A tale of two catheters

Study compares antimicrobial-impregnated CVCs

A study recently published in The New England Journal of Medicine shows a dramatic benefit of using central venous catheters (CVCs) impregnated with the antimicrobials minocycline and rifampin over CVCs impregnated with chlorhexidine and silver sulfadiazine.1

The study, conducted at 12 university-affiliated hospitals in the United States, evaluated 865 catheters, with 738 (85%) producing evaluable culture results.

It found the catheters impregnated with minocycline and rifampin (Cook Spectrum catheter) were one-third as likely to be colonized as catheters impregnated with chlorhexidine and silver sulfadiazine (the Arrow Gardblue catheter).

Just 28 of 356 catheters (7.9%) of the minocycline and rifampin impregnated catheters had been colonized, compared to 87 of 382 (22.8%) of catheters impregnated with chlorhexidine and silver sulfadiazine. Also, catheter-bloodstream infection was one-half as likely in catheters impregnated with minocycline and rifampin 1 of 356 [0.3%], compared those impregnated with chlorhexidine and silver sulfadiazine 13 of 382 [3.4%].

Rabih Darouiche, MD, associate professor of medicine, physical medicine, and rehabilitation at Baylor College of Medicine and the Veterans Administration Medical Center, and the lead researcher in the study, says the results are dramatic but not surprising.

"In vitro and animal studies have shown the superiority of one catheter vs. another," Darouiche told Home Infusion Therapy Management. "Not only that, but on a theoretical basis it was expected for three main reasons."

1. The minocycline and rifampin-coated catheter had antimicrobial activity on both the external and internal surfaces of the catheter. However, only the external surface of the catheter coated with chlorhexidine and silver sulfadiazine was treated with the antimicrobial agents.

2. The combination of minocycline and rifampin have shown in previous studies to be much more powerful against potential pathogens that cause catheter-related infection when compared to chlorhexidine and silver sulfadiazine.

3. "Although we did not mention it in the article, we think that the durability of antimicrobial protection is longer in the minocycline and rifampin vs. the chlorhexidine and silver sulfadiazine," says Darouiche.

The study focused on at-risk patients, such as ICU patients, patients with underlying malignancy or immunocompromised patients. CVCs were expected to remain in place for at least three days, and catheters inserted were polyurethane, triple-lumen catheters impregnated with one of the two coatings under investigation. Once the catheters were removed, the tips as well as subcutaneous segments of the catheters were cultured by the roll-plate method and the sonication methods.

Darouiche says more studies are necessary before further expectations of either catheter can be deduced.

"The same considerations would probably apply to TPN [total parenteral nutrition] because those patients are considered high risk. I don’t know if you use low-risk patients — particularly if you leave the catheters in for a short duration — you would have similar results," he says. "Only studies can show that."

Darouiche notes he and his colleagues may undertake a study in the future as to the long-term use of such catheters.

While antimicrobial-treated catheters are typically more expensive than their non-treated counterparts, Darouiche says they are worth the investment. And in the instance of this study, the minocycline and rifampin-coated catheters are clearly worth the additional $9 per tray set than their chlorhexidine and silver sulfadiazine treated counterparts.

Darouiche notes the minocycline and rifampin-coated catheters cost $70 for a tray, while the chlorhexidine and silver sulfadiazine treated catheters cost $61.

"If you have 100 patients, you will pay $9 times 100 extra to obtain one form of catheter than the other," he says. "Of these 100 patients, the rate of catheter-related bloodstream infection goes down from 3.4% to .3%, so you decrease the number of patients with catheter-related infection by three among each 100 patients who receive it. So you spend $900 more, but you save three times $29,000, or about $87,000 per 100 patients."2

References

1. Darouiche R, Raad I, Heard S, et al. A comparison of two antimicrobial-impregnated central venous catheters. N Engl J Med 1999; 340:1-8.

2. Pittet, et al. Nosocomial bloodstream infection in critically ill patients: Excess length of stay, extra costs, and attributable mortality. JAMA 1994; 271:1,598-1,601.