Differential effects of a gram-negative and a gram-positive infection on autogenous and prosthetic grafts

Abstract

A canine model was developed to study the differential response of a gram-negative and a gram-positive bacterial infection on autogenous and prosthetic grafts. After replacing segments of the femoral arteries of 15 dogs with autogenous vein in one groin and polytetrafluoroethylene in the contralateral groin, 108 colony-forming units ofnonmncinproducing Staphylococcus epidermidis (five dogs), Pseudomonas aeruginosa (five dogs), or sterile saline solution (five dogs) were directly inoculated onto the grafts. The grafts were examined 7 to 10 days after implantation. None of the control dogs exhibited inflammatory signs, and no grafts or anastomoses disrupted. S. epidermidis was unrecoverable from either graft material in any of the animals, although histologic evaluation confirmed neutrophils and bacteria in four of five animals in the vein and polytetraffuoroethylene groups. No dog inoculated with S. epidermidis had graft or anastomotic disruption. By contrast, P. aeruginosa was recovered from both types of grafts in all inoculated animals. Nentrophils, bacteria, and microabscesses were observed in all of these animals. In addition, three of five polytetrafluoroethylene grafts and all five vein grafts disrupted either at the anastomoses or in the body of the vein graft. Therefore S. epiderzaidis is a less virulent organism that may persist in graft walls despite negative cultures, whereas P. aeruginosa is a highly virulent organism that can disrupt native artery, vein grafts, and anastomoses. The graft material appears to be less important than the bacteria in determining the outcome of infection.

Management of early (<30 day) vascular groin infections using vacuum-assisted closure alone without muscle flap coverage in a consecutive patient series

“…Although some authors did not observe worse outcomes with Pseudomonas infection, 5,10 others have reported increased amputation rates or poorer graft salvage. 7,8,31 Calligaro et al 7 reported only 40% graft salvage when the offending organism was Pseudomonas. Pseudomonas infection was associated with 60% limb loss in a series reported by Seify et al 8 Since both our patients with Szilagyi III infections with Pseudomonas infections eventually needed graft removal, we now recommend graft removal in early Pseudomonas groin infections with exposed grafts.…”

Complications of arteriovenous hemodialysis access: Recognition and management

“…30,37,39 Arterial dissolution with aneurysm formation is more frequently encountered in infections with virulent organisms such as Pseudomonas or S aureus. [49][50][51] Grafts with convincing clinical findings of infection that produce no growth with standard culture techniques may occur as frequently as 25%. 47,48 This inconsistency is often attributed to preoperative antibiotic administration.…”

Pseudomonas aeruginosa infected aneurysm of the superficial femoral artery

“…[12][13][14] The reason for its pathogenicity probably lies with its capacity to adhere to the endothelium (via pili), resist phagocytosis (via mucoid exopolysaccharide capsule), and generate vascular disruption (via elastase and alkaline protease). 12,13,15 Moreover, Pseudomonas is very difficult to clear, possibly because of the organism's adaptability, minimal nutritional requirements, and relative antibiotic resistance. 12,13,15 The clinical presentation of infected aneurysm can be varied and subtle.…”