INFECTIOUS COMPLICATIONS OF CENTRAL VENOUS CATHETERS

Due to the multitude of invasive procedures of today's intensive care medicine, infections from central venous catheters have gained increasing attention. The incidence of bacteremias arising from such devices ranges from < 0.1 to 0.6 cases per 100 catheter-days. Factors influencing the incidence of catheter-associated infections are related to patient characteristics as well as the purpose and material of the catheter. Silicone catheters seem to carry a lower risk of infection than common polytetrafluorethylene catheters. The most frequently isolated bacteria in catheter-associated infections are coagulase-negative and coagulase-positive staphylococci, enterococci, and pseudomonas species. Septicemias due to Candida albicans frequently complicate the course of immune-compromised patients receiving total parenteral nutrition (TPE). Catheter-associated bacteremias (CAB) can arise from the contaminated hub, from which pathogens migrate intraluminally to the blood stream. When the catheter entry site is infected, bacteria may reach the blood via the extraluminal route and cause septicemia. Endemic outbreaks of CAB often originate from contaminated infusion fluids. As the clinical presentation of "catheter infections" is often uncharacteristic and insidious, a definite diagnosis depends on bacteriological examination of the catheter. Quantitative and semiquantitative culture techniques of the catheter tip help to distinguish colonization from contamination by numbers of colony-forming units per milliliter culture medium. Preliminary results can be obtained by simple Gram or acridine-orange staining of the catheter tip. The most important prophylactic measures to prevent CAB are strictly aseptic conditions when catheters are placed and meticulous care thereafter, preferably by specially trained nurses or "TPE teams". Other preventive measures are subcutaneous tunnelling of the catheter, antibiotic or antiseptic ointments at the insertion site, and filters to prevent bacteria in the infusion fluid from reaching the blood stream. Once a catheter is found to be infected, it should be removed immediately regardless of the fact that some authors report successful antibiotic treatment with catheters left in place. Due to the expected pattern of resistance of Staphylococcus epidermidis, vancomycin should be considered the drug of choice if calculated antibiotic therapy is initiated.