Infection Control for CNAs: Principles, Precautions, and Exam Guide

Infection control is the set of practices that prevent pathogens (bacteria, viruses, fungi, and other disease-causing microorganisms) from spreading between patients, from patients to staff, and from staff to patients. In a care facility, infections can be life-threatening, especially for elderly patients or those with weakened immune systems. Every procedure a CNA performs carries some risk of transmission, and infection control is how that risk is managed.

Unlike hand washing or blood pressure measurement, infection control is not a standalone skill with its own step-by-step checklist on the NNAAP exam. Instead, infection control principles are evaluated throughout every skill you perform during the exam. Your evaluator watches whether you wash your hands at the right moments, wear gloves when appropriate, handle contaminated items correctly, and maintain clean technique across the entire exam. This makes infection control the invisible framework underneath every other skill.

Why This Skill Matters on the CNA Exam

Because infection control is embedded in every skill rather than isolated in one, it is possible to lose points for infection control errors during a blood pressure measurement, a weight check, or any other skill on your exam. The evaluator uses a checklist for each skill that includes infection control steps. If you skip hand hygiene before a skill or handle a contaminated item without gloves, those points are deducted from the skill where the error occurred.

This also means infection control knowledge compounds. Students who understand why each precaution exists tend to apply it correctly even under the pressure of an exam, because they are not memorizing a list. They are making a decision based on a principle they understand. The time you spend now understanding the chain of infection and standard precautions will pay off across every skill in the exam, not just one.

Check with your state's testing provider for the specific infection control checklist items included in each skill's evaluation criteria, as wording can vary slightly by state.

Standard Precautions: The Baseline

Standard precautions are the foundation of infection control practice. The core idea is to treat the blood and body fluids of every patient as potentially infectious, regardless of their diagnosis, because you cannot tell by looking at someone whether they carry a pathogen. Standard precautions apply to every patient, every time.

Standard precautions include:

Hand hygiene before and after every patient contact and any time you may have been exposed to infectious material
Gloves whenever you may contact blood, body fluids, mucous membranes, or broken skin
Gown when your clothing or skin might be soiled with blood or body fluids
Mask and eye protection when there is a risk of splashing or spraying of blood or body fluids
Safe handling of sharps (needles, lancets) to prevent needlestick injuries
Safe disposal of contaminated materials in designated waste receptacles
Respiratory hygiene for patients or visitors who are coughing or sneezing

The Chain of Infection

The chain of infection is a model that describes how an infectious disease spreads. It has six links. Breaking any single link stops transmission. Understanding this model helps you make quick decisions in patient care rather than waiting to be told what precautions to use.

Pathogen (Infectious Agent): The microorganism that causes disease. Examples include influenza virus, MRSA bacteria, and Clostridium difficile. Different pathogens require different precautions based on how they spread.
Reservoir: The place where the pathogen lives and multiplies. In healthcare, reservoirs include patients, staff, visitors, equipment surfaces, and even the water supply in some cases.
Portal of Exit: How the pathogen leaves the reservoir. Respiratory droplets when a person coughs or sneezes, blood from a wound, feces, urine, and saliva are all portals of exit.
Mode of Transmission: How the pathogen travels from one host to another. The three main modes are contact (direct skin-to-skin or indirect via contaminated surfaces), droplet (large particles that fall within about 3 feet), and airborne (tiny particles that can travel farther and remain suspended in the air).
Portal of Entry: How the pathogen enters a new host. Mucous membranes in the eyes, nose, and mouth are common entry points. Broken skin, the respiratory tract, and the digestive tract are others.
Susceptible Host: The person who can be infected. Elderly patients, immunocompromised individuals, and those with open wounds are at higher risk. A healthy immune system provides some resistance, but CNAs can still carry and transmit pathogens even when they feel well.

Your primary tools for breaking the chain are hand hygiene (interrupts portal of exit and portal of entry), PPE (interrupts mode of transmission and portal of entry), proper disposal (eliminates reservoir), and patient isolation when needed.

Transmission-Based Precautions

When a patient has a known or suspected infection, standard precautions are not always enough on their own. Transmission-based precautions are added on top of standard precautions for specific routes of transmission. There are three types.

