The toll that catheter-related bloodstream infections (CRBSIs) exact on human life and the costs they add to healthcare are significant. Attributable mortality from CRBSIs is an estimated 12 percent to 25 percent for each infection, and the marginal cost to the healthcare system is approximately $25,000 per episode.1
A new study2 from Centers for Disease Control and Prevention (CDC) researchers is showing that for the first time in recent years, the number of bloodstream infections with methicillin-resistant Staphylococcus aureus (MRSA) associated with the use of a central line catheter has decreased by nearly half from 1997 to 2007.
To provide more data on the incidence of MRSA CRBSIs in U.S. intensive care units (ICUs), Deron C. Burton, MD, JD, MPH, of the CDC, and colleagues analyzed national healthcare-associated infection (HAI) surveillance data reported by hospitals to the CDC. These data, from 1997 to 2007, were used to calculate annual CRBSI incidence rates for seven types of adult and pediatric ICUs. From 1997 through 2007, 1,684 ICUs reported 33,587 CRBSIs, of which 2,498 (7.4 percent) were MRSA and 1,590 (4.7 percent) were methicillin-susceptible Staphylococcus aureus (MSSA). The researchers found that although the overall percentage of S aureus CRBSIs due to MRSA increased 25.8 percent from 1997 through 2007, the overall incidence rate of MRSA CRBSIs declined 49.6 percent from 1997 through 2007. This overall decline occurred despite an initial increase in infection rate from 1997 through 2001, after which the rate steadily declined through 2007.
From 2001 through 2007, MRSA CRBSI incidence declined significantly in all six adult ICU types and was stable in pediatric ICUs. Changes in MRSA CRBSI incidence ranged from -51.5 percent in medical-surgical ICUs without a major teaching affiliation to -69.2 percent in surgical ICUs. In every ICU type, MSSA central line-associated BSI incidence declined continuously and significantly from 1997 through 2007, with estimated incidence changes ranging from -60.1 percent in surgical ICUs to -77.7 percent in medical ICUs.
The authors suggest that these decreases in incidence may be attributable to efforts by healthcare facilities to improve adherence to CDC’s evidence-based prevention guidelines, the implementation of strategies designed to improve central line insertion and care practices, and increasing success in preventing MRSA transmission between patients by healthcare facilities.
“MRSA CRBSI incidence has declined in recent years in all major adult ICU types and has remained stable in pediatric ICUs,” the authors write. “The overall decline in incidence stands in sharp contrast to trends in percent MRSA, which give an incomplete picture of changes in the magnitude of the MRSA problem over time and may have led to a misperception that the MRSA CRBSI problem in ICUs has been increasing.” The researchers add that large declines in incidence across all types of CRBSIs, which included regular staph and drug-resistant staph, in all major non-neonatal ICU types also suggest that general CRBSI prevention efforts are succeeding and may have contributed to the declining MRSA trends.
“Further study is needed to assess MRSA infection incidence in other patient populations and patient care areas and to determine the effect of specific prevention measures and of participation in national HAI surveillance on the observed trends,” the researchers write.
“Despite the fact that MRSA prevalence continues to rise, efforts to prevent catheter infections are paying dividends, and the number of infections due to all types of Staphylococcus aureus, including MRSA, have been falling sharply since 2001,” says Mark E. Rupp, MD, president of the Society for Healthcare Epidemiology of America (SHEA).
Rupp says the drop in infection rates can be attributed to hospitals that are instituting and adhering to general practices that result in fewer infections, including measures to ensure proper catheter insertion and removal, hand hygiene, environmental cleanliness and antimicrobial stewardship.
Prevention strategies are upheld by proper resourcing of infection prevention programs, emphasizes Kathy Warye, CEO of the Association for Professionals in Infection Control and Epidemiology (APIC). “For reductions in HAIs to be sustained, adequate resources for the infection prevention profession must be deployed. Despite the current economic stress, now is not the time to ease up on efforts to prevent infections. APIC’s 2008 MRSA Pace of Progress report revealed that while three-quarters of hospitals have increased efforts to control the spread of MRSA, more than half say they could and should be doing more. Prevention of HAIs requires consistent application of proven measures throughout the healthcare system and the commitment and active engagement of hospital leadership so that infection prevention becomes a part of everyone’s job.”
Warye adds, “More research is also needed to determine if approaches that are successful in the ICU can be replicated elsewhere in the hospital where the majority of MRSA resides. Hospitals that are successful in reducing HAIs are using a multi-faceted approach, employing a group of interventions to address MRSA and other dangerous pathogens. Staff education, more aggressive hand hygiene programs, stricter use of contact precautions (e.g., gloves and gowns), more emphasis on environmental cleaning and targeted screening are examples.”
