Post on 10-Apr-2018
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Physical and Chemical Control of Microbes
I. Joseph ______ started _________ techniques with medicalapplications. By using carbolic acid (_______) -soaked rags andinstruments during and after surgery, gangrene and other infectionsfollowing surgery greatly diminished.
II. Terminology and Methods of ControlA. __________ means COMPLETE destruction of viruses and
microbes (including endospores) so that even if they are placedin a new growth medium, they will not revive or reproduce.
B. __________means to reduce the number of pathogens (includingviruses) until they are not a hazard, usually involving the use ofantimicrobial chemicals.
C. _____________ refers to removing toxins.D. __________ refers to a substantiallyreduced microbial population that meetsaccepted health standards.A clean appearance is expected!
Lister asepticphenol
Sterilization
Disinfection
SanitizationDecontamination
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E. Different situations warrant different levels of microbial control.1. daily life
Simple ___________with plain soap and water
is considered to be the single most important step inpreventing the spread of many infectious diseases!
handwashing
Sanitized items (not sterilized!!)
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2. hospitals
Danger of __________(hospital acquired) infections because of:
a. _________ condition of hospitalized patients
b. higher concentration of sick people with _________ microbes(*and many resistant forms!!)
c. _______ procedures (such as)
d. many health care workers are ______
e. lack of _______ care (handwashing
between patients, using gloves, etc.)
nosocomial
pathogenic
weakened
invasive
carriers
aseptic
3. microbiology/research/hospital laboratoriesmust use ________ techniquesa. Work surfaces should be ______.b. All media and instruments must be ______.c. Used ________ must be properly disposed of.
asepticclean
sterilecultures
surgery
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III. Selection of an antimicrobial procedure depends on many factorssuch as the type of _______, the extent of ____________,
____________ conditions, and potential risk of _________.
A. types of resistant microbes1. Bacillus and Clostridium can make ___________.
2. Mycobacterium has ______ cell walls.
3. ____________ is capable of metabolizing unusual
substances for food. (Like disinfectants!)
endospores
waxy
microbe contaminationenvironmental infection
Pseudomonas
B. the extent of contamination (size of the microbial population)1. Industry standard requires that ____% of the population is
killed with every __ minutes of exposure to the treatmenta. 100 microbes p 10 microbes p 1 microbe in __ minutesb. 1010 microbes p p p p p p p would take ___ minutes
SO, ________/_________ first helps reduce the populationbefore disinfection or sterilization.C. environmental conditions
1. _____________ (o heat o chemical action)2. _____3. ____, _______, _______, ______ can all block chemical action
90
2
4
20
washing scrubbing
temperaturepHdirt saliva blood feces
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D. Potential risk of infection
1. _______ items come into direct contact with body tissues.Critical
2. ____________ items come into contact with mucous membranes,but do not penetrate body tissues.
Semicritical
Surgical instruments
needles
Biopsy forceps
Respiratory equipment
Vaginalspeculum
Anal proctoscope
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3. ____________ items only touch keratinized skin surfaces.Noncritical
IV. Methods of Physical ControlA. ______ works by_________ cell proteins /enzymes.
It is the most common control method because it isfast, reliable, inexpensive & nontoxic.1. ______ heat
a. _______ 100C/10 minutes (kills most microbes& inactivates most viruses, but does not destroy__________).
Heat denaturing
MoistBoiling
endospores
stethoscope
Sphygmomanometer
(blood pressure cuff)
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Pasteurizationb. ____________: a brief heat treatment followed by rapid cooling.(Kills pathogens and reduces the number of spoilage organisms inmilk, juices, wine, beer: Does not sterilize!)
(1). LTLT (Low Temperature Long Term) 63C/30 minutes*(2). HTST (High Temperature Short Term) 72C/15 seconds
c. _________ (steam under pressure)(1). 15-20 psi/15-20 minutes/121C(2). ________ equipment, media, etc.(3). used in canning procedures to destroy
Clostridium botulinum __________!
Autoclave
Sterilizes
endospores
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2. ___ heat sterilizes.
a. Hot air ovens (160-170C/2-3 hours) used when ________ isundesirable.
b. ____________ (burning)
(1). _________/___________used to destroy disposable items,
soiled dressings, tissue specimens etc. @ 800C to 6500C
c. The hottest part of a Bunsen burner flame reaches 1,870C for______ during lab.
Dry
Incineration
flaming
Microbiologyis Fun!
moisture
furnaces incinerators
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B. Radiation (waves having energy but no mass) causes lethalchanges in DNA, denatures proteins, but doesnt reliably destroyendospores)!
