BIOL 203-204 Exam 4 Review

Decontamination

the neutralization or removal of dangerous substances, radioactivity, or germs from an area, object, or person

Bacterial Endospore

Hardest to kill, Endospores enable bacteria to lie dormant for extended periods, even centuries

Vegetative Cells

any of the cells of a plant or animal except the reproductive cells; a cell that does not participate in the production of gametes

Disinfection

Destruction of vegetative pathogens on inanimate objects

Sterilization

refers to any process that eliminates, removes, kills, or deactivates all forms of life and other biological agents

Antisepsis

techniques that prevent the entry of microorganisms into sterile tissues

Sanitization

Cleansing technique that removes microorganisms and debris from inanimate surfaces

Degermation

Cleansing technique that removes microorganisms and debris from living tissue

Microbial Death

permanent loss of reproductive capability, even under optimum growth conditions

Moist Heat

lower temperatures and shorter exposure time; coagulation and denaturation of proteins

Dry heat

moderate to high temperatures; dehydration, alters protein structure; incineration

Thermal Death Time

shortest length of time required to kill all test microbes at a specified temperature

Thermal Death Point

lowest temperature required to kill all microbes in a sample in 10 minutes

Autoclave

a strong, heated container used for chemical reactions and other processes using high pressures and temperatures

Pasteurization

heat is applied to kill potential agents of infection and spoilage without destroying the food flavor or value

Incineration

the destruction of something, especially waste material, by burning

Microbiastatic

slows the growth of microbes

Microbicidal

Destructive to microbes.

Desiccation

the state of extreme dryness, or the process of extreme drying

Ionizing Radiation

deep penetrating power that has sufficient energy to cause electrons to leave their orbit, breaks DNA

Filtration

any of various mechanical, physical or biological operations that separate solids from fluids by adding a medium through which only the fluid can pass.

Non-ionizing Radiation

little penetrating power so it must be directly exposed

Microbiological contaminants are best described as:

A- unwanted microbes present on or in a substance.

B- any and all microbes present on or in a substance.

C- pathogenic microbes present on or in a substance.

D- vegetative microbes present on or in a substance.

E- None of the choices are correct.

A- unwanted microbes present on or in a substance.

Which of the following microbial forms have the highest resistance to physical and chemical controls?

A-protozoan cysts

B- naked viruses

C- bacterial endospores

D- fungal spores

E- yeast

C- bacterial endospores

uestion 3 0.6 / 0.6 points

The process that destroys or removes all microorganisms and microbial forms including bacterial endospores is:

A- antisepsis.

B- sanitization.

C- sterilization.

D- degermation.

E- disinfection.

C- sterilization.

Which of the following types of control agents would need to be used to achieve sterility?

A- bactericide

B- virucide

C- sporicide

D- fungicide

E- germicide

C- sporicide

Dry heat:

A- is commonly used on liquids.

B- will sterilize at 121° C for 15 minutes.

C- cannot sterilize.

D- is used in devices called autoclaves.

E- is less efficient than moist heat.

E- is less efficient than moist heat.

The easiest microbial forms to kill or inhibit are:

A- protozoan cysts.

B- endospores.

C- vegetative bacteria and fungi.

D- naked viruses.

E- Mycobacterium and Staphylococcus.

C- vegetative bacteria and fungi.

The chemical agent that produces highly reactive hydroxyl-free radicals and also decomposes to O2 gas is:

A- Hydrogen peroxide.

B- Iodophors.

C- Chlorhexidine.

D- Cidex.

E- Cationic detergents.

A- Hydrogen peroxide.

Historically, which of the following was instilled into the eyes of newborn infants to prevent gonococcal infections?

A- formaldehyde

B- mercurochrome

C- phenol

D- triclosan

E- silver nitrate

E- silver nitrate

Which common hospital pathogen is able to grow abundantly in soap dishes?

A- Pseudomonas

B- Mycobacteria tuberculosis

C- Escherichia coli

D- Salmonella

E- Hemophilus influenzae

A- Pseudomonas

Using toilet bowl cleaner and nonionizing radiation to inanimate surfaces only removes or kills vegetative bacteria. The term that best describes this action is:

A- Sterilization

B- Disinfection

C- Antisepsis

D- Degermation

E- None of these are correct

B- Disinfection

Imagine that a parent has brought their child in for a routine vaccination. They say, "Before you give my child the shot, make sure to sanitize their skin!" Should you sanitize their child's skin? Why or why not? Make sure to show your understanding of the word sanitize in your answer.

Sanitization refers to any cleansing technique used on non-living objects that reduce the microbial load and therefore reduce the potential for infection. For example, you would sanitize dishes prior to serving food on them by washing them in the sink and drying them on the counter. You haven't sterilized them because there are still viable microbes present, but the number is low enough that it isn't likely to make you sick.

