Microbiology Chapter 6

natural host of leprosy?

armadillos

Examples of historical microbial control methods?

salting food

smoking food

pickling food

drying food

exposing food, clothing, and bedding to sunlight

burning clothing and corpses

storing water in copper and silver containers

define sepsis

the growth of microorganisms in blood and other tissues

define aseptic techniques

sterile methods that exclude all microbes

define antisepsis/degermation

application of chemical agents (antiseptics) to exposed body surfaces, wounds, and surgical incisions to destroy or inhibit pathogens

examples of physical agents for microbial control methods

heat (dry and moist) and radiation (ionizing and nonionizing)

examples of dry physical agents

incineration and dry oven

the microbial control method for incineration is….

sterilization

the microbial control method for dry oven is…..

sterilization

examples of moist physical agents

steam under pressure & boiling water, hot water, pasteurization

the microbial control method for steam under pressure is…..

sterilization

the microbial control method for boiling water, hot water, and pasteurization is…..

disinfection

examples of ionizing physical agents

X ray, cathode, gamma

examples of nonionizing physical agents

UV light

the microbial control method for X ray, cathode, and gamma is…..

sterilization

the microbial control method for UV light is…..

disinfection

examples of chemical agents for microbial control methods

gases and liquids (on animate objects and inanimate objects)

the microbial control method for gases is…..

sterilization and/or disinfection

the microbial control method for chemical liquids on animate objects is…..

antisepsis

the microbial control method for chemical liquids on inanimate objects is….

disinfection and/or sterilization

examples of mechanical removal agents for microbial control methods

filtration (air and liquids)

the microbial control method for mechanical air is…..

decontamination

the microbial control method for mechanical liquids is…..

sterilization

define disinfection

the destruction or removal of vegetative pathogens but not bacterial endospores. usually use only on inanimate objects.

define sterilization

the complete removal or destruction of all viable microorganisms. Used on inanimate objects.

define decontamination/sanitization

the mechanical removal of most microbes

______ physical agents are more effective than _____ physical agents

moist; dry

list examples of microbes from least to most resistant to microbial control agents

enveloped viruses, most gram-positive bacteria, non-enveloped viruses, fungi and fungal spores, most gram-negative bacteria, protozoan trophozoites, protozoan cysts, staphylococcus and pseudomonas, mycobacterium, bacterial endospores, and prions

Bacterial endospores:

considered the most _______ microbial entities

destruction of endospores is the goal of ______

Any process that will kill endospores will….

resistant; sterilization; invariably kill less resistant microbial forms

For the heat (moist) method:

temperature required to destroy endospores?

temperature required to destroy vegetative forms?

endospores are _______x more resistant than vegetative cells

120 C; 80 C; 1.5x

For the radiation (X ray) dosage method:

Grays required to destroy endospores?

Grays required to destroy vegetative forms?

Endospores are ______x more resistant than vegetative cells

4000 Grays; 1000 Grays; 4x

For the sterilizing gas (ethylene oxide) method:

amount required to destroy endospores?

amount required to destroy vegetative forms?

endospores are _______x more resistant than vegetative cells

1200 mg/L; 700 mg/L; 1.7x

For the sporicidal liquid (2% glutaraldehyde) method:

time required to destroy endospores?

time required to destroy vegetative forms?

endospores are _______x more resistant than vegetative cells

3 hours; 10 minutes; 18x

define bacteriostatic agent

microbes are prevented from multiplying but are not killed

define bacteriocidal agent

directly kill bacteria but do not lysis

define bacteriolytic agent

kill with lysis - often effect on membranes and cell walls cause lysis

example of bacteriostatic agent?

cold

example of bacteriocidal agent?

antibiotic

what factors influence killing by antimicrobials?

time, number of microbes, type of microbe, type of agent

increase temperature = _______ time it takes to kill viable cells

decrease

what are the cellular targets of physical and chemical agents?

the cell wall, the cytoplasmic membrane, cellular synthetic processes (DNA and RNA), proteins

what does surfactant do to the cell membrane?

allows for the membrane to break apart to allow for molecules to move into the cytoplasm of the cell

what does denaturation of a protein do?

active site can no longer accept the substrate, and the enzyme is inactive since the substrate will not be able to bind normally

_______ is the most widely used method of microbial control

heat

what are other methods of physical control?

radiation, filtration, ultrasonic waves, cold

it takes ______ time to sterilize for moist heat compared to dry heat

less

fire/incineration will __________

sterilize

boiling water will not kill endospores of ____________ or __________, but will kill the spores of __________

bacillus; clostridia; actinobacteria

you can complete dry heat sterilization at _______-________ C for ______-______ hours, but it will only work with…..

160-170 C; 2-3 hours; glass and metals

Autoclaves will ________, and are considered a….

sterilize; steam (wet heat)

for an autoclave to work, it will use ______ psi, _______ C, and _______ min

20 psi; 121 C; 15 min

pasteurization will ________ microbial load, but does not _______ _________

reduce; sterilize liquids

for incineration to occur with Bunsen burners, you will reach a temperature of….

