WILK ch5-7 Infection Control

What are the six links in the chain of infection that must all be present for disease transmission to occur?

Infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.

What is the difference between a pathogenic and a nonpathogenic microorganism?

A pathogenic agent produces disease, while a nonpathogenic agent does not, although nonpathogenic agents can still cause disease in susceptible individuals.

Name the five general categories of infectious agents.

Bacteria, viruses, fungi, protozoa and helminths, and prions.

What is the difference between passive and active immunity?

Passive immunity is protection transferred from another person or animal (immediate but temporary), while active immunity is protection the body develops itself by having the disease or by vaccination (takes time but can be lifelong).

What is the difference between a live attenuated vaccine and an inactivated vaccine?

A live attenuated vaccine contains a weakened form of the infectious agent and can give lifelong immunity, while an inactivated vaccine contains whole or partial inactive agents and immunity may require booster doses.

How do mRNA vaccines work, and what do they NOT do?

They deliver a genetic "message" that prompts cells to produce a viral protein (antigen) that triggers an antibody response; they cannot enter the cell nucleus or alter a person's DNA.

What is an asymptomatic carrier?

A patient who harbors and can transmit a pathogen but shows no signs or symptoms of disease.

What is cross-contamination?

The spread of microorganisms from one source to another, either person to person or person to an inanimate object and then to another person.

What are Standard Precautions and to whom do they apply?

A minimum standard of care that treats the blood, saliva, and body fluids of every patient as potentially infectious, applied to all patients and procedures regardless of known disease status.

What are Transmission-Based Precautions used for?

Extra precautions added on top of Standard Precautions when a patient has or is suspected of having a disease that spreads by contact, droplet, or airborne routes.

Give an example of a disease requiring droplet precautions.

Influenza virus, SARS-CoV-2, or Bordetella pertussis (whooping cough).

Give an example of a disease requiring airborne precautions.

Mycobacterium tuberculosis, measles, or SARS-CoV-2.

Give an example of an organism requiring contact precautions.

MRSA or vancomycin-resistant enterococci.

Which three bloodborne pathogens are of greatest concern to dental healthcare personnel?

Hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV.

Which bloodborne pathogen has a vaccine available for healthcare workers?

Hepatitis B virus (HBV); there is no vaccine for HCV or HIV.

What does a positive HBsAg (hepatitis B surface antigen) test indicate?

That the person is infectious with hepatitis B, whether the infection is acute or chronic.

What does a positive Anti-HBs test generally indicate?

Recovery and immunity to hepatitis B, either from past infection or from vaccination.

What cells does HIV primarily attack?

CD4 T lymphocytes (T-cells), which weakens the immune system's ability to fight opportunistic infections.

What CD4 T lymphocyte count indicates a person is at risk for opportunistic infections?

A CD4 count below 200 cells/mm3 (or below 14%).

What defines the AIDS stage of HIV infection?

A severely weakened immune system under attack from opportunistic infections, representing the last stage of HIV disease.

What are aerosols, droplets, and spatter, classified by size?

Droplet nuclei are about 5 μm, droplets range 5 to 100 μm, and spatter is greater than 100 μm.

What are aerosol-generating procedures (AGPs), and give two examples used in dentistry.

Procedures that create airborne aerosols; examples include ultrasonic scaling and use of high-speed handpieces.

What is one way dental hygienists can reduce microorganisms in aerosols before a procedure?

Have the patient perform a preprocedural rinse with an antiseptic mouthrinse such as 0.12% chlorhexidine gluconate.

What water quality standard must dental unit waterlines meet?

Less than 500 CFU/mL of heterotrophic water bacteria, meeting EPA drinking water standards.

Does flushing dental waterlines remove biofilm from inside the tubing?

No, flushing reduces planktonic (free-floating) bacteria but does not remove established biofilm from waterline walls.

What organizing principle governs all of Chapter 6, exposure control?

