APIC Conference: CDC sterilization guidance in policy vs. science limbo

APIC Conference

CDC sterilization guidance in policy vs. science limbo

HICPAC document is first update in 20 years

Though completed by the Centers for Disease Control and Prevention (CDC) in February 2003, updated guidelines for disinfection and sterilization of infectious agents in health care settings remain shelved due to a dispute between federal agencies.

The CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) has long since signed off on the draft guidelines, the first comprehensive CDC update on sterilization and disinfection in 20 years. However, the 274-page document — which has 21 pages of recommendations and more than 1,000 references — has yet to be finalized because of discrepancies between some of the recommendations and existing federal policies or label wording.

The Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) have each taken separate exceptions to recommendations in the CDC document.

"HICPAC produces science-based guidelines," said William Rutala, PhD, MPH, an epidemiologist at the University of North Carolina Hospital in Chapel Hill. "The recommendations are based on peer-reviewed scientific studies. What the FDA and the EPA want the CDC to do is to make recommendations based on the EPA and FDA regulations and registration claims. That is the reason that the guideline is not yet published. [It] is an issue of science vs. policy."

One of the principal authors of the document when he served on the HICPAC committee, Rutala spoke recently in Baltimore at the annual meeting of the Association for Professionals in Infection Control and Epidemiology (APIC).

The FDA snag deals with the CDC recommendation for high-level disinfection with glutaraldehyde for 20 minutes at 20° C. "That is supported by 34 studies in the scientific literature, although the [product] registration claim is typically 45 minutes at 25° C," he said.

The EPA issue deals with low-level disinfection, with the guideline saying a one-minute surface contact time is sufficient rather then 10 minutes. "The [HICPAC] guideline says to have to at least a one-minute contact time when you apply a germicide to a surface," he said. "It typically takes one to two minutes to dry so you wouldn’t have to reapply seven to 10 times to achieve the contact time. Again, that is supported by the literature."

The matter remains unresolved, with HICPAC acknowledging the FDA/EPA policies but noting that the document is "science-based," Rutala explained.

C. diff impervious to alcohol rubs

With spore-forming Clostridium difficle (C. diff) appearing in more virulent strains, Rutala was asked about the efficacy of alcohol handrubs against the pathogen. Despite the widespread switch to alcohol rubs, soap and water must be used to prevent cross-transmission of C. diff via health care workers’ hands, he said.

"Alcohol-based handrubs do not inactivate and do not effectively remove spores from hands," he warned. "We keep spores in alcohol as a way of retaining them over a long period of time. Spores are not inactivated by alcohol. Use soap and water for patients where C. difficile is a concern."

The HICPAC guidelines emphasize that C. diff requires multiple control measures including hand washing, barrier precautions, and meticulous environmental cleaning with an EPA registered disinfectant, he said. "That should be effective in preventing the spread of the organism."

However, in units with high endemic rates or during outbreaks, environmental cleaning should be done with a 1-to-10 dilution of household bleach.

"There are data which demonstrate the effectiveness of this chlorine preparation to reduce the incidence of C. difficle-associated diarrhea in a bone marrow transplant unit when the chlorine was compared to a quaternary ammonium compound," Rutala said.

In addition to C. diff, the HICPAC guidelines provide an overview of disinfection and sterilization procedures for a variety of emerging pathogens such as severe acute respiratory syndrome (SARS) corona virus, nororviruses, and avian influenza.

"Standard disinfection and sterilization procedures for patient care equipment are adequate to sterilize or disinfect instruments or devices contaminated with blood and other body fluids from persons infected with [these] emerging pathogens," Rutala noted.

For example, the corona virus that causes SARS can survive on surfaces for hours, but should be "relatively easy to kill" because it is an enveloped virus, he noted.

