Download Chapter 26 Microbial Growth Control

Chapter 26
Microbial Growth Control
Physical Antimicrobial Control
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Physical Antimicrobial Control
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Thermal Death Curve: Mesophilic Bacterium
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Thermal Death Curve: Mesophilic Bacterium
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Thermal Death Curve: Mesophilic Bacterium
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Thermal Death Curve: Mesophilic Bacterium
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Decimal Reduction Time vs Temperature
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Pasteurization
Times and Temperatures:
Pasteur’s original: half hour at 63oC-66oC as a Batch.
Originally designed to prevent spoilage of wine.
Later applied to milk to prevent Mycobacterium
bovis transmission of TB.
Milk current standard based on killing Listeria
monocytogenes, Campylobacter sps, Salmonella
and Escherichia coli O157:H7, Coxiella burnetti.
HEAT EXCHANGER: 72oC for 15 sec.
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HTST Pasteurization – Continuous
Counter Current Flow
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Countercurrent Heat
Exchanger
Small Heat Exchanger
Small Heat
Exchanger
Heat Exchanger
Diagram
Ultrapasteurization
Heat Exchanger : heats milk to 138oC for 3 sec (2 to 4 sec).
Ultrapasteruized milk is supposed to last 6 months at room
temperature without spoilage.
Milk is packaged in plasticized cardboard containers.
There’s a Story Here.
The Autoclave
and water !
Ultra Violet Lights Are ON
The mesh work
at the back
holds behind it
a HEPA Filter
so that sterile
air moves
outward as a
laminar flow.
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Radiation Kills Just Like
Heat
1 Gray (Gy) = 100 rads
1 rad = 100 ergs/g
Decimal Reduction
Doses of Ionizing
Radiation
Check out the D10 for humans
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It Works Beautifully with Food
Filtration
Depth Filters
Membrane Filters
Nucleopore Filters.
Bacteria stuck on
membrane filters.
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Membrane Filtration
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Antimicrobial Chemical Effects
Minimal Inhibitory Concentration
Lowest Concentrations    Highest Concentrations
We did these with microtiter plates in Chapter 31 (Fig 31.8)
Antiseptics
Antimicrobial Agents Used In Vivo
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Antimicrobial Spectra
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Antibiotic Production Today
Salvarsan and Paul Ehrlich
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Sulfa Drugs: Gerhard Domagk, 1930’s
First Chemosynthetic Antibiotics
Nucleoside Analogs
First ones were simple, more
complex one developed in
response the AID’s epidemic.
Quinolones
Ciprofloxacin
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Moxifloxacin
Naturally Occurring
Antimicrobials:
The Antibiotics
β-lactamase Resistant Ceftriaxone
A Cephalosporin
The Amino Glycosides: Target 30S ribosome
The Macrolides : Eythromycin
Targets the 50S ribosome
The Tetracyclines : Targets 30 S ribosome
Daptomycin and Platensimycin
Inhibits Fatty Acid biosynthesis
Cyclic Lipopeptide: alters Cell Membranes
Antibiotic Resistance
Antibiotic Resistance Mechanisms
1. Lacks structure antibiotic inhibits.
2. Impermeability.
3. Enzyme that alters structure of antibiotic.
4. Makes modification of antibiotic target.
5. Develops a resistant, alternate pathway.
6. Efflux Pump.
The Classics !
Epidemiological
Patterns of
Antibiotic
Resistance
Appearance of Drug Resistance
Resistance to
Vancomycin
over come by
converting the
carbonyl to a
methyl.
Computer Aided Drug Design
Other Antimicrobial Strategies
Natural Products  searches for fit into prokaryotic essential
enzymes from databases of plant or other organisms
secondary products.
This is how Platensimycin was discovered by a screen
of 250,000 known bio-products.
Drug Combinations  Augmentin is a combo drug containing
amoxicillin and the β-lactamase inhibitor Clavulanic
acid. See next slide.
Textbook Combo: Sulbactam and Ampicillin
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Augmentin = Clavamox = Tyclav
Amoxicillin
Clavunlanic Acid