Microbial Control chapter 6 Cont. LECTURE 4 Flashcards by Ala A

Difference between biospheres and endospores:

Biosphere: _____________

Endospore: ________________ in a cocoon and is resistant to many factors

1) community
2) DNA is wrapped up

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Types of microbial control

_______________: kill or remove all forms of microbial life

1) Sterilization

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Types of microbial control

_______________: substances that are applied to non-living objects to destroy microbes living on them.

Disinfection

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Types of microbial control

______________: antimicrobial substances that are applied to living tissue or skin to reduce the possibility of infection, sepsis, or putrefaction.

Antiseptics

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Types of microbial control

_________________: antimicrobial substance generally transported through lymphatic system to destroy microbes, bacteria towards the body.
May be natural, semisynthetic, or synthetic

Antibiotics

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Types of microbial control

_________________: reduce number of targeted pathogenic organisms to acceptable levels

Sanitization

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Control may be…

______________ – kill bacteria

______________ – slow bacterial growth

1) Bactericidal
2) Bacteriostatic

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Rate of Microbial Death

Important to know rate to __________________ for disinfection
Want to know ______________ needed to achieve acceptable level of sterilization for a specific purpose

1) develop standard protocols
2) minimum time

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Mechanisms of Microbial Control

Alteration of ____________________
- Create pores in outer membrane that __________________ and disrupt membrane integrity
Damage __________ (structure or enzymes) and ____________

1) membrane permeability
2) increase permeability
3) protein
4) nucleic acid

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Selection of Microbial Control Methods

Inexpensive, ____________, stable during storage, _____________.

1) fast-acting
2) selectively toxic

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Selection of Microbial Control Methods

Relative resistance of microbes

____________ are most resistant
- Killed by alkylating agents, 10% bleach, proper boiling conditions, prolonged exposure to ionizing radiation
_____________ – difficult to treat due to cell wall
- Antibiotic resistance is a problem
_____________– can survive harsh conditions allowing for transmission from host to host
_____________ – high resistance to some antibiotics due to efflux pumps

1) Endospores
2) Mycobacterium
3) Protozoa cysts
4) Gram-negatives

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Selection of Microbial Control Methods

Site to be Treated

____________ chemicals and extreme heat cannot always be used
Invasive devices need ________________ of treatment than noninvasive ones

1) Harsh
2) different level

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Selection of Microbial Control Methods

Environmental conditions

_______________ and _______ affect microbial death rates and efficacy of antimicrobial methods
Organic materials interfere with penetration of heat, chemicals, and some forms of radiation, and may _____________ chemical disinfectants

1) Temperature
2) pH
3) inactivate

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Evaluating Disinfectants and Antiseptics

Phenol coefficient

Compares a given agent’s ability to __________________ to that of phenol under standardized conditions
Greater than _____ indicates it’s more effective than phenol

1) control microbes
2) 1.0

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Evaluating Disinfectants and Antiseptics

Use-Dilution Test

Metal cylinders are dipped in bacteria cultures, dried, then each dipped in different dilution of disinfection.After incubation, the highest dilution that prevented microbial growth is _______________

most effective

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Evaluating Disinfectants and Antiseptics

In-Use Test

Swabs are taken from actual objects before and after treatment with disinfectant, then ________________ medium

1) incubated in appropriate

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Physical Methods of Control

Thermal Death Point – _______________________________________
Thermal Death Time – _______________________________________
Decimal reduction time (D) – ____________________________________
Moist Heat

1) lowest temp that kills all cells in a broth in 10 minutes
2) the time it takes to completely sterilize a particular volume of liquid at a set temp
3) time required to destroy 90% of microbes in a sample

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Moist Heat

Denatures proteins and destroys __________________.
More effective than _____________ (water better conductor of heat)

1) cytoplasmic membranes
2) dry heat

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Kills vegetative cells of bacteria and fungi, trophozoites of protozoa, and most viruses within 10 minutes

Boiling

Achieves true sterilization

Autoclaving

Used to kill pathogens in milk, ice cream, yogurt, and juices
Thermoduric and thermophilic prokaryotes survive

Pasteurization

Flash heating milk and other liquids to rid of all living microbes
140C for 1-3 seconds, followed by rapid cooling
Indefinite storage at room temp

Ultrahigh-temperature sterilization

Powders and oils that cannot be sterilized by boiling or steam or materials damaged by repeated exposure to steam
Requires higher temp for longer times than moist heat
171C for 1 hour or 160C for 2 hours
Incineration

Dry Heat

Refrigeration and Freezing

Decrease ________________, ________, and reproduction (except psychrophilic microbes)
Listeria and Yersinia (blood)

1) microbial metabolism
2) growth

Desiccation and Lyophilization Desiccation – \_\_\_\_\_\_\_\_\_\_\_\_ Lyophilization – \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

1) drying 2) freezing and drying

Use high concentrations of salt or sugar to desiccate cell Fungi have greater ability to tolerate hypertonic environments than bacteria

Osmotic pressure

Disrupts the structure of DNA

Radiation

Physical Methods of Control LIST ALL SIX OF THEM

Heat Refrigeration and Freezing Desiccation and Lyophilization filtration Osmotic pressure Radiation

Chemical Methods of Control Phenol and Phenolics * Intermediate- to low-level disinfectants that Denature __________ and disrupt cell membranes * May be modified to enhance _____________ action * Pine and clove oil are natural phenolic antiseptics (TEST QUESTION)

1) proteins 2) antimicrobial 3)

Chemical Methods of Control Phenol and Phenolics * Bisphenolics – 2 linked phenolics * __________________ (Lysol) * \_\_\_\_\_\_\_\_\_\_\_ * Effective in presence of contaminating ___________ materials * Disagreeable odor and possible side effects (skin irritation) * _________________ – causes brain damage in infants

