4.1 Microbiology: Bacteria, Viruses, Parasites, and Fungi

The Illinois esthetician exam is the National Interstate Council of State Boards of Cosmetology (NIC) National Esthetics Theory Examination. Domain I, Scientific Concepts, is 55% of the scored exam. I.A is basic knowledge of microbiology — bacteria, viruses, parasites, and fungi. Illinois does not replace that national science; it adds a legal overlay. 68 Ill. Adm. Code 1175.710 requires the licensing examination to cover sanitary rules and sanitary procedures, and 1175.115 is the sanitary-standard rule you apply in the room. Microbiology is how you decide which skin you may touch, which linens are safe, and when you must stop. You are not a physician. You do not diagnose. You recognize a contagious or inflamed presentation, refuse the service, and refer the client to a licensed medical professional.

Pathogenic Versus Nonpathogenic Bacteria

Bacteria are one-celled microorganisms. Most are nonpathogenic: they do not cause disease, and some are useful (they decompose waste or live harmlessly on intact skin). Pathogenic bacteria cause infection and disease. The exam will swap those two adjectives and expect you to notice. Pathogenic organisms of spa importance include staphylococci — pus-forming cluster cocci, including methicillin-resistant Staphylococcus aureus (MRSA) — streptococci, and other pus-producing bacteria that can turn a simple extraction into a spreading infection.

A local infection stays in one place: a pimple, a furuncle (boil), an abscess. A general infection (systemic) carries pathogens through the bloodstream. Fever, malaise, and spreading redness are medical problems, not extraction candidates. Contagious (communicable) disease can transfer from person to person. That transfer is the entire reason the Illinois treatment room has a disinfection protocol.

Pus is a clinical warning, not a product to “clear.” If a lesion is draining, inflamed, or spreading, 1175.115 already tells you to keep your hands off it. Microbiology explains why: the fluid is loaded with pathogenic bacteria, and your extractor, gauze, and chair become vehicles if you proceed.

The Three Shapes NIC Still Names

You will not Gram-stain a comedone on the clock. You will be asked which shape is round, which grouping is a cluster, and which bacterial form survives ordinary chemicals. Staphylococci in clusters are the pus-formers behind many boils. Streptococci in chains are associated with strep throat and some skin infections — not an esthetics diagnosis, but a reason to stay off inflamed tissue. Diplococci grow in pairs.

Spores Are the Hardest Microbial Form to Kill

When conditions are hostile, some bacteria — especially certain bacilli — form spores (endospores): dormant, dehydrated cells wrapped in a tough coat. Spores resist drying, heat, and many chemicals. Disinfection destroys most vegetative bacteria, fungi, and viruses; it does not reliably destroy spores. The only infection-control level that destroys all microbial life, including spores, is sterilization, typically a steam autoclave. That single sentence answers a large family of NIC items.

Illinois 1175.115 still requires everyday multi-use implements to be cleaned and disinfected (or discarded) after each client, and it requires a hospital-grade disinfectant on facial chairs. Autoclaving is the spore-killing method. It is not an excuse to skip Illinois chair disinfection, and a jar of disinfectant is not an autoclave. If a stem asks what is hardest to kill, the answer is the spore. If it asks what destroys the spore, the answer is sterilization — not an antiseptic wipe and not a 30-second dunk.

Viruses Cannot Live Independently

A virus is not a bacterium and not a cell. It is a submicroscopic particle that cannot live independently; it must invade a living host cell to reproduce. That is why “killing a virus with soap on the client’s lesion” is the wrong mental model. You prevent viral disease in the spa by refusing service on active lesions, by discarding single-use items, and by disinfecting nonporous tools and surfaces after every client.

