[Infections of intravascular perfusion sets]

Abstract

Catheter-related infections (CRI) are a leading cause of morbidity and sometimes a cause of death in cancer patients. For preventive strategies, intra- and extra-luminal colonization pathways should be taken into account. A definite diagnosis of CRI requires usually the removal of the catheter for culture of the catheter-tip. However, only about 20% of the catheters removed for suspicion of CRI actually prove infected. The diagnosis of CRI is likely when a bloodstream infection due to coagulase negative staphylococcus, S. aureus or Candida spp occurs, without other infectious focus. Among the catheter-tip culture techniques, quantitative methods offer the better sensitivity-specificity/complexity-cost compromise, and should be preferred to semi-quantitative ones. When a venous access port is removed because of suspected CRI, the catheter tip and the port itself should be both cultured. Immediate removal of the catheter and urgent antibiotic treatment are mandatory when severe local infection (such as tunnelitis or cellulitis) or severe sepsis occurs. Usually, a CRI due to S. aureus, Pseudomonas spp or Candida spp requires also the removal of the catheter. Diagnostic techniques without catheter removal may be only proposed when local or systemic severity signs are lacking. Recently, the measurement of the differential time to positivity between paired blood cultures drawn simultaneously on the catheter and on a peripheral vein has been proposed. Finally, the direct examination of blood drawn from the catheter using acridine-orange leucocyte cytospin test seems to be a promising and rapid method for the diagnosis of CRI. When a CRI is diagnosed, a treatment without catheter removal may be proposed when local or systemic severity signs are lacking mainly if coagulase negative staphylococci are involved; in such case, both systemic antibiotic therapy and lock-therapy should be associated. In case of clinical failure of this strategy after 48-72 hours, the catheter should be removed. If the sepsis persist, a residual infectious focus (thrombophlebitis, endocarditis, secondary localisation) should be investigated.