Microbiology Chapter 7

Endospores are resistant to

***Nitrate: prevents endospore germination desiccation, heat, chemicals, and radiation, nutrient depletion , UV, extreme heat and cold. becomes a dormant endospore spore contains: dna, ribosomes, enzymes which are essential for germination core is low water content- giving resistance to wet heat (boiling) small acid soluble proteins (SASP): role in dna production by binding to a tube like structure. prevent any damage from UV radiation and heat, chemicals. alcohol, sanitizing gels (good for bacteria) not good for spores. Harsh detergents needed cannot be used on skin.

Name a use for silver, mercury and copper when disinfecting using chemicals.

*Silver nitrate may be used to prevent gonorrheal ophthalmia neonatorum (newborn's eyes to prevent gonorrhea infections-bacterial and asymptomatic) *silver sulfadiazine is used in topical creams on burns- cleanser of tissue *Mercury is an antiseptic (is a cancer causing agent) , not used if we interact-no tissues. *copper sulfate is an algicide. blue green algae, kill by reducing ability to make chlorophyll

Chemical method: alcohols, heavy metals

1. Alcohols: -ethanol, isopropanol (rubbing alcohol) *denature proteins, dissolve lipids (any gram negative or any with envelopes on outside of them are going to be destroyed) *most hand sanitizers and wipes will be alcohols. 2. heavy metals: (acting like iodine and chlorine: found to attaching to proteins and disabling) -Ag, Hg, and Cu *Silver nitrate may be used to prevent gonorrheal ophthalmia neonatorum (newborn's eyes to prevent gonorrhea infections-bacterial and asymptomatic) *silver sulfadiazine is used in topical creams on burns- cleanser of tissue *Mercury is an antiseptic (is a cancer causing agent) , not used if we interact-no tissues. *copper sulfate is an algicide. blue green algae, kill by reducing ability to make chlorophyll

Know what the effectiveness of treatment depends on

1. Length of time of exposure -longer exposure kills more microbes *it takes longer to kill a high population load than a low population load exposed to same protocol. *A shorter treatment time (measured in multiples of the D value) is needed when starting with a smaller number of organisms 2. Susceptibility of the agent to that disinfecting agent or protocol. 3. Concentration of disinfecting agent or intensity of exposure. Depends on: 1. number of microbes -few, easier to rid, but may miss them if less (not long enough exposure or friction) -stragglers missed. the more microbes present, more time to eliminate population. 2. Environment (organic matter, temp., humidity): package with cardboard or plastic...optimal temperature and humidity. 3. Time of exposure: UV: quickly move wand- may not cause effect, less time. chemical antimicrobials are more effective at longer times. longer exposure compensates for lower temperatures. 4. microbial characteristics: spores or no, acid fast bacteria with waxy mycolic acid wall. endospores hard to destroy.

Terminology of Microbial Control

1. Sepsis: refers to microbial contamination 2. Asepsis: is the absence of significant contamination (Lister: experiments in surgery) prepare surgical field reducing microbial contamination while during surgery: clean tissue, block other tissues, sterile equipment, PPE --Aseptic surgery techniques prevent microbial contamination of wounds 3. Sterilization: remove ALL microbial life 4. Disinfection: (surfaces/nonliving )-removing pathogens (microbes cause sickness/illness/viruses) 5. Antiseptic:(from living tissues: hand sanitizer) removing pathogens from living tissue 6. Sanitization: lowering microbial counts to a safe level (why its ok to say 99% effective, hand sant. 70% alcohol or higher- remove all pathogens that have membranes (covid), viruses, cold and flu, Hiv. microbes with membranes that are killed with 70% alcohol: -work as antiseptic -virus (covid), flu viruses, cold viruses, hiv, *fecal matter: gram neg. , membranes outside - disrupted by sanitizer. not complete antiseptics. *dishwasher at restaurant to lower microbe counts-sanitizer 7.---cide: to kill 8.---stasis/stat: stop, inhibiting , not killing

living , tissue cleaners

1. antisepsis: antiseptics: reduces microbial load on tissue by a antimicrobial chemical . cleaning broken skin due to injury; cleaning before surgery boric acid, isopropyl alcohol, hydrogen peroxide, iodine (betadine) 2. degerming: -reduces through gentle to firm scrubbing and the use of mild chemicals. handwashing soap, alcohol swab

Chemical methods of control: Principles of effective disinfection- to clean surface or tissues

1. concentration of disinfectant: 70% in sanitizer 2. organic matter being treated cardboard, wood, plastic 3. ph: if add acid will chg ability to grow 4. time: short may not work

What factors should be considered when effectively disinfecting?

1. concentration of disinfectant: 70% in sanitizer 2. organic matter being treated cardboard, wood, plastic 3. ph: if add acid will chg ability to grow 4. time: short may not work Disinfection: reduce number of pathogenic organisms. with: disinfectant (inanimate objects), antiseptic (tissues), degerming(mechanical removal for microbes in limited area- soap or alcohol swab), sanitization (chemical agent on food handling equip. to meet public health standards. hot soap and water.

