New Technologies and Infection Control Practices to Prevent Intravascular Catheter-related Infections

CHRISTIAN BRUN-BUISSON

Service de Réanimation Médicale and Unité d'Hygiène et Prévention de l'Infection, Hôpital Henri Mondor and Université Paris ¹ 2, Créteil, France

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Although data suggest that the incidence of catheter-related infections is decreasing (1), these infections affect a large number of hospitalized patients because of increased use of intravascular devices. Catheter-associated bacteremia, the most serious consequence of catheter-related infections, is by far the leading cause of nosocomial bloodstream infection in intensive care units (ICUs) (2,3). Mermel has estimated that 80,000 such infections occur annually in ICUs, and that 200,000 cases have occurred throughout hospitals in the United States (4). Data from the National Nosocomial Infections Surveillance (NNIS) System show that the device-specific incidence of central venous catheter-related bacteremia varies in ICUs from 2.8 (in cardiothoracic ICUs) to 10 (in burn units) per 1,000 catheter-days, with a mean value of 5.3/1,000 catheter-days. Although the consequences of these infections in terms of mortality remain debated, with estimated varying from a low of 3% to a high of 25%, it is clear that they increase the duration of ICU stay and add a substantial burden to the cost of intensive care (4,5).

Major changes have been observed in the epidemiology of such infections, with coagulase-negative staphylococci taking the lead (up to 40% of all isolates form primary bloodstream infections) (2), and enterococci now being the second most common organisms, at least in medical ICUs (3). Many such nosocomial pathogens are multidrug resistant, thus further increasing the risk of therapeutic failure and poor outcome (6). In the United States, up to 50% of Staphylococcus aureus and > 80% of coagulase-negative staphylococcal isolates recovered from nosocomial bacteremia are resistant to oxacillin, and 25% of enterococci are now resistant to vancomycin.

Our understanding of the epidemiology and pathophysiology of catheter-associated infection has increased greatly during the past two decades. Dissemination of such knowledge and increased awareness of effective measures for prevention of catheter-related infections may account in part for the decreased device-specific incidence of infections reported in the past decade from hospitals contributing data to the National Nosocomial Infections Surveillance System (1). Catheter-related infection is at least theoreticallypreventable for the most part, provided strict adherence to infection control measures is observed. In 1996, the Hospital Infection Control Practices Advisory Committee (HICPAC) from the Centers for Disease Control (CDC) issued a guideline document (7). Building on knowledge accumulated since then, a revised version of this guideline is now available (8), which updates the recommendations on the basis of a number of more recent trials and meta-analyses of their results, and incorporates progress made via new technological advances.

What progress has been made in terms of prevention, and how and when can it be applied? The newer guideline (8) reflects more recent studies, which altogether suggest that the fewer unnecessary manipulations of the catheter and tubings, the better. For example, it is now accepted that dressings can be safely left in place for as long as 7 days and need not be changed unless there is evidence of local infection, or if the dressing is damp, soiled, loosened, or nonadherent; likewise, tubings need not be changed routinely more often than every 96 hours, peripherally inserted catheters can be left in place for as long as 96 hours, and routine scheduled replacement of well-functioning central venous catheters is not recommended. However, similarly to the previous version, the guideline took the conservative approach of recommending that pulmonary artery catheters and peripheral arterial catheters "need not be changed" more frequently than 5 days for the former and 4-5 days for the latter, because randomized trials assessing routine replacement strategies at longer intervals are still lacking (8). One major reason for allowing the same catheter to be kept in place for a longer time is the progress made in manufacturing intravascular devices: materials that are more resistant to adherence of colonizing bacteria are now used, as are heparin-bonded central venous catheters that reduce the risk of thrombus formation around the catheter lumen, and likely also the risk of infection.

Using catheters impregnated with antimicrobials (antiseptics or antibiotics) has emerged as a potentially valuable adjunct to prevention by other infection control measures. Several large trials have documented the preventive efficacy of antiseptic-coated catheters and a meta-analysis has confirmed that colonization and infection rates of catheters were reduced by about half, as compared with nonimpregnated catheters (9). Whereas both the former (1996) guideline (7) and the revised (2001) guideline (8) recommend that the use of antimicrobial or antiseptic-impregnated central venous catheters "should be considered if, after full adherence to other catheter infection control measures, there is still an unacceptably high rate of infection," the 2001 version provides a more precise framework for the use of such catheters by recommending that such catheters should also be used if patients are at high risk for catheter-related bacteremia (i.e., are receiving total parenteral nutrition, are immunosuppressed, or are in the ICU) and the catheter is expected to stay in place for > 4 days; however, no recommendation is made for the use of such catheters when the only risk factor for infection is a duration of catheterization of > 4 days. This conservative approach is due to the perceived risk of inducing resistance to antiseptics and/or antibiotics by impregnated catheters.

Although no bacterial resistance to antimicrobials impregnating or coating catheters has been documented during the clinical trials testing their preventive efficacy, there remains concern that widespread use of impregnated catheters may foster resistance to antimicrobial agents, whether antiseptics or antibiotics, among bacteria usually causing infection, that is, Staphylococcus epidermis, Staphylococcus aureus, or gram-negative bacilli. Topical antibiotics have been associated with emergence of resistance in the past and, although combinations are used in currently available catheters, there is little evidence to suggest that the occurrence of resistance would be avoided in the long term. In fact, the risk of development of resistance is theoretically higher in an environment where slime-encased bacteria adherent to plastic materials are partly protected from the action of antimicrobials and demonstrate lower susceptibility to these drugs (10). Therefore the recommendation that antimicrobial-impregnated catheters be used only when the infection rate remains high despite adequate infection control measures, and in selected high-risk groups of patients, appears to be sound, based on experience rather than on direct evidence from the literature. Only with more experience accumulating will it be possible to examine whether the reservations expressed in the guideline document were justified.

The guideline (8) therefore emphasizes infection control measures, based on observance of maximal barrier precautions during insertion of central venous lines, and aseptic manipulation of catheters during use. One of the more recent advances in this field is the availability of alcohol-based hand-rubbing solutions, now incorporated in the recommendation, which can be made easily available at the bedside at any time, and largely facilitate observance of hand hygiene (11) during catheter manipulation and in-use handling of lines (12). Prevention of catheter-related infection requires a multifaceted approach and attention to many details. More recent experience in targeting education of physicians in training (13) and quality improvement programs (12), together with a continuous surveillance program (1), suggests that infection rates can be reduced to a low level if attention of healthcare workers in ICUs is appropriately focused on this major problem.

	Footnotes

Correspondence and requests for reprints should be addressed to Christian Brun-Buisson, M.D., Service de Réanimation Médicale & Unité d'Hygiène et Prévention de l'Infection, Hôpital Henri Mondor & Université Paris, Créteil, France. E-mail: christian.brun-buisson{at}hmn.ap-hop-paris.fr

(Received in original form September 10, 2001 and accepted in revised form September 10, 2001).

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