1. Nonionizing rays = _____________radiationa. can be used to reduce the number
of organisms in air and on cleansurfaces
b. of limited use, cannot penetratematerials like cloth, glass, paper
2. Ionizing rays = ________ or _____________a. can be used to __________ items that are
heat or chemical sensitive, such as plasticsb. more effective, penetrates liquids and most
solids (used to treat Washington DC mail)c. In the US, radiation is approved to treatpork to prevent ___________, to treat beeffor ________ contamination and used totreat chicken for _________ contamination.
Ultraviolet (UV)
X-rays Gamma rayssterilize
trichinosisE. coli
Salmonella
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3. microwavesa. do not affect microbes directly, but may kill by _____ theygenerate
b. drawback is that microwave heating is ________
heat
uneven
C. Filtration (may be used for air, some heat sensitive materials suchas serum, vaccines, drugs, IV fluidsbeer/wine)
1. _____ ________ ________ ____ (HEPA) filtersremove airborne contaminants; used in operatingrooms, for people with allergies, etc.
2. In fluid filtration, _______ are separated from ________ bypassing through _______ with extremely fine poresa. Mechanical force or vacuum suction helps fluid through the filterb. does not sterilize unless pore size is small enough to trap
everything (smaller pores, o cost)
High-Efficiency Particulate Air
solids liquidsfilters
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V. Methods of ________ Control (* for heat sensitive items, largesurfaces)Destructive actions include injury to the cell _________,
denaturation of cell ________, inhibiting replication of _____.A. Disinfectants Vs Antiseptics
1. _____________ are chemicals used on inanimateobjects.
a. ___________ are chemicals that KILL/DESTROY germs.
(examples: fungicides, bactericides, viricides)
b. __________ refers to chemicals that donot kill, but prevent the growth of microbes.
(examples: bacteriostatic, fungistatic)2. __________ are disinfectants nontoxic
enough to be used on skin.
Chemical
membraneproteins DNA
Disinfectants
Germicides
Germistatic
Antiseptics
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B. Germicides are grouped according to their _______ (strength)
1. __________ destroy everything, including endospores(for sterilizing scalpels, respiratory therapy equipment,
proctoscopes, plastic Petri dishes, endoscopes)(ethylene oxide gas, hydrogen peroxide)
2. ____ level disinfectants (do not reliably destroyendospores) (used for GI endoscopes)(iodine, phenol, chlorhexidine, heavymetals such as silver nitrate)
3. ___________ level disinfectants (will kill Mycobacterium, but donot destroy all viruses or endospores, even with prolongedexposure) (used for stethoscopes, electrodes,
thermometers) (alcohols: ethyl alcohol, isopropyl)4. ____ level disinfectants (will not kill
Mycobacterium) (soaps, detergents)
High
Intermediate
Low
potency
Sterilants
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C. ______ _________ (5% Phenol is the standard against whichchemical agents are tested and compared)
1. Each chemical is compared for the same length of _____on the same _________ under ________ conditions
2. IF the chemical being tested requires a greater ____________or a longer ______ than phenol, its efficiency is _____ thanphenol.
IF the chemical being tested requires a lower concentration
or a shorter time than phenol, its efficiency is _______ thanphenol.
3. Ratio of: tested chemical activityphenol activity
< 1 means _____ efficient than phenol
> 1 means _____ efficient than phenol
Phenol coefficient
concentrationtime
greater
less
more
timeorganism identical
less
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D. Selecting the Appropriate germicidal chemical1. ________ (the benefit of disinfecting or sterilizing an item or
surface must be weighed against the risks associated with the useof that chemical) (hospital Vs home/office)
2. compatibility with the ________ being treated(metal, rubber, glass, plastic)
3. ________ may necessitate rinsing4. _____ and availability (bleach)5. ________ and stability (concentrates
require less space and store for longperiods, but when diluted/mixed, oftenhave limited shelf life)
6. _____________risk(safe disposal procedures needed)
Toxicity
material
ResidueCostStorage
Environmental
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VI. Methods used for Preservation (delaying spoilage) of PerishableProductsA. ________ preservatives (both nonfood and food)
1. organic ______ lower pH (inactivates enzymes, inhibits
growth, but does not always destroy microbes)2. ________ and _______inhibit germination of Clostridium
botulinum endospores!B. Low Temperatures
1. _____________
a. 0-10 C (___ C average)b. retards but does notprevent growth
2. ________a. ___ Cb. prevents growth but
does not kill allorganisms
Chemicalacids
nitrates nitrites
refrigerator
freezer
4
-20
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E. ____________ (freeze-drying)1. materials _______ frozen at temperatures well below 0C
2. vacuum while frozen to remove ________ (lightweight)3. biological cultures, medications, foods (expensive)
