Safety and efficacy of an improved antiseptic catheter impregnated intraluminally with chlorhexidine.

The safety and efficacy of a second-generation improved antiseptic catheter impregnated with silver sulfadiazine and increased levels of chlorhexidine on its outer surface and chlorhexidine alone on its luminal surfaces was compared in vitro and in vivo to standard antiseptic catheters impregnated with these antimicrobials on their outer surfaces only. In rat and pig intravenous models, the improved antiseptic catheter was significantly more effective in resisting both outer surface and luminal colonization compared with the standard antiseptic or control catheters. There was no evidence of tissue toxicity in any group.

In vitro and in vivo efficacy of catheters impregnated with antiseptics or antibiotics: evaluation of the risk of bacterial resistance to the antimicrobials in the catheters.

OBJECTIVE: To compare the efficacy of a new antiseptic catheter containing silver sulfadiazine and chlorhexidine on the external surface and chlorhexidine in the lumens to an antibiotic catheter impregnated with minocycline and rifampin on its external and luminal surfaces. DESIGN: Experimental trial. METHODS: Antimicrobial spectrum of catheters was determined by zones of inhibition. Resistance to luminal colonization was tested in vitro by locking catheter lumens with Staphylococcus epidermidis or Staphylococcus aureus culture after 7 days of perfusion. In vitro development of resistance to the antiseptic or antibiotic combination used in catheters was investigated. In vivo efficacy was tested (rat subcutaneous model) by challenge with sensitive or antibiotic-resistant bacteria. RESULTS: Antiseptic and antibiotic catheters exhibited broad-spectrum action. However, antibiotic catheters were not effective against Candida species and Pseudomonas aeruginosa. Both catheters prevented luminal colonization. Compared to controls, both test catheters resisted colonization when challenged with S aureus 7 and 14 days' postimplant (P<.05). Repeated in vitro exposure of S epidermidis culture to the antibiotic and antiseptic combinations led to small increases in the minimum inhibitory concentration (15 times and 2 times, respectively). Unlike the antibiotic catheter, the in vitro and in vivo activity of the antiseptic catheter was unaffected by the resistance profile of the test organism. Antiseptic catheters were more effective than antibiotic catheters in preventing colonization by rifampin-resistant S epidermidis in vivo (P<.05). CONCLUSIONS: Antiseptic and antibiotic catheters exhibit similar efficacy; however, when challenged with a rifampin-resistant strain, the antibiotic catheter appeared to be more susceptible to colonization than the antiseptic device.

Development of an infection-resistant LVAD driveline: a novel approach to the prevention of device-related infections.

BACKGROUND: Infection remains the single most important challenge to extended left ventricular assist device (LVAD) use and often arises from the percutaneous driveline exit site. We evaluated the ability of an LVAD driveline prototype impregnated with chlorhexidine, triclosan, and silver sulfadiazine to resist bacterial and fungal colonization. METHODS: The spectrum and duration of antimicrobial activity were evaluated in vitro by daily transfer of driveline segments embedded on agar plates inoculated with 10(8) colony-forming units (CFU) of Staphylococcus aureus (S. aureus), Staphlococcus epidermidis, Enterobacter aerogenes, Psuedomonas aeruginosa, and Candida albicans, and then measuring zones of inhibition around the sample subsequent to 24 hours of incubation at 37 degrees C. Antimicrobial activity was demonstrated against all organisms for greater than 14 days, and for over 21 days for gram-positive bacteria. To demonstrate in vivo efficacy of the treated driveline, 3-cm segments of driveline were implanted in the dorsal and ventral surface of rats. The exit site was inoculated with 10(6) CFU of S. aureus. After 7 days, driveline segments were aseptically explanted and assayed for bacterial colonization and retention of antimicrobial activity. One hundred percent of control segments were colonized (10(5) CFU S. aureus/cm) as against 13% of the test explants (< or = 330 CFU/cm; p < 0.0001). RESULTS: Subcultures of the insertion site and driveline pocket tissue resulted in 10(3) to 10(5) CFU per swab culture for control rats and 0 to 10(2) CFU/swab for test animals. Test drivelines retained 80% of anti-S. aureus activity. Gross and histological examination of the driveline and surrounding pocket revealed minimal tissue reactivity with positive signs of tissue ingrowth. CONCLUSION: An antimicrobial driveline may prevent early infections and facilitate ingrowth of tissue to provide long-term stability and protection against late infection.

Infection resistance of surface modified catheters with either short-lived or prolonged activity.

It has been suggested that the invasion of microbes into the catheter tract occurs mainly at the time of catheter insertion. To investigate whether the presence of an antimicrobial environment during the initial period after insertion is sufficient to reduce the risk of subsequent catheter colonization and infection, we evaluated the use of benzalkonium chloride-heparin bonded (BZK-hep) central venous catheters, which exhibit short-lived surface antimicrobial activity, using a rat subcutaneous model. Bacterial adherence on these catheters was determined, seven days after challenging the insertion site with 10(6) cfu of Staphylococcus aureus. A chlorhexidine-silver sulphadiazine impregnated catheter (Arrowg+ard), with longer lasting surface antimicrobial activity, and a hydrophilic coated catheter ('Hydrocath'), were evaluated simultaneously for comparison. Unlike Arrowg+ard antiseptic catheters, BZK-hep 'Hydrocath' and control catheters had significant bacterial adherence on their surface. Arrowg+ard catheters were colonized in 19% of the animals compared with 100% in all the other groups (P < 0.05; mean cfu cm-2: control = 1.3 x 10(6), BZK-hep = 4.3 x 10(5), Hydrocath = 2 x 10(5), Arrowg+ard = 71). Our results indicate that catheters with short-lived surface antimicrobial activity are unlikely to provide long-term protection against catheter-related infection. The efficacy of Arrowg+ard catheters may be due to the initial high rate of kill and prolonged antimicrobial activity.