"There are a couple of studies that have been done that discuss the effectiveness of some commonly used hospital disinfectants (e.g., low concentration of glutaraldehyde) against the SARS corona virus," Rutala said. "We are currently expanding these studies using the SARS corona virus at the UNC health care system; and hopefully in the near future, we will have some additional data."

Research on activity against other human corona viruses shows that quaternary ammonium compounds and phenolics are not effective, but tests continue with the SARS virus. "We have data that demonstrate that probably most of the most products that we would use would be effective, possibly with the exception of the phenolics and quaternary ammonium compounds," he added. "More data are necessary."

Avian flu, noroviruses, CJD

Little research has been done specifically with the Avian influenza A (H5N1) virus that has emerged in Asia as a possible pandemic strain. However, the limited data indicate efficacy against the avian virus by some of the phenolics, a quaternary ammonium compound, a peroxygen, and chlorine, Rutala said.

Meanwhile, as norovirus outbreaks increase, the pathogen threatens to become as much a problem for hospitals as it is for cruise ships. "There have been more outbreaks of norovirus in hospitals," he noted. "In fact, we had a recent outbreak, which resulted in closure of a ward." This group of viruses cannot be grown in cell culture, so feline calicivirus is used as a surrogate in research.

"Chlorine at concentration of 1,000 parts per million (ppm) is very effective in activating the calicivirus in one minute," Rutala said. "The other products that were effective included chlorine dioxide (1,000 ppm) and an accelerated hydrogen peroxide product that is available in Canada but not yet available in the United States."

The HICPAC guidelines also address a rare but extremely difficult situation, protecting patients against prions that cause Creutzfeldt Jakob disease (CJD). "This disease has an incidence of one death per million population, so in the United States, we have approximately 300 cases a year," he said. "There is no seasonal distribution, there is no geographic aggregation, and there is no immune response to CJD or prion diseases."

Similarly, there is no gender distinction in cases, but CJD does occur more frequently in the elderly, with the average age of cases 67 years old.

"It’s a long incubation disease, varying from months to years to decades; but once the disease begins, death occurs within six months," Rutala continued. "[CJD] is caused by prions, [which] are very resistant to disinfection and sterilization."

There has been some evidence of cross-transmission via contaminated medical instruments, but typically the cases are not completely resolved. "There have been four probable cases associated with brain surgery," Rutala said.

"Only one of those four cases had an index case. Essentially, you have people who develop CJD following brain surgery, so they suspect the neurosurgial instruments in disease transmission in those cases. We have had no cases since 1980, and we have no evidence that steam sterilization has ever failed."

The HICPAC guidelines call for conducting a CJD risk assessment that involves the patient, the tissue involved, and the devices to be used. A patient that is known to have suspect prion disease would be the first risk factor for CJD transmission.

"We have to consider the tissue because only certain tissues have been experimentally and epidemiologically associated with disease transmission," he pointed out. "Those tissues include brain, spinal cord, eyes. Then we have to consider the device, and we are really only concerned about critical and semicritical devices."

The risk threshold is crossed if a neurosurgical procedure involving the brain, spinal cord, or eyes is conduced on a patient suspected or known to be infected with a disease. The instruments used must be subjected to special prion reprocessing measures.

"You can use sodium hydroxide and steam sterilization," he said. "You can use 134° C for 18 minutes in a pre-vacuum sterilizer, or you can use 132° C for 60 minutes in a gravity-displacement sterilizer."

Higher temperatures actually yield reduced effectiveness against prions, so it is important not to go beyond the 134° C mark. Of course, there always is concern for the dreaded undiagnosed CJD case, which can lead to disruptive measures such as notifying patients on which the instruments subsequently were used.

"You should consider using the [prion] sterilization guidelines for neurosurgical instruments used on any patient undergoing a blind’ brain biopsy when a specific lesion has not been demonstrated," Rutala said. "If you don’t know the etiology of the disease and there is brain surgery, you should consider using special prion reprocessing for the instruments. Alternately, you can use disposable instruments."