TEST 2 MICROBIOLOGY Chapter 9 Guaranteed 100% mr.trott

Which viruses have a greater tolerance of harsh conditions?

non-enveloped viruses

disadvantages of hepa

not all viruses are eliminated and filtered media must be either liquid or gas

Bacteriostatic

not killed but not growing

What is more effective? slow freezing or quick freezing?

slow freezing

chemical reactions are what a lower temperatures?

slower

Surfactants (soaps and detergents)

soaps have hydrophilic and hydrophobic ends that are good degerming but not antimicrobials

Using an alcohol pad before taking a blood sample is an example of antisepsis.

True

nonionizing radiation

Ultraviolet rays that damage microbial DNA is an example of

Alcohols

Using isopropanol is an example of

surfactants

Using soap is an example of

Which of the following could be used to sterilize objects such as medical devices?

ethylene oxide

Which of the following is used to sterilize items that should not, or cannot, be exposed to heat or water?

ethylene oxide

surfactants

"Surface active" chemicals that reduce surface tension of solvents to make them more effective at dissolving solutes soaps and detergents

disadvantage of radiation

dangerous materials need shielding lack of public trust

Oxidizing agents

-Peroxides, ozone, and peracetic acid -Kill by oxidation of microbial enzymes -High-level disinfectants and antiseptics

ultra high temperature pasteurization

135 C for 1 second

ultra high temperature sterilization

140 C for 1-3 seconds

ultra high temperature sterilization (moist heat)

140 degrees Celsius for 1-3 seconds, then rapid cooling treated liquids can be stored at room temperature

incerneration

1870 C

what does protein function depend on?

3-D shape

Most effective alchohol

50-90 percent (70% optimum) 100% dehydrates but does not kill bacteria

Historical (batch) pasteurization treatment

63 C to 30 minutes

flash pasteurization

72°C for 15 seconds then rapid cooling

Assume that you have an antimicrobial agent specific for each of the targets listed below. Indicate which type of microbe would be most susceptible to the agent by placing it in the appropriate bin.

All bacteria: membrane proteins & glycolytic enzymes Gram-positive bact.- peptidoglycan Viruses-envelope proteins All bact. and viruses-nucleic acids As you consider which microbes could possibly contaminate work surfaces, it is important for you to understand antimicrobial targets. This information is essential for you to make the most appropriate choice in a given environment.

antimicrobial drugs

Antibiotics, semisynthetic, and synthetic chemicals Typically used for treatment of disease Some used for antimicrobial control outside the body

Pasteurization of milk (moist heat)

Batch method Flash pasteurization Ultrahigh-temperature pasteurization

Methods of microbial control using moist heat

Boiling Autoclaving Pasteurization Ultrahigh-temperature sterilization

Why is autoclaving rather than boiling water used for sterilization?

Boiling water does not kill everything, including bacterial endospores and some protozoan cysts Boiling water reaches a maximum temperature of 100 degrees Celsius, compared with autoclaving where the temperature reaches at least 121 degrees Celsius. Boiling water is not hot enough to kill endospores or cysts in a reasonable amount of time.

halogens

Chlorinating pools is an example of

Aldehydes

Compounds containing terminal -CHO groups Cross-link functional groups to denature proteins and inactivate nucleic acids Glutaraldehyde disinfects and sterilizes Formalin used in embalming and in disinfection of rooms and instruments

what are the effects of high temperatures?

Denature proteins Interfere with integrity of cytoplasmic membrane and cell wall Disrupt structure and function of nucleic acids

During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true?

Disinfectants are used to inhibit or destroy pathogens. Endospores and viruses can resist disinfectant treatment. Disinfection can occur by physical or chemical means. During production of a drug, all work surfaces must be disinfected to inhibit the growth of microbes. From a practical standpoint, sterilization (elimination of all microbes) of all work surfaces (e.g., benches, floors, chairs, equipment) is not feasible.

Denatures proteins and oxides metabolic and structure chemicals

Dry Heat

What requires a higher temperature for a longtime that moist

Dry heat

Desiccation

Drying inhibits growth due to removal of water

Desiccation

Drying out fruit to remove water is an example of

Lyophilization

Freeze-drying used for long-term preservation of microbial cultures Prevents formation of damaging ice crystals

What has a greater ability than bacteria to survive hypertonic environments.?

Fungi

biosafety level 4

Handling microbes that cause severe or fatal disease

Biosafety Level 2

Handling moderately hazardous agents

Biosafety Level 1 (BSL-1)

Handling pathogens that do not cause disease in healthy humans

Which of the following is an example of pasteurization?

