Control of microbial growth Chapter 13 (13%)

In microbial control, why is simple cleaning (like washing or vacuuming) often preferred over sterilization for non-surgical items?

Sterilization is labor-intensive and may degrade the quality of the item

Which extreme protocol results in the complete destruction of all living cells, spores, and viruses on an object, often using heat under pressure?

Sterilization

What is the term for reducing a microbial population to levels deemed safe for public health, usually involving both cleaning and disinfection?

sanitation

Which microbial control process involves the killing or removal of disease-producing organisms from inanimate surfaces only?

disinfection

What is the term for the antimicrobial process of removing pathogens from the surface of living tissues, such as skin?

antisepsis

In the clinical setting, what is the term for the mechanical removal of microbes from a surface, such as the act of hand washing?

degerming

Which broad class of antimicrobial agents is defined by its ability to directly kill the targeted microorganisms?

-cidal agents

Which class of antimicrobial agents works by inhibiting or controlling the growth of microbes rather than killing them?

-static agents

On a microbial death curve, what is the term for the specific length of time required to kill 90% of a population?

D-value (decimal reduction time)

When comparing the efficiency of two antimicrobial agents, what does a lower D-value indicate about the agent’s effectiveness?

more effective/faster killing

Which criteria for selecting a disinfectant ensures the agent remains powerful even when substances like blood or feces are present?

Fast-acting in the presence of organic materials.

Among the factors influencing the speed of disinfection, how does the initial population size affect the time required to reach a specific number of survivors?

Larger populations require longer exposure times

Why is the presence of organic materials, such as blood or feces, a critical factor to consider when selecting a disinfectant?

They can bind to and inhibit the action of the disinfectant

In genetic analysis, what instrument is used to visualize and separate DNA fragments based on size using an electric current?

DNA Electrophoresis

In the control of microbial growth, why is cleaning often preferred over sterilization for many objects and surfaces?

Prevents item degradation and toxic effects on users

In microbial control, what process results in the destruction of ALL living cells, spores, and viruses on an object, often using heat under pressure?

sterilization

What process reduces microbial populations to safe levels and typically involves both cleaning and the use of harsh detergents?

sanitation

What is the term for the killing or removal of disease-producing organisms from inanimate surfaces?

disinfection

Which antimicrobial measure specifically targets the removal of pathogens from the surface of living tissues, such as skin?

antisepsis

In physical control methods, what is the term for the lowest temperature that kills all bacteria in a 24-hour-old culture within 10 minutes?

thermal death point

What is the term for the total time required to kill all bacteria in a culture at a specific, predefined temperature?

thermal death time

Why is moist heat more effective at killing microorganisms than dry heat?

It denatures and coagulates essential proteins

To achieve sterilization of spores and thermophiles, what are the standard conditions for an autoclave?

121°C at 15 psi for 20 minutes

Which pasteurization method involves bringing the product temperature to 63°C (146°F) for 30 minutes?

Low temperature, long time (LTLT)

What pasteurization technique, also called flash pasteurization, brings the temperature to 72°C (162°F) for 15 seconds?

High temperature, short time (HTST)

Which heating process produces sterilized products with unrefrigerated shelf lives up to 6 months by using a temperature of 138°C (273°F) for 2 seconds?

Ultra high temperature (UHT)

in microbial storage, what is the term for the process of freeze-drying used to store many microorganisms?

Lyophilization

What sterilization method is used for heat-sensitive drugs or chemicals by passing them through membranes with tiny pore sizes?

filtration

During irradiation, what specific type of radiation causes the formation of thymine dimers to damage DNA?

UV light

Which group of chemical agents, including detergents, assists in the mechanical removal of microbes from surfaces?

surfactants

For sterilizing disposable plastics like petri dishes or sutures that cannot handle heat, what microbicidal/sporicidal gas is used?

ethylene oxide

Why is it difficult for bacteria to develop resistance to chemical agents like iodine?

The agent has multiple targets and diffuses easily

Who is credited with discovering penicillin, the first natural antibiotic, from a mold contamination?

alexander flemming

What was the first synthetic antimicrobial created, which is the active breakdown product of Prontosil

sulfanilamide

Which researcher determined the structure of penicillin using X-rays, allowing for the production of semisynthetic versions?

dorothy hodgkin

What term describes a chemical substance made by a microorganism that can inhibit the growth of or kill other microorganisms?

antibiotics

What term describes the ability of an antimicrobial to harm microbes without damaging the host?

selective toxicity

In antimicrobial therapy, what is the ratio of the maximum tolerable dose per kg to the minimum curative dose per kg?

chemotheraputic index

What is the term for a secondary infection that occurs when broad-spectrum antibiotics kill nonresistant normal microbiota, allowing pathogens to proliferate?

superinfection

Which type of antibiotic activity stops growth by inhibiting multiplication without directly killing the bacteria?

bacteriostatic

What term describes an agent that kills bacteria specifically by causing cell lysis or cell wall breakdown?

bacteriolytic

What is the term for the lowest concentration of a drug that will prevent the growth of an organism in vitro?

Minimal inhibitory concentration (MIC)

Because the MIC test cannot distinguish between static and cidal effects, what test is used to find the lowest concentration that results in no growth after drug removal?

Minimum bactericidal concentration (MBC)