Microbio CH9 MM

an oven is an example of ___

dry heat

What role does pressure play in an autoclave? The pressure crushes microorganisms. Pressure is applied to boiling water to prevent heat from escaping as steam. Pressure speeds up the heating process. Pressure forces oxygen out of the autoclave.

Pressure is applied to boiling water to prevent heat from escaping as steam. The application of pressure affects the temperature of a gas.

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

T

Why are endospores sometimes used in sterility indicators? Endospores have the ability to kill all remaining microbes. They are the hardest life form to kill. They release toxic gases that aid in the sterilization process. Bacterial endospores release an indicator dye used to test for sterility.

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.

Which of the following techniques can be used to sterilize microbiological media? a. pasteurization b. boiling c. autoclaving d. desiccation

c. autoclaving

Aseptic means free of pathogens. sterile. free of all microbes. clean. sanitized

free of pathogens.

Betadine contains what type of chemical agent? alcohol halogen aldehyde phenolic heavy metal

halogen

chlorinating pools is an example of ___

halogens

silver creams are examples of ___

heavy metals

Which of the following is an example of pasteurization? A surgeon washes her hands before surgery. A public toilet is treated with disinfectants. Heat is used to kill potential pathogens in apple juice. A nurse prepares an injection site with an alcohol swab. An autoclave is used to prepare nutrient agar.

Heat is used to kill potential pathogens in apple juice.

Which of the following is NOT a desirable characteristic of an ideal antimicrobial agent? A) it is inexpensive. B) it is stable during storage. C) it is harmless to humans. D) it only arrests growth of vegetative cells. E) it acts quickly.

D - it only arrests growth of vegetative cells

Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants? A) in-use test B) phenol coefficient C) thermal death point D) use-dilution test E) microbial death rate

D) use-dilution test

Disinfection

Def: Destruction of most microorganisms and viruses on nonliving tissue eg. Phenolics; alcohols; aldehydes; soaps The term is used primarily in relation to pathogens.

Antisepsis

Def: Reduction in the number of microorganisms and viruses, particularly potential pathogens, on living tissue eg. Iodine; alcohol Antiseptics are frequently disinfectants whose strength has been reduced to make them safe for living tissues.

Aseptic

Def: Refers to enviroment or procedure free of pathogenic contaminants eg. Preparation of surgical field; hand washing; flame sterilization of laboratory equipment Scientists, laboratory technicians, and health care workers routinely follow stanadrdized aseptic techniques.

Degerming

Def: Removal of microbes by mechanical means eg. Hand washing; alcohol swabbing at site of injection Chemicals play a secondary role to the mechanical removal of microbes.

Sanitization

Def: Removal of pathogens from objects to meet public health standards eg. Washing tableware in scalding water in restaurants Standards of sanitarization vary among governmental jurisdictions.

-cide, -cidal

Def: Suffixes indicating destruction of a type of microbe eg. Bactericide; fungicide; germicide; virucide Germicides include ethylene oxide, propylene oxide, and aldehydes.

Pasteurization

Def: Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages eg. Pasteurized milk and fruit juices Heat treatment is brief to minimize alteration of taste and nutrients; microbes still remain and eventually cause spoilage.

During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true? select all that apply Disinfectants are used to inhibit or destroy pathogens. Disinfectants destroy all microbes present on a surface. Endospores and viruses can resist disinfectant treatment. Disinfection can occur by physical or chemical means. Disinfection can be used to treat work surfaces as well as workers (i.e., washing hands).

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. Disinfectants destroy all microbes present on a surface. Endospores and viruses can resist disinfectant treatment. Disinfection can occur by physical or chemical means.

Boiling water for 10 minutes is effective in ridding it of A) protozoan cysts. B) enveloped viruses. C) bacterial endospores. D) actively growing bacteria. E) both growing bacteria and enveloped viruses.

E) both growing bacteria and enveloped viruses.

