TEST: Medical Microbiology - Chapter 7 Control of Microbial Growth

What would be the best method to sterilize heat-labile solutions?

membrane filtration

How would you describe the best pattern for microbial death?

the cells in a population die at a constant rate

Bacteriostatic

keeps cells at appropriate levels

Germicide

kills microbes

Viricide

inactive viruses

Sterilant

destroys all living microorganisms

Fungicide

kills yeasts and molds

How is an autoclave beneficial? What is a limitation?

-requires little time to achieve sterilization, kill endospores, can be used with glassware

-it cannot be used with heal-labile microorganisms

An agent used to reduce the number of bacteria on a toilet would most accurately be called a —-?

disinfectant

What 4 things are examples of oxidizing agents?

-chlorine

-hydrogen peroxide

-iodine

-ozone

Which method is used to preserve food by slowing the metabolic processes of foodborne microbes

freezing

Which concentration of ethanol is the most effective bactericide?

70%

Which pasteurization treatment is the most effective for controlling microbial growth?

140* C for 4 seconds

Which graph best depicts the effect of placing the culture in the autoclave for 15 mins at time x?

b

Which graph best depicts the effect of placing the culture at 7* C at time x?

d

Which compound is the most effective against Staphylococcus?

c

Which preservative is most effective?

potassium sorbate and sodium benzoate

The preservation of beef jerky from microbial growth relies on which method of microbial control?

desiccation

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization

False

Desiccation is a reliable form of sterilization

False

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature

True

Pseudomonas has been found growing in quaternary ammonium compounds (quats)

True

Moist heat destroys organisms by denaturing proteins

True

Some antimicrobial chemicals are considered to be disinfectants and antiseptics

True

The pH of the medium has no effect on the activity of the disinfectant being applied

False

Ultraviolet light (UV) causes irreversible breaks in DNA strands

False

Autoclaving is the most effective method of moist heat sterilization

True

Microorganisms placed in high concentration of salts and sugars undergo lysis

False

A suffix meaning “to kill”

-cide

Destroying or removing all forms of microbial life

sterilization

The absence of pathogens on an object or area

asepsis

The reduction of microbial populations to safe public health levels

sanitation

The chemical disinfection of living tissue, such as skin or a mucous membrane

antisepsis

The removal of transient microbes from skin by mechanical cleansing or by an antiseptic

degerming

Heat sufficient only to kill endospores of the botulism bacterium

commercial sterilization

The lowest temperature required to kill a liquid culture of a certain species of bacteria in 10 minutes

thermal death point

The time in minutes required to kill 90% of a bacterial population

decimal reduction time

Mild heating to destroy particular spoilage microorganisms or disease organisms in milk or similar products

pasteurization

A test for the effectiveness of a chemical disinfectant

phenol coefficient

The absence of water, resulting in a condition of dryness

desiccation

Ultraviolet light is a good example of _________ radiation

non ionizing

Sunlight owes its biocidal activity mainly to the formation of _________

singlet oxygen

A good example of ionizing radiation is ______, _______, and ___________.

-x rays

-gamma rays

-high energy electrons

Ethanol is usually used in concentration of about ____.

70%

A less irritating form of formaldehyde is ____________

glutaraldehyde

Steam under pressure is obtained in retorts, pressure cookers, and _________

autoclaves

Generally speaking, the group of microorganisms that is more resistant to osmotic pressure than bacteria area ________ such as ______ or _______.

fungi; yeasts; molds

Supercritical __________ ____________ is used for decontaminating foods and medical implants

carbon dioxide

Steam _______ _________ allows temperatures above boiling to be reached

under pressure