Vascular infections: medical and surgical therapies

Vein Harvest Wound Healing after Bypass Surgery for Critical Limb Ischemia

BACKGROUND

Lower-limb revascularization surgery, especially when performed using the great saphenous vein, predisposes patients to major surgical trauma on initially ischemic tissue. Vein harvest wounds (VHWs) after infrainguinal revascularization heal slowly. This study's aim was to assess the factors associated with VHW healing after infrainquinal bypass surgery for critical limb ischemia (CLI).

METHODS

A retrospective patient record study was conducted. All patients with CLI who underwent infrainguinal bypass surgery with autologous vein graft between January 1, 2015, and December 31, 2017, in the Turku University Hospital, were included. Follow-up data were collected until February 28, 2018. The following data was collected from the patient files; risk factors, ankle-brachial indices (ABIs), systolic toe pressures (STPs), the presence of an ischemic ulcer, VHW dehiscence, and the time when the VHW was completely healed. Procedures with outflow vessels at either popliteal or tibial artery were analyzed separately. Descriptive and univariate statistical analyses were performed.

RESULTS

Altogether, 195 patients were operated on for CLI, of whom 133 (68.2%) patients had ischemic ulcers. The mean follow-up time was 535.0 days (range 3.0-1143.0 days). The mean ABI improvement was 0.49 (P = 0.00), and STP improvement, 39.9 mm Hg (P = 0.00). The median time taken when VHW was healed was 48.0 days (95% confidence interval [CI], 39.4-56.6) in patients without ischemic ulcers and 82.0 days (95% CI, 59.7-104.3) in patients with ischemic ulcers, P = 0.03. VHW in patients who underwent popliteal artery bypass (62 days, 95% CI, 12.9-93.0) healed faster than VHW in those who underwent tibial artery bypass (132 days, 95% CI, 48.0-93.0), P = 0.02. Risk factors and the preoperative or postoperative ABIs or STPs had no effect on VHW healing time.

CONCLUSIONS

VHW healing was remarkably slower after revascularization surgery in patients with an ischemic foot ulcer than in those without ischemic ulcers.

Cross-sectional study on surveillance of surgical site infections after vascular surgery

Aims: To determine the incidence and risk factors for surgical site infections (SSI) after vascular surgery, to evaluate the Dutch safety bundle to reduce adverse complications and to analyze causative microorganisms of SSIs. Materials & methods: The 3.5-year study was divided into two periods: the control period (before bundle implementation) and intervention period (after implementation). Postdischarge surveillance was performed until 30 days after surgery. Causative microorganisms from in-hospital wound swabs were determined. SSI rates between both periods were compared and a risk analysis was carried out by performing a logistic regression. Results: The study included 1719 operations. The in-hospital SSI rate increased significantly over time. Out of 140 SSIs, 39% were diagnosed postdischarge. Risk factors were diabetes, age >60 years and operations classified as contaminated or dirty. Pseudomonas aeruginosa susceptibility was the highest for gentamicin (97%). All Staphylococcus aureus were methicillin susceptible. Conclusion: As patient demographics are important to determine the effectiveness of infection preventive measures, (postdischarge) surveillance is important for developing SSI interventions.

Vascular prostheses with covalently bound gentamicin and amikacin reveal superior antibacterial properties than silver-impregnated ones--an in vitro study

OBJECTIVE

This study aims to compare the antibacterial activities of vascular prostheses: silver-impregnated and modified with covalently immobilised antibiotics.

MATERIALS AND METHODS

Six types of protein-sealed vascular prostheses were modified with amikacin and gentamicin according to the method described in the Polish Patent Office. Their antimicrobial properties were estimated against 14 reference and clinical strains and compared with those of InterGard Silver grafts. Cytotoxicity of the tested grafts was estimated against human skin fibroblasts.

RESULTS

Prostheses modified with antibiotics in a stable covalent mode were found to be much more effective against bacterial growth and biofilm formation, as well as in case of methicillin-resistant Staphylococcus aureus (MRSA), than InterGard Silver. They inhibited the bacterial growth for at least 30 days, without losing higher than 10% of the initial amount of its drug content. They were also good, non-toxic matrices for growth of human skin fibroblasts.

CONCLUSIONS

Prostheses modified with covalently immobilised antibiotic according to our technique are much more effective than InterGard Silver at protection against bacterial growth. They are also compatible with human skin fibroblasts.

Surgical site and vascular infections: treatment and prophylaxis

Vascular infections typically include those of surgical sites, prosthetic grafts, and vascular ulcers, including some diabetic foot ulcers. Each of these infections represents a serious health concern, particularly among individuals with comorbid conditions who are at an increased risk of morbidity and mortality. Surgical site infections occur primarily as a result of contamination by skin organisms during surgery, whereas prosthetic graft infections result typically from a progressive wound infection. Diabetic foot ulcers and infections are especially complicated and difficult to treat. They occur in individuals with systemic illness that has compromising effects on the nervous, vascular, musculoskeletal, and immunologic systems. Vascular infections, like those elsewhere in the body, reflect an imbalance between the host and bacteria. Efforts to limit or prevent the likelihood of patients developing these infections centre on reducing the bacterial inoculum by means of asepsis and antisepsis. As well as size of the bacterial inoculum, the bacterial properties of pathogenicity and resulting virulence are also significant. The most frequent pathogenic bacteria encountered in surgical patients are Gram-positive cocci (e.g. Staphylococcus aureus and streptococci). Strains with multiple antibiotic resistance (e.g. meticillin resistant S. aureus [MRSA], S. epidermidis, and vancomycin-resistant enterococci [VRE]) can cause significant surgical site infection problems. Local resistance patterns and surveillance efforts are essential to ensure appropriate empiric antibiotic selection for prophylaxis or treatment.