Intravascular-catheter-related infections

Solvent-Free Fabrication of Self-Regenerating Antibacterial Surfaces Resisting Biofilm Formation

Biofilm formation on indwelling medical devices is a major cause of hospital-acquired infections. Monofunctional antibacterial surfaces have been developed to resist the formation of biofilms by killing bacteria on contact, but the adsorption of killed bacterial cells and debris gradually undermines the function of these surfaces. Here, we report a facile approach to produce an antibacterial surface that can regenerate its function after contamination. The self-regenerating surface was achieved by sequential deposition of alternating antibacterial and biodegradable layers of coating using a solvent-free initiated chemical vapor deposition method. As the top antibacterial layer gradually loses its killing ability due to the accumulation of debris, the underlying biodegradable layer degrades, shedding off the top surface layers and exposing another fresh antibacterial surface. Urinary catheters coated with monofunctional and self-regenerating antibacterial coatings both showed more than 99% bacterial killing ability at the initial antibacterial test, but the monofunctional surface lost its killing ability after continued exposure to concentrated bacterial solution, whereas the self-regenerating surfaces regained strong bacterial killing ability after prolonged exposure. Employing poly(methacrylic anhydride) and its copolymers with varied composition as the degrading layer, the degradation kinetics can be well-tailored and the self-regeneration duration spanned from minutes to days. The designed self-regenerating antibacterial surfaces could provide an effective approach to resist biofilm formation and extend the service life of indwelling medical devices.

Saving Infected Catheters: Why and How

Conventional management of dialysis catheter-related bacteremia involves administration of systemic antibiotics, as well as removal of the infected catheter. This approach adds burdensome and expensive procedures, and creates short-term problems for dialysis access. Recent research has shown that bacterial biofilms form routinely in the catheter lumen, and act as the nidus for bacteremic episodes. Instillation of a concentrated antibiotic-anticoagulant solution into the catheter lumen ('antibiotic lock') may permit successful treatment of the infection, while salvaging the patient's catheter. A number of recent studies have reported the success of an antibiotic lock protocol in about two thirds of cases of catheter-related bacteremia. Catheter replacement is only performed in those patients with protocol failures (persistent fever or positive surveillance blood cultures). In conclusion, routine application of an antibiotic lock protocol may reduce substantially the need for routine catheter replacement in hemodialysis patients with catheter-related bacteremia.

Treatment of dialysis catheter-related Staphylococcus aureus bacteremia with an antibiotic lock: a quality improvement report

BACKGROUND

Dialysis catheter-related bacteremia is often treated successfully by instilling an antibiotic-heparin solution into the catheter lumen (an antibiotic lock) in conjunction with systemic antibiotic therapy without removal of the catheter. The efficacy of this therapy is uncertain in Staphylococcus aureus bacteremia.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

113 catheter-dependent hemodialysis outpatients with S aureus catheter-related bacteremia treated with a standardized antibiotic lock protocol. Data for all patients with catheter-related bacteremia are recorded in a prospective database.

QUALITY IMPROVEMENT PLAN

In conjunction with systemic antibiotic therapy (vancomycin for methicillin-resistant S aureus or cefazolin for methicillin-sensitive S aureus), an antibiotic lock was instilled into each catheter lumen after each dialysis session for 3 weeks.

MEASURES

Treatment failure is defined as persistent fever after 48 hours of antibiotic therapy or recurrent S aureus bacteremia within 90 days. Clinical cure is defined as resolution of fever and no recurrence of bacteremia. Major infection-related complications within 6 months were documented.

RESULTS

The catheter could not be salvaged in 67 patients (59%) because of persistent fever in 40 patients and recurrent bacteremia in 27 patients. A clinical cure was achieved in 46 patients (41%). A serious complication of catheter-related bacteremia occurred in 9.7% of all patients (11 of 113 patients). Serious complications were observed in 25% of patients (10 of 40 patients) with persistent fever, but only 1.4% of all other patients (1 of 73 patients; P < 0.0001).

