BI-352 Chapter 9 (Physical and Chemical Control of Microorganisms)

Every time we ____ things, we spread microbes.

Touch

Even when things ____ clean, they are not really clean.

Look

Define Sterilization.

Kills all the things

Define Disinfecting.

Reduces the number to an acceptable amount (arbitrary number).

No life; has killed everything.

Sterilization

Reduced amount to an arbitrary number that was deemed acceptable; 99.9% effective.

Disinfecting

Anything that forms spores ____ be killed by disinfectants.

Cannot

Describe BSL-1.

Very safe. Mostly microbes that do not cause disease. Pose almost no risk to people working in those labs.

Describe BSL-2.

Actual pathogens, but working with things we have treatment for and can cure.

Describe BSL-3.

Cause potentially lethal diseases. Spread through respiratory transmission,

Describe BSL-4.

Pose the highest risk to the workers. Aerosol-transmitted or spread through bodily fluids. High fatality rates. No treatments or limited treatments available.

Microbes are not known to cause disease in healthy hosts and pose minimal risk to workers and the environment; ex: nonpathogenic strains of E. coli.

BSL-1

Microbes are typically indigenous and are associated with diseases of varying severity. They pose moderate risk to workers and the environment; ex: S. aureus

BSL-2

Microbes are indigenous or exotic and cause serious or potentially lethal diseases through respiratory transmission; ex: M. tuberculosis, SARS-COV1/2, MERS Cov

BSL-3

Microbes are dangerous and exotic, posing a high risk of aerosol-transmitted infections, which are frequently fatal without treatment or vaccines. Few labs are at this level; ex: Ebola and Marburg viruses.

BSL-4

BSL-4 labs works exclusively with ____ pathogens; there are no bacteria in this category.

Viral

Why do we not see bacterial species in the BSL-4 category?

Broad spectrum antibiotics; antivirals are very limited.

What are the different pieces of PPE an individual would wear when entering a BSL-3 lab (4)?

- Gloves

- Gowns or Lab Coats

- Masks, N-95 Mask, or Respirators

- Disposable Suits or Positive Pressure Suits

Define Sterile.

Kill everything, including spores.

Define Disinfection.

Reducing the number of microbes by an arbitrary amount.

Define Antiseptic.

A disinfectant that can be used on humans.

Define Degerming.

Washing with soap and water to mechanically remove microbes.

Define Sanitation.

Reducing the number of microbes to a specific number determined by the government.

What is the difference between sanitation and disinfection?

Sanitation has actual numbers that they are reducing to.

Not all disinfectants are ____.

Antiseptics

Define -cide/-cidal.

Kills microbes.

Define -stat/-static.

Stops growth, but does not kill.

Define D-Value.

How long it takes to kill 90% of the microbes (time needed to kill 90% of microbes).

90% death = ____ log reduction

1

What does aseptic technique prevent?

Prevents contamination (prevents bacteria from getting into our samples or harmful microbes from getting into patients).

What is the temperature of a refrigerator?

4 degrees Celsius

What is a standard freezer temperature?

-20 degrees Celsius

Temperature of the freezer where glycerol stocks are kept.

-80 degrees Celsius

Temperature of the freezer found in the cell suite that is used for long-term storage.

-150 degrees Celsius

Is a refrigerator bacteriostatic or bactericidal?

Bacteriostatic

Is a freezer (-20, -80, -150) bacteriostatic or bactericidal?

Bactericidal, but can counteract with glycerol (in which case, bacteriostatic).

Freezers are bactericidal unless you add ____ that prevent ice crystal formation, then bacteriostatic.

Reagents

____ can be used as a disinfectant or to sterilize, depending on the type.

Heat

How does heat kill?

Kills by altering membranes and denaturing proteins.

Define Thermal Death Point.

Lowest temperature that kills microbes in ten minutes.

Define Thermal Death Time.

Amount of time needed to kill all the microbes at a given temperature.

Temperature that is going to kill bacteria in a specified time of 10 minutes.

Thermal Death Point

Set temperature constant and figure out how long we need to heat that for in order to kill it.

Thermal Death Time

Heat Inactivation = ____ ____

Dry Heat

What are some examples of dry heat?

- Bunsen Burner

- Incinerator

What temperature is an incinerator?

Over 800 degrees Celsius

Is heat inactivation bacteriostatic or bactericidal?

Bactericidal, but does not kill endospores.

Predominantly used in dairy products, but other things as well.

Pasteurization

Define HTST Pasteurization.

High Temperature, Short Time. Milk heated to 72 degrees Celsius for 15 seconds, then bottled and immediately refrigerated.

HTST pasteurization does not kill all bacteria, because the milk eventually ____ (because of bacterial growth).

Spoils

Define UHT Pasteurization.

