Case 24: Diagnosis & Conclusions

Case 24 Index

Diagnosis: Catheter related blood stream infection (CRBSI) & tunnel infection of tunneled dialysis catheter

Case Summary: Catheter related infections are a significant cause of hospitalization and mortality in hemodialysis patients. Catheter dysfunction, erythema or tenderness of the exit site or subcutaneous tunnel, fever, chills, and other systemic signs of infection should raise suspicion for tunnel infection/exit site infection/catheter-related blood stream infection in a hemodialysis patient. Before we talk about prevention, let’s talk a bit about the classification of these infections and appropriate treatment strategies. Below is a cartoon showing the path of the tunneled dialysis catheter into the superior vena cava (SVC) and an image of a healthy appearing tunneled dialysis catheter without evidence of exit site or tunnel infection.

Though specific definitions may vary by association (i.e. KDOQI, IDSA, etc.), below are general features of CRBSI, tunnel infections, and exit site infections (click below).
Catheter related blood stream infection (CRBSI)
Bacteremia in a patient with a catheter, without evidence of another infectious source. The most sensitive and specific way to diagnose CRBSI is to draw cultures from both the catheter and hemodialysis circuit. 
Exit site infection
Erythema, tenderness, or induration less than 2 cm from the exit site of the catheter. May or may not be accompanied by CRBSI or purulent drainage.
Tunnel infection
Erythema, tenderness, or induration more than 2 cm from the exit site of the catheter. May or may not be accompanied by CRBSI or purulent drainage.

Exit site infections without CRBSI can be treated with antibiotics for 7- 14 days while tunnel infections require removal of the catheter in addition to systemic antimicrobial therapy (duration depends on the presence of absence of concurrent CRBSI). For tunnel infections – alternatively, if the patient does NOT have sepsis, the catheter can be exchanged after 2 or more doses of intravenous antibiotics with a maintained venotomy site and the creation of a new tunnel. 

CRBSI should be treated with longer duration of systemic antimicrobial therapy – 2- 6 depending on the organism.  And what about the catheters? Catheters can be removed, exchanged, or salvaged. Catheters should be replaced (removed or exchanged over a guide wire) in cases of CRBSI due to S.aureus or Pseudomonas species. Catheters should be removed urgently in cases of:

  • Severe sepsis
  • Hemodynamically unstable patients
  • Metastatic infection (i.e. endocarditis, osteomyelitis)
  • Evidence of a tunnel infection.

Cases in which catheter salvage may be considered include those with bacteremia with organisms other than S. aureus and Pseudomonas species who are clinically responsive to antimicrobial therapy or in those with limited vascular access. If the catheter is salvaged, antimicrobial lock therapy MUST be used in addition to systemic antimicrobial therapy.  (Of note, this approach is not recommended as the catheter biofilm is not treated with either the lock solution or systemic antibiotics) 

Finally, a word on prevention. In addition reduction of catheter placement, interventions include: sterile line placement, hand hygiene, application of antimicrobial ointments to catheter exit site, scrubbing of catheter hub prior to capping, patient and dialysis staff education, and regular dialysis unit surveillance of CRBSI with feedback.

For more, take a look here.

Case 24 Index
Case 24 Introduction
Case 24 Physical Exam