Log by Log: The Spores Left Behind by Low Log Disinfection
Halosil Blog

Timely insights on whole room disinfection.

HealthcareNovember 21, 2019

Log by Log: The Spores Left Behind by Low Log Disinfection

When it comes to eradicating dangerous pathogens from critical environments like healthcare facilities, it’s necessary to leverage the right whole room disinfection solution. After all, healthcare facilities like hospitals are known to house dangerous bacteria, fungi, and viruses, such as C. difficile (C. diff), C. auris, and norovirus. In fact, as a result of inadequate disinfection practices, one in 31 hospital patients will acquire at least one healthcare-associated infection (HAI) during their stay. As such, healthcare facilities are challenged to disinfect environments with the highest levels of efficacy in order to protect patients, visitors, and healthcare professionals. However, with so many claims and products on the market, choosing the appropriate disinfection solution can be confusing.

This is where the logarithmic scale comes into play. By offering a mathematical system by which to measure and grade how effective a given disinfectant may be against infectious pathogens and germs, the logarithmic scale provides a systematic way to select a whole room disinfection solution that eliminates the greatest number of pathogens for safer environments.

When using the logarithmic scale to select a whole room disinfection solution, it’s important to consider the following questions:

What Is the Difference Between Log Claims?

The logarithmic scale works with factors of 10 (one decimal point), meaning log reductions (or the decrease in pathogens) are separated by factors of 10, with each additional factor increasing the reduction of the number of live bacteria by 90%. For instance, according to the Environmental Protection Agency (EPA), log reduction as a percentage reduction alone looks something like this:

  • 1-log reduction = 90% reduction
  • 2-log reduction = 99% reduction
  • 3-log reduction = 99.9% reduction
  • 4-log reduction = 99.99% reduction
  • 5-log reduction = 99.999% reduction
  • 6-log reduction = 99.9999% reduction

When applied to a colony of one million C. diff bacteria, kill rates translate to the following:

  • A 1-log kill reduces the colony to 100,000 C. diff bacteria
  • A 2-log kill reduces the colony to 10,000 C. diff bacteria
  • A 3-log kill reduces the colony to 1,000 C. diff bacteria
  • A 4-log kill reduces the colony to 100 C. diff bacteria
  • A 5-log kill reduces the colony to 10 C. diff bacteria
  • A 6-log kill reduces the colony to 1 C. diff bacteria

It’s also important to note that only those disinfectants with an EPA-validated 6-log kill rate can make legal kill claims in regard to some of the most dangerous and infectious pathogens like C. diff and C. auris. These disinfectants can be found on List K.

Which Logs Measure Up to Cleaning, Sanitizing & Disinfecting Practices?

When attempting to eliminate dangerous diseases and their pathogens, it’s also important to know the difference in log power between cleaning, sanitizing, and disinfecting since they are not all equal in their claimed and actual log kill rates. For instance, cleaning only removes germs, dirt, and impurities from surfaces and objects. While this can decrease the number of allergens and microorganisms on surfaces, it should be noted that cleaning with soap and/or detergent does not have the power to actually kill germs. In contrast, sanitizing and disinfecting methods both have the power to kill pathogens; however, there is a difference in log kill rates between the two. An EPA-validated sanitizer kills 99.9% of microorganisms (a 3-log kill rate), while an EPA-validated disinfectant kills 99.99% of vegetative bacteria and viruses (a 4-log kill rate). The highest possible efficacy as granted by the EPA goes to sporicidal disinfectants, which kill 99.9999% of pathogens (a 6-log kill rate), making them the only solutions that can make kill claims against C. diff.

Which Delivery Methods Result in the Highest Log Reduction Rates?

Along with the disinfectant comes the delivery method. Since the EPA has validated disinfectants across a number of delivery methods, it is critical to evaluate the benefits and shortcomings of each. First comes spray and wipe. While there are spray and wipe solutions registered as sporicidal disinfectants, they are only effective on surfaces where the solution is directly sprayed—meaning pathogens continue to lurk in cracks and crevices. For this reason, spray and wipe methods are best used to reduce the bioload in a room instead of as the main source of disinfection against highly resilient, dangerous pathogens.

Next comes ultraviolet (UV) light-based systems. UV light is not an EPA-approved disinfectant, meaning UV light systems cannot make any claims in regard to sporicidal efficacy. In fact, some experts claim UV light can only achieve a 1-log kill rate, with C. difficile spores reduced by less than 93% even when using the most sophisticated dosage-sensing devices. Furthermore, the kill rate of UV light systems varies dramatically depending on the location of the device and surface since shadows and distance from the UV light impact efficacy.

In contrast, a sporicidal disinfectant delivered via dry fogging is able to eliminate pathogens in hard to reach areas beyond the reach of spray and wipe solutions, all while achieving a 6-log kill rate that far surpasses UV light.

A 6-Log Kill Rate for True Whole Room Disinfection

Low log disinfection solutions can leave dangerous pathogens like C. diff, C. auris, and norovirus behind. At Halosil, we understand the importance of assessing whole room disinfection log by log, which is why we pair our EPA-registered, 6-log disinfectant HaloMist™ with a dry-fogging delivery in our Halo Disinfection System® to achieve the highest possible efficacy. By offering a hands-free solution that is capable of delivering a 6-log disinfectant to every space and place in a given environment, healthcare facilities are empowered to reduce HAIs and keep populations healthier.

Ready to leverage a 6-log kill rate in your healthcare environment? Contact Halosil today.

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