Unit 3 Micro

chapter 13,14,15,16

Disinfection

Decreasing the microbial load on an inanimate object using chemical or heat methods.

• Common Agents: Chlorine bleach, phenols (e.g., Lysol).

• Application: Cleaning laboratory benches or clinical surfaces.

Sanitation

Decreasing the microbial load on inanimate items to safe public health levels (e.g., restaurants, public restrooms).

• Common Agents: Detergents containing phosphates, industrial-strength cleaners.

• Application: Commercial dishwashing of eating utensils.

Sterilization

Completely eliminating all vegetative cells, endospores, and viruses from an inanimate item.

• Common Agents: Pressurized steam (autoclave), chemicals, radiation.

• Application: Preparation of surgical equipment and needles.

Antisepsis

Decreasing or reducing the microbial load on living tissue/human tissue through chemical application.

• Common Agents: Boric acid, isopropyl alcohol, hydrogen peroxide, iodine (betadine).

• Application: Cleaning skin broken due to injury or cleaning skin before surgery.

Degerming

The mechanical action (movement) accompanied by soap to get rid of microorganisms from living tissue.

• Common Agents: Soap, alcohol swabs, hand-sanitizer.

• Application: Handwashing.

Sanitization

Lower microbial counts on eating utensils

Biocide/Germicide

Kills microbes

Bacteriostasis

Inhibiting, not killing, bacteria

Sepsis

refers to microbial contamination.

Asepsis

is the absence of significant contamination.

Aseptic surgery techniques

prevent microbial contamination of wounds. cutting Somebody open, doing/making Plates.

Commercial sterilization

Destroys endospores responsible for food poisoning in canned goods (canning process)

Pasteurization

Kills pathogens and reduces the number of spoilage-causing microbes while maintain food quality.( beer, wine, yogurt)

Desiccation

Removes available water by creating a hypotonic environment ( beef jerky)

Refrigeration

Inhibits growth; make food last longer

BSL-1 (Biosafety Level 1)

Microbes not known to cause disease in healthy hosts; pose minimal risk to workers/environment.

• Examples: Nonpathogenic strains of Escherichia coli.

• Note: Commonly found in a typical college lab.

BSL-2 (Biosafety Level 2)

• Indigenous microbes causing diseases of varying severity; pose a moderate risk.

  • Examples: Staphylococcus aureus.

  • Note: Usually don't cause major problems, but can be bad if they contact a mucous membrane.

BSL-3 (Biosafety Level 3)

Indigenous or exotic microbes causing serious/lethal diseases via respiratory transmission.

• Examples: Mycobacterium tuberculosis.

• Note: Highly transferable through respiratory droplets, but there is plenty of treatment available. Requires a filtration system running throughout the entire lab.

BSL-4 (Biosafety Level 4)

Dangerous, exotic microbes with a high risk of aerosol transmission; frequently fatal without treatment/vaccines.

• Examples: Ebola and Marburg viruses.

• Note: Highly transferable and high risk of fatality if encountered ("come across you will die"). Very few labs operate at this level.

Use-Dilution test

1. Metal rings dipped in test bacteria are dried. Salmonella cholerasuis, Staphylococcus aureus, & Pseudomonas aeruginosa)

2. Dried cultures placed in disinfectant for 10 min at 20°C

3. Rings transferred to culture media to determine whether bacteria survived treatment,

The purpose of this is to test the effectiveness of different disinfectants.

Disk-diffusion Test

• A disk-diffusion assay is used to determine the effectiveness of chemical agents against a particular microbe.

The zone of inhibition around each disc indicates how effective that antimicrobial is against the species being tested.

Base off how big your zone is going to determine how effective that particular antimactrobic agen is on your bacteria

Alkylating Agents: Gaseous Sterilants

Chemical agents used in gas form to sterilize things by denaturing proteins.

Ethylene oxide

A gaseous alkylating agent that denatures proteins to achieve sterilization.

Peroxygens

Oxidizing agents

-great for antiseptic but in low concentration

- can be used for surfaces decontaminate

Glutaraldehyde

performs the same function as formaldehyde but works at a lower concentration and is less toxic

Critical Instruments

Devices that touch the bloodstream or sterile tissue (e.g., needles, IVs).

