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.