What two actions do alcohols take on cells?

1. denature proteins - inhibits cell metabolism, and by 2. disrupting cell membranes, leads to lysis 70% - if 100% it has too rapid coagulation of surface proteins and prevents penetration into the cell ethanol- drinking alcohol. optimum concentration 70% isopropanol - rubbing alcohol, better disinfectant than ethanol. Kill bacteria, fungi, but not endospores or naked viruses. evaporates and leaves no residue not good on open wounds can cause proteins to coagulate. used mechanically to wipe microbes off skin before blood draw.

Know what radiation does and which can be effective on food

1. expose food to cobalt 60 or cesium 137 by passing through radiation chamber on a conveyor belt. does not directly contact radioactive material. not eating gamma irradiated food and does not alter nutritional quality (some loss of vitamins) alterations in taste or smell of high content food, meat and dairy (can be minimized at low doses of radiation at cold temp) FDA: safe for for meat, poultry, shellfish, fresh fruits and veges, eggs with shells, spices. labeled with radura 2. microwaves kill by heat: not especially antimicrobial : * will heat up the liquid the moisture in food and then heat will move throughout food particles to get them warm. --if high enough and hot enough will denature proteins of the bacteria on the food - really have to make sure hot enough to be antimicrobial *so if just expose something to microwaves, not going to be antimicrobial but if hot enough and wet enough, then will kill the bacteria: MOISTURE and HEAT (do not want to put something that is dry in the microwave, there is no heat to heat it up) 1. heat is absorbed by water molecules. 2. may kill vegetative cells in moist foods. 3. bacterial endospores that do not contain water are not damaged by microwave radiation. 4. solid foods are unevenly penetrated by microwaves. 4. waves 1mm to 1 m.

When would one use formaldehyde? How does it work?

1. formaldehyde: 37% disinfectant and biocide that can kill bacteria, viruses, fungi, and endospores- sterilization at low temp. embalming and tissue storage and is carcinogenic (why not used as antiseptic)

Radiation

1. ionizing radiation (x rays, gamma rays, electron beams) -ionizes water to release free radicals -damages DNA, used on plastic, med supplies, food *instead of high heat moisture (cant use autoclave) have to use ionizing rad tube or uv light tube. If needs to go all way throught material (then use this) if just surfaces then use uv. 2. Nonionizing radiation (UV, 260 nm) *just to sterilize surfaces, use UV, will damage DNA (adenine, thyamine, guan., cytosine) take 2 thymines next to each other in DNA, causes those to pair up instead of them pairing to their adenine. causes a kink in double helix (thymine dimer) that kink disrupts genes, damaged. -sometimes this damage disrupts cells cycle and cause cancer (that is why uv light can cause cancer) also, will make cell decide its dead and will destroy that cell and body will replace that cell. *This also happens to viruses:sars-covid 2- can stop virus from being able to replicate 3. microwaves kill by heat: not especially antimicrobial : * will heat up the liquid the moisture in food and then heat will move throughout food particles to get them warm. --if high enough and hot enough will denature proteins of the bacteria on the food - really have to make sure hot enough to be antimicrobial *so if just expose something to microwaves, not going to be antimicrobial but if hot enough and wet enough, then will kill the bacteria: MOISTURE and HEAT (do not want to put something that is dry in the microwave, there is no heat to heat it up)

Chemical methods

1. phenol co-efficient test (use dilution test): compares effectiveness of disinfectant compared to phenol. 2. Phenol: used by lister as a surgical antiseptic: (lister developed ,listerine, surg. antiseptics/ surgery techniques with phenols) -disrupts plasma membrane *they are an alcohol and alcohols disrupt plasma membranes -skin irritant, bad odor (not commonly used anymore)

non living cleaners

1.Disinfection: bleach, chlorine bleach, phenols (lysolo), glutaraldehyde -reduces or destroys by heat or antimicrobial chemicals -lab benches, clinical, bathrooms 2. Sanitization: reduces microbes to public health levels through heat and antimicrobial chemicals -commercial dishwashing , eating utensils, cleaning public restrooms -Detergents containing phosphates (finish) industrial str. cleaners cont. quat. ammon. compounds 3. sterilization: completely eliminates all vegetative cells, endospores, viruses -prep of surgical equip., and needles -pressurized steam (autoclave), chemicals, radiation

other heat methods notes

1.flame loop: completely oxidizing, burning killing, sterilizing .... can do in oven as well which is dry heat sterilization- as long a put in high temp: 2hr at 170deg.C (338/350)., not help with plastics, yes metals. 2.dessication- freeze drying .plasmolysis, salting, sugaring (shrinks cell membrane, pulls it away from cell wall-breaking of membrane is plasmolysis if in hypertonic solution, high salt or acid, water leaves cell to dilute outside 3. *freeze dry is similar: removing water prevents metabolism -cook food, freeze it and that makes ice crystals in all the food and then dry it- remove those ice crystals and there are little pockets where all the water would be--but there is no water in there, so any bacteria is going to have all the water removed and plasmolysis occurs, all food particles remain where they were when froze, then add water and it rehydrates and food returns back to how it was before and no microbial growth in it. *take out water from bacteria and they are dying. 4. slow freeze: ice crystals disrupt cell membrane, not a sterilization technique- sometimes can kill, ice can get jagged, can poke holes in cell membranes and kill cells , some can inhibit that from happening or decrease, crystallization cause of high salt concentration-- BACTERIAL static technique , stops growth but no necessarily kill.

milk pasteurization

72C for 15 seconds set diff temp and amounts of time ultra: kill all, but also minerals and vitamins high: also vit and minerals, denature- make it unfolded, kills healthy probiotics will do ultra high pasteurization and add in minerals, probiotics

Chemical methods: Aldehydes

Aldehydes -inactivate proteins by cross linking with functional groups Use medical equipment: -glutaraldehyde, formaldehyde, and ortho-phthalaldehyde * will replace or attach to functional groups that are on bacteria that may infect larger pieces of medical equipment

Biological safety levels

BSL-1 : agents are those that generally do not cause infection (coli and subtilis), just handwashing BSL2- moderate risk, commonly found, staphylococcus aureus and salmonella , hepatitus, mumps, . safety cabinents, more restrictions, aerosolization, *autoclave: pressured steam, sterilizing. BSL3- lethal infections by inhalation. mycobacterium , tuberculosis, bacillus anthracis, west nile, hiv: restricted access, surveillance, vaccinations, ppe, respirator, safety cabinent, hands free sink , eye wash, self closing and locking doors BSL 4: fatal: exotic bacteria, transmitted by inhalation, cause things that have no trmt. or vaccinations , ebola, marburg virus.

Explain what pasteurization is and what it's used for--moist heat

Boiling and autoclave not ideal for food - ruin consistency and other sensory qualities. Pasteurization uses heat but does not render food sterile. traditional pasteurization kills pathogens and reduces the number of spoilage causing microbes while maintaining food quality. Pasteur 1860 (beer and wine). milk exposed to 65C for 30 min. today: used to kill heat sensitive pathogens in milk or other food (juice, honey). Not sterile and will eventually spoil. Milk pasteurization : balance time and length of treatment: 1. high temp short time (HTST) pasteurization: exposes milk to a temp. of 72C for 15sec. (lower bacteria numbers but preserve quality) 2. Ultra high temperature (UHT) pasteurized: temp. 138C for 2 or more sec. (can be stored for long time in sealed cont. with out being refrigerated up to 90 days. Proteins -slight change in smell and taste.

Know what slow freezing does

Cell is cooled very slowly, at a decrease of .3-2C. until it reaches final storing temp at 196C or 320F. more harmful because ice crystals disrupt cell structure. slow freeze: ice crystals disrupt cell membrane, not a sterilization technique- sometimes can kill, ice can get jagged, can poke holes in cell membranes and kill cells , some can inhibit that from happening or decrease, crystallization cause of high salt concentration-- BACTERIAL static technique , stops growth but no necessarily kill.

Effectiveness of Treatment

Depends on: 1. number of microbes -few, easier to rid, but may miss them if less (not long enough exposure or friction) -stragglers missed 2. Environment (organic matter, temp., humidity): package with cardboard or plastic...optimal temperature and humidity. 3. Time of exposure: UV: quickly move wand- may not cause effect, less time. 4. microbial characteristics: spores or no, acid fast bacteria with waxy mycolic acid wall

disk diffusion method

Evaluates efficacy of chemical agents Filter paper disks are soaked in a chemical and placed on a culture Look for zone of inhibition around disks

Know how to remove microbes of a particular size from a liquid or gas

Filtration: removal of microbes by passage of a liquid or gas through a screen like material with small pores. used to sterilize heat sensitive material like: vaccines, enzymes, antibiotics, and some culture media. High efficiency particulate air filters (Hepa): operating rooms, and burn units to remove bacteria from air. membrane filters: uniform pore size. .22 and .45 pores to filter bacteria. .01 um pores . retain all viruses and some large proteins. _______________________________ Used for liquid or gas -For heat sensitive material : ---HEPA (high efficiency particle air): removes microbes -----will filter using paper but for gases (air, in vacuum cleaner) take out very small particles from air, will take out size .3 um and greater from air. (.2 um is size of most) GASES! ---membrane filtration: removes microbes less than .22um *LIQUIDS!!!! *filter paper- membrane filtration-liquids

Chemical: halogens, iodine, chlorine, bromine

Halogens: 7th column by noble gases 1. Iodine: denatures proteins, binds to enzymes (minerals used to complete active sites of enzymes, they help your metabolism work) iodine is an element that can bind to enzymes and make it so they wont work anymore *see iodine in alcohol, combined with potassium (IKI iodine potassium iodide, used in cleansing skin -tinctures: in aqueous alcohol -iodophors: in organic molecules (betadine) (iodine with other functional groups added) alter protein synthesis and membranes. unfolding protiens 2. chlorine: -bleach: hypochlorous acid (HOCl) chlorine attached to alcohol (oh) -chloramine: chlorine + ammonia (amm. is nitrogen) -oxidizing agents: breaking diff parts of the bacteria, similar to burning. break apart and bacteria dissolve and die. 3. bromine: used in water trmt to replace chlorine. soaking , in hot tub or spa more mild than bleach . If mix water and chlorine you are going to have a bleach solution (pools)

What are two methods of dry heat sterilization- physical

Kills by oxidation effects direct flaming: sterilize inoculating loops and needles. heat metal till a red glow. incineration: effective way to sterilize disposable items: paper cups, dressings ,and biological waste. hot air sterilization: oven: Oven 2 hours at 170C dry heat transfers heat less effectively than moist heat. not as effective as moist heat

ASKED: What does UV light do to bacteria:

Kills it damages dna by causing thymine dimers will cause thymine dimers to form which stops replication of DNA is nonionizing radiation

Know what the preferred method of sterilization is and the machine to use

MOist heat sterilization: penetrates cells better than dry heat 1. Autoclaves: raise temp above boiling point. Pressure and surgical equip. endospores, vegetative cells, viruses Chamberland designed 1879 with Pasteur. MOST EFFECTIVE Retorts: moist heat sterilization on a large scale. internal pressure and temp rise above boiling point of water. 121C or 132C at a pressure of 15 to 20lbs per square inch (psi) at 20 min or more (larger vol=longer exposure) temp of steam reaches 121C at twice atmospheric pressure. Autoclave: chamber filled with hot steam under pressure. preferred unless material is damaged by heat , moisture or high pressure. Most effective when direct contact with steam and contained to small volume of liquid. all endospores and organisms killed in 15 min. require no time to reach center of solid or large vol of liquid.

Moist Heat- physical

Moist heat: denatures proteins --autoclave: steam under pressure (preferred method of sterilization- remove all microbes) --- *Most used in hospitals and in labs!!! autoclave -providing higher temp and moisture needed to denature. and sterilize (remove all microbial life)

What is used to prevent endospore germination?

Nitrate: prevents endospore germination _Use minerals on hospital surfaces. forcing spores to germinate using minerals they are more vulnerable to UV/ heat.

Peroxygens

Oxidizing agents, used on Contaminated surfaces hydrogen peroxide: antiseptic, not good for open wounds can be broken down by catalase present in human cells. hydro. peroxide works by producing free radicals that damage cellular macromolecules. against gram positive and gram neg. , fungi, viruses and endospores. to kill endospores have to increase length of exposure time. 2. Benzoyl peroxide : peroxygen used in acne. it kills bacterium propionibacterium acnes.

chemical disinfectants

Phenolics: denature and disrupt membr. lysol disinfection. antibacterial soap. Metals: mercury, silver, copper, nickel, zinc:(bind to proteins and inhibit enzyme activity): topical antiseptic, wounds, eye in newborns, catheters antibacterial, mouthwash. halogens: iodine, chlorine, fluorine: (oxidation and destabilization of cellular macromolecules): topical antiseptic, handscrub, household bleach, dental alcohols: ethanol and isopropanol: (denature proteins and disrupt membranes): disinfectant and antiseptic Surfactants: quaternary ammonium salts. (lower surface tension of water to help with washing away microbes and disruption of cell membranes ,. oral rinse, hand scrub. Bisbiguanides: chlorhexidine alexidine: disruption of cell membranes-oran rinse , hands Alkylating agents: formaldehyde, glutaraldehyde (inacti. of enzymes and nuc. acid) dinsinfectant, tissue specimen storage, embalming., vaccine component Peroxygens: hydrogen, peroxide, benzoyl peroxide, (oxidation and destabilization of cell. macromolecules) antiseptic, disinfectant, acne, toothpaste Supercritical gases: co2: penetr. cells, forms carbonic acid, lowers intracell. pH. food preservation, disinfectioin of medical devices and transplant tissues. Chemical food preservatives: sorbic acid, benzoic acid, propionic acid, pot sorbate, sod. benzoate, ca proponate, nitrites, sulfur dioxide. (decrease Ph and inhibit enzymatic function) preservation of food. Natural food preservatives: nisin and natamycin (inhibition of cell wall synthesis) preservation of dairy, meats, beverages.

What chemicals were used by Lister in the first antiseptic? Why not used as much today?