Heat is used to kill potential pathogens in apple juice.

Osmotic pressure

High concentrations of salt or sugar in foods to inhibit growth Cells in a hypertonic solution of salt or sugar LOSE water Fungi have a greater ability than bacteria to survive hypertonic environments

Why do containers of liquid placed in an autoclave need to remain at least slightly open?

If they remain closed, they may implode. The extreme temperature and pressure changes within the autoclave may cause closed containers to implode.

121 degrees Celsius

It has been determined that the temperature in an autoclave should reach __________ for sterilization. Yes. The temperature is set at 121 degrees Celsius and 15 psi for 15 minutes to sterilize small volumes.

Which of the following is NOT a desirable characteristic of an ideal antimicrobial agent?

It only arrests growth of vegetative cells.

hypertonic solution of salt or sugar

LOSE WATER

What role does pressure play in an autoclave?

Pressure is applied to boiling water to prevent heat from escaping as steam Adding pressure to boiling water leads to higher water temperatures.

Place the various organisms in order from most resistant to least resistant to antimicrobial agents.

Prions Prions Bacterial endospores Bacterial endospores Mycobacteria cycsts of crypton Mycobacteria Small nonenveloped viruses cysts of other protozoa Small nonenveloped viruses Fungal spores Fungal spores Most Gram-negative bacteria active stage of protozoa Most Gram-negative bacteria Large nonenveloped viruses Vegative fungi Large nonenveloped viruses Most Gram-positive bacteria Most Gram-positive bacteria Enveloped viruses

heavy metals

Silver creams are examples of

What can affect the microbial death rates or alter the efficacy of antimicrobial methods?

Temperature and Ph

thermal death time

Time to sterilize volume of liquid at set temperature

The preferred method of sterilization during drug production is heat. Heat sterilization can occur in two forms: moist or dry. Autoclaving is the most commonly used application of moist heat for sterilization. Which of the following statements about autoclaving is true? Choose the statement about autoclaving that is true.

The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature. Autoclaving can be used to effectively and efficiently sterilize a variety of items used in the production of a drug. During autoclaving, the steam must contact all items or liquids. This is why items should be wrapped in porous materials rather than foil and liquids need to have loose caps. Although effective, sometimes autoclaving cannot be used for liquid sterilization (e.g., sterilizing a solution with heat-labile components).

Why are endospores sometimes used in sterility indicators?

They are the hardest life form to kill. If an autoclave kills endospores within a sterility indicator, it is safe to assume that everything else is sterilized.

What effect do aldehydes have on microbial organisms?

They damage proteins and DNA.

How do scientists ensure that autoclaved materials were actually sterilized?

They may place a sterility indicator with a special dye to detect the growth of endospores Some sterility indicators have dyes that change color in the presence of living bacteria, indicating that the correct sterilizing temperature and time have not been reached.

In use test

accurate determination of proper strength and application procedure for each situation medium monitored for growth swabs

Chemicals, radiation, and heat can do what to nucleic acids?

alter or destory

An antimicrobial chemical used on the skin is usually called __________.

an antiseptic Antiseptics often contain the same chemicals as disinfectants, but they are less concentrated and therefore safer to use on living tissues.

Enzymes

antimicrobial enzymes act against microorganisms human tears contain lysosme which digests peptidogylcan cell wall of bacteria and the is used to reduce the number of bacteria in cheese

Iodine

antiseptic (tincture of iodine betadine)

Which of the following techniques can be used to sterilize microbiological media?

autoclaving

The use of lysozyme during the preparation of cheeses and wines is effective in reducing the numbers of

bacteria.

Which of the following can be used to reduce microbes in the air of a patient's room?

both HEPA filters and ultraviolet light

Formalin (37% formaldehyde) is used for

both disinfection and sterilization.

Boiling water for 10 minutes is effective in ridding it of

both growing bacteria and enveloped viruses.

cytoplasmic membrane

controls passage of chemicals into and out of cell; when damaged, cellular contents leak out

ultraviolet

can damage dna but poor penetration in materials/tissues

hydrogen peroxide (H2O2)

can disinfect and sterilize surfaces Not useful for treating open wounds because catalase in wounded tissue transforms it to oxygen and water H2O2 -catalase-> O2 and H20

Hydrogen peroxide does NOT make a good antiseptic for open wounds because __________.

catalase in human tissues neutralizes it

what maintains integrity of cell?

