. epidermidis biofilm, were inserted into the peritoneal cavity of BALB/c mice. Three groups (36 mice in each) with pre-colonized implants received intraperitoneal treatment with Ltx21, vancomycin or placebo. Mice were euthanized on day 3 (n = 12), day 6 (n = 12) or day 8 (n = 12) post-implantation. Controls were mice with sterile implants (n = 18) and mice without surgery (n = 6). Bacterial reductions in cfu were analysed from implants and peritoneal fluid (PF). Inflammatory responses in serum and PF were measured.
Results:
Vancomycin resulted in a stronger reduction in cfu counts, both on pre-colonized implants and in PF, compared with Ltx21 and placebo. Complete bacterial clearance of the implants was not achieved in any of the groups. The implants pre-colonized with S. epidermidis 1457 resulted in a low-grade peritonitis. We observed, only on day 6, a significant increase in the PF leucocyte count in the group with pre-colonized implants compared with the group with sterile implants (P = 0.0364).
Conclusions:
Treatment with vancomycin or Ltx21 was not sufficient to achieve complete bacterial clearance of implants, underlining the difficulties of treating such infections. The low-grade infection may attenuate the inflammatory response and contribute to impaired bacterial clearance.
Insights
Neither vancomycin nor Ltx21 fully cleared Staphylococcus epidermidis biofilms in a mouse model of peritonitis. This study highlights challenges in treating device-related infections, as neither antimicrobial achieved complete bacterial eradication from implants.
Area of Science:
- Microbiology
- Infectious Diseases
- Biomaterials Science
Background:
- Biofilm-forming Staphylococcus epidermidis is a major cause of peritonitis in patients undergoing peritoneal dialysis.
- Device-related infections pose significant treatment challenges due to the bacteria's ability to form biofilms on implants.
Purpose of the Study:
- To compare the efficacy of a synthetic antimicrobial peptidomimetic (Ltx21) against vancomycin in treating Staphylococcus epidermidis-induced peritonitis in a murine model.
- To evaluate the impact of these treatments on bacterial load and inflammatory responses.
Main Methods:
- Mice received silicone implants pre-colonized with S. epidermidis biofilms and were treated with Ltx21, vancomycin, or placebo.
- Bacterial counts (cfu) were analyzed from implants and peritoneal fluid (PF) at different time points (days 3, 6, and 8).
- Inflammatory markers in serum and PF were measured to assess the host response.
Main Results:
- Vancomycin demonstrated a greater reduction in bacterial counts on implants and in PF compared to Ltx21 and placebo.
- Complete eradication of bacteria from the implants was not achieved with either treatment.
- A low-grade peritonitis was observed, with a significant increase in PF leucocyte count noted on day 6 in the infected group.
Conclusions:
- Current treatments with vancomycin or Ltx21 are insufficient for complete bacterial clearance from infected implants.
- The difficulty in eradicating biofilms underscores the challenges in managing device-related peritonitis.
- Low-grade infections may potentially attenuate inflammatory responses, further complicating bacterial clearance.
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