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In a randomized study of catheter colonization and catheter-related bacteremia rates in ICU patients, Maki and colleagues compared multi-lumen central catheters impregnated with chlorhexidene and silver sulfadiazine with non-treated catheters. They studied 403 catheters in 158 patients; catheters inserted in a pre-existing site over a guide wire were included. Treated catheters were less likely to be colonized at removal than control catheters (13.5% vs 24.1%; P = 0.005). More importantly, the rate of catheter-related bacteremia was reduced from 7.6/1000 catheter days to 1.6/1000 catheter days. The degree of reduction in infection was similar for newly inserted catheters and catheters placed over a guide wire. No antiseptic-resistant organisms were recovered from catheters or patients, and no adverse reactions occurred.
In a similar study, Raad and colleagues compared multi-lumen catheters treated with minocycline and rifampin with standard catheters. Approximately two-thirds of patients were in critical care units. This was also a large, randomized study with 298 catheters inserted into 281 patients. Twenty-six percent of control catheters were colonized on removal compared with 8% of treated catheters (P < 0.001). The rate of catheter-related bacteremia was 7.3/1000 catheter days for control catheters and 0/1000 patient days for treated catheters. No antibiotic resistant-organisms were isolated from patients.
Approximately 200,000 nosocomial primary bloodstream infections occur in the United States annually; the majority are due to central venous catheters. Although adherence to current Centers for Disease Control and Prevention (CDC) guidelines for catheter insertion and care1 can reduce the risk of infection, catheter related-bacteremia continues to be a major problem in large part because of the high-risk nature of the patient population requiring prolonged central venous access. Given the morbidity, mortality, and cost associated with nosocomial bacteremia, measures to further reduce the rate of catheter-related infection would be most welcome.
These two studies provide convincing evidence that catheters impregnated with antimicrobial substances can reduce the rate of catheter-related bacteremias in critically ill patients. Both studies share a number of significant strengths, including a randomized, double-blinded design, inclusion of large numbers of patients, meticulous culturing of catheters, and confirmation of the source of bacteremia by use of molecular epidemiologic techniques. In both, study and control patient populations were comparable and the difference in infection rates impressive. Both groups present cost-effectiveness analyses which indicate that, while treated catheters are significantly more expensive, their use would be associated with a net cost savings. Although these two studies are very encouraging, I believe that it may be premature to recommend routine use of central venous catheters coated with anti microbials. The populations studied were predominantly composed of critically ill patients, in whom the risk of catheter infection is particularly high. Patients with central catheters placed outside of critical care units have a lower risk of bacteremia approximately 2-3/1000 patient days if catheter care is provided by trained, dedicated personnel. Treated catheters have been used in a limited number of patients; the true rate of adverse events may not be apparent until they have been placed in a larger population of patients. The recent experience with Midline catheters provides a cautionary note: a significant rate of adverse systemic reactions was not recognized until the catheters were in widespread use.2 Finally, it is quite conceivable that antibiotic resistance will develop to the antimicrobials used to treat the catheters. For example, co-administration of rifampin and minocycline to patients colonized with methicillin-resistant Staphylococcus aureus led to isolation of strains resistant to these agents in a randomized trial of oral therapy.3
Still, this approach to preventing catheter-related bacteremia shows promise; studies to confirm the efficacy and safety of these catheters deserve high priority.
1. Department of Health and Human Services. Intravenous Device-Related Infections Prevention; Guideline Availability Notice. Federal Register, Sept. 27, 1995.
2. Mermel LA, et al. The risk of midline catheterization in hospitalized patients: A prospective study. Ann Intern Med 1995;123:841-844.
3. Muder RR, et al. A controlled trial of rifampin, minocycline, and rifampin plus minocycline for eradication of methicillin-resistant Staphylococcus aureus in long-term care patients. J Antimicrob Chemother 1994; 34:188-190.