Issam I. Raad, MD, professor and chairman of infectious diseases at the University of Texas M.D. Anderson Cancer Center, says that basic infection prevention practices, such as hand hygiene and maximum barrier protection, can decrease the risk and rate of CRBSI, but they cannot completely prevent them. “The growing experience is that infections will continue to occur despite the full implementation of such measures simply because central venous catheters (CVCs) create an open wound through the skin and connect the skin contaminated environment to the sterile bloodstream. Furthermore, these measures prevent contamination of the catheter at the time of insertion, but cannot prevent subsequent contamination/colonization during the dwell time.”
The pathogenesis of CRBSIs is described as such: “Migration of skin organisms at the insertion site into the cutaneous catheter tract with colonization of the catheter tip is the most common route of infection for peripherally inserted, short-term catheters. Contamination of the catheter hub contributes substantially to intraluminal colonization of long-term catheters.”1
The incidence of CRBSI can vary by type of catheter, frequency of catheter manipulation, and patient-related factors such as underlying disease and acuity of illness, so it is critical that clinicians understand the ramifications of these factors. Important pathogenic determinants of catheter-related infection are the material of which the device is made and the intrinsic virulence factors of the infecting organism. For example, studies have shown that catheters made of polyvinyl chloride or polyethylene are likely less resistant to the adherence of microorganisms than are catheters made of Teflon®, silicone elastomer or polyurethane. The adherence properties of pathogenic microorganisms also are significant in the pathogenesis of catheter-related infection; Staphylococcus aureus can adhere to host proteins on catheters.
“Understanding the risk factors and the pathogenesis of these infections is essential for the application of the appropriate and the most successful interventions,” Raad says. “There are many proposed interventions that deal with one aspect or one risk, but ignore the others. A comprehensive understanding of all risk factors is of utmost importance.”
Aside from the aforementioned evidence-based prevention strategies, CRBSI rates can be decreased with the use of antimicrobial-impregnated catheters.
“Our research team, as well as other independent investigators, have conducted a large number of prospective, randomized trials demonstrating the high efficacy of antimicrobial catheters and their cost effectiveness in preventing CRBSI,” says Raad. “Dr. Dennis Maki has referred to this technology as the ‘most intensively studied technology for the prevention of CRBSI for the past 30 years ... with significant benefit.”3
Raad continues, “In one of the largest reviews on the subject by Ramritu, et al., CVCs impregnated with minocycline and rifampin as well as those impregnated with chlorhexidine/silver sulfadiazine, were highly efficacious in preventing CRBSI, with a demonstrated superiority of the former. According to independent investigators, antimicrobial CVC could serve as a safety net to prevent breakthrough CRBSI that could occur after the implementation of infection control bundle. Evidence-based data strongly suggest that antimicrobial CVCs are complementary to infection control bundles and only upon the use of the two interventions together can one achieve consistently an average rate of CRBSI that is lower than 1 per 1,000 catheter days and move closer to the desired zero tolerance level.”
In February at the Society of Critical Care Medicine’s annual meeting, Raad presented data from a study of more than 100 cancer patients who had developed CRBSIs. The results demonstrated that exchanging an infected CVC for a CVC impregnated with minocycline and rifampin was significantly more effective at resolving the potentially fatal symptoms associated with CRBSIs, including acute fever and bacteremia, within 72 hours of insertion.
In the study, 40 patients had infected CVCs that were exchanged for CVCs impregnated with minocycline and rifampin, and 80 patients had the infected CVCs removed. Ninety-five percent of patients receiving the antimicrobial-impregnated CVCs reported eradication of bacteremia within 72 hours, with no cases of relapse or infection-related deaths. Comparatively, 88 percent of participants in the CVC removal group exhibited no clinical signs of bacteremia within 72 hours. There were six cases of relapse or infection-related deaths during the hospital stay in the CVC removal group.
“These findings suggest that there is a more effective way to manage CRBSIs in cancer patients than current guidelines, which recommend the removal of the infected CVC or replacing it with another CVC inserted at a new access site,” Raad says. “Although removing a CVC that has led to a CRBSI can help manage the infection, this is not always practical for cancer patients because there is additional cost and risk to the patient associated with replacement of the catheter at a new access site. Exchanging a CVC for an minocycline and rifampin-impregnated CVC not only reduces cost and risk associated with a new access site, but demonstrates superior clinical outcomes for this high-risk group of patients.”
Centers for Disease Control and Prevention. Guidelines for the Prevention of Intravascular Catheter-Related Infections. MMWR. 2002;51(No.RR-10).
Burton DC. Methicillin-Resistant Staphylococcus aureus central line-associated bloodstream infections in U.S. intensive care units, 1997. JAMA. 2009;301(7):727-736.
Crnich, et al. Clin Infect Dis 38;1287, 2004.