Micro chapter 13

disinfection

The process of killing and removing only some disease-causing organisms and microbes from inanimate surfaces

sterilization

The process of killing and removing all living cells, spores, and viruses on an object

antisepsis

The process of killing and removing only some disease-causing organisms and microbes from living surfaces

sanitation

The process of reducing the total number of the microbial population on a surface, to what is deemed and classified as a safe level, but not necessarily resulting in sterilization

1. Wet heat

2. Dry Heat

3. Filtration

4. Irradiation

5. Chemicals/Solvents

The five categories of methods that we can utilize to potentially achieve sterilization status are:

heat

pressure

An autoclave is a type of sterilizing instrument that incorporates the use of high _____ and high _____ in order to destroy microbes from a product

True

True or false: An autoclave can kill and destroy spores and hyperthermophiles.

False

True or False: All materials that need to be sterilized are suitable for scientists and researchers to use an autoclave as their means to reach sterilization

Filtration

What is a physical sterilization method that uses a filter with very small pore sizes, that allow the desired product undergoing the sterilization to pass through, but the filter captures undesirable contaminants like
bacteria, endospores, yeasts, molds, etc

False

True or False: A pore size of 0.2 μm is a standard pore size for most filtration systems, and the pore size is small enough to capture viruses out of the sample that is being filtered.

UV, gamma rays, X-rays, electron beams

What are some examples of irradiation methods that can be utilized to sterilize surfaces and objects?

False

True or false: UV radiation would be a great option to sterilize a very large, deep tub of saline to be packaged for IV saline drips

UV radiation is an excellent method to sterilize surfaces. Does not penetrate through those surfaces to sterilize beneath them. Because of this, most of the liquid that was being sterilized would never come in contact with the UV light, so a different sterilization method would be much better for this example.

Why would you not want to use UV radiation to sterilize a very large, very deep tub of saline to be packaged for IV saline drips?

Ionizing

high

_______ radiation, like Gamma rays, has _____ wavelengths, and therefore has higher energy. This type of radiation has the ability to disrupt bonds by removing electrons, protons, or neutrons

Non-ionizing

lower

___-_______ radiation, like Ultraviolet light, have ____ wavelengths, and therefore have lower energy, This type of radiation can only disrupt hydrogen and possibly alter covalent bonds

Cold, Pasteurization, and Canning

What are three types of physical methods that control microbial growth?

Greatly slows the growth of microbes, but does not necessarily kill already established populations. It tempers the growth drastically, though. It can even serve as a means of microbial preservation for long periods of time if kept cold enough.

What does “cold” do for controlling microbial growth?

Liquids are raised to a high enough temperature for a long enough time to kill the microbe Coxiella burnetii. Most other human pathogens are less heat stable than this organism, so if C. burnetti is killed, most everything else is too. Different types of pasteurization vary the heating temperature and time of exposure for a proper pasteurization effect.

What does “pasteurization” do for controlling microbial growth?

Uses the principles of high heat and pressure for a duration of time to kill microbes, especially spore-forming microbes, and proper canning follows procedures that ensure a 12-D standard (reducing the amount of spores by a 10¹² amount) is reached.

What does “canning” do for controlling microbial growth?

1. Presence of organic matter

2. Type of microbe(s) present

3. corrosiveness

4. stability, odor, and surface tension

What are examples of different factors that influence the efficacy of chemical agents on how well they might reduce microbial populations

Organic matter interferes with the chemical agent because the chemical can end up binding to the organic matter, and not come in contact with the microbial population

How does the presence of organic matter affect the efficacy of chemical agents?

Certain microbes are more resistant to certain chemicals than others, and mixtures of bacteria can create issues with certain chemicals, so a chemical needs to be chosen in accordance with to what microbes you are trying to destroy.

How does the type of microbe(s) present affect the efficacy of chemical agents?

The chemical should not damage or corrode surfaces, and what you use on one surface, like a table or a toilet, may not be the safest choice to use on your hands.