• Required Level: Must be completely sterilized (no microbes, endospores, or anything).

Semi-Critical Instruments

• Devices that contact mucous membranes or non-intact skin (e.g., endoscopes).

  • Required Level: Not necessary to be sterile, just clean (high-level disinfection).

Non-Critical Instruments

Devices that only contact intact skin (e.g., bedsheets, stethoscopes, blood pressure cuffs).

• Required Level: Low-level disinfection; needs to be clean but poses minimal infection risk.

Rate of Microbial Death

Microorganisms die at a constant rate whether treated with physical or chemical methods.

Logarithmic Reduction (Order of Magnitude)

The microbial population decreases by one order of magnitude (or 90%) for each set unit of time.

• Visual trick: You are consistently getting rid of one zero from the back (moving the place value by one place).

• We apply this treatment consistently until we get down to one or zero cells.

Thermal death point (TDP)

is the lowest temperature at which all the microorganisms in a particular liquid suspension will be killed in 10 minutes

Thermal death time (TDT)

the minimal length of time for all bacteria in a particular liquid culture to be killed at a given temperature

• Both TDP and TDT are useful guidelines that indicate the severity of treatment required to kill a given population of bacteria

Decimal reduction time (DRT, or D value)

is the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed.

-Canning for food

-effective a disinfectant

Decimal Reduction Time (DRT) / D-value

• The amount of time (or dose) required to decrease a microbial population by 90% (or 1 log).

  • Purpose: It is used to gauge commercial effectiveness of antimicrobial treatments.

Microbial Load vs. Time to Kill

The larger the microbial load, the longer it takes to kill them all.

• Reduction Tip: Removing organisms beforehand by washing reduces the total time needed for sterilization.

Heat Mechanism on Proteins

Both moist and dry heat denature proteins.

• Action: Increasing heat causes the protein to denature, rendering it non-functional ("protein not working, it bad").

Moist Heat Protein Denaturation Mechanism

It coagulates proteins by breaking the hydrogen bonds that hold the proteins in their 3-D structure.

Boiling as a Control Method

Kills vegetative forms of bacterial pathogens, almost all viruses, fungi, and their spores within about 10 minutes.

• Limitation: Endospores and some viruses are NOT destroyed by simple boiling.

• Scope: It can lead to sterilization for most things, but is not completely reliable for all.

AutoClave

A container, a piece of machinery that is going to Sterilize different Objects that I put into it ; anything that can withstand the heat and pressure (surgical equipment, TSA)

In order for something to be sterile it need to be in the autoclave

15 minutes

15psi

121*c

Halogens (lodine, Chlorine)

Oxidizing agents

Pasteurization

uses heating, which is sufficient to kill the organisms that cause the particular spoilage problem without seriously damaging the taste of the product.

• Started with preventing the spoilage of beer and wine

• Later applied to milk, ice cream, and yogurt

• All have their own pasteurization time and temperatures

Equivalent treatments

as the temperature increases, mush less time is needed to kill the same number of microbes.

Universal / Vat Pasteurization Conditions

63°C for 30 min

High-temperature short-time

72°C for 15 sec

• Most milk

Ultra-High-Temperature (UHT) Pasteurization

140°C for less than 1 second

• Used for individual coffee creamers found in restaurants

Advantages of Steam Sterilization

Nontoxic, easy to control/monitor, rapidly microbicidal, rapid cycle time, penetrates packing/lumens, and least affected by organic/inorganic soils.

Disadvantages of Steam Sterilization

Potential for burns, deleterious to heat-sensitive instruments, damages microsurgical tools over time, and leaves items wet (causing rust).

• Core Rule: Cannot be used for materials sensitive to heat, moisture, or pressure.

Dryheat

is going to be used to Sterilize things by oxidation , denaturing proteins but it's also oxidizing anything

Dry Heat Methods

Includes flaming (e.g., loops held at a 45° angle), incineration (destroying medical waste), and hot-air sterilization (ovens).

• Sterilization Criteria: Since these methods get rid of anything includingendospores, they achieve true sterilization.