High-yield viruses on the NIC list:

• Herpes simplex virus (HSV). HSV-1 commonly produces cold sores (fever blisters) on the lip. Steam, extraction, wax, or a peel over an active vesicle spreads virus on that face and onto your hands. Herpetic whitlow is a painful HSV infection of the finger — a classic occupational injury when an esthetician touches a lesion with a break in the skin or with a contaminated implement. Refuse the service. Do not “work around” a crusted vesicle with extra concealer.
• Human papillomavirus (HPV) causes warts. Do not pick, tweeze, extract, or otherwise “treat” a wart. Refer.
• Hepatitis B and hepatitis C are bloodborne viruses that infect the liver. They can persist on contaminated surfaces longer than many students expect. A nick during extraction, a shared implement that contacted blood, or poor cleanup after bleeding is the risk pathway.
• Human immunodeficiency virus (HIV) is also bloodborne. HIV does not persist in the environment the way a spore-forming bacillus can, but blood-to-blood and certain body-fluid exposures transmit it. Treat all blood as potentially infectious.

Hepatitis and HIV are not “skin diseases you treat with a mask.” They are reasons for glove use, implement disinfection, and stopping a service if blood appears. Standard Precautions, covered in the next chapter, rest on this microbiology.

Parasites and Fungi

Parasites live on or in a host and take nutrients. Two salon-stoppers:

• Pediculosis is infestation with lice. Head lice (pediculosis capitis) make headbands, towels, brow services, and facial headrests into fomite problems. Do not perform the service.
• Scabies is infestation with the itch mite Sarcoptes scabiei. Intense itching, burrows, and a contagious rash are a refuse-and-refer presentation. You do not confirm mites; a physician does.

Fungi include molds, mildews, and yeasts. Tinea is the ringworm group: tinea corporis (body), tinea capitis (scalp), tinea pedis (athlete’s foot). A circular scaly plaque is not a “dry patch to exfoliate.” Candida is a yeast that can infect skin folds and the mouth (thrush). Illinois even writes fungus into housekeeping: 1175.115(b)(26) requires walls, doors, windows, and ceilings to be clean and free of excessive spots, mildew, condensation, or peeling paint. Mildew on a treatment-room wall is a fungal sanitary failure, not décor.

Conjunctivitis (pink eye) is highly contagious. Do not perform lash services, brow services, or a facial that requires you to work at the orbital area. Eye pads, spatulas, and towels are classic fomites.

How Microbes Travel

Direct transmission is person-to-person contact: an ungloved hand on a herpetic lesion, then on your own eye or another client’s face.

Indirect transmission uses a contaminated object. That object is a fomite: a tweezer, a magnifying-lamp handle, a headband, a facial sponge (which Illinois already requires you to discard), or a chair that was not disinfected. The Illinois rule that facial chairs be cleaned and disinfected with a hospital-grade disinfectant before and after each client exists because the chair is a fomite.

Droplet transmission occurs when a cough or sneeze sprays respiratory droplets. Bloodborne transmission is exposure to blood or certain body fluids. Extractions, waxing over nicks, and accidental punctures are the esthetics settings.

Illinois: When You Must Refuse Service

Two 1175.115 sentences are the legal overlay on this science:

• No licensee shall be required or permitted to massage any surface of the skin or scalp where the skin is inflamed or where a skin infection or eruption is present (1175.115(b)(34)). An active HSV vesicle, weeping dermatitis, an inflamed MRSA boil, or a tinea plaque is “infection or eruption.” You do not extract it, steam it, or wax over it.
• No licensee shall be required or permitted to work upon a person suffering from a serious communicable disease, as defined in 77 Ill. Adm. Code 690 (1175.115(b)(35)). Owners and managers also may not knowingly permit a person with a serious communicable disease to work on the premises (1175.115(b)(33)).

Illinois does not ask you to become an epidemiologist. It asks you to keep contagious conditions out of the treatment room. Recognize and refer. Saying “that looks like herpes, I’ll just avoid the mouth” is still working on inflamed, infected skin. The correct exam answer is to decline the service and suggest the client see a physician.

High-yield combinations of science and the Illinois refuse rule:

• Herpetic whitlow on your own finger — you do not work until a physician has addressed the infection; you also inspect gloves and skin integrity before every client.
• Tinea on the face or body — no exfoliation, no wax, no mask on the lesion.
• Conjunctivitis — no lash or eye-area service.
• MRSA — a draining boil is both a local bacterial infection and a fomite factory. Stop. Do not cover it with a bandage and proceed.

1175.710 tests sanitary procedures because this is how a 750-hour Illinois graduate avoids becoming a vector. NIC I.A supplies the organisms. Illinois supplies the stop.