How does corrosiveness affect the efficacy of chemical agents?

What type of surface are you sanitizing? Does it have a lot of porous components or not? Does the product carry a harsh smell that should only be used in well-ventilated areas, etc.

How does stability, odor, and surface tension affect the efficacy of chemical agents?

Gas

____ Sterilization is a method that can be utilized as a way to sterilize solid products that cannot be exposed to high heat, pressure, certain chemicals, steam, etc.

True

True or false: Microbes can develop resistance to antimicrobial chemicals, similarly to how they develop resistances to antibiotics

selective toxicity

Antibiotics are chemical compounds that are synthesized by some organisms in order to kill other microbes, and these chemical agents exhibit ____ _____, which means the antibiotic compound only kills and harms the pathogen, not the host

Through a series of tubes, the concentration of the drug is diluted in a serial dilution, and a known volume of bacteria is added to the tubes and then incubated. When we see bacterial growth stop, we know the minimum inhibitory concentration is between two concentrations, the concentration we saw growth, and the next concentration where growth was inhibited.

How does a tube dilution test obtain the minimum Inhibitory Concentrations for antibiotics against certain bacterial species?

A bacterial species is inoculated via spread plate onto a growth medium, and certain MIC strips containing different antibiotics are placed down on it, and based on the ellipsis of growth, we can figure out quickly the MIC because it will be exactly at the point where growth just intersects with the strips .

How does a MIC strip test obtain the minimum Inhibitory Concentrations for antibiotics against certain bacterial species?

This test is similar to the MIC strip test in that we inoculate an organism via a spread plate, and we add multiple antibiotic discs to the plate in order to measure the zone of inhibition that results. This zone of inhibition will allow us to determined whether or not that microbe is resistant to the drug, intermediate to the drug, or susceptible to the drug based on the measurement of the zone of inhibition by applying it to the published data.

How does a Kirby-Bauer Disk Susceptibility Assay obtain the minimum Inhibitory Concentrations for antibiotics against certain bacterial species?

False

True or false: The minimum inhibitory concentration of a particular drug against a specific microbe is also always the minimum bactericidal concentration for that drug too.

When taken together, the drugs work better than they would if they were taken independently from one another.

What does it mean for a combination of antibiotics to be synergistic for a patient to take together?

When the drugs are taken together, they work worse or are completely ineffective than they would if they were taken independently from one another.

What does it mean for a combination of antibiotics to be antagonistic for a patient to take together?

1. Inhibit protein synthesis

2. Inhibits nucleic acid synthesis

3. Interrupt metabolic pathways and metabolic activity

4. Alter colloidal state of cytoplasm

5. Inhibit cell wall synthesis

6. Inhibit enzyme synthesis

7. Alter membrane permeability and integrity

What are the different types of Mechanisms of Action that different chemical antibiotics can utilize in order to kill and target bacterial cells?

1. Prevent intracellular accumulation

2. Prevent antibiotic binding to its target structure

3. Dislodge the antibiotic from its target site

What are the three main mechanisms of antibiotic resistance that microbes can utilize to protect themselves against antibiotic drugs?

The bacteria might destroy the antibiotic as it comes into the cell
before it can cause damage, the bacteria might use efflux pumps to get rid of the drug, it can alter its membrane permeability to not allow the drug to diffuse into the cell, etc.

How does preventing intracellular accumulation help microbes protect themselves against antibiotic drugs

The bacteria might change the target of the antibiotic
wants to bind to, so the drug no longer recognizes the structure and therefore cannot complete its drug action. The bacteria might change the chemical composition of the drug like adding methyl or phosphate groups onto the drug so it can be deactivated

How does preventing antibiotic binding to its target structure help microbes protect themselves against antibiotic drugs

If the antibiotic does bind to its target, the microbe might be
able to synthesize proteins that act like a “battering ram” to come in and dislodge the antibiotic from its binding site so normal metabolic activity can resume.

How does dislodging the antibiotic from its target site help microbes protect themselves against antibiotic drugs