While making rounds, I was paged to the dialysis unit to evaluate a patient on hemodialysis via a tunneled dialysis catheter, who began having chills and hypotension during a session. Unfortunately, this is not an uncommon situation and next series of thoughts are, this must be a catheter-induced infection, so… halt dialysis, obtain blood cultures, and initiate antibiotics.
Just four months into my nephrology fellowship, I did not expect that a large portion of my job included infectious disease management. While working at a county hospital serving many undocumented patients, I’ve learned about the prevalence and dangers of tunneled dialysis catheter (TDC) infections. Many patients who have a TDC are either an unsuitable candidate (many times after failed attempts/loss) for fistula/graft placement or awaiting one; it is during these periods when infections develop. Unfortunately, the risk of bacteremia is about 25% for the duration of the TDC and as a nephrology fellow, we are often on the front lines of catching these infections. Learning how to prevent and manage these infections appropriately is an obligation of every nephrologist-in-training. It is also a sobering reminder about the need to get permanent access placed before dialysis initiation and even more important to consider preemptive kidney transplant if this is an option for the patient.
What are the most common etiologies and pathogenesis?
The most common etiologies of bacteremia in TDC patients are skin flora and contamination of the catheter lumen. The pathogenesis includes migration from the skin along the outside of the catheter into the blood stream and direct inoculation from a biofilm containing pathogens.
What are the risk factors?
What are the most common organisms found?
Gram positive organisms are most often found, including staphylococcus (aureus and coagulase-negative), streptococcus, enterococcus. Gram negative organisms, such as klebsiella, e. coli, and pseudomonas comprise 20% of the line infections. Despite the use of maximal barrier precautions and a sterile technique, these line infections continue to occur. Although the tunneled cuff of these catheters helps reduce bacterial migration, the risk is still present.
What are the signs/symptoms?
The most sensitive signs are fevers and chills (especially if develops while on dialysis or immediately after a session) and should prompt evaluation for a TDC infection. If examination of the catheter exit site demonstrates erythema, induration, or tenderness, suspect catheter infection and plan for possible line removal.
What should be done if a catheter-related bacteremia is diagnosed?
Management options include catheter removal, guidewire exchange, or salvage, which depend on the severity of the infection and the etiology.
- The line should be removed (with placement of new catheter in a new site) if the patient is hemodynamically unstable, septic, has thrombophlebitis, endocarditis or sequelae of metastatic infection, or bacteremia despite 48-72 hours of appropriate antibiotics. In addition, if contamination is ruled out with blood cultures positive for either staphylococcus aureus, pseudomonas aeruginosa, any fungus, mycobacterium or if the organism is of low virulence (e.g. bacillus, micrococcus, propionibacterium) the line should be removed. For coagulase-negative staphylococcus, the line should be removed and antibiotics given if bacteremia persists after removal.
- Guidewire exchange should be performed if patients do not meet the above indications for line removal, if patients are afebrile after 48 hours of antibiotic therapy, clinically stable and without evidence of tunnel tract involvement. If line removal is recommended but cannot be done due to bleeding risk or lack of alternative access the guidewire exchange can be performed.
- Currently, there is no role for leaving the infected catheter in place without either replacing the catheter or antibiotic lock.
What is the role of antibiotic locks?
In cases where immediate catheter removal is not indicated, an antibiotic lock can be used in addition to systemic antibiotics. This lock aims to eradicate biofilms that develop inside of the catheter. Typically, a solution of either vancomycin, ceftazidime, or cefazolin is combined with heparin which is then instilled in the catheter and changed prior to each dialysis session. Typically, a guidewire exchange is recommended over lock solutions however; if there is resolution of fever and bacteremia, the cuffed catheter can be retained with continuation of antibiotic therapy (both systemic and lock) for 2-3 weeks. Unlike a few years ago, hemodialysis units are now allowing use of antibiotic locks, and they are reasonably priced.
What antibiotics should we prescribe and for how long?
Vancomycin is typically first-line empiric antibiotics, since most of these line infections are gram-positive in origin and high prevalence of methicillin resistant staph aureus. Based on the patient and their risk factors, additional gram-negative antimicrobial (i.e. gentamicin or ceftazidime) coverage should be started. It is crucial to de-escalate antibiotics as soon as possible based on culture data, as certain antibiotics can result in reducing residual kidney function (particularly aminoglycosides). Repeat blood cultures should be obtained 72 hours after starting treatment. Duration of therapy is typically 10-14 days but can extend to 4-6 weeks if persistent bacteremia post-catheter removal.
Where can I learn more?
Anita Shah, MD
Baylor College of Medicine