Esthetician (NIC Theory Exam) · Scientific Concepts
Esthetician (NIC Theory Exam): Microbiology and Infection Control Concepts
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Overview
This chapter is about germs and how to keep clients and yourself safe from them. You will learn the main types of microorganisms and the three levels of germ control. The exam often asks which level fits which tool or situation.
Bacteria, viruses, fungi, and parasites can all cause problems in a salon or spa. Bacteria are single cells, and some form round, rod, or spiral shapes. Viruses are much smaller and need a living host to multiply, so a disinfectant cannot treat a virus that is already inside a person.
Sanitation, disinfection, and sterilization are three steps up a ladder. Sanitation only lowers the number of germs on a clean surface. Disinfection kills most germs on hard, nonporous items, and sterilization kills every living microbe, including spores. A tool must be cleaned before it is disinfected, because dirt blocks the disinfectant.
Porous items such as cotton pads, wooden sticks, and emery boards cannot be disinfected, so they are used once and thrown away. Blood and body fluids are treated as possibly infectious on every client. Handwashing, gloves, and clean linens are everyday habits that help prevent the spread of infection.
Key concepts
Sanitation
The lowest level of germ control. Washing with soap and water lowers the number of germs on a surface but does not kill them all.
Memory tipSanitize = clean. It is the first step, not the last.
Disinfection
A level above sanitation that kills most germs on hard, nonporous surfaces such as metal tools and countertops. A product must be used with its label directions, including contact time.
Memory tipDisinfect after cleaning, and keep the item wet for the full contact time.
Sterilization
The highest level. It destroys all microbial life, including spores. Medical settings use an autoclave to do it.
Memory tipSterile = nothing alive is left.
Porous items
Items with tiny holes that soak up liquid, such as cotton pads, emery boards, and wooden spatulas. They cannot be disinfected.
Memory tipIf you cannot disinfect it, use it once and throw it away.
Standard Precautions
Treating all blood and body fluids as possibly infectious, no matter who the client is. This includes wearing gloves and cleaning up spills safely.
Memory tipAssume every client could carry something.
Bacterial shapes
Cocci are round, bacilli are rod-shaped, and spirilla are spiral. Staphylococci grow in clusters and are linked to many skin infections.
Memory tipRound = cocci, rod = bacilli, spiral = spirilla.
Bloodborne pathogen rules
Workplace rules require protecting workers from contact with infected blood. Exposure after a cut should be handled by washing, bandaging, and following the workplace plan.
Memory tipCut during a service: stop, glove up, clean, and cover the area.
Source: OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030, issued 1991, revised 2001) · as of 2001
Often tested
- The order is clean first, then disinfect. A dirty tool cannot be disinfected well.
- Only sterilization kills spores.
- Single-use porous items go in the trash after one client.
- Viruses need a living host; antibiotics do not work on them.
- Wash your hands before and after every client.
Easy to confuse: Three levels of germ control
| Level | What it does | Example |
|---|---|---|
| Sanitation | Lowers the number of germs | Washing a brush with soap and water |
| Disinfection | Kills most germs on hard surfaces | Soaking clean metal tweezers in a disinfectant |
| Sterilization | Kills all life, including spores | Autoclave for metal instruments |
3 sample questions
Verified practice questions from this unit.
Question 1. Which term means destroying all microbial life, including bacterial spores?
- ① Disinfection
- ② Sterilization
- ③ Sanitation
- ④ Antisepsis
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Answer: ② Sterilization
Key point: Sterilization kills all microbial life
Sterilization is the highest level of infection control. It destroys every living microbe, including hard-to-kill spores.
Wrong choices
- Disinfection: Disinfection kills most germs on nonporous surfaces but not all spores.
- Sanitation: Sanitation only cleans to lower the number of germs.
- Antisepsis: Antisepsis slows germs on skin and is not the same as sterilization.
Question 2. Which level of infection control only cleans a surface to lower the number of germs?
- ① Disinfection
- ② Sterilization
- ③ Sensitization
- ④ Sanitation
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Answer: ④ Sanitation
Key point: Sanitation = cleaning to reduce germs
Sanitation (cleaning) is the lowest level. It washes away dirt and many germs but does not kill them all.
Wrong choices
- Disinfection: Disinfection uses a chemical to kill most germs.
- Sterilization: Sterilization kills all microbial life.
- Sensitization: Sensitization is an allergic response, not a cleaning level.
Question 3. What must you do to a nonporous tool before you disinfect it?
- ① Dry it in the sun
- ② Rinse it with plain water only
- ③ Wrap it in a towel
- ④ Clean it with soap and water
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Answer: ④ Clean it with soap and water
Key point: Clean first, then disinfect
A disinfectant works only on a clean surface. Dirt and oils can block it, so wash the tool with soap and water first.
Wrong choices
- Dry it in the sun: Sunlight is not an approved cleaning step.
- Rinse it with plain water only: Plain water does not remove oils and debris well enough.
- Wrap it in a towel: A towel does not clean the tool and may spread germs.