Phenols and phenolics: Phenol: (carbolic acid): was first used by lister as a disinfectant 1. phenol co-efficient test (use dilution test): compares effectiveness of disinfectant compared to phenol. 2. Phenol: used by lister as a surgical antiseptic: (lister developed ,listerine, surg. antiseptics/ surgery techniques with phenols) -disrupts plasma membrane *they are an alcohol and alcohols disrupt plasma membranes -skin irritant, bad odor (not commonly used anymore) -used by lister as a disinfectant . not used today; skin irritant, and strong odor used in throat sprays and lozenges acts as a local anesthetic

in use test

Swabs taken from objects before and after application of disinfectant or antiseptic Swabs inoculated into growth medium and incubated Medium monitored for growth Accurate determination of proper strength and application procedure for each specific situation

Filtration- physical

Used for liquid or gas -For heat sensitive material : ---HEPA (high efficiency particle air): removes microbes -----will filter using paper but for gases (air, in vacuum cleaner) take out very small particles from air, will take out size .3 um and greater from air. (.2 um is size of most) GASES! ---membrane filtration: removes microbes less than .22um *LIQUIDS!!!! *filter paper- membrane filtration-liquids

use-dilution test

a method of determining the effectiveness of a disinfectant using serial dilutions

Heat: microbe control

alters membranes and denatures proteins *thermal death point (tdp): lowest temp that a bacteria can be killed at in a 10 min exposure (diff microbes respond to different high temps: endospores are more resistant C. botulinum is heat tolerant. *thermal death time(tdt): length of time needed to kill all microorgan. in a sample at a given temp. sterilization procedures: 1.Autoclaving 2.Boiling: less effective on endospores, yes kill vegetative , some viruses (not useful sterilization technique) 3.dry heat sterilization: aseptic technique (high heat steriliz. innoc. loops-incineration at high temp destroys all microorganisms) 2 hrs at 170C: dry heat sterilizer, oven 4. moist heat sterilization: more effective , penetrates cells better than dry heat (AUTOCLAVES)

What is added to cheese to prevent spoilage?

antibiotics: --nisin and natamycin prevent spoilage of cheese _________________________ Natural chemicals: nisin: antimicrobial peptide by lactococcus lactis and is effective against gram positive organisms. disrupts cell wall prod. leaving cells prone to lysis. to preserve cheeses, meats, beverages. Natamycin: antifungal macrolide antibiotic produced by bacterium streptomyces natalensis: prevent fungal growth in dairy products: cottage cheese, sliced, shredded cheese. 2.Propionic acid: inhibit and decrease intracell. ph. effective at higher ph, naturally produced in cheese. is added to other cheeses and baked goods to prevent mold.

antiseptics- Antisepsis

antimicrobial chemicals safe for use on living skin or tissue hydrogen peroxide and isopropyl alcohol iodine (betadine) antisepsis: process of applying an antiseptic selectively effective against microorganisms and able to penetrate deep without tissue damage.

measuring microbe control

bactericides kill bact. virucides kill virus, or inactivate fungicides: kill fungi bacteriostatic: inhibit bacteria fungistatic: inhibit fungi static treatments to not kill infectious- but they are less toxic to humans and animals

sanitization

cleansing to remove enough microbes to a level deemed safe for public health commercial food service hot water and air agents: pressurized steam (autoclave), chemicals, radiation

phenol coefficient

compares a chemical's antimicrobic properties to those of phenol 1.0 same effiveness or less than 1.0 then it is less effective than phenol. greater than 1.0 is more effective

What is a common surfactant?

decreases surface tension of liquids, so aids in microbe removal: Soap is a surfactant : what soap will do reduce surface tension of liquid so that when you vibrate bacteria they will detach more easily of surface. may be forming a biofilm and have attachment to each other, and also attachments to surfaces pili and fembre and capsules that help them stick to surfaces . soap attaches to bacteria, bacteria then is attaching to soap instead of attaching to the surface. decreasing ability for them to stay stuck on your skin with surfactant, then rub it like you are supposed to, then will wash away microbe. -soap: degerms: reducing surface tension, 9detach and surr. the diff. microbes and friction will remove the microbes. a higher temp will help to do this also., but not vital. **from tissue!

Chemical methods- Surfactant

decreases surface tension of liquids, so aids in microbe removal: Soap is a surfactant : what soap will do reduce surface tension of liquid so that when you vibrate bacteria they will detach more easily of surface. may be forming a biofilm and have attachment to each other, and also attachments to surfaces pili and fembre and capsules that help them stick to surfaces . soap attaches to bacteria, bacteria then is attaching to soap instead of attaching to the surface. decreasing ability for them to stay stuck on your skin with surfactant, then rub it like you are supposed to, then will wash away microbe. -soap: degerms: reducing surface tension, 9detach and surr. the diff. microbes and friction will remove the microbes. a higher temp will help to do this also., but not vital. **from tissue! -acid-anion detergents: sanitize (lower microbial counts) -quaternary ammonium salts:(in detergents also) bactericidal due to change in permeability of membrane, and spill their contents

