Efficacy of Antiseptic Solutions in Treatment of Staphylococcus Aureus Infected Surgical Wounds with Patches of Vascular Graft: An Experimental Study in Rats

Abstract

Background and objectives: Treatment of a prosthetic vascular graft infection (PVGI) remains a challenging problem in vascular surgery. The aim of this study was to design a novel rat model for treatment of peripheral vascular prosthesis infection caused by Staphylococcus aureus (S. aureus) and to determine the efficacy of different antiseptic solutions in suppressing or eradicating infection from the wound and the graft material itself. Materials and methods: A piece of Dacron vascular prosthesis was surgically implanted at the dorsum of 48 Wistar rats and the wounds were infected with 5 McFarland standard inoculum of S. aureus. Suppurating wounds were daily irrigated with different antiseptic solutions: octenidine dihydrochloride, povidone-iodine, chlorhexidine digluconate, and sterile saline. The antimicrobial action of antiseptics was defined according to their capability to eradicate bacteria from the graft surroundings and bacteriological examination of the graft itself. Extended studies on wound microbiology, cytology, and histopathology were performed with an additional group of 10 rats, treated with the most effective antiseptic-octenidine dihydrochloride. Results: Four-day treatment course with octenidine, povidone-iodine, and chlorhexidine resulted in 99.98% (p = 0.0005), 90.73% (p = 0.002), and 65.97% (p = 0.004) decrease in S. aureus colonies in wound washouts, respectively. The number of S. aureus colonies increased insignificantly by 19.72% (p = 0.765) in control group. Seven-day treatment course with octenidine eradicated viable bacteria from nine out of 10 wound washouts and sterilized one vascular graft. Conclusions: A reproducible rat model of PVGI with a thriving S. aureus infection was designed. It is a first PVGI animal model where different antiseptic solutions were applied as daily irrigations to treat peripheral PVGI. Seven-day treatment with octenidine eradicated bacteria from the wound washouts for 90% of rats and one vascular graft. Further studies are needed to investigate if irrigations with octenidine could properly cure vascular bed from infection to assure a successful implantation of a new synthetic vascular substitute.

Keywords: S. aureus; antiseptic; rat model; vascular graft infection.

Figure 1

An arrow in the image points to a hardened swelling at the incision site with a purulent fistula on day six—before the beginning of treatment.

Figure 2

Changes in S. aureus colony counts in wound washouts along the time of treatment. Four-day treatment course resulted in significant drop in S. aureus colony counts for octenidine group (p = 0.0005, n = 12), povidone-iodine group (p = 0.002, n = 10), and chlorhexidine group (p = 0.004, n = 10). Insignificant change was detected in control group (p = 0.765, n = 11).

Figure 3

Macroscopic findings of the wound for rat treated with octenidine dihydrochloride (day 13): (A) a crust at the incision site; (B) a cutaneous fistula at the incision site; and (C) excised cutaneous fistula with a crust for microbiological and histopathological evaluation.

Figure 4

The results of extended PVGI treatment with octenidine dihydrochloride. Seven-day treatment course resulted in significant drop in S. aureus colony counts in wound washouts (p = 0.002, n = 10).