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Know the terms in table 9.1
antiseptic
aseptic
-cide, -cidal
digerming
pasteurization
sanitization
-stasis, -static
sterilization
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How do antimicrobial agents work?
- Damage cells walls
- damage cytoplasmic membrane
- damage to proteins & nucleic acids
- fatal mutations
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describe 3 factors that affect antimicrobial efficacy
- site to be treated
- relative susceptibility of microbes
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describe physical methods of microbial control:
moist heat- boiling, autoclaving, and pasteurization
- more effective than dry heat
- boiling- kills vegetative cells of bacteria and fungi
- autoclaving- steam under pressure to get higher temperature
- pasteurization- kills pathogens in milk, ice cream, yogurt, fruit juice
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describe physical methods of microbial control;
dry heat
increase temperature for long periods used for powder, oils and objects that are damaged by moisture
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describe physical methods of microbial control;
refrigeration and freezing
slows microbial metabolism, growth and reproduction
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describe physical methods of microbial control;
Dessication and lyophilization
drying to preserve food
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describe physical methods of microbial control;
filtration
passage of liquid or gas through a sieve to trap microbes
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describe physical methods of microbial control;
osmotic pressure
- ancient method to preserve food.
- Increase concentration of salt and sugar
- cells desiccate
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describe physical methods of microbial control;
radiation
- electron beam- surface
- ionizing- sterilize meat, spices
- Gamma rays- penetrate better but take hours
- UV- healthcare doesn't penetrate well
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Describe the chemical methods of microbial control including:
Phenol and phenolics
May have halogens or other functional groups, intermediate low level
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Describe the chemical methods of microbial control including;
Alcohols
- intermediate
- Denature proteins and disrupt cell membranes
- remain active on surfaces
- bactericidal, fungicidal, virucidal against enveloped viruses- not effective on spores
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Describe the chemical methods of microbial control including:;
Halogens
- intermediate
- Iodine, chlorine, bromine, fluorine
- effective against vegetative bacterial and fungal cells, fungal spores, some endospores, protozoan cyst and many viruses
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Describe the chemical methods of microbial control including:;
Oxidizing agents
- High level
- peroxides, ozones, peracetic acid
- oxidize enzymes and prevents metabolism
- Hydrogen peroxide- sterilize
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Describe the chemical methods of microbial control including:
surfactants
- soaps and detergents
- degerming agents, poor microbial agents
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Describe the chemical methods of microbial control including:
Heavy metals
- low level
- denature proteins, silver nitrate in newborns eyes to prevent neissena
- silver in surgical dressings
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Describe the chemical methods of microbial control including:
Aldehydes
cross-link proteins- denature them and inactivate nucleic acids
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Describe the chemical methods of microbial control including:
Gaseous agents
- rapidly penetrate paper and plastic warps into every crack
- denature proteins by cross-linking proteins
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Describe the chemical methods of microbial control including:
enzymes
- Human tears contain lysozyme- digest peptidoglycan cell wall
- used for food processors to reduce the number of bacteria in cheese
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Describe the chemical methods of microbial control including:
Antibiotic/ semisynthetics/ synthetics
- antibiotics- produced by microbes naturally
- semisynthetics- chemically altered antibiotics
- synthetics- wholly manmade
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