Actinomyces spp. Prosthetic Vascular Graft Infection (PVGI): A Multicenter Case-Series and Narrative Review of the Literature

BACKGROUND

Actinomycosis represents a challenging and under-reported complication of vascular surgery. Optimal management of Actinomyces spp. prosthetic vascular graft infection (PVGI) is highly uncertain because of the paucity of reports on this disease.

METHODS

We conducted a retrospective case-series of Actinomyces-PVGI that occurred in the last five years in two major university hospitals in northern Italy. We searched for previously published cases in the scientific literature.

RESULTS

We report five original cases of Actinomyces spp. prosthetic vascular graft infection following aortic aneurysm repair. Our literature review retrieved eight similar cases. Most patients were immunocompetent males. Most infections were polymicrobial (11/13 cases), with a prevalence of A. odontolyticus involvement (3/13 cases were associated with. Salmonella spp. infection). All cases had a late presentation (≥4 months from graft placement), with 61% associated with an aorto-enteric fistula. All patients received antibiotic therapy, but the duration was highly heterogeneous (from two weeks to life-long antibiotics). The patients without surgical revision experienced septic recurrences (2/13), permanent dysfunction (1/13), or a fatal outcome (2/13), while of the remainder who underwent vascular graft explant, six recovered completely and one developed a periprosthetic abscess. In two cases follow-up was not available.

CONCLUSIONS

This case-series aims to raise the diagnostic suspicion and to describe the current management of Actinomyces-PVGIs. We highlight a high heterogeneity in antibiotic duration, choice of the antibiotic regimen, and surgical management. Higher reporting rate is advisable to produce better evidence and optimize management of this rare complication of vascular surgery.

Case Report and Literature Review of Prosthetic Cardiovascular Mucormycosis

We report a rare case of aorto-bi-iliac prosthetic allograft mucormycosis in a 57-year-old immunocompetent patient in France. Outcome was favorable after surgery and dual antifungal therapy with liposomal amphotericin B and isavuconazole. In a literature review, we identified 12 other cases of prosthetic vascular or heart valve mucormycosis; mortality rate was 38%.

Case report: Analysis of phage therapy failure in a patient with a Pseudomonas aeruginosa prosthetic vascular graft infection

Clinical case of a patient with a Pseudomonas aeruginosa multidrug-resistant prosthetic vascular graft infection which was treated with a cocktail of phages (PT07, 14/01, and PNM) in combination with ceftazidime-avibactam (CZA). After the application of the phage treatment and in absence of antimicrobial therapy, a new P. aeruginosa bloodstream infection (BSI) with a septic residual limb metastasis occurred, now involving a wild-type strain being susceptible to ß-lactams and quinolones. Clinical strains were analyzed by microbiology and whole genome sequencing techniques. In relation with phage administration, the clinical isolates of P. aeruginosa before phage therapy (HE2011471) and post phage therapy (HE2105886) showed a clonal relationship but with important genomic changes which could be involved in the resistance to this therapy. Finally, phenotypic studies showed a decrease in Minimum Inhibitory Concentration (MIC) to ß-lactams and quinolones as well as an increase of the biofilm production and phage resistant mutants in the clinical isolate of P. aeruginosa post phage therapy.

Multimodality imaging of an aortic graft infection

Aortic prosthetic vascular graft infections (PVGI) are rare complications of the aortic surgery, with an incidence of 0.5%-6%. Although rare, they carry mortality rates as high as 25%-88%. Improvement in diagnostic imaging modalities in the last two decades, together with early diagnosis, aortic PVGI associated mortality was reduced. These imaging methods include transesophageal echocardiography (TEE), computed tomography angiography (CTA), and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). In this case report, we focus mainly on three imaging modalities as TEE, CTA, and 18F-FDG PET/CT and showed their role in the assessment of aortic PVGI.

Phage treatment of an aortic graft infected with Pseudomonas aeruginosa

Management of prosthetic vascular graft infections caused by Pseudomonas aeruginosa can be a significant challenge to clinicians. These infections often do not resolve with antibiotic therapy alone due to antibiotic resistance/tolerance by bacteria, poor ability of antibiotics to permeate/reduce biofilms and/or other factors. Bacteriophage OMKO1 binding to efflux pump proteins in P. aeruginosa was consistent with an evolutionary trade-off: wildtype bacteria were killed by phage whereas evolution of phage-resistance led to increased antibiotic sensitivity. However, phage clinical-use has not been demonstrated. Here, we present a case report detailing therapeutic application of phage OMKO1 to treat a chronic P. aeruginosa infection of an aortic Dacron graft with associated aorto-cutaneous fistula. Following a single application of phage OMKO1 and ceftazidime, the infection appeared to resolve with no signs of recurrence.

Thoracic Aortic Graft Infection due to Candida Albicans with Multiple Embolism in the Left-side Vessels of the Body

A 79-year-old Japanese man who had undergone thoracic aortic replacement 10 years prior presented with a 3-day history of sore throat. He was initially diagnosed with pharyngitis; however, multiple emboli in the vessels of the left side of the body were recognized. He was diagnosed with thoracic aortic graft infection caused by Candida albicans, with multiple embolisms. Anti-fungal therapy was initiated, but surgical removal of the graft was not performed because of the high risk associated with the operation, and he eventually died. Inappropriate use of antibiotics might have led to a severe fungal infection. As such, the inappropriate use of antimicrobial agents should be avoided.