Microbiology Exam 2

bactericide

an agent that destroys bacteria but not necessarily their spores

formalin

aqueous formaldehyde (HCHO) solution - 37% by mass, 40% by volume, irritant of the skin, eyes, nose, and throat. Ingestion causes severe pain, vomiting, coma and death. Possible cacinogen.

halogens

group 17 elements, strong oxidizers

Ultraviolet (UV) light

inhibits growth by damaging genetic material, organisms must be exposed directly, paper can prevent UV light from penetrating enough to kill microbes.

aldehydes

react with proteins in microorganisms and alter their chemical structure

Physical/mechanical methods of control.

remove microbes without necessarily killing or preventing their growth

fumigation

spraying chemicals or vapors into the air to kill insects or small animals that carry microbial pathogens to humans.FUMIGANT is the fumigation agent.

Disinfection

the destruction of disease-causing microorganisms. Generally, it is applied to an inanimate object. Does NOT inactivate microbial endospores - however, it does kill most vegatative microbes. During disinfection, the number of microbes is reduced to the point that they no longer present a serious health hazard which is sanitation.

phenol coefficient test

the standard by which alll disinfectants are measured

filtration

the use of biological filters to mechanically remove bacteria from liquids, principally used when the liquid cannot be heated to control the organisms.

glutaraldehyde

(dialdehyde) cold chemical sterilant in 2% solution, germicidal in 10 min., kills endospores in 3 to 12 hours, less toxic than HCHO, pH sensitive (alkaline environment), throat, and lung irritant - headaches, difficulty breathing, nosebleeds, burning eyes, skin rash, brownish staining of hands, hives or nausea.

cresol

(lysol) (C6H5CH3 - - toluene derivative) ---high level exposure result in irritation and burning of skin, eyes, and throat, abdominal pain and vomiting, heart damage, anemia, liver and kidney damage, facial paralysis, coma and death:::: commonly used because works well in the presence of other organic compounds, crude cresols form colloidal suspensions in water.

Desirable qualities of disinfectant

1. ability to attack most types of microbes 2. rapid action 3. low toxicity to body tissues 4. effective in the presence of organic matter 5. highly soluble in water 6. stability 7. harmless to fabric and metal 8. easily available 9. high penetrating power 10. inexpensive

Factors influencing the action of disinfectants

1. nature of disinfectant 2. concentration of the disinfectant 3. number of microbes present 4. kind of microbes present 5. nature of the material to be disinfected 6. time of exposure to disinfectant 7. temperature of disinfectant during exposure 8. pH of disinfectant during exposure

hexachlorophene

450 times more effective as gemicide than phenol, once used in soaps, deodorants, toothpaste, talcum powder, mouthwash and shaving cream - now only available with a prescription but is an ingredient in several commercial embalming chemicals.

quaternary ammonium compounds

Benzalkonium chloride, Zephiran chloride ---disinfectancts and antiseptics that damage cell membranes and denature proteins, surface active agents that alter the suface tension of cell membranes causing cell contents to leak out, destroying the cell. Deactivated in the presence of soap, alkaline substances and other organic matter found in items such as gauze, innefective against spores, fungi and viruses, may only be bacteriostatic. Skin and respiratory irritant, may cause birth defects in pregnant women, neutralized in hard water.

ethyl alcohol

CH3CH2OH grain alcohol

Chemicals two broad categories.