cell wall

disinfectants

cleaning surfaces

Copper

controls algal growth

cyctoplasmic membrane contains what?

cytoplasm

what does extreme heat or certain chemicals do to proteins?

denature protein

Phenols and phenolics

denature proteins and disrupt cell membrane effecrive in the presence of organic matter remain active for prolonged time commonly used in health care settings, labs, homes have disagreeable odor and possible side effects

Alchohol

denature proteins and disrupt cytoplasmic membranes more effective than soap in removing bacteria from hands swabbing of skin with alchohol prior to injection removes most microbes

-cide, -cidal

destruction of a type of microbe exp: bactericide, fungicide, germicides

Sterilization

destruction of all microorganisms and viruses in or on an object exp: preparation of microbiological culture media and canned food. typically achieved by steam under pressure, incineration or by ethylene oxide gas

Disinfection

destruction of most microorganisms and viruses on nonliving tissue exp: use of phenolics, alcohols, aldehydes . this term is used primarily in relation to pathogens.

positively charged orgainic surfactants

detergents

Chemotherapeutics

disease treatment

Chlorine

disinfectant added to water

gluatraldehyde

disinfects and sterilizes many industrial uses

HEPA filter

filter out > 0.3 mn particales (300mn)

Which of the following could be used to sterilize a heat-sensitive liquid such as urea broth?

filtration

Aseptic means

free of pathogens.

Which of the following is bacteriostatic?

freezing below 0∘C

Which of the following is used for microbial control in fresh fruits and vegetables?

gamma rays

Betadine contains what type of chemical agent?

halogen

biosafety level 3

handling of microbes in safety cabinets

amphipathic

having both a hydrophilic region and a hydrophobic region

Heavy metals

heavy metal ions denature proteins and are low level bacteriostatic and fungistatic agents

Silvadene, a topical treatment for burns, contains 1% silver. What category of chemical control agent is in Silvadene?

heavy metals

Compared to moist heat methods, dry heat needs which of the following in order to sterilize effectively?

higher temperature and increased time Air does not conduct heat as effectively as water does, so sterilization methods that rely on hot air require more time and higher temperatures than methods involving moisture.

Where are you likely to find an autoclave?

in a dentist office A dentist office would use an autoclave to sterilize its instruments before use on a patient

the ultimate means of sterilization

incineration (1870 flaming loops)

heavy metals

inhibition of growth by their presence 1% silver nitrate to prevent blindness caused by n. gonnorrea thimerosal used to preserve vacciness copper controls algal growth

Halogens

intermediate level antimicrobial chemicals and they damage enzymes by denaturation

Alchohols

intermediate level disinfectants exp: ethanol, isoproanol,

peractic acid

is an effective sporicide used to sterilize equipment

what is the method of microbial control based on?

it is based of site of medical procedure

Methanol is not used because of what?

it is toxic

High-level germicides

kill all pathogens, including endospores

intermediate level germicides

kill fungal spores, protozoan cysts, viruses, pathogenic bacteria

Low-level germicides

kill vegetative bacteria, fungi, protozoa, and some viruses

microwave

kills by heating substances

At each stage of production, sterility of the preparation is a major consideration. When considering appropriate measures to implement to control microbial growth, one must think about the susceptibility of possible microbial contaminants. Apply your knowledge of the structural features of microbes and the mechanisms of action for antimicrobial agents to rank the following microbes according to their susceptibility.

least susceptibile prions endospores Gram-negative bacteria Gram-positive bacteria enveloped virus most susceptible Microbial structure plays an important role in susceptibility to antimicrobials. While you might think that a viral envelope would confer protection, it is more easily broken down than a protein coat. Gram-positive bacteria tend to be more susceptible to agents that attack the cell wall (recall that they lack an outer membrane). Bacterial endospores are designed to withstand extreme stress; this also means that they are more difficult to eliminate compared to bacterial cells. Prions remain the most resistant of all; however, recently, an enzyme has been shown to be effective in eliminating prion contamination on medical instruments.

x ray

less penetration

Quatenary ammonium compounds (surfactants)

low level disinfectants, disrupt cellular membranes, ideal for many medical and industrial applications exp: cepacol mouthwash and batine

thermal death point

lowest temperature that kills all cells in broth in 10 minutes (temp variable)

methods used for evaluating disinfectants and antiseptics: use dilution test

metal cylinders dipped into broth cultures of bacteria and dried contaminated cylinder immersed into dilution of disinfectant most effective agents entirely prevent growth at highest dilution current standard test in the US. new standard being developed

Methods of microbial control called ________ arrest the growth of microbes.