Which of the following is used to sterilize items that should not, or cannot, be exposed to heat or water? A) triclosan B) formaldehyde C) hydrogen peroxide D) calcium hypochlorite E) ethylene oxide

E) ethylene oxide

Which of the following is bacteriostatic? A) heating in an oven at 171°C for an hour B) filtration C) autoclaving D) flash Pasteurization E) freezing below 0°C

E) freezing below 0°C

Silvadene, a topical treatment for burns, contains 1% silver. What category of chemical control agent is in Silvadene? A) halogens B) surfactants C) aldehydes D) oxidizing agents E) heavy metals

E) heavy metals

Which of the following can be used to reduce microbes in the air of a patient's room? ultraviolet light ethylene oxide HEPA filters both HEPA filters and ultraviolet light both ethylene oxide and ultraviolet light

both HEPA filters and ultraviolet light

Formalin (37% formaldehyde) is used for sterilization. antisepsis. sanitization. disinfection. both disinfection and sterilization.

both disinfection and sterilization.

Strachan suggested the "hygiene hypothesis" in 1989, although his idea is almost impossible to demonstrate experimentally. Since Strachan's hypothesis is almost impossible to demonstrate using experimentation, how did he most likely arrive at such an assertion? -by comparing cases of allergy-associated disorders from years past to those of the present -by intentionally exposing children to various pathogens -through the observation that older people rarely get sick -by comparing vaccination records of individuals with immune disorders and those without

by comparing cases of allergy-associated disorders from years past to those of the present It would be unethical to intentionally expose some children to disease in order to prove a hypothesis. Hypotheses of this nature are best studied using past evidence.

Which of the following could be used to sterilize a heat-sensitive liquid such as urea broth? a. autoclaving b. pasteurization c. filtration d. lyophilization

c. filtration

using soap is an example of ___

surfactants

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 disinfectants viruses bacteria

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.

type of microbe would be most susceptible to the agent

1. all bacteria - glycolytic enzymes and membrane proteins 2. gram-positive bacteria - peptidoglycan 3. gram-negative bacteria - 4. viruses - envelope proteins 5. all bacteria and viruses - nucleic acids

It has been determined that the temperature in an autoclave should reach __________ for sterilization. 100 degrees Celsius 212 degrees Fahrenheit 121 degrees Celsius 121 degrees Fahrenheit

121 degrees Celsius Yes. The temperature is set at 121 degrees Celsius and 15 psi for 15 minutes to sterilize small volumes. For something to be truly sterilized, it must be heated at temperatures above boiling.

An antimicrobial chemical used on the skin is usually called __________. a disinfectant an antiseptic a germicide a sterilant

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

The use of lysozyme during the preparation of cheeses and wines is effective in reducing the numbers of A) fungi. B) bacteria. C) prions. D) viruses. E) all microbes

B) bacteria.

Which of the following is used for microbial control in fresh fruits and vegetables? A) microwaves B) gamma rays C) ultraviolet light D) X-rays E) electron beams

B) gamma rays

Why is autoclaving rather than boiling water used for sterilization? Autoclaving uses dry heat instead of water. Boiling water does not kill everything, including bacterial endospores and some protozoan cysts. Autoclaving is much faster than boiling water. Boiling water is too hot and may denature proteins.

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.

Why do containers of liquid placed in an autoclave need to remain at least slightly open? so that you may pour out the contents into sterile containers before the temperature drops below 100 degrees Celsius to allow oxygen to penetrate the media If they remain closed, they may implode. A closed container would block any heat from entering the media.

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

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? -Autoclaving requires extensive exposure times in order to achieve sterilization. -When autoclaving solid items, they should be wrapped in foil to help maintain sterility. -The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature. -Autoclaving is preferred over dry heat because it can effectively be used to sterilize a wide variety of items, including liquids, powders, metal instruments, and glassware.

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).

What effect do aldehydes have on microbial organisms? They inhibit enzymes. They disrupt cytoplasmic membranes. They disrupt membranes and enzyme function. They damage proteins and DNA. They damage nucleic acids.

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. They may take a sample of the media being sterilized and inoculate it onto a plate for incubation. They inspect the materials under a microscope to search for contaminating microorganisms. There is no need to verify sterility when proper time, pressure, and temperature are maintained.

They may place a sterility indicator with a special dye to detect the growth of endospores Yes. 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.

