Diagnosis and treatment of vascular infections is complex and depends on a variety of factors, including the location of the infected tissue, the microbiology of the infection, and patient-specific factors, such as anatomy and immune status. Purulent or suppurative thrombophlebitis is inflammation of a peripheral or central venous wall because of the presence of microorganisms. Endarteritis (or infective arteritis) and mycotic aneurysms are infections of the arterial walls; arterial aneurysms or pseudoaneurysms are usually present because endarteritis may be difficult to diagnose unless an aneurysm is present. The term mycotic aneurysm is a misnomer that refers to any arterial aneurysm of infectious cause, fungal or bacterial, and may also include secondary infections of pre-existing aneurysms or pseudoaneurysms. Vascular graft infections present an even wider spectrum of disease that depends on the type and location of the graft. Management of infections located on vascular prostheses is further complicated by the fact that prosthesis excision can jeopardize a patient's life and organ function, and alternative grafting techniques, including ex situ bypass, autologous reconstruction, and a variety of other graft materials, must be considered. Finally, endovascular repair of aneurysms has resulted in a variety of infectious complications of endovascular stents, stent-grafts, and other intra-arterial devices.
Pathogenesis and diagnosis
Septic thrombophlebitis is characterized by inflammation with suppuration of the vein wall. The various anatomic sites of this serious condition determine the clinical significance and manifestations. Superficial suppurative thrombophlebitis is most often a complication of indwelling intravenous catheters or intravenous substance use. Suppurative thrombophlebitis due to intravenous catheters occurs more commonly with plastic than with steel cannulas. Irritation of the vein wall and subsequent development of purulent thrombophlebitis occurs more often with polyethylene catheters than with Teflon or Silastic catheters and is higher in lower extremity cannulation. Central vein thrombosis is a relatively common complication of central venous catheterization, occurring in as many as one-third of patients in some autopsy and clinical series. Peripherally inserted central venous catheters are also associated with increased risk of symptomatic thrombosis. Suppurative thrombophlebitis of the thoracic central veins results from the bacterial or fungal contamination (sepsis) of these often asymptomatic thrombi. The second major type of septic thrombophlebitis occurs by invasion from adjacent primary nonvascular infections and includes Lemierre's syndrome (internal jugular vein septic thrombophlebitis) as well as other entities discussed elsewhere. Lemierre's syndrome, although rare, usually follows an oropharyngeal infection and occurs most often in previously healthy patients aged 16 to 25 years.