Day #8 - The Bacteremia that Won't Go Away

Today the discussant described evaluating for exit site and tunnel infections and differentiated these from catheter tip infections with bacteremia. We then talked about diagnosis and management of line-related infections focussing of a few specific pathogens. Here are a few take-away points:

One should obtain paired, labeled blood cultures from the periphery and line in question. The differential time to positivity can help determine whether the line is the source of the infection as follows

• Line and blood simultaneously positive suggests that the line is not the focus
• Line positive 2 hours before periphery suggests that the line is the focus
• Line positive and blood negative may suggest colonization only

In cases of Staphylococcus aureus, Pseudomonas sp., or Candida sp. unless there is some tremendously good reason to keep the line it should be removed.

• Failure to remove the focus/line can be associated with adverse outcomes including metastatic infection and death.
  
• Changing over a wire or reinsertion at the same side is not ideal but sometimes the only solution.
• If the line is not medically necessary and is easy to remove without complication it should probably be removed in most line related infections.
  

Treatment is then dependent on the presence or absence of metastatic infection and should be tailored to the organism and its sensitivities.

• One should be vigilant for evidence of metastatic infection or complications.
  
• Recurrent bacteremias with the same organism are highly suggestive of an occult/endovascular focus.
  

I will also take this moment to point out that for sensitive Staphylococcus aureus treatment with VANCOMYCIN is inferior to a BETA-LACTAM in the non-severly allergic patient.

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We also talked about two interesting pathogens involved in this case:

• Staphylococcus lugdunensis which is a coagulase-negative staphylococci which has virulence similar to Staphyloccocus aureus and is a cause of endovascular infections such as native-valve infective endocarditis
• Achromobacter xylosoxidans ss xylosoxidans which is a rare gram negative rod which has been known to cause infections such as bacteremia and more rarely pneumonia, abscesses and meningitis. Patients with malignancies seem to be particularly at risk.