Microbial Growth Control Flashcards
Physical control methods
Heat Autoclaving Pasteurization Filter Cold Desiccation High osmotic pressure Radiation
Factors influence effectiveness of chemical control
Dilution
Time
pH
Organic matter
Types of disinfectants
Phenol Halogens Heavy metals Alcohol Surface active agents Quats Aldehydes (PHHASQuAl)
Removal of all microbial life
Sterilization
Killing c. Botulinium
Commercial sterilization
Removal or pathogens
Disinfection
Removal of pathogens from LIVING TISSUE
antisepsis
Lower microbial counts on utensils
Sanitation
Removal of microbes from LIMITED AREA
Degerming
Kills microbes
Biocide / germicide
INHIBITING microbes
Bacteriostasis
Use light for metabolism
Have chlorophyll
Use carbon dioxide and oxygen - main byproduct
Organic products
Phototrophs
Use hydrogen and sulfur
Chemotrophs
Needs oxygen
Increase o2
Decrease co2
Aerobic
Needs less oxygen
Decrease o2
Increase co2
Anaerobic
Time required for a bacteria to grow and divide
Generation time
Depicts how a bacteria behaves in a certain medium
Growth curve
Growth curve phases
Lag
Log
Stationary
Decline
Effectiveness of antimicrobial depends on
Characteristics of microbe Number of microbe Environment Time of exposure (C-NET)
Lowest temp at which all cells in a culture are killed in 10mins
Thermal death point
Time to kill all cells in a culture
Thermal death time
Minutes to kill 90% of a population at a given temp
Decimal reduction time
Effect of moist heat
Protein denaturation
Autoclaving
Moist heat Steam under pressure 15mins 121C 15psi
Pasteurization
63c for 30 mins
73c for 15 sec
140c for 1 sec
Reduce spoilage
Pasteurization
Kills by oxidation
Dry heat sterilization
Hot air sterilization
170c for 2hrs
Removes microbes by trapping in filter
Filtration
Inhibits microbial growth
Low tempreature
Refrigeration
Deep freezing
Lyophilization
Deep freezing
-20c or -80c
Prevents metabolism
Dessication
Causes plasmolysis
Osmotic pressure
Damages dna
Radiation
Types of radiation
Ionizing
Non ionizing
Microwaves
Ionizing radiation
Xray
Gamma rays
Electron beams
Surface sterilization only
Non ionizing radiation
UV
Evaluating a disinfectant
Dilution test
Disk diffusion
Dilution test
Metal ring dipped in bacteria - dry
Dried ring place in diluted disinfectant
Transfer to culture
Determine if bacteria survived the treatment
Disruption of plasma membrane
Phenols
Types of phenolics
O-phenylphenol (lysol)
Hexachlorophene
Triclosan
Turpinol ( pine-sol)
Halogens
Iodine Povidone iodine Sodium hypochlorite Bromine tablets Chlorine gas
Denature protein by breaking disulfide bonds
Iodine and betadine
Heavy metals
Strong oxidizers
Bromine
Chlorine
Denatures proteins and dissolve lipids
Alcohol
Heavy metals
Mercurachron
Copper sulfate
Zinc chloride
Silver nitrate
Antiseptic for wounds
Mercurachron
Algicide
CuSo4
Mouth wash
Znc chloride
Antiseptic for eyes, wounds
Silver nitrate
Surface active agents
Soap
Acid anionic detergents
Degerming
Soap
Sanitizing
Acid anionic detergents
Disrupt plasma membrane
Denature proteins
Quats
Quats
Benzalkonium cl
Roccal
Cationic detergents ( cetylpyridinium )
Zephiran
Benzalkonium cl
Cepacol
Cetylpyridinium chloride
Inactivate proteins by cross linkingnwith functional groups
Aldehydes
Disinfectant for hospital equipments
Aldehydes
Denature proteins
Dissolve membranes
Acids and bases
Naoh
Floor cleaner
Ammonium hydroxide
Break down lipids
Benzoid caid
Food products
Gas sterilants
Denature proteins
Ethylene oxide
Sterilize hospital equip
Disposable lab plastic ware
Carcinogenic
Dialysis equipment
Peracetic acid
Swimming pool
O3
Cl2
Skin
H2o2
Most resistant - least resistant
Prions Endospore of bacteria Mycobacteria Cysts of protozoa Vegetative protozoa Gram neg Fungi Gram pos Virus wd envelope
Poor in endospore
Good in mycobacteria
Phenolics
Alcohols
Not effective in both endospore and mycobacteria
Quats
Fair effectiveness in endospore and mycobacteria
Chlorines
Fair im endospores
Good im mycobacteria
Aldehydes
Factors affecting microbial control
Temperature
Species
Environment