Disinfection from a Scientific Perspective

The effectiveness of a disinfectant cleaner is influenced by the product’s active ingredient, its concentration, and thus the dosage. Accurate dosages can only be achieved by precisely measuring the substances and water. The manufacturer’s instructions for the product must be read carefully and adhered to strictly. User safety and the impact on surface coatings are crucial. Dirt affects the disinfectant’s efficacy; therefore, an appropriate cleaning method must be selected, as the substance alone is insufficient.

Surface disinfectants are only necessary in specific situations, such as for removing bodily fluid stains, during disease outbreaks when required, and in healthcare settings where cleaning agents and effective mechanical cleaning alone are insufficient for eliminating pathogenic microorganisms. The correct choice of agent necessitates knowledge of the disinfectants’ capacity to destroy various microorganisms, as different biocides (disinfectants) are effective against different types of microorganisms.

According to the Biocidal Products Regulation, professional users of biocides, or disinfectants, must possess appropriate training, meaning they must have completed relevant courses.

Effect of Disinfectants on Microorganisms

+++ very effective; ++ moderately effective; + limited effect; – no effect

Microorganisms Listed in the Table

Cocci are spherical bacteria. Cocci include staphylococci (e.g., Staphylococcus aureus, which causes skin infections), streptococci (e.g., Streptococcus pneumoniae, which causes pneumonia), and enterococci (e.g., Enterococcus faecalis, which causes urinary tract infections).

Rods are small rod-shaped bacteria belonging to several different bacterial genera. These include, among others, bacteria of the Listeria genus (food poisoning), Pseudomonas-type rods (e.g., Pseudomonas aeruginosa, which causes urinary tract and skin infections), and enterobacteria (e.g., Escherichia coli, which causes urinary tract infections, and Salmonella, which causes general infections).

An endospore or spore is a reproductive cell that can survive harsh conditions such as dry, warm environments. For example, Clostridium difficile, which causes diarrhea, is a spore-forming bacterium. Disinfectants are less effective at destroying spores; quaternary compounds and ethanol do not destroy them at all.

Bacteria causing tuberculosis, such as Mycobacterium tuberculosis. Tuberculosis is considered a dangerous infection. Quaternary compounds do not destroy such bacteria.

Fungi include molds and yeasts. Many fungi cause superficial infections in humans, affecting areas like the skin, nails, and feet. Molds can occur in damp rooms. Quaternary and ethanol-based agents are not very effective at destroying them.

Due to their structure, viruses’ susceptibility to disinfectants is expressed by the Klein-DeForest classification. Group A viruses are “enveloped” viruses, meaning they have a lipid or fat layer on their exterior. These viruses are more susceptible to disinfectants because many disinfectants dissolve fats. Group A includes, for example, influenza viruses. Group B consists of non-enveloped viruses with a protein capsid (e.g., hepatitis) and presents a more complex case compared to Group A viruses, as they lack a lipid layer on their surface. Group C viruses are similar to Group B viruses but smaller. This causes difficulties regarding the effectiveness of disinfectants. This group includes polio, adeno, and noroviruses, among others. Chlorine compounds and peroxygens destroy these viruses effectively, while quaternary compounds are less effective.

The table above serves as a general guideline. When selecting disinfectants in healthcare, it is crucial to ensure the chosen biocide’s efficacy against the specific microorganism intended for destruction. This efficacy is demonstrated by EN test results.

Other Disinfection Methods

In addition to chemical disinfection, increasingly new disinfection methods are being adopted.

UV Light

  • UV-C from 200 to 280 nm – disinfection and bactericidal effect
  • UV-B 280 – 315 nm – for medical use (e.g., medical procedures such as psoriasis treatment for the skin)
  • UV-A – used in therapeutic procedures, tanning, and insect control.

UV-C radiation breaks down DNA and RNA in bacteria, viruses, and spores, meaning it renders them harmless. All bacteria and viruses tested so far respond to UV-C disinfection.

The UV-C solution has been tested for the following bacteria and viruses:

  • Adenovirus type 15
  • Bacillus anthracis spores – Anthrax spores
  • Candida
  • Clostridium tetani
  • Salmonella typhimurium
  • Feline Calicivirus
  • Giardia lamblia
  • Porcine Epidemic Diarrhea
  • Porcine Respiratory and Reproductive Syndrome
  • Influenza
  • Staphylococcus aureus
  • Salmonella enteritidis
  • Cryptosporidium parvum
  • Legionella pneumophila
  • Rabies virus
  • Escherichia coli – O157:H7
  • Campylobacter jejuni
  • Canine Parvovirus
  • Bovine Coronavirus (BCV)
  • SARS-CoV-2

Different microorganisms may, however, require different contact times.

Both room disinfection robots and disinfection cabinets are manufactured for disinfecting surfaces and air. It is crucial that no people or other living organisms are present in the room when using UV-C light, as this method also destroys beneficial microorganisms on human skin and mucous membranes. Additionally, UV-C light can cause burns similar to sunburn.

Hydrogen Peroxide Dry Vapor

A device similar to a steam cleaning machine, which sprays hydrogen peroxide ( H2O2 ) and silver ions. It is effective on dry and clean surfaces, such as in a gym.

Probiotic Cleaning Agents

They contain bioactive substances. They operate, for example, on the principle of reverse osmosis – water is forced by pressure to move through a semi-permeable layer from a stronger solution towards a weaker one. In this way, the cell is destroyed. Microbes can also secrete enzymes that, for example, break down urea in dry urinals (odor removal).

Regardless of the disinfection method, conscious cleaning is essential, involving appropriate cleaning techniques, equipment, and agents. Dirt on surfaces reduces the effectiveness of disinfection by almost all methods.

Helge Alt, Puhastusekspert, using sources: