Transcript Chapter 5: Control of Microbial Growth

Chapter 11: Physical and Chemical Control of Microbes
I.
aseptic
Lister started _________
Joseph ______
techniques with medical
phenol
applications. By using carbolic acid (_______)
-soaked rags and
instruments during and after surgery, gangrene and other infections
following surgery greatly diminished.
II. Terminology and Methods of Control
Sterilization
A. _____________means
COMPLETE destruction of viruses and
microbes (including endospores) so that even if they are placed
in a new growth medium, they will not revive or reproduce.
Disinfection
B. __________means
to reduce the number of pathogens (including
viruses) until they are not a hazard, usually involving the use of
antimicrobial chemicals.
Decontamination refers to removing toxins.
C. _______________
Sanitization refers to a substantially
D. ____________
reduced microbial population that meets
accepted health standards.
A clean appearance is expected!
E. Different situations warrant different levels of microbial
control.
1. daily life
handwashing with plain soap and water
Simple ____________
is considered to be the single most important step in
preventing the spread of many infectious diseases!
2. hospitals
nosocomial (hospital acquired) infections because of:
Danger of ___________
weakened condition of hospitalized patients
a. _________
pathogenic
b. higher concentration of sick people with ____________
microbes (*many resistant forms!!)
invasive procedures (such as)
c. _______
carriers
d. many health care workers are ______
aseptic care (handwashing
e. lack of _______
between patients, using gloves, etc.)
3. microbiology/research/hospital laboratories
aseptic techniques
must use ________
clean .
a. Work surfaces should be ______
sterile .
b. All media and instruments must be ______
cultures must be properly disposed of.
c. Used ________
III. Selection of an antimicrobial procedure depends on many factors
microbe the extent of ____________,
contamination
such as the type of _______,
environmental conditions, and potential risk of _________.
infection
____________
A. types of resistant microbes
endospores
1. Bacillus and Clostridium can make ___________.
waxy cell walls.
2. Mycobacterium has ______
Pseudomonas is capable of metabolizing unusual
3. ____________
substances for food. (Like disinfectants!)
B. the extent of contamination (size of the microbial population)
90
1. ‘Industry standard’ requires that ____%
of the population is
2 minutes of exposure to the treatment
killed with every __
4 minutes
a. 100 microbes  10 microbes  1 microbe in __
20 minutes
b. 1010 microbes        would take ___
washing
scrubbing first helps reduce the population
SO, ________/_________
before disinfection or sterilization.
C. environmental conditions
temperature
1. _____________
( heat  chemical action)
pH
2. _____
saliva _______,
dirt _______,
blood ______
feces can all block chemical action
3. ____,
D. Potential risk of infection
Critical items come into direct contact with body tissues.
1. _______
Semicritical
2. ____________
items come into contact with mucous membranes,
but do not penetrate body tissues.
Noncritical items only touch keratinized skin surfaces.
3. ____________
IV. Methods of Physical Control
denaturing cell proteins /enzymes. It is the
Heat works by_________
A. ______
most common control method because it is fast, reliable,
inexpensive & nontoxic.
Moist heat
1. ______
Boiling 100°C/10 minutes (kills most microbes &
a. _______
endospores
inactivates most viruses, but does not destroy __________).
Pasteurization a brief heat treatment followed by rapid cooling.
b. ____________:
(Kills pathogens and reduces the number of spoilage organisms in
milk, juices, wine, beer: Does not sterilize!)
(1). LTLT (Low Temperature Long Term) 63°C/30 minutes
*(2). HTST (High Temperature Short Term) 72°C/15 seconds
Autoclave (steam under pressure)
c. __________
(1). 15-20 psi/15-20 minutes/121°C
Sterilizes equipment, media, etc.
(2). ________
(3). used in canning procedures to destroy
endospores
Clostridium botulinum __________!
2. ___
Dry heat sterilizes.
moisture is
a. Hot air ovens (160-170°C/2-3 hours) used when ________
undesirable.