1500 C

autoclaves are effective against….

all types of microorganisms (including spores)

define pasteurization

controlled heating at temperatures will below boiling

pasteurization is used for….

milk, beer and other beverages

cold will _______ growth, but won’t _______ microbes

slow; kill

microbes cannot grow in the cold since…..

there is not enough energy for the microbe to do so

define desiccation

dehydration

desiccation can preserve foods because it…

reduces the amount of water available for microbial growth (doesn’t usually kill microbes, just stops them from growing)

can some pathogens be preserved upon desiccation?

yes

define lyophilization

a combination of freezing and drying (preserves it even more)

how to achieve osmotic pressure?

adding large amounts of salt or sugar to foods creates a hypertonic environment

osmotic pressure causes _______ in bacteria

plasmolysis

define plasmolysis

contraction of the cell as a result of loss of water from the cell

in a hypotonic solution, the cell will ________, but in a hypertonic solution, the cell will _______

swell; shrink

what radiation types are suitable for microbial control?

gamma rays, x rays, ultraviolet radiation

increase energy and decreasing the wavelength size → what color?

purple

UV rays cause damage to DNA by forming….

pyrimidine (specifically thymine) dimers

if there are a lot of mutations on the DNA due to UV light, the cell will….

die off

what type of radiation will go through everything?

ionizing radiation (like gamma rays)

the wavelength of _______ nm is useful for UV radiation

254

what is decontamination by filtration?

air or fluid is strained through a filter with openings large enough for liquid to pass through, but too small for microbes to pass through

decontamination by filtration uses liquids that cannot be heated, like….

drugs or blood serum

desirable qualities of a germicide:

rapid action in _______ concentrations

soluble in ______ or _______

_______-spectrum microbicidal action without high toxicity to….

penetration of ________ _______ to sustain a….

low

water; alcohol

broad; human and animal tissues

inanimate surfaces; cumulative or persistent action

desirable qualities of a germicide:

resistance to….

________ or ________ properties

_________ and ________ properties

__________ and _________

becoming inactivated by organic matter (like blood)

noncorrosive; nonstaining

sanitizing; deodorizing

affordable; readily available

Chlorine (bleach):

Target what microbes?

Level of activity?

Toxicity?

Inactivated by _______ and unstable in ________

sporadical (slowly)

intermediate

gas is highly toxic, solution irritates skin

organics; sunlight

Phenolics:

Target what microbes?

Level of activity?

Toxicity?

poor _________ and ________

some bacteria, viruses, fungi

low to intermediate

dan be absorbed by skin and can cause CNS damage

solubility; expensive

chlorhexidine:

Target what microbes?

Level of activity?

Toxicity?

_______ acting, mild, and has ______ ________

most bacteria, some viruses, fungi

low to intermediate

low toxicity

fast; residual effects

alcohols:

Target what microbes?

Level of activity?

Toxicity?

________ and _______ acting

most bacteria, viruses, fungi

intermediate

toxic if ingested; a mild irritant; dries skin

flammable; fast

hydrogen peroxide, stabilized:

Target what microbes?

Level of activity?

Toxicity?

improved ________ and works well in ______ _______

sporadical

high

toxic to eyes and toxic if ingested

stability; organic matter

quaternary ammonium compounds:

Target what microbes?

Level of activity?

Toxicity?

weak solutions can _______ microbial growth; easily ________

some bactericidal, virucidal, fungicidal activity

low

irritating to mucous membranes; poisonous if taken internally

support; inactivated

soaps:

Target what microbes?

Level of activity?

Toxicity?

used for removing….

certain very sensitive species

very low

nontoxic; few if any toxic effects

soil, oils, debris, and reducing load

silver nitrate:

Target what microbes?

Level of activity?

Toxicity?

discolors _______

bactericidal

low

toxic, irrtating

skin

glutaraldehyde:

Target what microbes?

Level of activity?

Toxicity?

non inactivated by ________ ________ and also ________

sporadical

high

can irritate skin and toxic if absorbed

organic matter; unstable

ethylene oxide gas:

Target what microbes?

Level of activity?

Toxicity?

_______ in pure state; good ________ and materials must be _______

sopracidal

high

very dangerous to eyes, lungs; carcinogenic

explosive; penetration; aerated

cellular targets for modes of action of germicides?

proteins, nucleic acids, cell wall and cell membrane

define aqueous iodine

topical antiseptic, treatment for burned nd infected skin

define iodine tablets

used for disinfecting water

define iodophors

complex of iodine and alcohol

all classes of organisms are killed by ________ if proper concentrations and exposure times are used, but is not adversely affected by _______ _______ and _____

iodine; organic matterl pH

what are cresols?

phenolic derivatives combined with soap

what are bisphenols?

aerosol sprays and cleansing soaps

what is triclosan?

disinfectant and antiseptic chemical added to many products

what is chlorhexidine?

hand scrubbing, surgical prep, and other medical uses

what are the four phenolics? Which one is the most commonly used?

cresols, bisphenols, triclosan, and chlorhexidine (all have carbon rings in them)

most common is triclosan

negative effects of triclosan in household products:

excreted in the urine of _____% of Americans

detectable levels in _____________ sources

degrades into a toxic ________-like compound when exposed to _________

promotes __________ to triclosan

recommend banning its use in……

75%

groundwater

dioxin; sunlight

resistance

non-medical applications

what is dioxin?

they take a long time to break down once they are in the environment (highly toxic and can cause cancer and developmental problems)

surfactants:

have limited _______ _______

disrupt ______ _________

________ grow in soap dishes

mainly used for….

microbicidal power

cytoplasmic membrane

pseudomonas

mechanical removal of microbes

what is pseudomonas?

gram negative bacteria that causes infection in humans, mostly in hospital patients