Treatment of haemodialysis catheter-related infections

Anand Vardhan, Jon Davies, Indiver Daryanani, Alex Crowe and Peter McClelland

Department of Nephrology, Royal Liverpool University Hospital and Arrowe Park Hospital, Wirral UK

Sir,

We read with interest the editorial by Peter Blankestijn [1] in the October 2001 issue of Nephrology Dialysis Transplantation on the ‘Treatment and prevention of catheter-related infections in haemodialysis patients’. In our unit, tunnelled dialysis catheters serve as the vascular access for 23 patients (21% of the dialysis population). Nine of these have arterio-venous fistulae awaiting maturation, and for the remaining 14 (13%), dialysis catheters provide the sole means of access.

Sepsis has been the main limiting factor in the use of tunnelled dialysis catheters in our unit, resulting in the loss of 56% of the lines during the year 2000. Episodes of sepsis were treated with high doses of broad-spectrum i.v. antibiotics. Catheters were removed early, upon failure of clinical improvement or on advice from microbiologists.

Following reports of the utility of antibiotic-heparin line locks [24] we formulated a protocol involving the use of such locks in addition to i.v. antibiotics with a view to disinfecting and salvaging the dialysis catheters. Patients who had tunnelled lines and signs of sepsis had blood cultures taken from both lumens of the catheter, and from a peripheral vein. They received a bolus of i.v. vancomycin (1000 mg) and gentamicin (3 mg/kg). The dialysis lines were then ‘locked’ with a solution containing 100 µg/ml of vancomycin, 20 µ/ml of gentamicin and 5000 IU/ml of heparin until the patient returned for the next dialysis session, 48–72 h later. Stability of this antibiotic-heparin solution was verified in vitro by the quality control unit at our hospital pharmacy. The choice of antibiotics was based on the organisms involved in line sepsis at our centre over the last year. Vancomycin and gentamicin provided cover against most organisms cultured from dialysis lines. The concentration of antibiotic solution to use was less straightforward; it had to be concentrated enough to achieve minimum inhibitory concentration and yet not precipitate inside the line in the acidic pH of heparin [5].

Once the blood culture results were available, systemic antibiotics were modified accordingly. Antibiotic line-locks were replaced at the end of each dialysis session, and the previous solution aspirated and discarded. This was continued for a period of 2 weeks. If patients remained symptomatic beyond 72 h of initiation of therapy, the line was removed. Patients who recovered, and completed their 2-week course of systemic antibiotics and antibiotic locks, had a follow-up blood culture taken from the lines 1 week after the end of treatment. If these were negative the strategy was deemed successful in eradicating the infection.

Over the past 6 months we have treated 32 episodes of suspected dialysis catheter-related sepsis. In six of these patients, blood cultures were sterile and the patients remained well. Sepsis was therefore excluded and the antibiotics were stopped. Twenty-six patients had positive blood cultures confirming sepsis. Treatment was successful in 16 patients (62%) i.e. the patients recovered clinically, their dialysis catheters did not require removal and blood cultures from the catheters 1 week after the end of treatment were sterile. The organisms causing infections that were successfully cleared were as follows: four methicillin-sensitive Staphylococcus aureus (25%); two methicillin-resistant S. aureus (12%); six coagulase-negative staphylococci (39%); one pseudomonas (6%); one Escherichia coli (6%); and two mixed organism infections (12%). Treatment failed to salvage nine dialysis catheters (35%). However, five of these patients remained well during the course of the treatment but had positive blood cultures 1 week after the end of antibiotic therapy. Interestingly, they cultured organisms other than the ones identified at the beginning of therapy. Four patients continued to be clinically unwell and cultured the same organism during the course of treatment. The dialysis line was removed in all nine of these cases. Organisms cultured in this group were two methicillin-sensitive S. aureus (22%), three methicillin-resistant S. aureus (34%), two coagulase-negative staphylococci (22%) and two mixed organisms (22%). Of the initial 26 patients, one (3%) continued to have positive blood cultures for coagulase-negative staphylococci at the end of the treatment but remained clinically well throughout. The dialysis line in this case was not removed.

Osteomyelitis and infective endocarditis with septic embolization are serious complications of dialysis catheter-associated sepsis, occurring when catheter removal has been delayed. We have not encountered these in our patients so far and continue to keep a close eye on patients on the protocol. The protocol itself has shown promise since we have been able to salvage almost two thirds of the lines, although we will need to treat many more patients before we can come to any firm conclusions. Previously, most of these lines would have had to be removed and replaced. It has been reassuring to find that S. aureus, both methicillin-sensitive and -resistant strains, can be eradicated by the use of antibiotic locks in conjunction with systemic antibiotics. There has been a dichotomy between clinical and bacteriological cures. Some patients who had achieved a clinical cure still had positive blood cultures in samples taken from the dialysis catheter at the end of treatment. While it is well-documented in the literature that catheters get colonized following their insertion [2,6] it is unclear as to whether these merit removal on the basis of positive cultures of samples taken from the line when the patient is clinically well. The dose of antibiotic used in the locks remains open to debate [7].

We agree with the author that removal of a tunnelled dialysis catheter is not mandatory in all patients with documented sepsis. The use of antibiotic-heparin locks in conjunction with systemic antibiotics appears to be effective and safe. However, more studies are required to confirm this observation.

Notes

Email: anand.vardhan{at}rlbuhutr.nwest.nhs.uk Back

References

  1. Blankestijn PJ. Treatment and prevention of catheter-related infections in haemodialysis patients. Nephrol Dial Transplant2001; 16: 1975–1978[Free Full Text]
  2. Dittmer ID, Sharp D, McNulty CAM, Williams AJ, Banks RA. A prospective study of central venous haemodialysis catheter colonization and peripheral bacteraemia. Clin Nephrol1999; 51: 34–39[ISI][Medline]
  3. Sodemann Klaus, Polaschegg Hans-D, Feldmer B. Two years' experience with Dialock and CLS (a new antimicrobial lock solution). Blood Purif2001; 19: 251–254[ISI][Medline]
  4. Boorgu R, Dubrow AJ, Levin NW et al. Adjunctive antibiotic/anticoagulant lock therapy in the treatment of bacteraemia associated with the use of a subcutaneously implanted haemodialysis access device. ASAIO J2000; 46: 767–770[ISI][Medline]
  5. Vercaigne LM, Sitar DS, Penner SB, Bernstein K, Wang GQ, Burczynski FJ. Antibiotic-heparin lock: in vitro antibiotic stability combined with heparin in a central venous catheter. Pharmacotherapy2000; 20: 394–399[ISI][Medline]
  6. Mermel LA, Farr BA, Sherertz RJ et al. Guidelines for the management of intravascular catheter-related infections. Clin Infect Dis2001; 32: 1249–1272[Medline]
  7. Berrington A, Gould FK. Use of antibiotic locks to treat colonized central venous catheters. J Antimicrob Chemother2001; 48: 597–603[Abstract/Free Full Text]




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