Incineration (burning)
b. ____________
furnaces
incinerators
(1). _________/___________used
to destroy disposable items,
soiled dressings, tissue specimens etc. @ 800°C to 6500°C
c. The hottest part of a Bunsen burner flame reaches 1,870°C for
flaming
______ during lab.
Microbiology
is Fun!
B. Radiation (waves having energy but no mass) causes lethal
changes in DNA, denatures proteins, but doesn’t reliably destroy
endospores)!
ultraviolet
1. Nonionizing rays = ________
radiation
a. can be used to reduce the number
of organisms in air and on clean
surfaces
b. of limited use, cannot penetrate
materials like cloth, glass, paper
X-rays or _____________
Gamma rays
2. Ionizing rays = ________
a. can be used to __________
items that are
sterilize
heat or chemical sensitive, such as plastics
b. more effective, penetrates liquids and most
solids (used to treat Washington DC mail)
c. In the US, radiation is approved to treat
trichinosis
pork to prevent ___________,
to treat beef
E. coli contamination and used to
for ________
Salmonella contamination.
treat chicken for _________
3. microwaves
heat they
a. do not affect microbes directly, but may kill by _____
generate
uneven
b. drawback is that microwave heating is ________
C. Filtration (may be used for air, some heat sensitive materials such
as serum, vaccines, drugs, IV fluidsbeer/wine)
High-Efficiency
1. _____
________Particulate
________ Air
____ (HEPA) filters remove
airborne contaminants; used in operating rooma, for people with
allergies, etc.
liquids
solids are separated from ________
2. In fluid filtration, _______
by
filters with extremely fine pores
passing through _______
a. Mechanical force or vacuum suction helps fluid through the filter
b. does not sterilize unless pore size is small enough to trap
everything (smaller pores,  cost)
Chemical Control (* for heat sensitive items, large
V. Methods of ________
surfaces)
Destructive actions include injury to the cell _________,
membrane
DNA
proteins inhibiting replication of _____.
denaturation of cell ________,
A. Disinfectants Vs Antiseptics
Disinfectants are chemicals used on inanimate objects.
1. _____________
Germicides are chemicals that KILL/DESTROY germs.
a. ___________
(examples: fungicides, bactericides, viricides)
Germistatic refers to chemicals that do not kill, but
b. __________
prevent the growth of microbes .
(examples: bacteriostatic, fungistatic)
Antiseptics are disinfectants nontoxic enough to be used on
2. __________
skin.
potency (strength)
B. Germicides are grouped according to their _______
Sterilants destroy everything, including endospores
1. __________
(for sterilizing scalpels, respiratory therapy equipment,
proctoscopes, plastic Petri dishes, endoscopes)
(ethylene oxide gas, hydrogen peroxide)
High level disinfectants (do not reliably destroy endospores)
2. ____
(used for GI endoscopes) (iodine, phenol, chlorhexidine, heavy
metals such as silver nitrate)
Intermediate level disinfectants (will kill Mycobacterium, but do
3. ___________
not destroy all viruses or endospores, even with prolonged
exposure) (used for stethoscopes, electrodes, thermometers)
(alcohols: ethyl alcohol, isopropyl)
Low level disinfectants (will not kill Mycobacterium)
4. _____
(soaps, detergents)
Phenol coefficient
C. ______
_________ (5% Phenol is the standard against which
chemical agents are tested and compared)
time
1. Each chemical is compared for the same length of _____
identical conditions
organism under ________
on the same _________
concentration
2. IF the chemical being tested requires a greater ____________
less than
time than phenol, its efficiency is _____
or a longer ______
phenol.
IF the chemical being tested requires a lower concentration
or a shorter time than phenol, its efficiency is _______
greater than
phenol.