Desiccation

dehydration; the process of being rendered free from moisture raisins, prunes, jerky all require water for metabolism, controls growth may not kill all microbes or endospores, may regrow with favorable conditions and water is restored. lyophilization: evaporation for dehydration: rapidly frozen and placed under vacuum, water lost by sublimation. less damage, original qualities. water activity: water content in foods. add solutes salts or sugars

Heat: physical method

denatures proteins -decimal reduction time (DRT): the time, in minutes, it takes to kill 90% of a population of a bacteria at given temp. how long it takes various bacteria to be killed to get 90% of population down - diff amounts of heat to-Sanitize that surface--reduce growth

resistant

difficult to be killed

alkylating agents

disinfecting chemicals; inactivates enzymes and nucleic acids. 1. formaldehyde: 37% disinfectant and biocide that can kill bacteria, viruses, fungi, and endospores- sterilization at low temp. embalming and tissue storage and is carcinogenic (why not used as antiseptic) 2. Glutaraldehyde: 2 reactive aldehyde groups- acts quicker. 2% for sterilization is Cidex. surfaces and surgical equipment. Irritates skin-not an antiseptic

Bisbiguanides- chlorhexidine

disrupt cell membranes, causing cell contents to gel chlorhexidine against yeasts, gram-positive bacteria, gram neg bacteria, poor: Mycobacterium tuberculosis and non enveloped viruses, not sporicidal

susceptible

easy to be killed

critical items

inside body: surgical instruments, catheters, iv fluids. semicritical: in contact with mucous membranes or nonintact skin but do not penetrate tissues: not need to be sterilized but yes to high level of disinfection . noncritical: contact but not penetrate: bed linins, furniture, crutches, stethoscopes, blood pressure cuffs.

Which halogens are used? What is bleach? What is ammonia? What is betadine?

halogens: effective alone or in compounds: iodine: tincture, alcohol solution . one of first antiseptic used Halogens: 7th column by noble gases 1. Iodine: denatures proteins, binds to enzymes (minerals used to complete active sites of enzymes, they help your metabolism work) iodine is an element that can bind to enzymes and make it so they wont work anymore. combines with amino acid tyrosine in proteins and denatures proteins. *see iodine in alcohol, combined with potassium (IKI iodine potassium iodide, used in cleansing skin -tinctures: in aqueous alcohol - one of first antiseptics used. *stains skin and clothes, somewhat irritating -iodophors: is a compound of iodine complexed with an organic molecule, increasing iodine's stability and efficacy. in organic molecules (betadine) (iodine with other functional groups added) alter protein synthesis and membranes. unfolding proteins. compounds with iodine that are slow releasing. Betadine is brand of povidone-iodine, used as a hand scrub by medical personnel before surgery and topical antisepsis of a patients skin before incision. ****BETADINE ****Isodine 2. chlorine: disinfection, -bleach: hypochlorous acid (HOCl) chlorine attached to alcohol (oh). This creates the strong oxidant HOCL, uncharged and enters cells easily. -bleach (sodium hypochlorite) -chlorine gas is in municipal water and wastewater trmt plants -chlorine gas: sodium hypochlorite, sodium hypochlorite, and calcium hypochlorite used in food processing and restaurant industries. -hypochlorite salts: sodium and calcium hypochlorites used for disinfection of swimming pools. 3. chloramine: (disinfectants) chlorine + ammonia (amm. is nitrogen) -oxidizing agents: breaking diff parts of the bacteria, similar to burning. break apart and bacteria dissolve and die. -drinking water 3. bromine: used in water trmt to replace chlorine. soaking , in hot tub or spa more mild than bleach . If mix water and chlorine you are going to have a bleach solution (pools) *cryptosporidium resistant- protozoan parasite- protective outer shell

degerming

handwashing microbial numbers reduced by gently scrubbing living tissue skin scrubbing living tissue

disinfection

inactivates most microbes on the surface and uses antimicrobial chemicals or heat: not sterile, some microbes remain. by chemicals. Disinfectants: fast, stable,easy. lab benches, surfaces, bathroom Chlorine bleach or chlorine: Clean non living surfaces. phenols (lysol), glutaraldehyde vinegar: acidity kills most microbes. endospores can survive when vegetative are dead

radiation

ionizing radiation: x rays, gamma, high electron beams. alters mol. structure and damages cell components. ex: introduces double strand breaks in DNA. mutations. cells death. xray and gamma: paper and plastic (sterilize packaged materials) plastic petri dishes. gloves, iv tubes, latex, transplantation, drugs, medical equip. NONionizing radiation: disinfection and less energy: UV causes thymine dimer to form between adj. thymines within a single strand of dna. when dna polymerase encounters this dimer it does not incorporate approp. complem. nucleotides (2 adenines) and leads to mutations. purify water, 260 nm for surgical suites, cabinants, hoods. does not penetrate surfaces and does not pass through plastics or glass, cells must have direct exposure to light.

