Week 3 (Chapter 2,3,8): Control of Micorbial Growth

What is the importance of controlling microorganisms in dentistry?

To prevent the transmission of diseases in the dental setting and protect clients and staff from exposure to infections.

When removing PPE, which item is removed first?

Gloves

Which step breaks the chain of infection?

Removing any element of the chain

Which disinfectant is considered intermediate-level and commonly used for spills

Intermediate-level chlorine compound

A bacterial plasmid may provide

Antibiotic resistance

The microorganism most associated with toxigenic food poisoning without entering the body is

Straphylococcus aureus

Which type of flora is responsible for disease transmission and is easily removed with handwashing?

Transient flora

Define asepsis.

A method that prevents contamination by unwanted microorganisms; the absence of infection or infectious materials.

What is cross-contamination?

A process that allows the transfer of microorganisms between persons and/or environmental surfaces or to a sterile object.

What are the pathways for cross-contamination?

1. Client to Dental Team 2. Dental Team to Client 3. Client to Client 4. Dental Office to Community 5. Community to Client

What is the difference between obligate aerobes and obligate anaerobes?

Obligate aerobes require oxygen for growth, while obligate anaerobes cannot survive in the presence of oxygen.

What are bactericidal agents?

Agents that kill bacteria.

What are bacteriostatic agents?

Agents that stop the growth of bacteria but do not necessarily kill them.

Define sterilization.

A process intended to destroy or kill all microorganisms in a material or on an object.

What is disinfection?

A process that decreases or minimizes the number of pathogenic organisms on objects or in materials.

What is pasteurization?

A heat process employed to reduce the number of bacteria and destroy pathogens, commonly used in dairy products.

What is lyophilization?

A process of preserving microbes by removing water, rapidly freezing the sample, and drying it using a vacuum pump.

What are the three types of sterilization?

1. Heat Sterilization (steam & dry heat) 2. Gas Sterilization 3. Chemical Sterilization.

What is the role of biologic monitors in sterilization?

To monitor the use and function of heat and gas sterilizers using spores of Geobacillus stearothermophilus and Bacillus atrophaeus.

What are standard precautions?

A set of infection control practices used to prevent the transmission of diseases through contact with blood, body fluids, nonintact skin, and mucous membranes.

What is the goal of infection control?

To reduce the dose of microorganisms that may be shared between individuals or between individuals and contaminated surfaces.

What is the difference between endogenous and exogenous diseases?

Endogenous diseases are caused by microorganisms in or on the body, while exogenous diseases are caused by microorganisms not normally present in the body.

What are opportunistic pathogens?

Microorganisms that cause infectious diseases only when favorable conditions exist.

What is the significance of asymptomatic carriers?

Persons who have disease agents in their bodies but do not show recognizable symptoms, posing a risk for disease transmission.

What factors influence microbial growth?

Nutrient availability, temperature, pH, moisture, and oxygen levels.

List three common antibiotics recommended for use in dentistry.

1. Amoxicillin 2. Clindamycin 3. Metronidazole.

What are the modes of disease transmission?

1. Direct Contact 2. Indirect Contact 3. Droplet Infection 4. Airborne Infection.

What is the definition of toxigenic diseases?

Diseases caused by exogenous microorganisms that produce toxins without entering and multiplying in the body.

What are the common sources of disease agents in a dental office?

The mouth is the major source of disease agents.

What is the rationale for infection control?

To take action to stay healthy, avoid contact with infectious materials, limit the spread of contaminants, and make objects safe for use.

What are the three main types of heat sterilization?

Steam, dry heat, and unsaturated chemical vapor.

What temperature range is used in heat sterilizers?

121°C to 190.6°C.

What is the purpose of biological monitoring in heat sterilization?

To monitor the effectiveness of sterilization using bacterial spores.

What is a disadvantage of ethylene oxide gas sterilizers?

They have a long exposure time, high cost, and require special handling.

What is liquid chemical sterilization used for?

Items that can be damaged by heat sterilization.

Name two chemicals used in liquid chemical sterilization.

Glutaraldehyde and special hydrogen peroxide.

What is high-level disinfection (HLD) and why is it discouraged?

It is a process using high-level disinfectants that are toxic and may not destroy all microorganisms.

What is the primary goal of disinfection?

To reduce and kill disease-producing microorganisms, but not bacterial endospores.

List three types of disinfectants.

Alcohols, quaternary ammonium compounds, and glutaraldehyde.

What environmental factors influence microbial growth?

Temperature, atmospheric pressure, pH, salinity, osmotic pressure, hydrostatic pressure, and radiation.

What temperature range do mesophiles thrive in?

22°C to 45°C, with optimal growth at 37°C.

What are thermophiles and their ideal growth temperature?

Heat-loving bacteria that thrive at 45°C to 70°C, ideally at 56°C.

What is the temperature range for psychrophiles?

1°C to 22°C, with optimal growth at 7°C.

What pH range do most microorganisms prefer for optimal growth?

Neutral pH around 7.0.

What is a barophile?

An organism that thrives at high pressures, such as deep-sea bacteria.

What is the effect of ultraviolet light on microorganisms?

It damages DNA, leading to mutations and cell death.

Who was Paul Ehrlich and what did he contribute to antimicrobial history?

He was the first to use chemotherapeutic drugs, specifically sulfonamides, to treat bacterial infections.

What is penicillin and who discovered it?

An antibiotic discovered by Alexander Fleming that kills staphylococci bacteria.

What are the common types of antimicrobials used in dentistry?

Chlorhexidine, phenols, quaternary ammonium compounds, and antibiotics.

What is the primary action of antibiotics?

They interfere with bacterial cell wall formation, preventing growth.

What are the consequences of antibiotic overuse?

Increased resistance, toxicity, and allergic reactions.

What is the difference between bactericidal and bacteriostatic agents?

Bactericidal agents kill bacteria, while bacteriostatic agents inhibit their growth.

Pathogens

Microbes causing disease

Opportunistic pathogens

Normally harmless until conditions permit disease

Endogenous

From the body's own flora

Exogenous

From outside the body

Toxigenic

Caused by toxins produced in contaminated food (botulism)

Asepsis

Preventing contamination

Cross-contamination

Transfer of MO's between surfaces, people, instruments

Universal precautions

Treat all clients as infectious

Standard precautions

PPE + handling of all body fluids (except sweat)

Modes of Transmission

Ways in which infections are spread

Direct contact

Touching tissues/fluids

Indirect contact

Instruments, surfaces

Droplet infection

Sprays, splatter, aerosols

Airborne

TB, measles; require N95 respirator

Chain of Infection

Infection requires ALL: Agent → Reservoir → Portal of exit → Mode of transmission → Portal of entry → Susceptible host

Sterilization

Destroys all microorganisms including spores

Disinfection

Reduces or kills pathogens but NOT spores

Antimicrobials

Inhibit microbe metabolism or replication

Antibiotics

Act only on bacteria (not viruses or eukaryotic cells)

CDC

Provides expertise, research, and guidelines to prevent disease and promote health

Hand Hygiene

Perform when visibly soiled OR before/after client care

PPE (Order of Donning)

1. Hand hygiene 2. Gown 3. Mask or N95 4. Eye protection 5. Gloves

Sterilization & Instrument Processing

Clean → package → sterilize → store

Environmental Infection Control

Use surface barriers, preclean before disinfecting

Dental Unit Waterlines (DUWLs)

Flush lines 20-30 seconds between clients (CDC)