Hydrogen peroxide does NOT make a good antiseptic for open wounds because __________. a. catalase in human tissues neutralizes it b. it evaporates too quickly c. it is too toxic for human cells d. it is too expensive for this type of use

a. catalase in human tissues neutralizes it Human cells, like many other cells, contain protective enzymes such as catalase that are used to guard against the toxic byproducts of oxygen and its metabolism.

Which of the following could be used to sterilize objects such as medical devices? a. ethylene oxide b. silver nitrate c. 100% alcohol d. orthophenylphenol

a. ethylene oxide

using isopropanol is an example of ___

alcohols

Milk that can be stored for months at room temperature has been treated by which of the following methods? a. flash pasteurization b. ultrahigh-temperature sterilization c. ultrahigh-temperature pasteurization d. batch pasteurization

b. 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.

decreased/increased exposure: -having pets -gardening outside -washing hands regularly -sharing food or drink w/ family -discarding away food that falls on the floor -wiping surfaces w/ disinfectants -being involved in team sports -remaining indoors

decreased exposure: -wiping surfaces with disinfectants -washing hands regularly -discarding away food that falls on the floor -remaining indoors increased exposure: -gardening outside -being involved in team sports -having pets -sharing food or drink with family Although we tend to think of exposure to microbes as a bad thing, according to the "hygiene hypothesis," such exposure encourages good use of our immune system. Exposure to microbes may also help to prevent an overreaction, which may lead to immune system-associated disorders.

Sterilization

def: Destruction of all microorganisms and viruses in or on an object eg. Preparation of microbiological culture media and canned food

-stasis, -static

def: Suffixes indicating inhibition but not complete destruction of a type of microbe eg. Bacteriostatic; fungistatic; virustatic Germistatic agents include some chemicals, refrigeration, and freezing.

drying out fruit to remove water is an example of ___

desiccation

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? small viruses fungi bacteria such as E. coli yeast

fungi bacteria such as E. coli yeast The use of membrane filters offers an effective alternative to autoclaving for the sterilization of liquids. It is essential to choose the correct pore size for filtration to ensure that any possible contaminants are trapped by the filter and do not become part of the final solution. Therefore, always choose a filter with a pore size that is significantly smaller than your smallest possible contaminant.

Compared to moist heat methods, dry heat needs which of the following in order to sterilize effectively? higher temperature and shorter time higher temperature and increased time lower temperature and shorter time lower temperature and increased time

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 high school cafeteria in a chemistry lab in a dentist office in the home

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

rank the following microbes according to their susceptibility

least susceptible: prions>endospores>gram-negative bacteria> gram-positive bacteria>enveloped virus 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.

Methods of microbial control called ________ arrest the growth of microbes. antiseptic microbiostatic degerming microbicial sanitizing

microbistatic

ultraviolet rays that damage microbial DNA is an example of ___

non ionizing radiation

Damage to the cell wall will adversely affect a bacterial cell by making it more susceptible to __________. radiation alcohols high temperature osmotic pressure

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

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? moist heat surfactants desiccation radiation

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 __________. - soap is an excellent antimicrobial agent - the fatty acid tail of a soap molecule is an excellent oxidizing agent, while the opposite end of the molecule contains alcohol - 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 - the hydrophobic end of the soap molecule attaches to the cell wall of bacteria and the hydrophilic end of the molecule attracts water. The result is that the bacteria are washed away with the water

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 warm up cultures to sterilize equipment and media to incubate cultures to wash equipment

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

Desiccation, a time-honored method of preserving food, is effective because the -UV light used in the process of sun drying penetrates effectively. -freezing step of the process kills microbes. -salt concentration is too low to support metabolic function. -heat of the process kills microbes. -water content is too low to support metabolic function.

water content is too low to support metabolic function.

Some believe that if you drop a piece of food on the ground, you have approximately five seconds to pick it up and eat it. If you leave it longer than five seconds and eat it, you will likely become sick. In light of the "hygiene hypothesis," there may be some truth to the "Five-Second Rule." If one were to ascribe to the Five-Second Rule, which of the following places would be the most appropriate place to apply it? a school a hospital a library your home

your home Although it is risky to ingest something that has come into contact with the ground, you are much less likely to come across diseases like hepatitis, norovirus, or RSV in your home. So, if you are willing to risk eating contaminated food, your home is likely a safer place than public domains.