Catheter-Related Infections: Diagnosis and Intravascular Treatment

Abstract

The diagnosis of catheter-related infections relies on the presence of clinical manifestations of infection and the evidence of colonization of the catheter tip by bacteria, mycobacteria or fungi. The reference method to confirm the latter requires the withdrawal of the catheter for culturing, which frequently turns out to be inconvenient, unnecessary and costly. New methods try to avoid these inconveniences and to assess the presence of tip colonization without withdrawal. One of these methods uses quantitative blood cultures with a jump (> or = 5) in colony counts between blood obtained from the catheter lumen and simultaneously from a peripheral vein. It has a high sensitivity (>80%) and specificity (94%-100%) but is cumbersome and requires both an easy backflow of blood in the catheter and the existence of bacteremia. Cytocentrifugation and acridine orange staining of blood withdrawn from an infected catheter lumen has a sensitivity and a specificity of over 90% for the diagnosis of tip colonization. "Superficial cultures" consist in the semiquantitative culture of the hub, of the skin surrounding the catheter entrance and of the first (1 cm) subcutaneous portion of the catheter after swabbing. Sensitivity of this method is >90% and specificity is >80%, and positive and negative predictive values for catheters (considering together those with and without clinical data of infection) are 66% and 97%, respectively. Endoluminal brushing has turned out to be an impractical and unreliable procedure, at least in our experience. New methods based on the speed of bacterial growth to detectable levels of microorganisms in conventional blood cultures are a new and interesting way of assessing catheter-related infections. Besides, as use of antimicrobial-coated catheters becomes more prevalent, the existing definitions of catheter colonization and catheter-related infection may need to be modified, because such coatings may lead to false-negative culture results. Many catheter infections, diagnosed without catheter withdrawal, can be handled nowadays with the so-called "antibiotic lock-in technique", which consists in locking the infected catheter lumen with a solution containing antibiotics. A high proportion of infected catheters, mainly those with coagulase-negative staphylococci, can be maintained in place and sterilized with this technique, including catheters in patients with therapeutic failure after receiving conventional intravenous antibiotic therapy. New diagnostic and therapeutic techniques may avoid the unnecessary withdrawal of thousands of efficient, difficult to replace and expensive intravascular lines.

Totally Implantable Venous Access Devices in Children Requiring Long-Term Chemotherapy: Analysis of Outcome in 122 Children from a Single Institution.

“…According to the literature, the rate of catheter-related infections in long-term central venous access catheters ranges from 0.6 to 27 % depending on the catheter type and location and the patient's constitution [6]. Immunosuppressed patients with port systems were found to have a median of 0.2 infections per 1000 catheter-days (range 0-2.7 per 1000 catheter-days) [7].…”

Parenteral nutrition line sepsis: the difficulty in diagnosis

“…A PN line can become infected in a number of ways: (1) poor aseptic technique when inserting the line; (2) migration of organisms along the line; (3) poor aseptic technique and line care when using the line; (4) contaminated infusions; (5) haematogenous spread from distant foci of infection (3) .…”

Catheter-related bloodstream infections: catheter management according to pathogen

“…Other routes of infection are haematogenous seeding from a distant infection or, rarely, contaminated infusate. Approximately 65% of catheter-related infections originate from the skin flora, 30% from the contaminated hub and 5% through other pathways [14].…”