Bronchoscopes implicated in two TB outbreaks
Complex devices require tricky reprocessing
Contaminated bronchoscopes have been implicated in the deaths of two patients and the infection of three others. The two episodes involving bronchoscopes contaminated with Mycobacteri-um tuberculosis, one in Maryland and the other in South Carolina, appeared to underscore the importance of following the rules when it comes to cleaning and disinfecting the instruments.1
The incidents "gave many doctors pause," says Carol Pozsik, RN, MPH, TB controller of South Carolina, where two patients died of MDR-TB after undergoing bronchoscopies at a hospital. In each of the two outbreaks, investigators determined that both aspects of reprocessing the endoscopes i.e., cleaning and disinfection were faulty and to blame.
3 reasons for failure
Most experts agree there’s no mystery to what happens when infection is transmitted via a contaminated bronchoscope.
"When there’s a failure, it’s usually because of one of three reasons: insufficient cleaning, inappropriate use of disinfection, or failure to follow recommended practices," says William Rutala, PhD, MPH. Rutala is the author of guidelines for the selection of disinfectants published by the Association for Practitioners in Infection Control2 in Washington, DC, and a professor of infectious disease and director of epidemiology at University of North Carolina (UNC) Hospitals in Chapel Hill. He is best known for having helped settle a fractious dispute over how much time to spend and at what temperature hospitals needed to disinfect their instruments (longer than the 10 minutes that surveys showed some people spent but not as long as the 45 minutes the U.S. Food and Drug Administration claimed was necessary).3
Rutala’s conviction that simply following the rules is adequate lends more reassurance than one might think, given that the subject at hand is the complicated workings of a bronchoscope.
"Many people consider these flexible endoscopes to be black boxes because you can’t see what’s going on inside," says Steve Goldstine, DDS, PhD, manager of microbiology in the endoscope division of Olympus America, the Belleville, NY-based company that makes most of the flexible endoscopes used in bronchoscopy today. "You put something in at one end and pull something out at the other but you don’t know what the relationship between the two events is. Did bacteria multiply inside? Did they take a vacation? Are they hiding out?"
The black-box factor colors almost all the discourse, some of it quite heated, that has taken place over the years between certain divisions within the Centers for Disease Control and Prevention (CDC) in Atlanta and the endoscope makers, Goldstine says. "Practicing physicians say that the infection rate is exceedingly low, but other people might tell you that’s true only in recorded cases."
One reason for the debate, ironically, has to do with the instruments’ virtues. Since most procedures performed with flexible endoscopes are outpatient, patients don’t need to be followed as closely as if they’d been hospitalized.
Plus, what follow-up does occur suggests there isn’t that much to worry about. "We’re a transplant center, so a lot of our patients are actually inpatients," says Nancy Gondzur, RN, clinic manager for the endoscopy department of the University of Wisconsin Clinic and Hospital. "When they’re discharged, they are instructed to contact us if there’s a spike in their temperature or they experience shortness of breath or other symptoms." The center doesn’t get that many calls, either, she adds. "It’s possible there are more infections out there than we know about," she concedes. "But if there are, they’re low-grade; people recover in a day or two."
In 1992, Olympus and other bronchoscope makers decided to go on the offensive, Goldstine says. "They went into laboratories and began trying to find out whether if you put a dozen bugs into one of these things, you could get a dozen back out." The answer, it appeared, was in the affirmative.
Specifically, the tests found more than 95% of test inoculum was recoverable, he says. As part of its ongoing efforts to reassure people that endoscopes can be cleaned, Olympus maintains a program whereby it loans out the costly equipment for people to perform their own tests.
Disposable endoscope "condoms," which fit over the optic portion of the endoscope, are already commercially available for devices used strictly for some diagnostic procedures, Goldstine says. Certainly, their application to bronchoscopy would allay any remaining fears about contamination. But the condoms wouldn’t make sense in cases where a therapeutic procedure also is performed which in bronchoscopic procedures is often the case. "Then, obviously, you’d have to break through the condom, and you’d be back to square one," he says.
Bronchoscopes in the autoclave?
If the scopes could be steam sterilized, that also would ease anxieties, he reasoned. How long before users can put a bronchoscope into the autoclave? "I don’t know," Goldstine says. "I do know that of all the products we make, the flexible scopes will be last because they’re so complicated. It’s not around the corner."
Despite the fact that bronchoscopes still are a lot harder to sterilize than scalpels, for example, reports of cases of true infection from them are "vanishingly small," he says.
More often, instances of pseudoinfection occur, such as in a lavage. "The lavage fluid may contain bugs from the bronchoscope and not the patient," he says. By comparison, reports of true passage of infection from one patient to another are relatively rare, he adds.
