MRSA rampant among patients on dialysis

MRSA rampant among patients on dialysis

Emerging vancomycin resistance also linked

The rate of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection in dialysis patients is higher than for any other known patient population and is 100 times higher than for the general population, the Centers for Disease Control and Prevention reports.¹

In 2005, the incidence of invasive MRSA infection among dialysis patients was 45.2 cases per 1,000 population. People receiving dialysis are at high risk for infection with invasive MRSA compared with the general population, in which rates of invasive MRSA have ranged from 0.2 to 0.4 infections per 1,000 population. The findings "underscore the need for continued surveillance and infection-control strategies aimed at reducing infection rates and preventing additional antimicrobial resistance among persons receiving dialysis," the CDC emphasized. The CDC report refers ICPs to 2001 infection control guidelines for dialysis, which emphasize that standard precautions – as opposed to more rigorous contact isolation measures — are generally adequate for dialysis settings. However, the emerging data on MRSA raise the question of whether lack of compliance with infection control measures is a part of the problem. In a nutshell, could dialysis settings be amplifying the problem?

"We know that adherence to infection control guidelines is a challenge in many settings," says Cynthia A. Lucero, MD, an epidemic intelligence service officer in the CDC's division of healthcare quality promotion. "This [dialysis] study did not attempt to assess adherence to infection control guidelines by physicians or dialysis center personnel or the effect of treatment in a dialysis center setting on the risk of infection. I am not aware of any U.S. study that has specifically done that. Hopefully, this report will serve to inform or remind individuals providing care to dialysis patients that recommendations for preventing transmission of infections and antimicrobial resistance among dialysis patients have been published by CDC and are available for reference. Care providers may wish to review these recommendations to make sure that risks of infection are minimized where possible."

The number of dialysis patients continues to increase. The dialysis population reached 335,963 at the end of 2004, triple the number from 1988 and up 16% since 2000, the CDC reports. Repeated hospitalizations and surgeries along with administration of prolonged courses of antimicrobial agents increase exposure to potential pathogens and create opportunities for antimicrobial resistance in the dialysis population.

Hemodialysis patients are especially vulnerable to vascular-access infections because they require vascular access for prolonged periods and undergo frequent puncture of their vascular-access site, the CDC noted. The primary risk factor for bacterial infections among dialysis patients is vascular-access type. Risk is highest for catheters, intermediate for grafts, and lowest for native arteriovenous fistulas. Despite higher rates of bacteremia among patients with catheters, the percentage of U.S. dialysis patients with an indwelling hemodialysis catheter is increasing. The most basic strategy to prevent catheter-related bacteremias, including invasive MRSA infections among hemodialysis patients, is minimizing the use of catheters for long-term vascular access, the CDC emphasizes.

"Where possible, alternate means of vascular access for hemodialysis treatment should be considered," Lucero says. "Arteriovenous fistulas and grafts have lower risk of infection than catheters but may not be appropriate for all patients. When catheters are necessary, health care workers should be sure to maintain good hand hygiene and infection control practices, including proper needle insertion technique."

Should dialysis patients be screened?

The high rate of MRSA in dialysis patients also raises the question of whether they should be targeted in active surveillance screening efforts when admitted to hospitals. "Screening of dialysis patients should be considered only in selected circumstances after other measures have proved ineffective in significantly reducing transmission," she says, citing the most recent guidelines on the issue by the CDC's Healthcare Infection Control Practices Advisory Committee (HICPAC).²

"All facilities should become familiar with and utilize the strategies outlined in that document," she says. "The most general, or first-tier, approach to reducing these infections includes administrative engagement, education and training of health care personnel, judicious use of antimicrobial agents, standard precautions for all patients, contact precautions for patients known to be infected or colonized [with MRSA], environmental measures and surveillance to determine whether additional interventions are needed. If infection rates at a facility do not decline after these interventions, the facility should consider adding components of the second-tier, or intensified intervention strategies, which may include active surveillance cultures."

Since MRSA infections are often treated with vancomycin, the explosion of the pathogen within the dialysis population raises concerns about rising antibiotic resistance. Most of the reported cases of patients with either vancomycin-intermediate S. aureus (VISA) or vancomycin-resistant S. aureus (VRSA) have been hemodialysis patients. In addition, a VISA case was recently reported involving a community-acquired strain of USA 300. Again, the patient had a history of dialysis.

"The dialysis population is growing and emergence of vancomycin resistance is an important concern for this population," Lucero says. "Infections occurring in these patients are frequently treated with vancomycin. Physicians should use all available information, when treating infections in dialysis patients. If susceptibility testing results are available, the physician may be able to consider other antibiotic choices."

(Editor's note: The HICPAC guidelines on multidrug-resistant organisms are available at www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf.)

Reference

1. Centers for Disease Control and Prevention. Invasive Methicillin-Resistant Staphylococcus aureus Infections Among Dialysis Patients — United States, 2005. MMWR 2007; 56(09): 197-199.