High Level Disinfection

The CDC estimates 2 million people in the United States are infected annually by hospital-acquired infections, resulting in 20,000 deaths. The proper cleaning of invasive medical equipment is a key step to addressing some of the worst HAIs.

In the 1950s Spaulding devised a hierarchy of microorganisms according to the level of difficulty to inactivate them using typical hard surface disinfectant products. The most difficult to inactivate are bacterial endospores, and the lowest tier includes microorganisms generally considered to be most susceptible to inactivation using typical hard surface disinfectants are enveloped viruses.

The ability to kill bacterial endospores distinguishes between products that are “high level disinfectants” or the much higher standard of “sterilants”. Sterilants ensure that microbial life on a surface has been destroyed.

There are numerous classes of chemicals that are used to clean and disinfect invasive medical instruments and devices. These include sodium hypochlorite compounds, peracetic acids, hydrogen peroxide, glutaraldehyde solutions, ortho phthalaldehyde solutions, formaldehyde, gas plasma and ozone gas.

Of these, sodium hypochlorite and ortho phthalaldehyde are not sterilisers.

Of the remaining liquid chemical sterilants, attention needs to be paid to the following characteristics:

  • pH,
  • shelf life,
  • opened package shelf life,
  • re-use life,
  • use of a chemical indicator of Minimal Effective Concentration (MEC),
  • need for pre-activation,
  • air monitoring requirements for occupational safety and hazard assessments,
  • toxicity profile,
  • biodegradability, and
  • product disposal.

Increasingly medical devices used for diagnostic procedures are becoming more intricate with a mix of construction materials from plastics, to glass, rubber, fibre optics, and metals. Chemical differences between the different disinfectants can have very different and sometimes deleterious effects on the materials (stainless steel, glass, etc.) of medical devices being treated. In addition, the required treatment conditions or device preparation (wrapped or unwrapped, heat sensitivity, etc.) can vary significantly for different medical devices.

Of all of the options, a pre-activated, pH neutral, lower volatility, complexed aldehyde like that found in Microbidex-G (in both ready-to-use, and concentrated formats) may offer a better sterilizing solution.

Microbide is currently pursuing registration for several complexed aldehydes for their use as high level disinfectants and sterilants for the cleaning of invasive medical instruments and devices. Given these formulations’ reduced volatility the products are more effective than current commercial alternatives and less hazardous to those that work with sterilants.