Pre-clinical in vivo Models of Vascular Graft Coating in the Prevention of Vascular Graft Infection: A Systematic Review

OBJECTIVE

Vascular graft infection (VGI) remains an important complication with a high mortality and morbidity rate. Currently, studies focusing on the role of vascular graft coatings in the prevention of VGI are scarce. Therefore, the aims of this study were to survey and summarise key features of pre-clinical in vivo models that have been used to investigate coating strategies to prevent VGI and to set up an ideal model that can be used in future preclinical research.

DATA SOURCES

A systematic review was conducted in accordance with the Preferred reporting items for Systematic Reviews and Meta-Analysis guidelines. A comprehensive search was performed in MEDLINE (PubMed), Embase, and Web of Science.

REVIEW METHODS

For each database, a specific search strategy was developed. Quality was assessed with the Toxicological data Reliability Assessment Tool (ToxRTool). The type of animal model, graft, coating, and pathogen were summarised. The outcome assessment in each study was evaluated.

RESULTS

In total, 4 667 studies were identified, of which 94 papers focusing on in vivo testing were included. Staphylococcus aureus was the organism most used (n = 65; 67.7%). Most of the graft types were polyester grafts. Rifampicin was the most frequently used antibiotic coating (n = 43, 48.3%). In the outcome assessment, most studies mentioned colony forming unit count (n = 88; 91.7%) and clinical outcome (n = 72; 75%). According to the ToxRTool, 21 (22.3%, n = 21/94) studies were considered to be not reliable.

CONCLUSION

Currently published in vivo models are very miscellaneous. More attention should be paid to the methodology of these pre-clinical reports when transferring novel graft coatings into clinical practice. Variables used in pre-clinical reports (bacterial strain, duration of activity coating) do not correspond well to current clinical studies. Based on the results of this review, a proposal for a complete and comprehensive set up for pre-clinical invivo testing of anti-infectious properties of vascular graft coatings was defined.

Antimicrobial prophylaxis in dermatology

Few circumstances in dermatology warrant antimicrobial prophylaxis. In cutaneous surgery postoperative infections are too infrequent and insufficiently severe to justify preventive antibiotics, except rarely. Petrolatum is as effective as, and cheaper than, topical antibiotic ointment to cover surgical wounds. In patients with numerous staphylococcal skin infections, oral clindamycin 150 mg every day for 3 months safely reduces further episodes. For recurrent cellulitis, oral penicillin or erythromycin 250 mg twice daily or monthly intramuscular benzathine penicillin decreases subsequent attacks. In patients with frequent episodes of genital or labial herpes simplex an antiviral agent such as valacyclovir 500 mg to 1 g every day is effective as a suppressant.

Comparison of the resistance to infection of intestinal submucosa arterial autografts versus polytetrafluoroethylene arterial prostheses in a dog model

PURPOSE

Prosthetic graft infection represents a most challenging complication to the vascular surgeon. Although expanded polytetrafluoroethylene (ePTFE) grafts have an acceptable patency rate, especially in the large-diameter arterial location, bacterial contamination of this material usually requires surgical removal of the graft.

METHODS

We compared the resistance of large-diameter ePTFE grafts and grafts constructed of small intestinal submucosa (SIS) to deliberate infection with Staphylococcus aureus. Eighteen dogs were divided into two equal groups, and the infrarenal aorta was replaced with either ePTFE or SIS graft material. One hundred million S. aureus organisms were deposited directly on the graft at the time of surgery, and the dogs were observed for 30 days.

RESULTS

One dog with an ePTFE graft died of hemorrhage from anastomosis site at 21 days. Of the remaining eight dogs with ePTFE grafts, four had positive culture results from the removed graft material, and all had histologic evidence for persistent infection. These dogs also had chronic fever, and the average white blood cell count at day 30 was 15,600/mm3. All nine dogs with SIS grafts had patent grafts, were afebrile after the first week, had an average white blood cell count of 11,500/mm3 at 30 days (p value = NS), had negative culture results, and had the histologic appearance of graft remodeling with collagen that was free of active inflammation.

CONCLUSIONS

We conclude that large-diameter arterial SIS grafts are more resistant to persistent infection with S. aureus than ePTFE grafts in this dog model of deliberate bacterial inoculation.