How is a catheter infection associated with infective endocarditis (IE) diagnosed?

Updated: Jan 03, 2019
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

The diagnosis of catheter infection may be made in 1 of 2 ways. Culturing the device via the roll-plate semiquantitative method is the most common approach but requires a catheter removal. In the case of long-term catheters, blood may be drawn simultaneously through the line and the peripheral vein. If it is impossible to draw blood from a peripheral vein in the presence of a multilumen catheter, one sample may be obtained through each of 2 catheter lumens.

In a catheter infection, the colony count of the sample obtained from the suspected port is 3-fold greater than that drawn from a peripheral vein or from another port of the catheter. Retrieval of organisms from blood drawn from a catheter hub at least 2 hours earlier before their growth is detected in the blood obtained from peripheral vein meets the differential time to positivity criteria of a catheter infection.

A sterile culture of the insertion site has a highly negative predictive value for line infection.


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