3. Ratio of: tested chemical activity
phenol activity
less efficient than phenol
< 1 means _____
more efficient than phenol
> 1 means _____
D. Selecting the Appropriate germicidal chemical
Toxicity (the benefit of disinfecting or sterilizing an item or
1. ________
surface must be weighed against the risks associated with the use
of that chemical) (hospital Vs home/office)
material being treated (metal, rubber,
2. compatibility with the ________
glass, plastic)
Residue may necessitate rinsing
3. ________
Cost and availability (bleach)
4. ______
Storage
5. _________
and stability (concentrates require less space and
store for long periods, but when diluted/mixed, often have limited
shelf life)
Environmental
6. _____________risk
(disposal procedures needed)
VI. Methods used for Preservation (delaying spoilage) of Perishable
Products
Chemical preservatives (both nonfood and food)
A. ________
acids lower pH (inactivates enzymes, inhibits
1. organic ______
growth, but does not always destroy microbes)
nitrates and _______
2. ________
nitrites inhibit germination of Clostridium
botulinum endospores!
B. Low Temperatures
refrigerator
1. _____________
a. 0-10° C (___°
C average)
4
b. retards but does not prevent growth
freezer
2. ________
a. -20
___° C
b. prevents growth but does not kill all organisms
osmotic pressure by adding _____
sugar
salt or ______;
C. Increased _______
causes water to leave the cell, killing it.
Desiccation (dehydration) of the material (natural [sun] or
D. ___________
artificial)
E. ____________
Lyophilization (freeze-drying)
rapidly frozen at temperatures well below 0°C
1. materials _______
moisture (lightweight)
2. vacuum while frozen to remove ________
3. biological cultures, medications, foods (expensive)
Chap 12: Elements of Chemotherapy
I. Terminology
Chemotherapy = use of chemical agents to treat disease
A. ____________
Chemotherapeutic
B. _________________
agent (CTA) = chemical agent used for
treatment of disease (even cancer)
Antimicrobial
C. _____________
agent (AMA) = chemical agent used to treat
diseases caused by microbes
II. Antimicrobial Agents
A. Types of antimicrobial agents
Natural agents = metabolic products produced by
1. ________
certain groups of fungi and fungal-like bacteria that are
antibacterial in action
Synthetic
2. __________
agents = produced in the laboratory
3. _______________
agents = derivatives of natural agents
Semi-synthetic
altered in the laboratory by adding chemical groups to
improve effectiveness
B. Modes of action
enzymes
1. interfere with microbe’s chemosynthesis by inhibiting ________
2. Disruption/interference with
competitive inhibition
a. of an essential metabolite by _________
(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid crosslinkages of peptidoglycan) (p. 78)
c. by damaging the cell ___________ (Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
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.)
e. by inhibiting nucleic acid (______ and/or ____) synthesis
(Antiviral: AZT inhibits reverse transcriptase.)
(Antibacterial: rifampin inhibits RNA polymerase.)
(Antifungal: griseofulvin inhibits RNA polymerase.)
Folic acid
PABA
B. Modes of action
enzymes
1. interfere with microbe’s chemosynthesis by inhibiting ________
2. Disruption/interference with
a. of an essential metabolite by competitive
_________ inhibition
(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
wall
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid crosslinkages of peptidoglycan) (p. 78)
c. by damaging the cell ___________ (Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
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.)
e. by inhibiting nucleic acid (______ and/or ____) synthesis
(Antiviral: AZT inhibits reverse transcriptase.)
(Antibacterial: rifampin inhibits RNA polymerase.)
(Antifungal: griseofulvin inhibits RNA polymerase.)
Glycan
“backbone”
B. Modes of action
enzymes
1. interfere with microbe’s chemosynthesis by inhibiting ________
2. Disruption/interference with
a. of an essential metabolite by competitive
_________ inhibition
(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
wall
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid crosslinkages of peptidoglycan) (p. 78)
membrane
c. by damaging the cell ___________
(Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
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.)
e. by inhibiting nucleic acid (______ and/or ____) synthesis
(Antiviral: AZT inhibits reverse transcriptase.)
(Antibacterial: rifampin inhibits RNA polymerase.)
(Antifungal: griseofulvin inhibits RNA polymerase.)
hydrophilic
amphipathic
hydrophobic
B. Modes of action
enzymes
1. interfere with microbe’s chemosynthesis by inhibiting ________
2. Disruption/interference with
a. of an essential metabolite by competitive
_________ inhibition
(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
wall
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid crosslinkages of peptidoglycan) (p. 78)
membrane
c. by damaging the cell ___________
(Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
protein synthesis at 70s ribosomes (p. 79)
d. by inhibiting ________________
(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.)
e. by inhibiting nucleic acid (______ and/or ____) synthesis
(Antiviral: AZT inhibits reverse transcriptase.)
