chapter 9 - physical and chemical control of microbes

what is considered asepsis

free of pathogens or other contaminating organisms

what are aseptic techniques

practices to prevent entry of infectious agents into sterile tissues; prevents infection

what aseptic techniques are in health care

range from sterile methods to antisepsis

what should be of the utmost importance in our lives

controlling our degree of exposure to potentially harmful microbes

four ideal possible outcomes of microbial control

sterilization, disinfection, decontamination, antisepsis

what is another term for decontamination

sanitization

what is another term for antisepsis

degermation

what is antisepsis/degermation

reducing microbe numbers on human skin by scrubbing, immersing in chemicals, or both

what is a stipulation for antisepsis/degermation

must be safe for use on living tissues

what is decontamination/sanitization

reduces microbe contamination to safe levels

key points for decontamination/sanitization

commonly used on materials that must be sanitized for reuse, like in commercial entities

some chemicals in decontamination/sanitization can be _____ and ______

disinfectants; sanitizers

chemicals with higher concentrations are considered

disinfectants

lower concentrations are considered

sanitizers

what is disinfection

destruction of vegetative pathogens (not endospores) and removal of harmful microbial products (toxins) from material

key points on disinfection

used on inanimate objects (harmful to living tissue) common uses: boiling food utensils, applying 5% bleach to surfaces

what is sterilization

destruction or removal of all viable microbes (including spores and viruses)

what is the key point of the term sterile

term only used for sterilized material (nothing is slightly sterile)

key points of sterilization

reserved for inanimate objects (dangerous to sterilize body) common uses: surgical instruments, syringes, commercially packaged food

what is heat (autoclave) an example of

sterilization

what are sterilants (chemical agents capable of destroying endospores) an example of

sterilization

what is bleach used for

disinfection

what is iodine used for

disinfection

what is heat (boiling used for)

disinfection

what is soap used for

decontamination/sanitization

what are detergents used for

decontamination/sanitization

what are commercial dishwashers used for

decontamination/sanitization

what is alcohol used for

antisepsis/degermation

what are surgical hand scrubs used for

antisepsis/degermation

-cide means

has the ability to kill (antimicrobial agents used to destroy certain microbes)

-static means

to stand still (prevents microbes from multiplying, does not directly kill)

what are germicides and microbicides

chemical agents that kill microorganisms

function of a bactericide

destroys bacteria (except endospores)

function of a fungicide

can kill fungal spores, hyphae, yeasts

function of a virucide

inactivates viruses

function of a sporicide

destroys bacterial endospores

function of microbistatic

preventing microbe growth (not direct killing)

function of bacteriostatic

prevent growth of bacteria on tissues or on objects in the environment

antiseptics and drugs often have ________ effects because ______ compounds can be toxic to human cells

microbistatic; microbicidal

microbial control methods for devices depend on _____

patient contact

critical medical devices contact

with sterile tissues (needles forceps)

semicritical devices contact

contact with mucosal membranes (endoscopes)

noncritical devices contact

do not touch the patient or only touch intact skin (blood pressure cuff)

critical medical devices sterilization/disinfection

must be sterilized before use

semicritical devices sterilization/disinfection

high level disinfection, preferably sterilized

noncritical devices sterilization/disinfection

low level disinfection

metal tools have higher cost and associated maintenance because they can _________

be autoclaved and reused

plastic tools are generally inexpensive because they are ________

single use and disposable

plastic tools generate significant amounts of _________

biohazardous waste

microbe death is determined by

the permanent loss of reproductive capability

microbes vary in

susceptibility to microbicides

death of microbe populations are

not instantaneous

active cells die _______ than less metabolically active cells

more quickly

number of microbes

factor affecting antimicrobials

types and nature of microbes

factor affecting antimicrobials

enviornment

factor affecting antimicrobials

concentration and length of treatment time

factor affecting antimicrobials

presence of solvents, organic matter, and inhibitors

factor affecting antimicrobials

more microbes =

longer time to kill all

biofilms increase _____

resistance

temperature and pH can greatly affect ___________

antimicrobials

saliva, blood, feces, etc. can _______ treatments

inhibit

effect of agents on cell wall

block wall synthesis or digest/degrade wall

effects of agents on cytoplasmic membrane

disrupts lipid layer, creates hole allowing damaging chemicals to enter and important ions to exit

effect of agents on cellular synthesis

interrupts synthesis of proteins, prevents replication, causes mutations

effects of agents on proteins

denature proteins (break down bonds and disrupts structure) or block substrates from binding to active site

microbial control methods target ____________

microbes from the environment or on the body that can cause infection or food spoilage

populations often contain ___________

mixtures of microbes with vast differences in resistance and harmfulness

bacterial endospores have traditionally been considered ________

the most resistant microbial entities (prions are an exception)

the goal of sterilization is ____________

the destruction of bacterial endospores

methods that kill endospores will kill __________

all less resistant microbial forms

heat

physical method of control

cold

physical method of control

desiccation

physical method of control

radiation

physical method of control

filtration

physical method of control

osmotic pressure

physical method of control

chemical method of control

antimicrobial chemicals are wide ranging and can occus as liquids, gasses, and even solids

hot water, boiling water, or steam temperature is between

60 and 135 degrees

primary effect of moist heat methods

coagulation and denaturation of proteins (microbicidal)

what is the result of coagulation and denaturation of proteins

stops cellular metabolism

what is autoclaving

steam under pressure

increased pressure in autoclave chamber

raises temperature of steam

at ___ psi above normal, steam is ____

15;121 degrees C

autoclaving kills all _______

organisms and endospores

pressure alone does not kill microbes, __________ does

increased temperature

what is pasteurization

heat applied to liquids, high temp for a short time

pasteurization retains _________

flavor and nutritional value

pasteurization eliminates

pathogenic bacteria, reduces overall numbers of non pathogens

what is dry heat

hot air or an open flame

what is the temp range of dry heat

160 degrees C -1000’s of degrees C

what does dry heat do

dehydrates cell and denatures  proteins, stops cellular metabolism

in dry heat methods, very high temperatures ___________

oxidize cells (burns them to ashes)

what is incineration

direct exposure to intense heat the ignites and destroys microbes

what is the hottest point of bunsen burner

1870 degrees C

heat range of furnaces and incinerators

800 - 6500 degrees C

what is a hot air oven

heated circulated air that transfers heat to materials in the oven

sterilization in a hot air oven requires exposure to what range of heat to kill endospores

150 - 180 degrees C

moist heat is ______ than dry heat

more efficient

lower temperatures and shorter times achieve ___________

the same effect