Chemical and mycobacteria

mercury: no activ. phenolics: good at controlling bisphenols: no activ. quat.amm. com.: no act chlorines: fair iodine: good alcohols: good glutaraldehyde: good chlorhexidine: fair

endo spores and chemical

mercury: no activity phenolics: poor at controlling bactericidal bisphenols: no act. quat. ammon. compounds: no activ. chlorines(bleach): fair iodine: poor alcohols: poor glutaraldehyde : fair chlorhexidine: no activ.

Decimal reduction Time (DRT)

minutes to kill 90% of a population at a given temp D Value Death curve Reduction is logarithmic rate of killing remains constant even when population size varies Heat: denatures enzymes and other proteins of microorganisms. heat reisitance varies . TDP; thermal death point; lowest temp. at which microbes in liq suspension will be killed in 10 min. TDT: thermal death time: minimal length of time in which all bacteria will be killed at given temp. Decimal reduction time (DRT): time in min. at which 90% of bacteria at given temp will be killed. canning industry.

microbial characteristics

most resistant 1. prions: infectious proteins, what causes mad cow disease, in nervous system of cow and clumps of protein in cow brain, kind of how alzheimer's works (signals not as good in nervous system). infect in human: in dna and attach and move in our DNA and can disrupt a gene.Hard to detect and treat. 2. endospores of bacteria 3. mycobacteria: acid fast bacteria, *with endospores and mycobacteria: can use alcohols, aldehydes, chlorine/bleach(will damage hair). alcohol works but not as good against endospores, they are coated with keratin. Exposure time needs to be longer ____________________________ 4. cysts of protozoa 5. vege. protozoa: cannot use antibiotics against they are eukaryotes, if hatched from cysts or both of these need anti protozoan medications) 6. gram neg bacteria: (lipopolysaccharide membrane on outside, can kill them with alcohols, rubbing alcohol, can disrupt membrane and kill bacteria middle) 7. fungi, including most fungal spores (black mold and spores, need antifungals: kitan cell wall make it alittle harder: bleach and antifungals work) 8. viruses without envelopes: easy (no covering, their protein coat is main cover on outside- can attack and attach an disable) 9. gram positive bacteria (thick peptido glycan wall- tetra peptide cross bridges are susceptible to penicillins) 10. viruses with lipid envelope (sars covid has this, alcohol works, uv light, bleach. though is very small so it is easy to miss.) least resistant: easily killed

most resistant

most: prions endospores of bacteria mycobacteria cysts of protozoa vegetative protozoa gram negative bacteria fungi, including most fungal spores viruses without envelopes gram positive bacteria viruses with lipid envelopes least resistant

Formites

objects contaminated with infectious material that contains the pathogens

Chemical: organic acids, nitrite , antibiotics

organic acids:(preservatives) -inhibit metabolism (affect the enzymes of metabolism) -sorbic acid, benzoic acid, and calcium propionate Nitrate: prevents endospore germination antibiotics: --nisin and natamycin prevent spoilage of cheese

control of microbial growth

physical control of growth of microbes: 1.-UV 2.-Dry heat sterilization: ---oven: 2hrs., 170deg.C=steralization ---Flaming: incineration 3.Desication: -freeze drying: removing water prevents metalbolism --Salting: increased osmotic pressure 4. Freezing: --Slow freezing is bactericidal ----ice crystals disrupt cell membranes ----not a sterilization technique **On lab practical 2

aseptic technique

prevent contamination of sterile surfaces. asepsis: prevent contam. of patient with microbes and infectious agents. sepsis: systemic inflamm. response: high fever, increased heart and respiratory rates, death. sterile field: free of vegetative microbes, endospores and viruses. commercial sterilization: heat at temp low enough to preserve food but high enough to destroy common pathogens *C. botulinum in soil. 121C for 2.52 min.

Refrigeration and freezing

psychrophiles (prefer cold) refrigerator: 0 and 7C- inhibits microbial metabolism, preserves food and medical supplies.(lab cultures) freezing below 2C, stop microbial growth and even kill susceptible organisms on safe way to thaw frozen foods is in the refrigerator, immersed in cold water changed every 30 min., or in microwave keeping food at temp not conductive for bacterial growth. halted growth can restart in thawed food cultured and medical: ultra low temp -70C or lower (dry ice in an ultra low freezer or nitrogen tanks (-196C)

chart most to least

sars: can be killed washing hands and cleaning surfaces gram positive : dont have a lipid envelope , easy to break cross bridges with out lipid = easy to kill fungi: can explode with a hypertonic solution gram neg.: have lipid envelope ,

Sterilization- complete elimination

sterilization: complete removal: vegetative cells, endospores, viruses (lab, medical, food service) Physical: high heat, pressure, filtration Chemicals: sterilants: kill all microbs and viruses and with correct exposure endospores pressurized steam (autoclave), chemicals, radiation