Lyophilizationrapidly
moisture
C. Increased _______ pressure by adding _____or _____; causes water to leave the cell, killing it.
D. ___________ (dehydration) of the material(natural [sun] or artificial)
osmotic saltsugar
Desiccation
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Elements of Chemotherapy
I. TerminologyA. ____________ = use of chemical agents to treat diseaseB. _______________ agent (CTA) = chemical agent used fortreatment of disease (even cancer)C. ___________ agent (AMA) = chemical agent used to treat
diseases caused by microbesII. Antimicrobial Agents
A. Types of antimicrobial agents1. _______ agents = metabolic products produced by
certain groups of fungi and fungal-like bacteria that areantibacterial in action
2. _________ agents = produced in the laboratory3. _____________ agents = derivatives of natural agents
altered in the laboratory by adding chemical groups toimprove effectiveness
ChemotherapyChemotherapeutic
Antimicrobial
Natural
Synthetic
Semi-synthetic
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B. Modes of action1. interfere with microbes chemosynthesis by inhibiting ________2. Disruption/interference with
a. of an essential metabolite by _________ inhibition(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
enzymes
competitive
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PABA
Folic acid
Competitive Inhibition
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B. Modes of action1. interfere with microbes chemosynthesis by inhibiting ________2. Disruption/interference with
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid cross-linkages of peptidoglycan) (p. 78)
enzymes
wall
Glycanbackbone
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B. Modes of action1. interfere with microbes chemosynthesis by inhibiting ________2. Disruption/interference with
c. by damaging the cell ___________ (Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
membrane
hydrophilic
Amphipathic
enzymes
hydrophobic
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B. Modes of action1. interfere with microbes chemosynthesis by inhibiting ________2. Disruption/interference with
d. by inhibiting ________________ at 70s ribosomes (p. 79)(Erythromycin inhibits translocase, freezing the ribosome on
the mRNA.)(Tetracycline blocks tRNA attachment to mRNA)(Chloramphenicol inhibits transferase, preventing peptide
bond formation between amino acids.)
(Streptomycin causes a misreading of mRNA.)
protein synthesis
enzymes
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e. by inhibiting nucleic acid (______ and/or ____) synthesis(Antiviral: AZT inhibits reverse transcriptase.)(Antibacterial: Rifampin inhibits RNA polymerase.)(Antifungal: Griseofulvin inhibits RNA polymerase.)
DNA RNA
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2. ________ of activity = range of microbes inhibited or killed
a. ______spectrum usually effective against Gram+ and Gram-bacteria
(1). useful when no time to figure out exactly which microbe iscausing disease
(2). disadvantage is that it disrupts normal flora too (resulting in
_________ infections caused by opportunists).b. _______spectrum requires identification of the pathogen3. Tissue distribution, metabolism & excretion
a. ______ in body fluids (to be distributed in the blood)b. _______ in body fluids (so it is not broken down easily)
assuring constant and effective levels in the body (pH of
stomach may limit ____ administration unless coated)c. must be _________ by body tissues affectedd. _________ refers to the elimination rate of a drug
(this dictates the ___________ of dosage needed)
Spectrum
Broad
secondaryNarrow
Soluble
absorbed
Stable
Half-life
oral
frequency
C. Criteria that determine the effectiveness of antimicrobial agents1. ________ toxicity = destroys or inhibits microbe without
affecting host cellsSelective
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4. should be non __________ and not cause adverse reactions5. should be non __________ to reduce development of resistant
strains
D. Disadvantages of antimicrobial therapy1. ______ effects on normal tissues (especially liver &/or kidneys)2. disturb ____________3. ________ reactions4. development of __________ strains of bacteria, usually by
producing _________ that destroy AMA (such as penicillinase)a. _________ occur naturallyb. resistance genes on _________ that can be spread from
bacterial cells to other bacterial cells by ____________,______________, or ____________.
allergenicmutagenic
toxicnormal flora
Allergicresistant
enzymesmutations
plasmidsConjugation
TransformationTransduction
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F. AMA testing = _________________ method (p. 66)1. procedure
a. Inoculate a solid ______ of bacteria on agarb. Place paper disks saturated with various _________ on the
surfacec. ________24 hours and then observe
2. The principle behind this is that during incubation, the antibioticdiffuses into the agar and, if effective, ________ growth of thebacteria in its presence.
3. observations
a. _________________ (no growth around the disk means theAMA is effective)
b. _________ colonies are isolated colonies in the zone ofinhibition (They represent
________ cells from the originalpopulation!)
inhibits
Zone of inhibition
Satellite
Location ofsatellite coloniesif present
resistant
Overlapping antibiotics (withsynergistic effects) may be needed
if satellite colonies appear.
disk-plate diffusion
lawn
antibiotics
Incubate