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Prophylactic antibiotics prevent bacterial biofilm graft infection
T M Bergamini1, J C Peyton, W G Cheadle
1Department of Surgery, University of Louisville School of Medicine, Kentucky.
Abstract:
Bacterial biofilm graft infection is due to prostheses colonization by Staphylococcus epidermidis, a pathogen frequently recovered from perigraft tissues of man during vascular procedures despite the use of asepsis and prophylactic antibiotics. The effect of preoperative intraperitoneal cefazolin, administered at a standard (15 or 30 mg/kg) and high (120 mg/kg) dose, on the prevention of bacterial biofilm infection was studied in a rat model. Seventy-four Dacron grafts, colonized in vitro with S. epidermidis to produce an adherent biofilm (3.19 +/- 0.71 x 10(7) colony-forming units/cm2 graft), were implanted in the dorsal subcutaneous tissue at 0.5, 2, and 4 hr after antibiotic administration. The study strain was a slime-producing clinical isolate with minimum inhibitory concentration (MIC) of 15-30 micrograms/ml to cefazolin. Subcutaneous tissue antibiotic levels were determined at each time interval. One week after implantation, the concentration of bacteria in the surface biofilm by quantitative agar culture was significantly decreased (P less than 0.05) only for grafts implanted when antibiotic tissue levels were greater than or equal to the MIC of the study strain. The result of no growth by biofilm broth culture was significantly achieved (P less than 0.01) only for grafts implanted 0.5 hr after high dose cefazolin, in which the tissue antibiotic level was above the MIC of the study strain. Antibiotics can markedly reduce the bacteria concentration of a prosthetic surface biofilm. The effectiveness of prophylactic antibiotics on the prevention of graft infection is dependent upon maintaining an adequate antibiotic level in the perigraft tissues for the duration of the procedure.
Insights
Prophylactic cefazolin effectively reduced Staphylococcus epidermidis biofilm on vascular grafts in rats, but only when perigraft tissue levels exceeded the antibiotic
Area of Science:
- Infectious Diseases
- Surgical Infections
- Pharmacology
Background:
- Bacterial biofilm graft infection, primarily by Staphylococcus epidermidis, is a significant complication in vascular procedures.
- Despite aseptic techniques and prophylactic antibiotics, perigraft tissue colonization remains a concern.
- Understanding antibiotic efficacy in preventing biofilm formation on prostheses is crucial.
Purpose of the Study:
- To evaluate the effect of preoperative intraperitoneal cefazolin on preventing bacterial biofilm infection in a rat vascular graft model.
- To determine the optimal timing and dosage of cefazolin for preventing graft colonization.
Main Methods:
- Seventy-four Dacron grafts were colonized with Staphylococcus epidermidis to form a biofilm.
- Rats received cefazolin at standard (15-30 mg/kg) or high (120 mg/kg) doses, with grafts implanted at 0.5, 2, or 4 hours post-administration.
- Bacterial concentrations in biofilms and perigraft tissue antibiotic levels were quantified.
Main Results:
- Bacterial concentration in the graft biofilm was significantly reduced when perigraft tissue antibiotic levels met or exceeded the minimum inhibitory concentration (MIC) of the study strain.
- Complete eradication of biofilm bacteria (no growth) was achieved only with high-dose cefazolin administered 0.5 hours prior to implantation, ensuring tissue levels above the MIC.
- The effectiveness of cefazolin was directly correlated with maintaining adequate perigraft tissue antibiotic concentrations.
Conclusions:
- Preoperative cefazolin administration can significantly reduce bacterial concentration on prosthetic graft biofilms.
- Maintaining perigraft tissue antibiotic levels above the MIC is critical for effective prevention of graft infection.
- Optimal prophylactic antibiotic strategies require careful consideration of dosage, timing, and achievable tissue concentrations.