CDC urges routine HCV testing in hemodialysis

New guidance also emphasizes bacterial threat

Routine screening for hepatitis C virus (HCV) and a new emphasis on preventing bacterial infections are the key changes in revised guidelines for infection control in hemodialysis patients by the Centers for Disease Control and Prevention.

"Probably the single biggest change is the recommendation for testing [patients] for hepatitis C every six months," says Jerome I. Tokars, MD, MPH, a medical epidemiologist in the CDC division of healthcare quality promotion. "That was previously not recommended."

The CDC now recommends routine HCV screening for all chronic hemodialysis patients on admission and semiannually. Clinicians should promptly review results and ensure that patients are managed appropriately.¹ The HCV test results, whether positive or negative, should be reported to other medical units or hospitals when hemodialysis patients are transferred for care. Routine HCV testing should include use of an enzyme immunoassay (EIA) to test for anti-HCV, and then supplemental or confirmatory testing with a more specific assay. Routine testing for hepatitis B virus continues to be recommended, but the CDC reiterates that HIV testing of hemodialysis patients for purposes of infection control is not recommended. Infection control precautions to prevent both bloodborne and bacterial infections also are outlined in the new guidance. (See recommendations, p. 82.)

Since 1990, limited data on testing to evaluate the incidence of HCV infection has revealed annual rates of 0.73% to 3% among hemodialysis patients. None of the patients who seroconverted had received transfusions in the interim or were injecting-drug users, the CDC reports.

"It suggests that there is a certain constant, low level of transmission going on," Tokars says. "This [testing recommendation] is to try and recognize when and where that is happening and focus some light on that. That is the main reason for doing the testing."

The number of years on dialysis is the major risk factor independently associated with higher rates of HCV infection. For example, studies have found an average of 12% HCV infection of patients on dialysis for less than five years. However, that climbs to 37% for patients receiving dialysis for more than five years, the CDC reports. Many hemodialysis centers already are testing patients for HCV, according to CDC data. During 1992-1999, national surveillance indicated that the proportion of centers that tested patients for HCV increased from 22% to 56%, the agency reports. HCV testing can be used to identify clusters, guide medical interventions, and reinforce infection control measures.

"Probably with any positive [HCV] test you would do some kind of investigation," Tokars says. "If there is more than an occasional one, there may be some type of pattern [of transmission]."

Some 190,000 hemodialysis patients in the United States are threatened by infections because their treatment requires vascular access for prolonged periods. (See box, at right.) To meet this threat, the new CDC guidelines are designed to assist infection control professionals and clinicians in some 3,000 freestanding and hospital-affiliated hemodialysis centers.

In the dialysis setting, repeated opportunities exist for person-to-person transmission of infectious agents by contaminated devices, equipment, and supplies, environmental surfaces, or the unwashed hands of staff. Hemodialysis patients are immunosuppressed, which increases their susceptibility to infection. They require frequent hospitalizations and surgery, which means more exposure to pathogens.

"Hemodialysis patients just by the nature of their needs, from a medical point of view, are prone to infectious complications," says Robert Sharbaugh, PhD, international director of infection control at Hill-Rom Inc. in Charleston, SC., who worked with the CDC in developing the guidelines. "Over the last decade or so, there have several bacteria that have emerged that are resistant to most antibiotics. It is these very bacteria that tend to pick on debilitated people, and hemodialysis patients certainly fit into that category."

In that regard, the new guidelines emphasize the threat of bacterial infections, particularly those that are antibiotic resistant. "In recent years, bacteria are really a bigger threat to dialysis patients then the bloodborne pathogens are," Tokars says.

During the 1990s, the prevalence of antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) increased rapidly in hemodialysis units. In 1999, the CDC launched a surveillance system for bloodstream and vascular access infections in outpatient hemodialysis centers to determine the incidence and risk factors.

"We are hoping through that surveillance program we will be able to improve and focus prevention measures," Tokars says, adding that the CDC is gathering data to publish a supplemental guideline on preventing bacterial infections in hemodialysis patients later this year.

The much-feared rise of vancomycin resistance has been strongly linked to hemodialysis settings, in part because the antibiotic can be conveniently administered and has been a stalwart weapon against MRSA. However, the CDC reports that cefazolin, a first-generation cephalosporin, could be substituted for vancomycin in many patients and still be administered in centers three times a week during dialysis. The concern is that continuous, long-term use of vancomycin will select out resistant strains that could spread through the health care system. Some of the first cases of VRE emerged in dialysis patients in the 1980s. More recent studies have found that 12% to 22% of hospitalized patients infected or colonized with VRE were receiving hemodialysis, the CDC reports. Though very few in number, the infection that has caused the greatest concern among hemodialysis patients is S. aureus with intermediate resistance to vancomycin (VISA). Concerns rose about this potentially untreatable infection when it first appeared in a case in Japan in 1996, and since then a total of five U.S. patients have been infected.

"Five of the first six [VISA] patients have been on dialysis," Tokars says.

Reference

1. Centers for Disease Control and Prevention. Recom-mendations for preventing transmission of infections among chronic hemodialysis patients. MMWR 2001; 50:1-43.