Infection Control Today - 01/2004: THE INVASION OF THE ANTIMICROBIALS

THE INVASION OF THE ANTIMICROBIALS

By John Roark

On both the consumer and healthcare front, there is a ubiquity of products containing antibacterial and antimicrobial properties. The question is, is the germ-fighting enhancement necessary or useful?

Finding a simple household liquid soap product that does not contain antibacterial chemicals has become a challenging pursuit. The utility of this sort of antibacterial product is based entirely on inference, says Bill Schaffner, MD, chairman of the Vanderbilt Medical Center infection control committee. As far as Im aware, there are no data to suggest that the use of household soaps, cleaners, etc, are associated with a reduction in either respiratory or enteric disease.

There are theoretical reasons to believe that they might be effective. But is the reduction greater than just using simple soap and water? That remains a big question mark, says Schaffner, And I think frankly in the minds of most infectious disease physicians and those involved in infection control, its a very dubious proposition. But it obviously has sales appeal.

The use of antimicrobial chemicals in commercial products has all of us crossing our fingers and fretting, but there has been no real development of resistance ... yet, he continues. Theres no scientific reason to believe that the use of Triclosan will predispose to resistance of bugs to conventional antibiotics. In fact, many of us are rather surprised that more resistance has not yet developed. But it hasnt.

Does that mean that we should continue using them? I think thats a question that is beyond our capacity to influence, frankly, says Schaffner. There are huge commercial imperatives out there, which doesnt mean that any of us recommend it we dont. What we all recommend is good handwashing. This is particularly true in the winter respiratory season, because not only can you transmit winter respiratory viruses through close contact (sneezing, coughing, and the like), but contaminated hands clearly have been shown to be a vehicle for transmission. So when you come in from the outside, wash your hands. Obviously, wash your hands after youve used the restroom, wash your hands when you are about to prepare food or eat. Wash your hands frequently, just as your mama told you. It isnt hightech, but that doesnt mean its not highly effective.

Infection-resistant Devices

When we move into the healthcare environment and we begin to address issues such as urinary catheters, or indwelling intravenous or intra-arterial catheters that may be impregnated either with an antibiotic or some sort of other antibacterial substance, there the issues are quite specific, says Schaffner.

In July 2001, the Agency for Healthcare Research and Quality (AHRQ) published the document, Making Healthcare Safer: A Critical Analysis of Patient Safety Practices, listing the 11 most highly rated patient safety practices. No. 11 on the list was Use of antibioticimpregnated central venous catheters to prevent catheter-related infections.1

Thats a very credible government agency that really studies patient improvement practices and outcomes, says Charles Edmiston, PhD, CIC, associate professor of surgery at the Medical College of Wisconsin and hospital epidemiologist at Froedtert Memorial Lutheran Hospital. So there is this data out there that strongly suggests that these devices may be beneficial, especially in high-risk patients. Most of us agree that these devices may not have a complete universal application, but they certainly seem to warrant consideration in high-risk patients, for example, ICU patients.

ETHICON has recently developed an antiseptic surgical suture impregnated with Triclosan. Theres an interest in looking at this type of device to reduce the incidence of selected wound infections, especially in high risk patients, says Edmiston. Triclosan is an antiseptic that disrupts cell membranes of bacteria. Its very safe. The thought process is that this antiseptic-impregnated device may have a measurable benefit in superficial incisional site infections about 40 to 60 percent of the infections that we see in hospitalized infections. Were talking about those infections that we classify as superficial incisional. Thats the key, because this device is not going to have any benefit for organ space, for example, for deep infection. But many of us think it will have a benefit on skin surface incision infections.

There is a wide body of interest in these antiseptic-impregnated devices, says Edmiston. The key, obviously, is safety. And there is a lot of safety data on many of these compounds. Obviously there is a premium associated with using a device like this. The issue is, for most of us who look at these devices, not what is the risk versus benefit because many of these devices have been well tested; theyre safe but benefit vs. cost. You look at the intrinsic benefit of the device versus the acquisition cost.

All of us would like to see devices that are infection-resistant, Schaffner stresses. One can always develop a theoretical rationale for the introduction of various presumably antibacterial substances into devices. But what it comes down to is doing the prospective placebo-controlled clinical trials. That is of course, the sort of level of evidence that all of us would not only like to see, but would be required by licensing agencies for a new pharmaceutical agent of one kind or another. But unfortunately, the requirements for new medical instruments are not that stringent.

But when you suddenly encounter a manufacturers sales representative in your office, if you ask for those kind of clean data prospective control trials they are rarely, if ever, available, says Schaffner.

Schaffner cites cost as a primary reason for the absence of prospective controlled trials. They are clearly expensive, he says. You usually need to have large numbers of patients, often a multicenter trial, the company has got to mock up the device to include placebos and real devices; it requires the whole mechanism of doing clinical trials. Its very expensive and cumbersome, and of course the company as much as they are in love with their own product is looking at a big investment with an uncertain outcome. Suppose the results of the trial show that there isnt much benefit? All of a sudden, everything that the company has invested is at risk. And because its not required by the FDA for licensure, why risk doing that? If you and I were running a company and were responsible financially to stockholders, we would not put the venture at that kind of risk.

So, we have a circumstance where all of us would like to see effective products tried, but when they come to market, the level of evidence indicating their effectiveness is very thin and uncertain, continues Schaffner. Thats unfortunate. And at the moment, neither the CDC nor the FDA nor the NIH would be in any way inclined to sponsor those kinds of studies, never mind industry itself. So we have a large vacuum here which is not to say that anything is illegal, its just not as rigorous as we would like and that often leaves us in a quandary.

Why dont the clinicians involved perform their own studies? Time, says Schaffner.

If you sit down with a biostatistician and calculate how many patient days of exposure you would have to have among current catheters vs. the new catheters, you could see that in any reasonably sized unit, you would have to do the study for eight years before you have enough data to have a statistically valid result at which point the surgeons become sobered. They understand. And thats why we always say, Now you understand, or at least you have an appreciation why it is that we think that these sorts of studies ought to be required pre-licensure. It would be very unusual for an individual institution to be able, even if they could organize the study, to get enough information in a reasonable period of time to securely answer that question.

So the answer is not complete on this issue. I think a lot of us are looking at these antiseptic-impregnated devices, seeing whether or not theres breakthrough or development of resistance against these materials, says Edmiston. But even though a definitive answer is not yet available, he believes that progress is being made.

I think thats why theres an interest in these antiseptic-impregnated devices. One thing we should always appreciate is that these devices should never be considered Band-Aids. These are not devices that we are going to use because our technique is sloppy and this is going to replace or supplement our poor technique. I always view these devices as adjunctive, as devices that we use along side and in combination with our standard infection control practices. Or if were talking about devices that have an antiseptic coating and used in patients, these devices are adjunctive along with appropriate surgical prophylaxis. But having said that, I really believe that some of these devices truly have a benefit, especially in our higher-risk patient populations.

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