Chapter 23 - Control of Microorganisms

Sporicides

kill bacterial and mold spores, can also be used during the process of terminal disinfection of embalming instruments and equipment.

Fungicides

kill both fungi and their spores.

Insecticides

kill insects

Larvicides

kill larvae, which are the wormlike forms of newly hatched insects.

Thermal death point

lowest temperature at which all microorganisms are killed in 10 minutes.

scrubbing

manual process by which microorganisms are removed from a surface.

Thermal death time

minimum time it takes to kill all microorganisms present.

Steam under pressure

most effective form of controlling microbial growth because pressure, temperature, and length of exposure can be controlled.

Dry heat

requires much more exposure time than most moist heat methods of decontamination. less effective than moist heat because proteins do not denature as easily when they are dry.

Decimal reduction time

time in minutes it takes to kill 90% of the present microorganisms.

Incineration

used most frequently in funeral homes to treat hazardous waste. is a form of sterilization because both vegetative bacteria and the bacterial endospore are inactivated

Chlorine

used to treat municipal drinking water and for the maintenance of swimming pools. often combined with water to create sodium hypochlorite.

-static

will prevent the growth of a particular type of microorganism.

Chemical methods of controlling microorganisms

- chemical antimicrobial agents - halogens - Phenol compounds - Quaternary Ammonium Compounds

Factors influencing chemical agents

- nature of disinfectant - concentration of disinfectant - nature of the material to be disinfected - number of microorganisms present - type of microorganism present - length of exposure to disinfectant - temperature of the disinfectant during exposure - disinfectant's pH during exposure

Physical methods of controlling microorganisms

- scrubbing - temperature - light

Hexachlorophene

450 times more effective as a germicide than phenol. commonly used in soaps, deodorants, toothpaste. replaced by chlorhexidine in many places.

Quaternary Ammonium Compounds

AKA quats, chemical disinfectants and antiseptics that damage cellular membranes and denature microbial proteins. capable of altering the surface tension of cell membranes causing their cellular contents to leak out. deactivated in the presence of soap and other organic matter. Benzethonium chloride; benzalkonium chloride; ceepryn chloride.

Phenol (carbolic acid)

Lister first used as disinfectant during surgery. slightly acidic, has a sickening sweet and tarry odor. available commercially as a liquid

iodophore

a compound of iodine and a surfactant such as a detergent that can slowly release free iodine. (providone-iodine, or Betadine)

Formalin

a concentrated, liquid form of formaldehyde used as a disinfectant in which formaldehyde gas is dissolved in water. 37% formaldehyde by mass and 40% formaldehyde by volume

-cide

agents that will kill a particular type of microorganism

Thymines

aromatic bases, known as pyrimidines, produced by the body to form nucleic acids, which contain genetic material.

Boiling

at sea levels water boils at 100 C and takes approximately 10 minutes to sterilize water that does not contain endospores. kills vegetative bacteria, most viruses, and fungi.

Moist heat

boiling, free-flowing steam, and steam under pressure.

Alcohol

control microbial growth by denaturing proteins and by dissolving lipids in the cell membrane of microorganisms. most effective in aqueous solution because proteins are not soluble in high concentrations of this.

Iodine

controls microbial growth by oxidizing certain molecules within the microbial cell can be used in the form of either a tincture or an iodophore

Disinfection

destruction of pathogenic agents by chemical or physical means by applying the disinfectant to an inanimate object. offers less control of the growth of microorganisms. does not inactivate microbial endospores but does kill most vegetative microorganisms. *applied to inanimate objects"

Halogens

disinfectants that work by oxidizing the components of microbial cells. six elements found in the next to the last column on the far right side of the periodic table.

Cold

do not kill all vegetative cells or endospores. inhibits growth of microorganisms

Glutaraldehyde

effective disinfectant and is actually a cold chemical sterilant when activated in a 2% solution which is germicidal in 10 minutes and kills endospores in 3 to 12 hours. inactivates the DNA and RNA of microorganisms less toxic than formaldehyde is pH sensitive, only active in alkaline environment

Cremation

form of incineration. human remains placed in retort at approximately 1600 F.

Light (UV)

form of non-ionizing radiation that can effectively control the growth of microorganisms placed directly in its path. inhibits microbial growth by damaging the cell's genetic material. some microorganisms develop bonds between adjacent thymines in their DNA.

Aldehydes

group of organic compounds that control microbial growth by reacting with the proteins in microorganisms and altering their chemical structure.

Phenol compounds

include phenol, cresols, and hexachlorophene. control microbial growth by denaturing proteins and disrupting cell membranes.

Germicides

kill a variety of different types of microorganisms but not necessarily their spores.

Bactericides

kill bacteria but not necessarily their spores.

Viricides

kill viruses

Sterilization

offers highest level of microbial growth control. process of completely removing or destroying all life-forms, endospores, or their products on or in a substance.

Cresols (lysol)

phenolic compounds derived from a chemical known as toluene. 3 slightly different forms (ortho, meta, and para). used to produce the commercial product Lysol.

Autoclave

piece of equipment that works like a pressure cooker

Antisepsis

process by which microbial growth is inhibited on living tissue to prevent infection. *applied to living tissues"

Free-flowing steam

process called fractional sterilization, items placed in this type of steam for 30 minutes on successive days. waiting overnight allows endospores that weren't killed to germinate, turning into vegetative cells. steaming again kills them, then repeat process.

Tincture

solution of iodine and alcohol that is primarily used as an antiseptic