Perhaps for that reason, few published guidelines exist for reprocessing bronchoscopes. "In the field of GI scopes, there are literally dozens of recommendations," Goldstine says. "But nothing exists like that in bronchoscopy."
There are two aspects to reprocessing the devices: cleaning and disinfection, or sterilization. "Cleaning’s in vogue now it’s the thing to talk about because there aren’t a lot of guidelines," he says.
As long as there is attention to mechanical cleaning of ports and to internal and external channels with appropriate detergent, the cleaning procedures should be effective, Rutala says. Still, there’s not as much information as he says he’d like to see on variations in cleaning technique. "It would be nice to know whether different cleaning procedures provide the same results or not. It’s important to do experiments to see whether small differences in technique make a difference such as using enzymatic detergent vs. a water-soluble detergent."
In the meantime, Rutala says he’s convinced that even if there are slight differences, the end result is the same: a suitable reduction in the microbial load.
"The key is manual cleaning," Gondzur says. "That means using a brush through the biopsy channels and sucking and washing. You resuction after you brush until what you’re suctioning is clear. And if your brush is dirty, you clean it off and keep brushing until the brush is free of debris." Gondzur uses an enzymatic cleaner and a detergent, she adds.
Disinfection became the focus of controversy in 1994 when the FDA pulled the rug out from under hospitals by assuming the worst-case scenario namely, that no one would take the trouble to clean the scopes before plunging them into disinfectant. The result was a new set of instructions on the labels of chemical disinfectants, directing users to soak their instruments for 45 minutes at a temperature of 25 degrees centigrade.
"People became very upset," says Goldstine. "The common practice had been to soak for 20 minutes at 20 degrees centigrade." Raising the temperature several degrees required some effort; and the longer soak time meant the instruments would be sitting in glutaraldehyde instead of being available for use.
Rutala argued convincingly that the new labeling requirements were, literally, overkill. "Studies have shown a 4 to 6 log reduction in microorganisms" that is, a drop of between 10,000 to a million microorganisms "associated with disinfection after 20 minutes at 20 degrees centigrade, and a 4 log reduction associated with cleaning," he says. "There shouldn’t be any surviving organisms after that 8 to 10 log reduction. That means you’ve got a patient-ready endoscope."
Though the FDA stands firm, Rutala’s position carried the day with professional associations, including the Association for Professionals in Infection Control and Epidemiology and others, which published recommendations incorporating the shorter soak time and lower temperature. "Most people today are using 20 minutes at 20 degrees," adds Rutala. "I would be comfortable with any member of my family undergoing one of these procedures at UNC Hospitals. I’m satisfied there’s not an infection risk associated with their use."
Some facilities bypass the issue of how long to disinfect by opting instead to sterilize, Goldstine says. There are two ways to do so: using a sterilizing machine that employs a liquid chemical, paracetic acid; or using a gas, ethylene oxide. Both methods of sterilization still presume, of course, that the user has first cleaned the instrument.
A final alcohol rinse is a good idea, too
If ethylene oxide is used to sterilize the bronchoscope, the equipment is placed into a sealed container and finishes the process dry, Goldstine says. If a sterilizing machine (or glutaraldehyde) is used, the scopes emerge from reprocessing dripping wet; and in that case, experts recommend, as a final step, an alcohol rinse, he says.
"It helps dry the internal parts of the scope, the small channels that may contain some water," he says. "If there’s any dust around, bacteria could start multiplying." By coincidence, alcohol also has the ability to kill any mycobacteria that may be lurking in the scope’s innards.
In addition, American Society for Testing and Materials standards suggest that the person charged with reprocessing the scopes is as important as how the devices are reprocessed. On this subject, the standards make these points:
• Only one or two people per shift one primary person and one back-up person should be responsible for reprocessing duties.
• Responsibility for reprocessing "should not be delegated" from one person to another.
• The person responsible should understand, and be able to put into practice, the manufacturer’s directions on reprocessing the instrument. The person should have attained the proper educational level and should not be a temporary person to whom the task is delegated.
• He or she must understand the mechanical aspects of the equipment.4
References
1. Am J Respiratory Crit Care Medicine. Abstracts, International Conference. 1997; 155:A225.
2. WA Rutala. APIC Guidelines for selection and use of disinfectants. Am J Infect Control 1990; 18:100-113.
3. WA Rutala. FDA Labeling requirements for disinfection of endoscope: A counterpoint. Infect Control Hosp Epidemiol 1995; 16:231-235.
4. American Society for Testing and Materials. Standard practice for cleaning and disinfection of flexible fiberoptic and video endoscopes used in the examination of the hollow viscera. Annual Book of ASTM Standards. Designation: F1518-94. July 1994.
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