(Antibacterial: rifampin inhibits RNA polymerase.)
(Antifungal: griseofulvin inhibits RNA polymerase.)
B. Modes of action
enzymes
1. interfere with microbe’s chemosynthesis by inhibiting ________
2. Disruption/interference with
a. of an essential metabolite by competitive
_________ inhibition
(Sulfa drugs mimic PABA, blocking folic acid synthesis) (p. 77)
wall
b. by weakening/disrupting the bacterial cell ______
(Penicillin inhibits the enzyme that builds the amino acid crosslinkages of peptidoglycan) (p. 78)
membrane
c. by damaging the cell ___________
(Polymixin cleaves the
layers of the membrane like a knife) (p. 78)
protein synthesis at 70s ribosomes (p. 79)
d. by inhibiting ________________
(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.)
RNA synthesis
DNA and/or ____)
e. by inhibiting nucleic acid (______
(Antiviral: AZT inhibits reverse transcriptase.)
(Antibacterial: rifampin inhibits RNA polymerase.)
(Antifungal: griseofulvin inhibits RNA polymerase.)
C. Criteria that determine the effectiveness of antimicrobial agents
1. Selective
________ toxicity = destroys or inhibits microbe without
affecting host cells
Spectrum
2. __________
of activity = range of microbes inhibited or killed
a. ______spectrum
usually effective against Gram+ and GramBroad
bacteria
(1). useful when no time to figure out exactly which microbe is
causing disease
(2). disadvantage is that it disrupts normal flora too (resulting in
secondary infections caused by opportunists).
__________
Narrow
b. _______spectrum
requires identification of the pathogen
3. Tissue distribution, metabolism & excretion
Soluble in body fluids (to be distributed in the blood)
a. ______
Stable in body fluids (so it is not broken down easily)
b. _______
assuring constant and effective levels in the body (pH of
oral administration unless coated)
stomach may limit ______
c. must be _________
absorbed by body tissues affected
Half-life refers to the elimination rate of a drug
d. _________
frequency
(this dictates the ___________
of dosage needed)
allergenic and not cause adverse reactions
4. should be non __________
mutagenic to reduce development of resistant
5. should be non __________
strains
D. Disadvantages of antimicrobial therapy
toxic effects on normal tissues (especially liver &/or kidneys)
1. ______
normal flora
2. disturb ____________
Allergic reactions
3. ________
resistant strains of bacteria, usually by
4. development of __________
enzymes that destroy AMA (such as penicillinase)
producing _________
mutations occur naturally
a. _________
plasmids that can be spread from
b. resistance genes on _________
Conjugation
bacterial cells to other bacterial cells by ____________,
Transduction
______________,
or Transformation
____________.
E. Avoid disadvantages by
Discriminate (careful) use of AMA
1. __________
a. Dr: proper ____________
identification of disease
prescription of AMA
microbe & proper __________
b. patient: maintain proper levels by
(1). taking medication at prescribed
intervals
_________
(2). taking medication for prescribed
time
length of _____
Synergistic effect of combination of 2-more AMA when
2. _________
resistance is likely to develop
disk-plate diffusion
F. AMA testing = _________________
method (p. 66)
1. procedure
lawn of
a. Inoculate a solid ______
bacteria on agar
b. Place paper disks saturated with
antibiotics on the surface
various _________
Incubate 24 hours and then observe
c. ________
2. The principle behind this is that during incubation, the antibiotic
inhibits growth of the
diffuses into the agar and, if effective, ________
bacteria in its presence.
3. observations
a. _________________
(no growth around the disk means the
Zone of inhibition
AMA is effective)
Satellite colonies are isolated colonies in the zone of
b. _________
inhibition
resistant cells from the original population!
They represent ________
Overlapping antibiotics
(with synergistic
effects) may be needed
if satellite colonies
appear.
Location of
satellite colonies
if present