Contact Precautions

Used for pathogens spread through direct or indirect physical contact. Examples include MRSA (a drug-resistant form of staph bacteria), C. difficile (a serious intestinal infection), and scabies. Requirements typically include: wearing gloves and a gown for all room entry, dedicating equipment (stethoscope, blood pressure cuff) to a single patient so it does not carry pathogens from room to room, and careful hand hygiene especially after removing gloves since some contact pathogens like C. diff are not killed by alcohol-based sanitizers and require soap and water.

Droplet Precautions

Used for pathogens spread by respiratory droplets produced when a person coughs, sneezes, or talks. Droplets are relatively large and fall within about 3 to 6 feet of the source. Examples include influenza, whooping cough (pertussis), and some forms of meningitis. Requirements typically include: a surgical mask when within 3 to 6 feet of the patient, and keeping the patient's door closed.

Airborne Precautions

Used for pathogens spread through tiny particles that can remain suspended in the air for extended periods and travel beyond 6 feet. Examples include tuberculosis (TB), measles, and chickenpox. Requirements typically include: a fit-tested N95 respirator (not just a surgical mask), placement of the patient in an airborne infection isolation room with negative air pressure that keeps contaminated air from flowing outward when the door is opened.

Medical Asepsis vs. Surgical Asepsis

These two terms come up in CNA training and are worth understanding clearly.

Medical asepsis (also called clean technique) means reducing the number of pathogens and preventing their spread. This is what CNAs practice during most daily care tasks. Hand washing, wearing gloves, and proper disposal of used supplies are all examples of medical asepsis. You are not creating a sterile environment, but you are keeping contamination to a minimum.

Surgical asepsis (also called sterile technique) means eliminating all microorganisms, including spores. This is used for procedures that involve entering the body through the skin (like inserting a catheter or changing a sterile wound dressing). CNAs may assist with sterile procedures, but the sterile technique itself is typically performed by nurses. On the NNAAP exam, you are expected to understand the difference and maintain clean technique throughout your skills.

How Infection Control Is Evaluated Throughout the Exam

Your evaluator is watching for infection control compliance during every skill, not just the hand washing skill. Here is what that looks like in practice:

You are expected to wash hands at the start and end of every individual skill
You are expected to don gloves before any contact with body fluids or potentially contaminated surfaces
You should remove gloves and perform hand hygiene if you need to touch a clean surface mid-skill (for example, reaching for documentation materials after touching a patient)
Any item that has been in contact with a patient is considered contaminated and should be handled accordingly
You should never place clean equipment on contaminated surfaces
If you breach any of these principles during a skill, it may result in point deductions from that skill's score

Common Mistakes to Avoid

Skipping hand hygiene between skills. Many students wash their hands before the first skill and do not repeat it before subsequent skills, because they are focused on the next task. Every skill starts and ends with hand hygiene.
Wearing gloves when they are not needed. Wearing gloves for non-contact tasks like writing or adjusting bed rails gives a false sense of protection and can spread contamination from gloves to surfaces you did not intend to touch.
Reusing or adjusting gloves mid-skill. If a glove tears or becomes visibly contaminated during a skill, stop, remove both gloves, wash your hands, and put on a new pair before continuing.
Placing clean supplies on the patient's bed or overbed table without a clean barrier. These surfaces are considered contaminated. If you set clean supplies directly on them, the supplies are now contaminated too.
Not recognizing which type of transmission-based precaution applies. On the written portion of the NNAAP exam, questions about which PPE to use for a patient with TB or MRSA are common. Know the three precaution types and their corresponding PPE requirements.
Treating alcohol-based hand sanitizer and soap as interchangeable. For most pathogens, hand sanitizer is acceptable. For C. difficile, friction with soap and water is required because alcohol does not kill C. diff spores. In exam scenarios involving C. diff, specify soap and water.

Key Terms to Know

Pathogen: A microorganism capable of causing disease
Reservoir: The source where a pathogen lives and multiplies
Standard precautions: Infection control practices applied to every patient regardless of diagnosis
Contact precautions: Added precautions for pathogens spread by physical contact
Droplet precautions: Added precautions for pathogens spread by respiratory droplets within approximately 6 feet
Airborne precautions: Added precautions for pathogens that travel through the air over long distances (TB, measles, chickenpox)
Medical asepsis (clean technique): Reducing pathogens and preventing their spread during routine care
Surgical asepsis (sterile technique): Eliminating all microorganisms for procedures that enter the body
Chain of infection: The six-link model describing how an infection spreads from source to host

Infection control principles apply to every skill on the NNAAP exam. If you are preparing for certification, browse CNA programs in your state to find one that includes supervised clinical practice.

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