Hot-Air vs. Autoclave Conditions

Hot-air requires a higher temperature and longer time than an autoclave.

• Hot-air: 170°C for 2 hours.

• Autoclave: 121°C for 15 minutes at 15 psi.

When to Choose Dry Heat Over Moist Heat

Use dry heat for items that cannot withstand moisture or pressure.

Filtration

on liquids more specifically liquids that can’t

be autoclaved small enough to get rid of microbes

-some culture media, enzymes, vaccines, and antibiotic solutions

Low Temperature Effect on Microbes

Inhibits microbial growth (bacteriostatic effect).

• Methods: Refrigeration, deep freezing, and lyophilization (freeze-drying).

Desiccation Effect on Microbes

Prevents metabolism by removing water/drying out the environment.

Osmotic Pressure Effect on Microbes

• Creates a hypertonic environment that causes plasmolysis (cell shrinking).

Chlorine

is good either as a gas or in combination with other chemicals

Clorox

Disinfects different surfaces, especially in food processing.

• Common uses: Dairies, food establishments, and drinking water.

Chlorine Dioxide

A gas that can get rid of endospores in an environment.

• Specific target: Used to kill anthrax endospores.

Chloramines

-used for the military to disinfect drinking water

-(chlorine and ammonia) released slowly and used in sanitizing glassware and eating utensils

Radiation

is going to lead to sterilization and would be a great way for us to sterilize our food; kills microorganisms

lonizing radiation

gamma rays, X-rays, of high-energy electron beams; has shorter wavelength than nonionizing radiation.

is where they make holes in that sugar phosphate backbone.

Nonionizing radiation

UV light; damages DNA during reproduction of the cell

-cause dimers thymine dimers

Radiation Processing and Packaging Advantage

Due to deep penetration, products can be processed in their fully sealed, final packaging.

• Benefit: This limits the risk of contamination following sterilization.

Radiation Temperature Independence

Has no heat dependence. It operates efficiently at ambient and sub-zero temperatures.

• Benefit: Safe for temperature-sensitive materials (pharmaceuticals/biological samples). It doesn't cause temperatures to increase or decrease. radiation can happen in regular temperature

Radiation Chemical and Residue Safety

No volatile or toxic chemicals are needed, leaving no residue on the sterilized product and producing no end products requiring disposal.

Radiation Material Versatility & Speed

Sterilizes products with variable density, size, or thickness in seconds to minutes.

• Note: It is cheap and acts as a great way to sterilize our food.

Radiation cons

• Some types of packaging that we use for food that break down when they are exposed to X-rays or gamma rays

• Capital costs are high and specialized facilities are often needed.

• The waste produced from using this method for food is a major issue.

Does irradiated food become radioactive?

No.

• At commonly used levels, gamma irradiation does not induce radioactivity in the treated sample itself.

Phenol (Carbolic Acid)

Used to be part of surgical handwashing protocols Ignaz Semmelweis but is a skin irritant.

Phenolics (Derivatives)

• Chemical derivatives of carbolic acid that are not irritating and remain stable in organic compounds.

  • Mechanism: Injures lipid plasma membranes.

  • Great for: Disinfecting pus, saliva, and feces.

Heavy Metals Mechanism of Action

Kill microbes via oligodynamic action and by denaturing proteins, disrupt plasma membranes, mess up DNA and RNA

• Heavy metals are NOT selectively toxic.

  • Toxicity: They are very toxic and "kill everybody" meaning they damage your own cells, bacteria cells, and any other cells in your body.

Silver (Ag) Applications

Used in various clinical and everyday applications.

• Silver nitrate: Historically used as eye drops in newborns.

• Silver sulfadiazine: Used as a topical cream for burns.

• Other surfaces: Used in band-aids and on doorknobs.

Mercury (Hg)Applications

Mercury compounds (mercurochrome): Not very effective, toxic, and historically used to treat syphilis. Also used in thermometers

Copper (Cu) Applications

Used as an algicide to kill algae, and used in water pipes and doorknobs and pottery linings.

Iodine Effectiveness

One of the most effective antimicrobial agents out of all.

• Targets: Kills most bacteria, many endospores, various fungi, and some viruses.

