Transcript Bacterial Classification

Control of Bacterial Growth
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Chemical Methods
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Phenols
Halogens
Biguanides
Alcohols
Surface active agents
Aldehydes
Heavy metals
Acids & bases
Gases
Peroxygens
Control of Bacterial Growth
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Phenols & Phenolics
– Lister & carbolic acid
– penetrate plasma membrane & precipitate
proteins
– phenol coefficient - chemical agents
evaluated relative to phenol
– Related to phenols are cresols one of which
is the active ingredient in Lysol
– Bisphenols also related to phenols but also
contain halogens i.e. hexachlorophene
Control of Bacterial Growth
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Halogens
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Chlorine & drinking water
Ca(OCl)2 or NaOCl - bleach
Iodine
Betadine (Iodine and organic solvent)
Chloramines
Hexaclorophene
Control of Bacterial Growth
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Chloramine
– N2Cl
– Alternative to chlorination
– More stable and does not dissipate as rapidly as free
chlorine.
– Lower tendency than free chlorine to convert organic
materials into chlorocarbons (carcinogens)
– Lacks the distinct chlorine odor of the gaseous
treatment and so has improved taste
Control of Bacterial Growth
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Hexachlorophene
– Topical antiinfective, antibacterial agent
– often used in soaps
and toothpaste
– pHisoHex
– Thought to be
carcinogenic; may be
teratogenic
Control of Bacterial Growth
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Triclosan
Anti-bacterial
often used in toothpaste
At in-use concentrations,
triclosan acts as a biocide
withith multiple
cytoplasmic and
membrane targets
lower concentrations,
appears to target fatty
acid biosynthesis
Control of Bacterial Growth
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Alcohols
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70% ethanol
isopropanol
require some water to be effective
used in conjunction with other agents
Control of Bacterial Growth
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Biguanides
– Avagard – chlorhexidine
– Polyaminopropyl biguanide (PAPB)
– Killing effect related to damage of plasma
membrane
– the polymer strands are incorporated into
the membrane, which disrupts the
membrane reduces its permeability
– Mycobacteria and endospores are resistant
Control of Bacterial Growth
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Biguanide,
Polyaminopropyl
biguanide
used for disinfection on
skin and in cleaning
solutions for contact
lens, deodorant body
sprays
Effective at low
concentrations
Control of Bacterial Growth
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Surface Active Agents
– soaps - emulsification of oils increases
bacterial removal - deodorant soaps
contain triclocarban or triclosan
– acid-anionic agents used in dairy industry
– quaternary ammonium compounds - work
best against G+ bacteria, less effective
against G-; also kill fungi protozoa and
viruses; Psuedomonas resistant
Control of Bacterial Growth
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Aldehydes
– react with a variety of organic functional
groups: -NH2, -OH, -SH
– Formaldehyde
– Glutaraldehyde
– used for embalming
Control of Bacterial Growth
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Heavy Metals
– usually toxic
– Silver nitrate used on infants eyes
(replaced by antibiotics)
– Copper sulfate used as algicide
– Mercury toxicity and resistance
– Zinc chloride and oxide in toothpaste
Control of Bacterial Growth
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Acids and Bases
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pH extremes inhibit growth of bacteria
acid (pickles and tomatoes)
trisodium phosphate in detergent
Propionic acid in bread
Benzoic acid in soft drinks
Control of Bacterial Growth
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Gases
– ethylene oxide - strong oxidizer and
alkylating agent
– very penetrating
– possible carcinogen
– does not damage instruments but
expensive to use
Control of Bacterial Growth
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Peroxygens - Oxidizing Agents
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Ozone - being used in water treatment
Hydrogen peroxide -surface disinfecting
Benzoyl peroxide - skin treatment
Peracetic acid - used in food processing
because residue is non-toxic