Degermation is same principle, but used to describe living tissue - reduce the microbial load to reduce the chance of infection. So in this case, the correct term would be to degerm the child's skin prior to the vaccination.

Explain the statement from your textbook, "Destroying them (endospores) is the goal of sterilization." Make sure to explain what an endospore is and show your understanding of the word sterilization in your answer.

An endospore is a dormant version of a bacterial cell. Certain genera (genera is the plural form of genus) of bacteria like Clostridium and Bacillus are able to form these hardy structures in times of stress - most often due to nutrient deprivation. They concentrate their genetic information to one portion of the cell and surround it with a tough shell. They can then remain dormant (little metabolism and no reproduction) until conditions improve and they become vegetative again. In the endospore form they can withstand high heat, boiling, cold, freezing, and even some chemicals.

So if the process of sterilization is to kill/remove all microbes including endospores from a surface then we know that if we have killed the endospores (the hardest of all microbes to kill) then we have definitely killed all of the easier to kill microbes (vegetative bacteria, fungi, protozoa) along the way.

Why is hydrogen peroxide so effective against anaerobes like Clostridium tetani that have infected a puncture wound? Make sure to explain what an anaerobe is as well as the action of hydrogen peroxide in your answer.

Anaerobes like Clostridium tetani (the bacteria that causes Tetanus) hate oxygen. They don't use it in their metabolism and if they often do not have the enzymes needed to neutralize oxygen free radicals so it can actually damage their cellular components and cause death in the case of an obligate anaerobe.

C. tetani is present in the soil as an endospore because for an anaerobe, the oxygen filled atmosphere that surrounds the soil is a stressful environment. But, if you step on a nail that is contaminated with the endospores (the nail doesn't have to be rusty - it just has to puncture your skin), now the spores are pushed deep into your tissue where there isn't as much oxygen. They can then become vegetative, metabolize, and reproduce causing an infection.

So one way that you can treat a puncture wound (in addition to being up to date on your Tetanus vaccine) is to use hydrogen peroxide. Hydrogen peroxide helps in two ways. One, it is an oxygen free radical which we know that anaerobes do not like. Two, it on contact with an enzyme called catalase which is produced by some microbes as well as our own human cells, hydrogen peroxide is broken down into water and oxygen gas (O2.) This Oxygen gas will bubble up out of the wound and carry debris and other contaminants that were pushed deep into the wound back up to the surface.

Why would surfactants be more effective against gram-negative bacteria than against gram-positive bacteria? Make sure to show your understanding of the differences between the two types of bacteria

The big difference between gram-positive and gram-negative bacteria is their cell wall composition. A gram-positive bacterial cell wall is made up primarily of a thick layer of peptidoglycan. Gram-negative cells also have peptidoglycan, but it is a thin layer and it is covered up by an external layer of phospholipids called the outer membrane.

Surfactants or surface-acting-agents lower the surface tension of membranes. Surfactants are polar molecules like soaps that have a hydrophilic and hydrophobic portion. This allows them to work their way into membranes and make them leaky. Things that are bad for the cell like chemicals can now more easily get in and important things the cell needs are no longer trapped in the cell and can leak out.

Gram-negative cells would be more susceptible to surfactants because the surfactant could disrupt the outer membrane and then easily pass by the thin layer of peptidoglycan to get to the cell membrane (which it would also disrupt.) Gram-positive cells would be somewhat less susceptible to surfactants due to their thick layer of peptidoglycan that would block and/or delay the surfactant from getting to the cell membrane.

Is pasteurization considered sterilization? Explain your reasoning.

Pasteurization is a technique used in food preparation that reduces the microbial load in food using short periods of moderate heat (15 seconds of 71.6 degrees Celsius) or very short periods of high heat (2-5 seconds of 134 degrees Celsius.) The intent is that fewer microbes in the food equals delayed spoilage and will lengthen shelf-life.

Pasteurization is not sterilization because it is not the removal of ALL microbes.

Clostridium difficile spores can often be found on all surfaces of an infected patient's room (even the ceiling!) Consider the different types of surfaces and propose a plan to sterilize a C. difficile contaminated room.

Endospores are the most resistant form of microbe.

One of the most common chemicals used to clean something contaminated with C. difficile spores is bleach as long as it is a high enough concentration with a long enough contact time. Here is an example of a protocol using bleach: https://www.cloroxprofessional.com/assets/pdf/NI-18797_Clorox_Healthcare_Bleach_Germicidal_Wipes_Protocol.pdf

Hydrogen peroxide products (again at the correct concentration and contact time) can also be used. Here is an example of a protocol: http://www.virox.com/files_docs/content/pdf/msds/CdiffIsolationRoomProtocolwithTBandGelJune2011.pdf

There are some new ideas out there as well using UV light and metals: http://www.medscape.com/viewarticle/709367