• Safety: Can actually be used on your body without any bad side effects (acts as an antiseptic).

Tincture of Iodine

A solution of iodine combined with alcohol.

Iodophor

Iodine combined with an organic molecule so that the iodine is released slowly.

• Examples: Betadine & Isodine.

• Applications: Commonly used for skin disinfection, wound treatment, and water treatment.

Alcohol Examples & Mechanisms

Ethanol and Isopropanol.

• Action: Denature proteins and dissolve lipids.

Alcohols on Wounds

Not very effective for wounds on their own, You have to do a mechanical motion of rubbing to make it more effective.

• Best use: Used for degerming or to enhance other chemicals (like in tinctures)

Soap Mechanism of Action

Acts as an emulsifier for degerming.

• Structure: Has a hydrophilic (water-loving) end and a hydrophobic (water-fearing) end.

• Function: The hydrophobic ends attach to things like dirt and oil to lift them away.

Acid-Anionic Detergents

Surface-acting agents used primarily for sanitizing.

Cationic Detergents Mechanism

Bactericidal agents that kill microbes by denaturing proteins and disrupting plasma membranes.

• Environmental note: Antimicrobial soaps are not good for the environment.

Quats Physical Properties

A stable, non-toxic, inexpensive, colorless, odorless, and tasteless type of chemical soap that smells like grapes.

Quats Antimicrobial Spectrum

Highly effective against gram-positive bacteria.

• Other targets: Fungicidal, amoebicidal, and virucidal against enveloped viruses.

Major Limitation/Exception of Quats

Pseudomonas bacteria can actually grow inside quats.

Clinical Risks of Quats

Mostly harmless to healthy individuals, but poses a risk if exposed to an opportunistic pathogen.

• At-risk groups: A major problem for sick people, the very young, the elderly, and pregnant individuals.

Chemotherapeutic Agents

• Any sort of chemical used to treat disease.

  • Examples: Standard medications, prescription drugs, and herbal supplements.

Antibiotics

• Chemicals excreted/produced by one species (typically bacteria or fungi) to inhibit the growth of another microorganism.

  • Classification: Antibiotics are a specific category of chemotherapeutic agents.

Evolutionary Purpose of Natural Antibiotics

• Decreasing competition in the environment.

  • Goal: By inhibiting surrounding microbes, the producing organism keeps all the local resources for itself.

Paul Ehrlich

• Tried to find a treatment for syphilis that would kill the disease without killing the host.

• Compound 606

Compound 606

is the chemical that he created that was Selectively toxic, arsenic based, first synthetics

-Significance: It was selectively toxic and the first synthetic antimicrobial agent.

-Magic Bullet A drug exhibiting selective toxicity meaning it is toxic to one specific type of cell (the pathogen) but not another (the host).

fully synthetic

antimicrobial agent made entirely in a lab,

Alexander Fleming

• The first to discover a naturally produced antimicrobial agent, penicillin, in 1928.

  • Source: Penicillin is a natural antimicrobial agent made by a fungus.

Semisynthetic Antibiotics

• Natural antibiotics that have been chemically modified in a lab.

  • Purpose: To broaden their spectrum, decrease toxicity to humans, or make them more effective.

When choosing an antimicrobial several factors must be considered?

Selected toxic

Bacteriostatic vs. Bactericidal

Mechanism of Activity (Target)

Optimal Dose (MIC) & Mode of Administration

Side effects

Drug Interaction

Bacteriostatic vs. Bactericidal (Cidal) Toxicity

• Cidal compounds are going to be more toxic and a little harsher on the host than static compounds.

  • Application: Sometimes you need to kill whatever is in the body, not just stop its growth.

Mechanism of Activity (Target)

• What a particular antimicrobial is targeting in the pathogen.

  • Note: Some drug targets are better than others depending on the target organism.

Optimal Dose (MIC) & Mode of Administration

Figuring out how much drug to give, and how it is getting into the body (e.g., ingestion vs. injection).

Synergism vs. Antagonism

• Synergism: The medications being taken work together to enhance the effect.

• Antagonism: The antimicrobial interacts with other foods, medications, or vitamins to produce bad or reduced effects.