Download Lecture Summary MicrobialControl(CH5)

V. Quarternary Ammonium Compounds (Quats)
This is a group of positively charged detergents that are non-toxic enough to be
used as disinfectants on food surfaces. Since these compounds are positively charged
(due to the ammonium ion), they react with membranes such as cell membranes, which
are negatively charged. They do not kill endospores, Mycobacteria, or naked viruses.
This class of compounds is also used for products such as mouthwashes,
benzalkonium chloride or cetylpyridinium chloride are examples of “quats”. If you shake
your mouthwash and it foams, there is a quat in it!
VI. Heavy metals
Most kill by binding to the sulfhydryl groups of proteins and interfere with their
function. Metals such as silver is used in the form silver sulfadiazine for dressings in burn
patients. Another form of silver is 1% silver nitrate which was used in the eyes of
newborns to prevent eye infections from Neisseria gonorrhoeae, which can cause
blindness. Now an antibiotic solution is used instead for newborns. Copper is used to
keep down algal growth in fish tanks as copper sulfate. And mercury is found in paint
products to reduce mold growth.
VII. Soaps
Regular soap just works to remove the organisms by reducing the surface tension.
This is a very effective way to remove organisms that you have on hands, etc. Fancy
antibacterial soaps are nice for use in the bathroom and kitchen area but we should really
think twice about using them in the shower all over the skin. Remember, you need those
healthy normal microbiota!!