Lesson 13.3 Using Chemicals to Control Microorganisms

algicide

. Copper sulfate is a common ___________ used to control algal growth in swimming pools and fish tanks.

iodophor

An _____________ is a compound of iodine complexed with an organic molecule, thereby increasing iodine's stability and, in turn, its efficacy.

intracellular pH

Chemical preservatives are added to a variety of foods. Sorbic acid, benzoic acid, propionic acid, and their more soluble salts inhibit enzymes or reduce _______________________.

benzene ring

Chemically, phenol consists of a _____________________ with an -OH group, and phenolics are compounds that have this group as part of their chemical structure.

copper, nickel, and zinc

Doorknobs and other surfaces in clinical settings are often coated with ___________________________________ to prevent the transmission of microbes.

antiseptics

Glutaraldehyde and o-phthalaldehyde are used as hospital disinfectants but not as _______________.

oligodynamic

Heavy metals are _____________________, meaning that very small concentrations show significant antimicrobial activity.

argyria

If too much silver accumulates in the body, for example, it can result in a condition called _________, in which the skin turns irreversibly blue-gray. One way to reduce the potential toxicity of heavy metals is by carefully controlling the duration of exposure and concentration of the heavy metal.

phenol

In the 1860s, British surgeon Joseph Lister (1827-1912) began using carbolic acid, known as _________, as a disinfectant for the treatment of surgical wounds

oxidizing

Iodine works by _____________ cellular components, including sulfur-containing amino acids, nucleotides, and fatty acids, and destabilizing the macromolecules that contain these molecules. It is often used as a topical tincture, but it may cause staining or skin irritation.

sulfur-containing amino acids

Ions of heavy metals bind to ________________________________________________ strongly and bioaccumulate within cells, allowing these metals to reach high localized concentrations. This causes proteins to denature.

bacteriostatic

Mercury compounds like mercuric chloride are mainly _________________ and have a very broad spectrum of activity.

syphilis

Mercury is an example of a heavy metal that has been used for many years to control microbial growth. It was used for many centuries to treat ________.

bacteria; fungi

Nisin and natamycin are naturally produced preservatives used in cheeses and meats. Nisin is effective against gram-positive ________________ and natamycin against _______.

supercritical fluid

Pressurized carbon dioxide in the form of a ____________________ easily permeates packaged materials and cells, forming carbonic acid and lowering intracellular pH. Supercritical carbon dioxide is nonreactive, nontoxic, nonflammable, and effective at low temperatures for sterilization of medical devices, implants, and transplanted tissues.

TRUE

TRUE/FALSE Mercury-based compounds have fallen out of favor for use as preservatives and antiseptics.

FALSE

TRUE/FALSE Soaps are classified as disinfectants.

hydrogen peroxide

The most widely used peroxygen is_________________________ (H2O2), which is often used in solution to disinfect surfaces and may also be used as a gaseous agent.

triclosan

The phenolic compound ___________, found in antibacterial soaps, plastics, and textiles is technically an antibiotic because of its specific mode of action of inhibiting bacterial fatty-acid synthesis..

skin irritant,

Today, carbolic acid is no longer used as a surgical disinfectant because it is a _________________ but the chemical compounds found in antiseptic mouthwashes and throat lozenges are called phenolics.

Sulfites

__________ are used in the wine industry but may cause asthmatic reactions in some individuals.

Sulfites

___________ are used in winemaking and food processing to prevent browning of foods.

Nitrites

___________ are used to preserve meats and maintain color, but cooking nitrite-preserved meats may produce carcinogenic nitrosamines.

Tincture

___________ refers to a disinfecting chemical dissolved in alcohol.

Bleach

____________ is an example of halogens.

Phenolics

_____________ are stable, long-acting disinfectants that denature proteins and disrupt membranes. They are commonly found in household cleaners, mouthwashes, and hospital disinfectants, and are also used to preserve harvested crops.

Alcohols

_____________, including ethyl alcohol and isopropyl alcohol, are commonly used antiseptics that act by denaturing proteins and disrupting membranes.

Halogens

______________, including chlorine, fluorine, and iodine, are also commonly used for disinfection. Chlorine compounds, including sodium hypochlorite, chloramines, and chlorine dioxide, are commonly used for water disinfection. Iodine, in both tincture and iodophor forms, is an effective antiseptic.

Surfactants

______________, including soaps and detergents, lower the surface tension of water to create emulsions that mechanically carry away microbes. Soaps are long-chain fatty acids, whereas detergents are synthetic surfactants.

Peroxygens,

________________, including hydrogen peroxide, peracetic acid, benzoyl peroxide, and ozone gas, are strong oxidizing agents that produce free radicals in cells, damaging their macromolecules. They are environmentally safe and are highly effective disinfectants and antiseptics.

Heavy metals

_________________, including mercury, silver, copper, and zinc, have long been used for disinfection and preservation, although some have toxicity and environmental risks associated with them.

Formaldehyde

__________________ is used for the storage of tissue specimens, as an embalming fluid, and in vaccine preparation to inactivate infectious agents.

Formaldehyde

__________________ works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic.

Bisbiguanides

___________________ disrupt cell membranes, causing cell contents to gel. Chlorhexidine and alexidine are commonly used for surgical scrubs, for handwashing in clinical settings, and in prescription oral rinses.

Ethylene oxide

___________________ is a type of alkylating agent that is used for gaseous sterilization. It is highly penetrating and can sterilize items within plastic bags such as catheters, disposable items in laboratories and clinical settings (like packaged Petri dishes), and other pieces of equipment.

Alkylating agents

_____________________ effectively sterilize materials at low temperatures but are carcinogenic and may also irritate tissue. Glutaraldehyde and o-phthalaldehyde are used as hospital disinfectants but not as antiseptics. Formaldehyde is used for the storage of tissue specimens, as an embalming fluid, and in vaccine preparation to inactivate infectious agents. Ethylene oxide is a gas sterilant that can permeate heat-sensitive packaged materials, but it is also explosive and carcinogenic.

Quaternary ammonium compounds (quats)

____________________________ are cationic detergents that disrupt membranes. They are used in household cleaners, skin disinfectants, oral rinses, and mouthwashes.