How do chemicals added to food inhibit microbial growth?

supercritical fluids: Supercritical carbon dioxide: penetrates cells and forms carbonic acid--lowers ph of cell. can be augmented with increased temp. and rapid cycles of pressurization and depressurization- which will produce cell lysis. vegetative cells, if used with peracetic acid can kill endospores. Benefits: scCo2 nonreactive, nontoxic, nonflammable properties of co2 and is effective at low temp. ***preserves objects integrity and is used for treating food (spices and juices and medical devices) _________________________ Chemical food preservatives: -inhibit microbial growth and minimize spoilage in some: 1. sorbic acid, benzoic acid ,and propionic acid: and more soluble salts: potassium sorbate, sodium benzoate, and calcium propionate: **all control growth of mold in acidic food. nontoxic and metabolized by humans, are flavorless so do not compromise flavor. sorbic acid: inhibit cellular enzymes, those in citric acid cycle, and catalases and peroxidases. dairy, bread, fruit and vegetables. benzoic acid: fruits, berries and fermented foods , spices. decreases intracell. pH, interferes with oxidative phosphorylation and uptake of amino acids into cells. benzoic acid or sodium benzoate: fruit juices, jams, ice creams, pastries, soft drinks, gum, pickles. Propionic acid: inhibit and decrease intracell. ph. effective at higher ph, naturally produced in cheese. is added to other cheeses and baked goods to prevent mold. sulfur dioxide: prevents browning of foods and preservation of dried fruits. winemaking. interfere with the disulfide bond. Nitrites: processed meats and stop germination of endospores. reduced to nitric oxide which reacts with heme groups and iron sulfur groups. gives meat its red color. when ntric acid reacts with iron sulfur enzyme ferredoxin in bacteria, prevents atp synthesis. are carcinogenic. Natural chemicals: nisin: antimicrobial peptide by lactococcus lactis and is effective against gram positive organisms. disrupts cell wall prod. leaving cells prone to lysis. to preserve cheeses, meats, beverages. Natamycin: antifungal macrolide antibiotic produced by bacterium streptomyces natalensis: prevent fungal growth in dairy products: cottage cheese, sliced, shredded cheese.

UV

swab, cover half lid- windows filter uv light expose various amounts of time: one side completely exposed and one side completely covered. Side covered will grow and survive-not exposed to the light. If completely covered- biofilm formed, no killing How long to that physical method of control?

Video on bacteria : quorum sensing

talk make chemical words and act as a group virulets: they get in and wait, count molecules, right cell number launch and overcome host. interfere with conversation and is new antibiotic idea Pseudomonas aeruginosa: cystic fibrosis, immune compromised , get a catheter or a stent, breathing tube -so virulent: forms biofilms and virulence, chemical communication, korum sensing grow and release small molecules, when enough of molecule is around it indicates enough other cells are around then all bacteria together make a biofilm which is how sit on surfaces and adhere to tissue and the group together secretes the toxins/chemical that make us sick, ***we want to interfere with that conversation, we have found the chemical they communicate with: used chemistry and changed the structure of that molecule to make the one on the right- it changed the signal molecule (word) into an inhibitor - the one that turns on quorum sensing to turning off quorum sensing. *Biofilm: put pseud. in plate, group moves out over plate. add inhibitor pseud. cannot move *found can shut down biofilm and toxin secretion!! test tubes: green when secreting next: cant secrete not green. last: inhibitor greatly reduces ability to secrete toxin Animal: if no infection alive if give- all die if give with inhibitor =good now... Have to make inhibitor medicine like- (make potency and make safe) -also make biofilm resistant materials (catheters/stents)- embed into materials. infection resistant. microbiology and chemistry

Chemical methods. Toxic Gas

toxic gas (ethylene oxide) -denature proteins -Use: heat sensitive material that are large objects, like bedding and surgical implants. *like oxidation, break apart. gas chamber.

How would a surgical implant be sterilized?

toxic gas (ethylene oxide) -denature proteins -Use: heat sensitive material that are large objects, like bedding and surgical implants. *like oxidation, break apart. gas chamber.

Pasteurization- physical

using heat to kill pathogens in a liquid reduces spoilage organisms and pathogens does not affect taste Equivalent Treatments: -63 degr. C for 30 min. ---high temp. short time: 72 deg. C for 15 sec ---ultra high temp: 140deg. C for less than 1 sec.(flash kill)

Know how salting affects bacteria physical method

water activity: water content in foods. add solutes salts or sugars water is drawn to area of high solute. high osmotic pressure honey is 80% sucrose: few microorganisms can grow Osmotic pressure: high concentrations of salts and sugar in foods to increase osmotic pressure and create hypertonic environment. Plasmolysis: water levels leave cell, plasma membrane shrinks from cell wall, stops growing , dies. *yeats and molds are more resistant to high osmotic pressure *staphylococci spp. that are on skin are resistant to osmotic pressure.