microbistatic

what is pasteurization used for?

milk, ice cream, yogurt, and fruit juices

what is more effective than dry heat?

moist heat

Is pasteurization sterilization?

no

advantages of hepa

no thermal damage to product

what can interfere with the penetration of heat, chemicals and some forms of radiation and may inactivate chemical disinfectants?

organic materials

cells burst due to what?

osmotic effects when damaged

Damage to the cell wall will adversely affect a bacterial cell by making it more susceptible to __________.

osmotic pressure Without a strong, functional cell wall, the bacterial cell cannot resist sudden changes in osmotic pressure and can die as a result.

dry heat.

oven is an example of

Strachan's hypothesis not only includes fewer exposures to pathogens but also fewer exposures to everyday microbes that do not normally cause people to become ill. Exposure to which of the following microscopic substances will most likely lead to an allergy in an individual with an over reactive immune system?

pollen It is believed by some that exposure of children to normal viruses and bacteria found around the home may lead to a decrease in allergic reactions, such as asthma and hay fever.

(moist heat): autoclaving

pressure applied to boiling water prevents steam from escaping boiling temperatures increases as pressure increases autocalve conditions : 121 c, 15 minutes, 15 psi

Damage to proteins and nucleic acids can do what?

produce fatal mutants halt protein synthesis through action or RNA

Antisepsis

reduction in the number of microorganisms and viruses, particularly potential pathogens, on living tissue exp: Iodine/alcohol to prepare skin for an injection. antiseptics are frequently disinfectants whose strength has been reduced to make them safe for living tissue

aseptic

refers to an environment or procedure free of pathogenic contaminants Exp; Prep of surgery. health care, scientist, and lab tech workers routinely check to make sure they're following standardized techniques

Decreases microbial metabolism, growth, and reproduction

refridgeration and freezing

Degerming

removal of microbes by mechanical means Chemicals play a secondary role to the mechanical removal of microbes

Sanitization

removal of pathogens from objects to meet public health standards exp: washing tableware. standards of sanitization vary among gov. jurisdictions

Baking

requires long periods 160 C for 2 hours 171 C for 1 hour

Ozone (O3)

similar effects as H2O2. ozone treatment of drinking water

-stasis, -static

suffixes indicating inhibition but not complete destruction of a type of microbe bacteriostatic, fungistatic, virusstatic. Germistatic agents include some chemicals, refrigeration, and freezing

Strachan suggests that fewer exposures to childhood illnesses may lead to unintended consequences, including an increase in overreactions of the immune system (allergies). According to the readings in Chapter 9, which of the following is a chemical method to control the growth of microbes?

surfactants The list of chemical methods of microbial control further includes phenols, alcohols, halogens, oxidizing agents, heavy metals, aldehydes, gaseous agents, enzymes, and antimicrobial drugs.

Handwashing with regular soap is effective because __________.

the hydrophobic end of the soap molecule breaks up oily deposits and the hydrophilic end of the molecule attracts water. This combination makes soap a good de-germing agent

What is the purpose of an autoclave?

to sterilize equipment and media Autoclaves are used to ensure that equipment and media are sterile, or free of contamination.

What was recently banned in household soaps and cleaners?

triclosan

T/F refrideration halts growth of most pathogens

true

Milk that can be stored for months at room temperature has been treated by which of the following methods?

ultrahigh-temperature sterilization Ultrahigh-temperature sterilization kills all forms of living microbes: UHT-sterilized milk can be kept at room temperature indefinitely without spoilage, although flavor changes may occur.

Pasteurization

use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages exp: heat treatment is brief to minimize alteration of taste and nutrients;microbes remain and eventually cause spoilage

Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants?

use-dilution test

Formalin (Aldehyde)

used in embalming and disinfection of rooms and instruments

moist heat

used to disinfect, sanitize, sanitize, sterilize, and pasteurize denatures proteins and destroys cytoplasmic membrane

Thimerosal

used to preserve vaccines

advantages of radiation

very effective with little product damage

Gamma ray

very good penetration

Desiccation, a time-honored method of preserving food, is effective because the

water content is too low to support metabolic function.

When is a microbe considered dead?

when it is irreversibly incapable of reproduction

One alternative to autoclaving for sterilization of liquids is filtration. Imagine that you are using a filter to sterilize a drug solution. You use a filter with a 0.22 μm pore size. Which of the following microbes will effectively be removed by this filter?

yeast, fungi, bacteria such as E. coli

heat tolerant microbes survive with pasteurization?

yes