1) Orthophenylphenol 2) triclosan 3) organic 4) Hexachlorophene

Chemical Methods of Control Alcohols * Bactericidal, fungicidal, virucidal (enveloped) * Intermediate-level disinfectants that denature proteins and disrupt \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

cytoplasmic membranes

Chemical Methods of Control Alcohol * More effective when __________ (denaturation requires water) * Quick evaporation leaves no residue, but may not contact ___________ long enough to be effective * Pre-injection swabbing more physical removing (degerming)

1) diluted 2) microbes

Chemical Methods of Control Halogens * Intermediate-level disinfectants; mechanism not completely understood * Effective against ________________ and fungal cells, fungal spores, some bacterial endospores and protozoan cysts, and many viruses

1) vegetative bacterial

Chemical Methods of Control Halogens * Iodine * iodine tablets to disinfect water no longer thought good b/c _________ survive.Filtration is a better idea * tinctures or iodophors slowly release iodine.Ex) \_\_\_\_\_\_\_\_\_\_ * chlorine * bromine * used in hot tubs b/c it evaporates more slowly than __________ at high temp * fluorine (as fluoride)

1) protozoan cysts 2) betadine 3) chlorine

Chemical Methods of Control Oxidizing agents * High-level disinfectants and antiseptics that oxidize enzymes to \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ * Particularly effective against ______________ microbes (deep puncture wounds) * Hydrogen peroxide

1) prevent metabolism 2) anaerobic

Chemical Methods of Control Oxidizing agents * ______________ – sometimes used for drinking water (Canada, Europe) * More effective than chlorine, but expensive and harder to maintain effective concentration * ______________ – effective sporicide * Food processors and medical personnel use to sterilize equipment * Not adversely affected by organic contaminants, leaves no toxic residue

1) Ozone 2) Peracetic acid

Chemical Methods of Control Surfactants * Reduce surface tension of solvents by ________________ the attraction among molecules * Soaps * One end hydrophobic, the other hydrophilic * Hydrophobic end break up oily deposits into tiny droplets * Hydrophilic ends attract water molecules * Tiny droplets of oily material harbor bacteria and are easily dissolved and washed away by water * Good degerming agent, but poor antimicrobial

1) decreasing

Chemical Methods of Control Surfactants * Detergents * Positively charged _____ surfactants, more soluble in water than soaps * Quaternary ammonium compound (quats) * Ammonium cation (NH4+) disrupt cell membranes so cells lose essential internal ions * Bactericidal, fungicidal, virucidal (enveloped) * Colorless, tasteless, harmless to humans, but action retarded by organic contaminants, and deactivated by soaps * P. aeruginosa thrives in quats * Low-level disinfectant * Zephiran, Cepacol, mouthwashes that foam

organic

Chemical Methods of Control Heavy Metals * Combine with sulfur atoms in molecules of cysteine to denature proteins * \_\_\_\_\_\_\_-level bacteriostatic and fungistatic * Not used much anymore * Used to use 1% silver nitrate to preven blindness by N. ______________ in newborns.Now use less irritating and broader spectrum agents

1) Low 2) gonorrhoeae

Chemical Methods of Control Heavy Metals * Sill used in some surgical dressings, burn creams, and catheters * Thimerosal (mercury-containing compound to preserve vaccine) was largely replaced after US Public health Service recommended safer alternatives in 1999 * Whole-cell pertussis, some __________ against tetanus, flue and meningococcal meningitis still contain thimerosal * Copper interferes with chlorophyll. Used to control algal growth in reservoirs, fish tanks, swimming pools, water storage tanks

vaccines

Chemical Methods of Control Aldehydes * ________________ (liquid form) and ______________ (gaseous form) are highly reactive chemical * 2% solution of glutaraldehyde kills bacteria, viruses, and fungi.10 minutes exposure disinfects most objects in clinical settings; 10 hours sterilizes * 37% formaldehyde in water (formalin) is used for embalming and disinfecting isolation rooms, exhaust cabinets, surgical instruments, and reusable kidney dialysis machines. * Irritating to __________ membranes and carcinogenic * Denature proteins and inactivate \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

1) Glutaraldehyde 2) formaldehyde 3) mucous 4) nucleic acids

Chemical Methods of Control Gaseous Agents * Items that cannot be treated with _________ or \_\_\_\_\_\_\_\_(heart-lung machine components, sutures, plastic laboratory ware, mattresses, pillows, artificial heart valves, catheters, electronic equipment, dried or powdered foods * **Ethylene oxide, propylene oxide, beta-propiolactone**

1) liquids or heat

Chemical Methods of Control Gaseous Agents * Penetrate paper and plastic wraps and diffuse into every crack to denature _________ and \_\_\_\_\_\_\_\_\_\_. * NASA uses _______________ to sterilize spacecrafts.Large hospitals use to sterilize heat sensitive instruments and equipment * **Extremely hazardous to people, highly explosive, extremely poisonous (must flush with air to remove all traces), potentially carcinogenic**

1) proteins 2) DNA 3) ethylene oxide

Chemical Methods of Control Enzymes * Lysozyme in human tears digests ______________ cell walls * Prionzyme approved by EU in 2006

peptidoglycan

Chemical Methods of Control Antimicrobials * \_\_\_\_\_\_\_\_\_\_\_\_\_, semisythetics, synthetics

Antibiotics

Chemical Methods of Control LIST ALL 10 OF THEM

1) Phenol and Phenolics 2) Alcohols 3) Halogens 4) Oxidizing agents 5) Surfactants 6) Heavy Metals 7) Aldehydes 8) Gaseous Agents 9) Enzymes 10) Antimicrobials