Standard Precautions applied through personal protective equipment and consistent barrier techniques for every patient.

List the components of personal protective equipment (PPE) discussed in Chapter 6.

Gloves, masks or respirators, protective eyewear or face shield, hair coverings, and protective clothing/gowns.

What is the minimum bacterial filtration efficiency (BFE) recommended for a surgical mask covering the nose and mouth?

At least 95% BFE.

When should DHCP use an N95 or equivalent respirator instead of a surgical mask?

For patients with suspected or confirmed airborne disease such as active tuberculosis or COVID-19, in poorly ventilated settings, or for procedures likely to generate significant droplet spatter or aerosols.

How often should a surgical mask be changed during routine procedures?

At least every hour, or sooner if it becomes wet.

What is the difference between resident flora and transient flora on the skin?

Resident flora are bacteria that live permanently on the skin, while transient flora are picked up temporarily from surfaces or patients and are the main target of hand hygiene.

What is the minimum recommended duration for a routine handwash?

About 40 to 60 seconds, with at least 15 seconds of active rubbing.

Name two examples of antimicrobial agents used in an antiseptic handwash.

Chlorhexidine and iodine/iodophors (also triclosan or PCMX).

List the four indications for performing hand hygiene given in the chapter.

Before and after treating each patient, before regloving after a torn or punctured glove, after ungloved contact with contaminated objects, and whenever hands are visibly soiled.

What materials are used to make nonlatex gloves?

Neoprene, block copolymer, vinyl, and nitrile.

Why must nonlatex gloves be available in a dental practice?

Because some patients or clinicians have latex allergies and require latex-free alternatives.

List two factors that can compromise glove integrity.

Extended wearing time and exposure to certain chemicals (oils, some disinfectants) can create microscopic tears; physical wear and stretching can also weaken the material.

What is the difference between critical, semicritical, and noncritical instruments/items?

Critical items penetrate soft tissue or bone and must be sterilized; semicritical items contact intact mucous membranes and have lower transmission risk but still require sterilization when possible; noncritical items only contact intact skin and need only disinfection.

What is the difference between disinfection and sterilization?

Disinfection kills most microorganisms on a surface but not necessarily resistant spores, while sterilization destroys all forms of microbial life, including spores.

What temperature and time are required for gravity displacement steam autoclave sterilization?

250°F (121°C) for 15 to 30 minutes.

What temperature and time are required for dry heat oven sterilization?

320°F (160°C) for 120 minutes.

Name the three types of tests used to verify a sterilizer is working properly.

An external chemical indicator, an internal chemical indicator, and a biologic (spore) monitor.

What organism is used to biologically test a steam autoclave?

Geobacillus stearothermophilus (formerly Bacillus stearothermophilus).

How often should biologic monitoring of a sterilizer be performed?

Weekly, or whenever the unit is repaired or relocated.

Why is precleaning instruments important before sterilization?

Leftover organic debris can shield microorganisms from heat or chemical exposure and cause sterilization to fail.

Name the three precleaning methods described for instruments.

Manual scrubbing, an instrument washer/thermal disinfector, and ultrasonic processing.

What is the purpose of barriers and surface covers in the treatment room?

To protect contact surfaces from contamination so they do not need to be disinfected between every patient, saving time while maintaining asepsis.

What defines a "significant exposure" in occupational postexposure management?

Contact with blood or certain body fluids through a needlestick, cut, or splash onto mucous membranes or nonintact skin.

What should a dental healthcare provider do immediately after a significant occupational exposure?

Follow the practice's postexposure protocol, which includes immediate care of the wound/site and prompt reporting and evaluation, followed by appropriate testing and follow-up.

How does chapter 5's "chain of infection" concept connect to the PPE and sterilization content in chapters 6 and 7?

Every precaution, barrier, and sterilization method described in chapters 6 and 7 works by breaking one specific link in the infection chain described in chapter 5.