Scientific Concepts and Infection Control
What this domain tests
Microbiology as it is actually applied behind the chair: how pathogens travel from client to client, which level of decontamination each item needs, and the safety habits a state inspector checks first.
Pathogens you will meet
Bacteria come as cocci (round), bacilli (rod), and spirilla (spiral); some form spores that survive ordinary disinfectants. Viruses such as hepatitis B, HIV, and herpes simplex are not destroyed by a sanitizer alone. Fungi cause tinea capitis and tinea barbae; parasites include pediculosis and scabies. Standard (universal) precautions mean treating every client's blood and body fluids as infectious - no exceptions for clients who "look clean."
Four levels of decontamination
- Cleaning - soap, detergent, and water remove visible debris; it is not disinfection.
- Sanitizing - reduces bacteria to a safe level; fine for floors, linens, and non-critical surfaces.
- Disinfecting - destroys most pathogens with an EPA-registered hospital-grade product, typically a 10-minute full immersion for implements.
- Sterilizing - destroys all microbial life including spores; autoclave at 250°F and 15 psi for 15–20 minutes, or use dry heat.
Nonporous items (metal shears, combs, nippers) can be disinfected. Porous items (files, buffers, cotton, wooden sticks) cannot be reliably disinfected and must be discarded or given to the client. Always clean before you disinfect, then store in a closed container. Keep an SDS on file for every chemical - OSHA requires it.
Worked example
A client arrives with a round, scaly, itchy patch on the scalp. Reasoning: this pattern suggests tinea capitis, a fungal infection, not dandruff. The service is declined and the client is referred to a physician. The comb used is cleaned, then immersed for 10 minutes in hospital-grade disinfectant; the cape is laundered; porous items are discarded. You do not "work around" the spot - the entire service is postponed.
Traps that cost marks
Treating sanitize and disinfect as synonyms; trusting a UV cabinet or a jar of blue liquid without prior cleaning; reusing a porous file; assuming a client with no visible symptoms cannot be contagious.