Cide = kill........static= inhibit growth

iodophores

a compound consisting of iodine (I) combined with a carrier, such as polyvinylpyrrolidone, often used as a preoperative skin disinfectant (Betadine, Wescodyne) - non irritating, non staining, virtually oderless, kills bacteria, molds and some viruses quickly [tincture of iodine is a solution of idodine and alcohol, used as antiseptic, can stain skin]

Sterilization

a process of COMPLETELY removing or destroying ALL life forms and/or their products on or in a substance. Provides the highest level of microbial growth control.

gemicide

a substance that destorys microbes, not necessarily their spores

fungicide

a substance that kills fungi and spores

larvicide

a substance that kills insect larva

insecticide

a substance that kills insects

hypochlorites (bleaches)

chlorine (Cl) containing compounds, sodium ________, (NaOCl): liquid bleach, 5% solution; 1:10 solution effective for disinfecting and cleaning - irritating to skin and mucous membranes, corrosive, inactivatied by the presence of organic matter, lethal if combined with ammonia (NH3) or formaldehyde HCHO

alcohols

disinfectant that denatures cell proteins and dissolves lipids in the cell membrane, most effective in 70% aqueous solution, may be added to other disinfectants to enhance germicidal power - mild antiseptics and generally non toxic to living tissue - volatile (may evaporate before germicidal effect occurs), do not kill bacteria endospores, inactivated by organic matter, considered intermediat level disinfectancts.

boiling (moist heat)

disinfection process not sterilization, at sea level water boils at 100 C, 10 min. needed to kill vegetative bacteria, most viruses and fungi.- higher elevations (lower pressure) lower boiling temp. (10,000 ft. 89.1 C)

sedimentation

heavier particles settle to the bottom of the container and liquid can be decanted

1

if disinfectant is as effective as phenol, its phenol coefficient number is....

1 ( a fraction of 1)

if it is less effective than phenol, its number is .......

1 (a multiple of 1)

if it is more effective than phenol, its number is.....

Heat

kills microbes by denaturing the proteins they contain and proteins are denatured more easily when they are wet. One of the most reliable means of controlling the presence of microbes or their growth.

dry heat

less effective than moist ____, higher temps. and higher exposure times needed. Care must be taken in that objects be able to withstand the heat without charring or burning. (165 - 200 degrees C for 1 to 3 hours.)

scrubbing

manual process by which microbes are removed from a surface. Should be vigorous and forceful on inanimate objects, but human remains should never be treated with great force due to the possible damage that can occur to the tissues of the body. May be facilitatede by the use of soaps, detergents or disinfectants. Used in practice of mortuary hygiene.

moist heat

more effective than dry ____, because proteins denature more easily when ______, lower temperatures and shorter exposure times (121 degree C for 15 min.)

incineration

organisms removed by burning, a form of sterilization because both vegetative bacteria and the endospores are inactivated, drawbacks because the object itself is also destroyed and the waste matter must burn completely. Cremation is a form of incineration.

free flowing steam (moist heat)

steam NOT under pressure, fractional sterilization is a 3 day process to kill both vegetative and edospores that germinate - 30 min. exposure time.

Antiseptic (bacteriostatic)

the prevention or inhibiting the growth of causative microbes. Can be used on living tissue because not as harsh as disinfectants. Does not result in the immediate killing of the organism, it simply stops or greatly inhibits the growth of bacteria.

phenol

(carbolic acid) (C6H5OH) - sickeningly sweet and tarry odor, flammable, skin exposure shown to cause chemical burns, liver damage, diarrhea, dark urine and hemolytic anemia, breathed in when smoking tobacco, due to toxic nature phenolic derivatives have replaced phenol as disinfectant and antiseptic.

phenolic compounds

(coal tar derivatives) control microbial growth by denaturing proteins and disrupting cell membranes, not effective in killing bacterial endospores

isopropyl alcohol

[(CH3)2CHOH rubbing alcohol] - does NOT destroy hydrophilic (loves water) viruses

Disinfectant

a chemical or physical agent that kills disease-causing microbes.

virucide(viricide)

an agent destructive to viruses

steam under pressure (moist heat)

autoclave (pressure cooker), higher pressure, higher temperature (15 psi, 121 C) shorter exposure time (15 min.) sterilization process.

Cold

inhibits growth but does NOT kill all vegetative cells or endospores, therefore it is bacteriostatic.