Materials that will be used during surgery must be sterile and free of all living microorganisms, be they bacteria or viruses. The same does not hold true of surfaces, which are continually exposed to the environment, making it impossible for us to sterilize them. The most we can do with surfaces is to reduce the microbial burden to a level that will significantly reduce the chance that there will be an infection caused by microorganisms on hands or surfaces. This is where disinfectants enter the scene. Disinfectants come in various forms for various purposes. They also have varying abilities to decrease the number of viable organisms present. Here are some helpful tips and points to keep in mind as you consider the right tool for your surface disinfection needs.

1. Disinfectants won't be sufficiently effective if the surface is dirty. This is especially true with proteinaceous substances such as blood. Disinfectants have to get to the area that has to be treated and organic matter of all kinds will prevent their penetration to the surface you want to disinfect. Treating the area with a detergent will usually take care of the problem by breaking up the material covering the surface to be disinfected.

2. One product for all surfaces. Ideally, you'll select a single product to disinfect OR surfaces. Choosing the best product for your conditions will depend on the types of surgeries performed and the environment in which your OR is situated, as well as the product's effectiveness against organisms of concern, cost, ease of use, storage, impact on surfaces and potential irritation to users' skin, eyes and mucous membranes.

3. What do regulators say? Four regulatory bodies influence the disinfectant you choose:

• The EPA regulates chemicals that are used on such surfaces as OR tables, Mayo stands and gurneys.
• The FDA oversees the effectiveness and safety of high-level disinfectants, generally used on equipment that will contact the human body, such as glutaraldehyde (Cidex), hydrogen peroxide and peracetic acid.
• OSHA requires that in order to decontaminate a surface, the disinfectant must be effective against HIV or hepatitis B virus.
• Part of the Joint Commission's infection control standard (IC.02.01.01.1) is the requirement "to minimize, reduce or eliminate the risk of infection."

4. Low, intermediate or high? There are three levels of disinfectants as categorized by the EPA:

• Low-level disinfectants kill some viruses and bacteria but are unable to get rid of M. tuberculosis. TB is not transmitted from surface to surface. But its importance in disinfectant categorization is that the bacterium has an outside layer composed of lipids that is hard to penetrate. If the disinfectant can get through this outer layer, it should be able to get through the outer wall of most microorganisms.
• Intermediate-level disinfectants kill most viruses and bacteria, including M. tuberculosis.
• High-level disinfectants are chemicals that sterilize equipment that comes in contact with mucous membranes, such as fiberoptic endoscopes. They don't necessarily kill bacterial spores. They're usually used to reprocess reusable medical devices that shouldn't be exposed to high heat. These disinfectants are the ones used to sterilize equipment.

5. Beware bacteria that form spores. Bacterial spores are like seeds, which explains why some bacteria survive harsh environments. Most disinfectants don't affect bacteria. Among the disease-causing bacteria that form spores are Clostridium difficile (C. diff) and Clostridium tetani (tetanus). An instrument used on a patient with C. difficile or an area that had a patient with the organism can become contaminated with spores very quickly. Unless you use adequate disinfection procedures and products, other patients and personnel handling the patient or entering the area may become colonized. The "right" conditions can change colonization to infection very quickly.

6. The big three bacteria. A disinfectant that is EPA-approved for use in an outpatient surgical facility must be active against three bacteria:

• Salmonella choleraesuis, a Gram-negative rod that is used to represent bacteria such as Escherichia coli.
• Staphylococcus aureus, a Gram-positive coccus. S. aureus is the same bacterium as MRSA, the organism we're all worried about. A disinfectant active against S. aureus will be effective against MRSA, too.
• Pseudomonas aeruginosa, another Gram-negative bacterium. It's the cause of many nosocomial or hospital-acquired infections.

7. Stronger the agent, the better it kills? Not true for many disinfectants. A 1:10 dilution of household bleach (prepared fresh daily) is very effective in killing HIV as well as C. difficile vegetative cells and spores. One would expect 100 percent to be the best concentration of alcohol to kill bacteria and viruses, but mixing alcohol into a water-based solution makes it easier for alcohol to penetrate and kill cells. Alcohol gels and foams used as hand disinfectants are usually about 65 percent to 70 percent alcohol. This concentration is most effective in denaturing protein, thereby killing the germs. Quaternary ammonium compounds are usually used at dilutions of about 1:1,000. These chemicals, as well as most others, should be left on the surface for at least 10 minutes in order to be most effective.