Proper sterilization may ward off deadly CJD transmission

Healthcare Purchasing News, May, 2001

With all the attention given to "mad cow" disease and the associated risks of acquiring Creutzfeldt-Jakob disease -- the human form of bovine spongiform encephalopathy. -- many healthcare professionals are increasingly concerned about proper handling of medical instruments to prevent cross-transmission.

Such concerns certainly have merit, particularly given two recent incidents where inadequate sterilization put hundreds of patients at risk for deadly infection. In Sault Ste. Marie, Ontario, 250 patients from the Group Health Centre were tested for HIV and/or hepatitis after a mistake was made during the sterilization of an older endoscope. An additional 20 Centre patients were advised to be tested for tuberculosis.

In another instance, eight patients from Tulane University Hospital and Clinic, New Orleans, were notified that they could contract CJD because instruments used on an infected patient were subsequently used on them. Tulane officials said the instruments applied to the CJD patient were put through "normal washing and sterilization processes." The risk of CJD is "reduced by washing, but not eliminated by normal sterilization procedures," officials said in a prepared statement.

Although at press time no cases of transmission had been reported by either facility, sources agree they highlight the need for increased educational awareness.

"These incidences are bringing to light some very important issues regarding adequate instrument processing and how just one slip-up in technique can put patients and healthcare facilities in dangerous situations," said David Lewis, Ph.D., research microbiologist at the Environmental Protection Agency's National Exposure Research Laboratory, Athens, GA. "Healthcare institutions need to realize what does and doesn't work in managing contaminated -- or potentially contaminated -- instruments."

Deadly mistakes

According to Lewis, traditional methods of endoscope disinfection, such as soaking in glutaraldehyde, could harden particles, making decontamination of devices used on a CJD patient even more difficult.

Complicating matters further is that the cause of CJD is still under debate. The fatal brain disorder may be transmitted by proteinaceous infectious particles called prions, which presumably transform protein molecules into infectious, deadly ones by altering the shape of the molecules, said Cecile Sardo, founder of the Creutzfeldt-Jakob Disease Foundation in Miami. Some CJD researchers have even questioned whether bacteria could be the cause, although that theory has been the subject of great controversy.

What is known is that endoscopes can't withstand the high temperatures necessary to eradicate prions. Additionally, no reliable method exists to determine whether chemically treated prions are no longer infectious, said Bill Jarvis, M.D., associate director for program development, Centers for Disease Control and Prevention.

"If that weren't enough of a concern, instruments are often inappropriately cleaned and are subsequently used on other patients," he explained. "In fact, it's probably more common than we even realize that facilities fail to meet even the minimal standards. Scopes, in particular, are a challenge because they often have channels that are too long or narrow to brush."

CDC recommendations

To keep risks to a minimum, the CDC encourages healthcare facilities to have decontamination procedures in place to handle materials potentially contaminated with CJD.

Several precautionary approaches believed to be effective include the following measures:

Local care of exposure sites:

a. Percutaneous exposure to blood, cerebrospinal fluid, or tissue (especially brain) of an infected person should be immediately followed by irrigation of the wound with 0.5% sodium hypochlorite;

b. Any skin contact with possibly infectious materials should be followed by washing with 1N sodium hydroxide; and

c. Washing with soap and water should follow any mucous membrane contact with possibly infectious materials.

Decontamination of a patient care device after use on patients with CJD:

Although there is no evidence of CJD transmission via body substances (i.e., blood, urine, bronchial fluid, GI secretions), some experts recommend that when a patient-care device is contaminated with body substances, it should be sterilized as follows:

a. Steam autoclave for 1 hour at 132 degrees C;

b. Immerse in 1N sodium hydroxide for one hour at room temperature; and

c. Immerse in 0.5% sodium hypochlorite for two hours at room temperature.

Some experts also suggest that patients presenting symptoms of CJD be assumed infected, and that surgical instruments be handled accordingly. Some facilities prefer to use disposable devices, while others take reusable instruments out of circulation after use.

"If you wait until a definitive diagnosis, it could be too late because those instruments may have already been used on other patients," Jarvis warned.