[Table of Contents]

Canada Communicable Disease Report - Supplement
Volume: 23S8
December 1997

INFECTION CONTROL GUIDELINES

Preventing Infections Associated with Indwelling Intravascular Access Devices

Intravascular Device-Associated Infection

Several definitions based on clinical signs and symptoms, culture results of entry site skin, and culture results of intravascular cannulae have been proposed for intravascular device-associated infection (see Section C in the Introduction).

Three methods for quantitative catheter culture have been proposed: flushing, sonication, and a semiquantitative roll plate. The latter has largely been accepted as the standard of practice, but may miss cases in which contamination of luminal surfaces cause infection. Concordance between cannula hub and tip culture reports is <= 25%⁽¹¹²⁾. Acridine orange staining of intravascular catheter segments or of cytospun lysed blood have also been used, in addition to a culture-brush, which is passed down the lumen of indwelling lines. Scanning electron microscopy also has been used as a research tool to evaluate the extent of intra- versus extra-luminal biofilm. Non-quantitative broth immersion culture does not provide meaningful results and should not be used.

The clinical outcomes of interest are clinically apparent intravascular catheter site infection and primary bloodstream infection. Skin or cannula cultures have limited sensitivity, specificity and predictive value for these outcomes (Table 3)^(112,113). Interpretation of skin culture studies is sometimes complicated by use of cannula-tip colonization as the outcome studied. Routine culturing of intravascular catheter tips has little impact on clinical decisions and is not a cost-effective practice⁽¹¹⁴⁾.

RECOMMENDATIONS

1. Routine culturing of intravascular catheter tips, insertion sites or fluids should not be used as a routine infection prevention measure. If intravascular device-associated infection is suspected, blood cultures should be drawn from a peripheral site and the intravascular line if appropriate. Consideration may be given to obtaining blood cultures from all of the lumens of a multi-lumen intravascular catheter. (Category A; Grade III)

2. Cannula tips If intravascular device-associated infection is suspected and the cannula is to be removed, a 1 cm portion of the distal tip should be obtained aseptically and cultured semiquantitatively by roll plate, flush or sonication method.

3. Cannula site skin To obtain a sample for culture at the cannula exit site, the dressing should be removed and, before the entry site is cleaned, a sample for culture should be obtained by rolling a culture swab once forwards and backwards at the insertion site.

4. Catheter hubs (optional) (Figure 1) When the intravascular device is removed, consideration may be given to culturing the internal surfaces with a sterile swab after appropriate decontamination of the external surfaces.

5. Infusion fluids If an intravascular system is discontinued because of suspected fluid contamination, fluid should be cultured as follows:

   1. Fluid should be aspirated aseptically from the intravascular line or the fluid container, administration set, or both, and should be placed in a sterile container and sent to the laboratory. Lot numbers of fluids and additives should be recorded.

   2. Fluid should be cultured aerobically for bacteria and fungi by broth or membrane filter technique. If intrinsic contamination (contamination during manufacture) is suspected, the local health authority and the Bureau of Infectious Diseases, Health Protection Branch, should be notified immediately.

Table 3 Positive Predictive Accuracy of Semiquantitative Cannulae Tip Culture for Bacteremia
Reference	Number of Catheters Cultured	Mean Placement Time (days)	Prevalence of Associated Sepsis (%)	Positive Predictive Value (%)
Collignon	780	5.5	2.0	8.8
Moyer	101	10.0	5.0	20.0
Sherertz	60	19.0	8.0	45.0
Liñares	135	24.0	14.8	72.0
Reproduced with permission from: Collignon P, Munro R. J Clin Microbiol 1988; (26):1076.

Figure 1
Sources of infection of a percutaneous intravascular device(2) (Figure is used with permission of author and publisher.)

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