March 13, 2006
Is Anything Sterile Yet?
By Michael D. Shaw
A current hot topic among newspaper health writers these days is hospital-acquired infections. Depending on how much the particular media outlet wants to scare you, they’ll cite alarming statistics, refer to antibiotic resistant pathogens, and might even include an up-close and personal story about some poor infected soul. Most of the time, the article will conclude with a clever finding that we can do a lot to combat the problem with proper hand-washing. If only…
Missing from all the coverage is the entire matter of sterility of medical instruments. You see, if a contaminated device is put inside the rarefied environment of the human body, especially in an individual who is already sick, disaster can easily follow. Perhaps this matter is not discussed in the popular media since it is somewhat technical. Perhaps there are other reasons.
Let’s define some terms. According to the Centers for Disease Control:
Cleaning, the physical removal of organic material or soil from objects, is usually done by using water with or without detergents. Generally, cleaning is designed to remove rather than to kill microorganisms. Sterilization, on the other hand, is the destruction of all forms of microbial life; it is carried out in the hospital with steam under pressure, liquid or gaseous chemicals, or dry heat. Disinfection, defined as the intermediate measures between physical cleaning and sterilization, is carried out with pasteurization or chemical germicides.
In practice, high-level disinfection kills all organisms, except high levels of bacterial spores, and is effected with a chemical germicide cleared for marketing as a sterilant by the Food and Drug Administration. No doubt, sterility is better, but for economic reasons, high-level disinfection takes it place in many cases, since it is usually much quicker. Besides, what are a few spores among friends?
The classical method of assuring that a load (of instruments and devices), as it is called, is sterile after being treated by the sterilizer, is to include a biological indicator (BI). The BI contains a bacterial species deemed difficult to kill by the particular sterilization method employed. The BI is removed after the sterilization cycle, and is cultured to test the cycle. Most BI’s require 48 hours for the results to develop.
Best hospital practices, in fact, will specify that the load should not be released until the results of the BI are available. So far, so good, right?
The only problem is that few hospitals have enough inventory of instruments to support a true BI-based release. After all, that would be expensive. Surely, there has to be an alternative to waiting 48 hours? Welcome, my friends, to the world of parametric release.
In essence, parametric release means that if you are operating the sterilizer in accordance with proper settings, the load is—by definition—sterile. Of course, certain standards and guidelines apply. On the one hand, there is a rigorous standard that will certify parametric release, that is intended for manufacturers of medical devices, or large facilities that specialize in sterilizing loads for others.
Yet, this standard is so rigorous that even many of these facilities prefer to run the loads, ship the goods, and track the BI. If the BI is positive, then they will recall the load.
In hospitals, the load is run and released, and follow-up is supposed to be done if the BI tests positive—48 hours later. Cold comfort that there is merely a recommended practice, proffered by a professional association, that addresses this matter at all.
The scientific among you are probably wondering about how many BI’s are positive, and what occurred afterward. Some of you might even like to know if there are higher incidences of positive BI’s at certain hospitals, or in conjunction with certain methods of sterilization. These are all good questions, but the answers are not available.
Hospitals are notoriously secretive about information such as this, and, frankly, since there is little third party oversight, some cynics wonder about the veracity of such information, even if it were to be released.
When it’s your turn to be on the operating table, you should ask all sorts of questions about your procedure, including how the instruments are sterilized. Once you identify yourself as knowledgeable, plenty of information will be forthcoming. And, if more people do this, current bad practices on sterilization will have to be improved, since a lawsuit is even more expensive than an adequate inventory of instruments.