2.1.1. Bacteria, Viruses, and Fungi — What the Exam Tests
💡 First Principle: Each class of pathogen has a different structure and therefore a different vulnerability. The reason disinfectants must be bactericidal, virucidal, AND fungicidal is that one product killing bacteria does not guarantee it kills viruses or fungi — they are fundamentally different organisms requiring different mechanisms of destruction.
Bacteria are single-celled organisms. Most are destroyed by proper disinfection. The exam-relevant exception is spore-forming bacteria — some bacteria produce protective shells (spores) that survive disinfection and require sterilization to destroy. This is why sterilization exists as a separate, higher level than disinfection.
Viruses are not cells — they are genetic material wrapped in a protein coat. They cannot reproduce on their own and must invade a host cell. The viruses most relevant to esthetics are bloodborne pathogens: Hepatitis B (HBV), Hepatitis C (HCV), and HIV. All three can be present in blood and body fluids. Properly used EPA-registered disinfectants with virucidal properties destroy them on surfaces.
Fungi cause infections like ringworm (tinea corporis), athlete's foot (tinea pedis), and nail fungus (tinea unguium). Fungal infections of the skin are contagious and are a contraindication for service in the affected area. Fungicidal products specifically target the cell structure of fungi.
| Pathogen Type | Examples Relevant to Esthetics | Destroyed By |
|---|---|---|
| Bacteria (vegetative) | Staphylococcus, Streptococcus | Disinfection |
| Bacteria (spore-forming) | Bacillus, Clostridium spores | Sterilization only |
| Viruses | HIV, HBV, HCV | EPA-registered virucidal disinfectant |
| Fungi | Ringworm, tinea | EPA-registered fungicidal disinfectant |
| Parasites | Lice, scabies mites | Service decline; does not apply to disinfectants |
⚠️ Exam Trap: The exam may present a scenario where a surface has been "disinfected" and ask whether it is now safe from all pathogens. The correct answer is no — disinfection does not destroy bacterial spores. Only sterilization achieves destruction of all microbial life.
Reflection Question: If your disinfectant is labeled "bactericidal and virucidal" but not fungicidal, and a client has a fungal infection on their skin, why is this a problem beyond just the client contraindication?