Ultra High Temperature. Milk heated at 138 degrees Celsius for at least two seconds, then sealed in an airtight container for up to 90 days without refrigeration (before opening).

What is Pascalization?

Increasing pressure.

What types of patients is Hyperbaric Oxygen Therapy used on?

- People who suffer significant burns

- Divers

What does Hyperbaric Oxygen Therapy entail?

A lot of pressure and influx of oxygen.

In a Hyperbaric Oxygen Chamber, the chamber has a high level of oxygen, and we use the pressure to push it into the tissue to oxygenate it, so ____ bacteria (ex: Clostridia) will not grow.

Anaerobic

Define Autoclave.

Moist-heat and pressure.

What is moist-heat?

Steam

The autoclave ____, because it kills the endospores.

Sterilizes

Need steam and heat to penetrate the ____.

Endospores

What are two ways we can test effective autoclaving?

- Tape

- Ampules (endospores in a vial)

Define Dehydration.

Removing moisture through the use of salt or sugar.

Add a layer of salt or sugar to draw the water out through ____ in dehydration.

Osmosis

Define Desiccation.

Drying out (dry out in oven).

Define Lyophilization.

Freeze drying (use cold to dry out).

Is dehydration bacteriostatic or bactericidal?

Depends on the organism's resistance to osmotic pressure. Could be bactericidal, bacteriostatic (if can resist osmotic pressure) or have no change.

What are examples of Ionizing radiation?

X-rays and Gamma Rays

What are examples of Non-Ionizing radiation?

UV

Ionizing radiation is ____, but does not kill endospores.

Bactericidal

Ionizing radiation is often used to "sterilize" things inside packaging, because it ____ packaging.

Penetrates

Is Non-Ionizing radiation bacteriostatic or bactericidal?

Depending on dose, bacteriostatic to bactericidal. Higher amounts of UV means more bactericidal. Lower amount of UV means more bacteriostatic.

Non-ionizing radiation is ____-____ (anything inside a package is not getting any UV exposure).

Non-Penetrating

Why would a bacteria be more resistant to UV?

The bacteria forms endospores.

Define Filtration.

Used to filter air or liquids.

What kind of filter is used to filter air?

HEPA Filter

What kinds of microbes does a HEPA filter trap?

Traps all microbes (bacteria, viruses, etc)

Describe the shape of a HEPA Filter.

Filter in an accordion-fashion, and between that are aluminum separators. Creating many areas for the viruses and bacteria to get trapped.

A HEPA filter traps ____ microbes.

All

What are the two main liquid filters?

- Vacuum Filtration

- Syringe Filtration

Describe the process of Vacuum Filtration.

Liquid is poured in top of an apparatus. There is a filter on the bottom. The apparatus is connected to a vacuum that is going to pull the air out and help mediate the flow through the top to the bottom. The liquid is collected at the bottom.

Describe the process of Syringe Filtration.

Using the plunger of a syringe to force the liquid through the filter.

What are the syringe filter sizes?

0.45 micrometers and 0.2 micrometers

Liquid filtration allows what to pass through?

Viruses

What are two reasons to use vacuum filtration over syringe filtration?

- Volume of Liquid

- Viscosity of Liquid

Is filtration bacteriostatic or bactericidal?

Filtration is neither -cidal nor -static, it just traps the microbes in a location. Over time, the microbes are not going to have the nutrients they need to survive, so they will eventually die.

What chemical control method did Joseph Lister use?

Joseph Lister first used a 5% phenol solution for handwashing, disinfecting surgical equipment, and disinfecting sight of incision.

Contains phenol and was named in honor of Joseph Lister.

Listerine

How do phenolics work?

Denatures proteins and disrupts membranes.

What are the targets of phenolics?

Gram positive bacteria better than gram negative bacteria.

Phenolics are a ____ ____, meaning they damage the skin and make infection more likely; they are very effective, but harmful.

Skin Irritants

Phenolics are classified as what?

Disinfectant (no longer used on skin, so it is not an antiseptic).

What are some examples of Heavy Metals?

Copper, Silver, Zinc, Nickel, Mercury

Heavy metals have ____ antimicrobial properties.

Natural

How do Heavy Metals kill microbes?

Bind proteins (if enzymatic, block activity; if non-enzymatic, alter protein conformation and protein binding partners).

What are some examples of Halogens?

Iodine, Chlorine, Fluorine

How does Iodine work?

Oxidizes cellular components (sulfur-containing amino acids, nucleotides, fatty acids).

Iodine is considered to be ____, because it can be used on the skin.

Antiseptic

How does Chlorine work?

Oxidant, Irritant

What is chlorine gas used in?

Waste water treatment.

What are chloramines used in?

Used in water.

How does Fluorine work indirectly?

Decreases the acid tolerance of the bacteria.