LIMITATIONS

This was a single-center study. Serum antibiotic levels were not measured.

CONCLUSIONS

Routine antibiotic lock therapy is not appropriate for patients with S aureus catheter-related bacteremia. Serious complications occur primarily in patients with persistent fever.

Treatment of catheter-related bacteraemia with an antibiotic lock protocol: effect of bacterial pathogen

BACKGROUND

The standard therapy of dialysis catheter-related bacteraemia involves both systemic antibiotics and catheter replacement. We reported recently that instillation of an antibiotic lock (highly concentrated antibiotic solution) into the catheter lumen after dialysis sessions, in conjunction with systemic antibiotics, can successfully treat many episodes of catheter-related bacteraemia without requiring catheter removal. The present study evaluated whether the likelihood of achieving a cure with this protocol depends on the type of pathogen.

METHODS

This was a historically controlled interventional study of an antibiotic lock protocol for the treatment of catheter-related bacteraemia. We analysed prospectively the likelihood of clinical cure (fever resolution and negative surveillance cultures) with an antibiotic lock protocol among patients with dialysis catheter-related bacteraemia. In addition, infection-free catheter survival was evaluated for up to 150 days, and compared with that observed among patients managed with routine catheter replacement.

RESULTS

Overall, the antibiotic lock protocol was successful in 33 of 47 infected patients (70%) with catheter-related bacteraemia. The likelihood of a clinical cure was 87% for Gram-negative infections, 75% for Staphylococcus epidermidis infections, and only 40% for Staphylococcus aureus infections (P = 0.04). The median infection-free catheter survival with the antibiotic lock protocol was longer than that observed among patients with routine catheter replacement (154 vs 71 days, P = 0.02).

CONCLUSIONS

The clinical success of an antibiotic lock protocol in eradicating catheter-related bacteraemia while salvaging the catheter is highly dependent on the bacterial pathogen. Thus, the overall success rate in an individual dialysis programme will depend on the relative frequencies of different bacterial pathogens.

Management of hemodialysis catheter-related bacteremia with an adjunctive antibiotic lock solution

BACKGROUND

Tunneled dialysis catheters are complicated by frequent systemic infections. Standard therapy of catheter-associated bacteremia involves both systemic antibiotics and catheter replacement. Recent data suggest that biofilms in the catheter lumen are responsible for the bacteremia, and that instillation of an antibiotic lock (highly concentrated antibiotic solution) into the catheter lumen after dialysis sessions can eradicate the biofilm.

METHODS

We analyzed prospectively the efficacy of an antibiotic lock protocol, in conjunction with systemic antibiotics, for treatment of patients with dialysis catheter-associated bacteremia without catheter removal. Protocol success was defined as resolution of fever and negative surveillance cultures one week following completion of the protocol. Protocol failure was defined as persistence of fever or surveillance cultures positive for any pathogen. In addition, infection-free catheter survival was compared to that observed in institutional historical control patients treated with catheter replacement.

RESULTS

Blood cultures were positive in 98 of 129 of episodes (76%) in which patients dialyzing with a catheter had fever or chills. Protocol success occurred in 40 of 79 infected patients (51%) treated with the antibiotic lock. Protocol failure occurred in 39 cases (49%): 7 had persistent fever, 15 had positive surveillance cultures (9 for Candida and 6 for bacteria), and 17 required catheter removal due to malfunction. Each of the pathogens in the surveillance cultures was different from the original pathogen in that patient. Eight of the 9 secondary Candida infections and all 6 secondary bacterial infections resolved after catheter exchange and specific antimicrobial treatment. Overall catheter survival with the antibiotic lock protocol was similar to that observed among patients managed with catheter replacement (median survival, 64 vs. 54 days, P = 0.24).

CONCLUSIONS

Use of an antibiotic lock, in conjunction with systemic antibiotic therapy, can eradicate catheter-associated bacteremia while salvaging the catheter in about one half of cases. Moreover, this management approach offers clinical advantages over routine catheter exchange.