Esthetician (NIC Theory Exam) Microbiology and Infection Control Summary

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.

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.

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.

The label lists the time a disinfectant must stay wet on a clean surface to work. If it dries early, the tool is not properly disinfected.

Wrong choices

• How long the bottle can be stored: Storage life is the shelf life or expiration date.
• How long the tool should be stored after use: Storage of tools is a separate step.
• How much water to add: Dilution is given as a mixing ratio, not contact time.

Blood can carry disease, so protect yourself with gloves. Stop the bleeding and clean the area. Throw away soiled single-use items in a sealed bag and disinfect reusable tools.

Wrong choices

• Wipe the area with a damp cloth and continue: A damp cloth does not control infection risk and you may spread blood.
• Rinse the tool in water and reuse it: Rinsing does not disinfect a tool that touched blood.
• Ask the client to ignore it: Ignoring a wound is unsafe for both of you.

Remove debris first, then use the disinfectant on a clean tool for the full contact time listed on the label.

Wrong choices

• Disinfect, then clean and rinse: Disinfecting before cleaning wastes the disinfectant because dirt blocks it.
• Rinse in alcohol, then store: A quick alcohol rinse is not full disinfection.
• Dry it and store it without further steps: Storing without disinfecting leaves germs on the tool.

Bacteria come in three basic shapes. Cocci are round, bacilli are rod-shaped, and spirilla are spiral.

Wrong choices

• Bacilli: Bacilli are rod-shaped, not round.
• Spirilla: Spirilla are spiral-shaped, not round.
• Protozoa: Protozoa are single-cell animals, not bacteria.

A pathogen is a germ that can cause disease. Bacteria, viruses, fungi, and parasites can all be pathogens.

Wrong choices

• Harmless: Harmless germs are called nonpathogenic.
• Helpful to the body: Helpful germs are nonpathogenic.
• Resistant to heat: Heat resistance has nothing to do with causing disease.

Cold sores come from the herpes simplex virus. Viruses cannot be treated with antibiotics.

Wrong choices

• Ringworm: Ringworm is a fungal infection.
• Staph infection: A staph infection is caused by bacteria.
• Head lice: Head lice are parasites.

Porous items soak up fluids and cannot be reliably disinfected. They are discarded after one client.

Wrong choices

• Soak them in disinfectant overnight: Soaking does not make a porous item safe to reuse.
• Wipe them with a damp cloth: Wiping does not reach inside the material.
• Let them air dry and reuse them: Air drying does not kill germs.