Microbial Control chapter 6 Cont. LECTURE 4 Flashcards
Difference between biospheres and endospores:
Biosphere: _____________
Endospore: ________________ in a cocoon and is resistant to many factors
1) community
2) DNA is wrapped up
Types of microbial control
- _______________: kill or remove all forms of microbial life
1) Sterilization
Types of microbial control
- _______________: substances that are applied to non-living objects to destroy microbes living on them.
Disinfection
Types of microbial control
- ______________: antimicrobial substances that are applied to living tissue or skin to reduce the possibility of infection, sepsis, or putrefaction.
Antiseptics
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
Types of microbial control
- _________________: reduce number of targeted pathogenic organisms to acceptable levels
Sanitization
Control may be…
______________ – kill bacteria
______________ – slow bacterial growth
1) Bactericidal
2) Bacteriostatic
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
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
Selection of Microbial Control Methods
- Inexpensive, ____________, stable during storage, _____________.
1) fast-acting
2) selectively toxic
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
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
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
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
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
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
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
Moist Heat
- Denatures proteins and destroys __________________.
- More effective than _____________ (water better conductor of heat)
1) cytoplasmic membranes
2) dry heat
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
