Chapter 11 (Microbial control: agents)

Decontamination

The destruction, removal, or reduction in number of undesirable microbe

sepsis

the growth of microorganisms in the tissues

• on infected wounds

• blood infection

asepsis

techniques that prevent the entry of microbe into sterile tissues

• used in surgery

• ex A surgeon wearing sterile gloves and using sterilized instruments

antiseptic

chemicals applied to body surfaces to destroy or inhibit vegetative pathogens

disinfection

destruction of vegetative pathogens on inanimate objects

sanitization

cleansing technique that removes microorganisms and debris from inanimate surfaces

Degermation

PHYSICALLY cleansing technique that removes microorganisms and debris from living tissue

• Hand scrubbing before surgery, wiping skin with alcohol before an injection

sterilization

the removal or destruction of all viable microbes

moist heat > temperature ( physical methods of control)

lower temp + shorter exposure time

• coagulation + denaturation of proteins = stop cellular metabolism

desiccation ( physical methods of control)

gradual removal of water from cells > metabolic inhibition

• NOT EFFECTIVE BEC > cells retain ability to grow even without water

radiation ( physical methods of control)

energy emitted from atomic activities + dispersed at high velocity through matter or space

• two types of radiation

  • ionizing radiation

  • nonionizing radiation

filtration ( physical methods of control)

physical removal of microbes by passing a gas or liquid through filter

• sterilizes heat sensitive liquids and air in hospital isolation units + industrial clean rooms

dry heat > temperature ( physical methods of control)

moderate to high temp

• dehydration

• alters proteins structure

• includes incineration

Cold > temperature ( physical methods of control)

micro biostatic = inhibits the growth or multiplication of microbes

refrigeration 0-15 celcius + freezing < 0Celciu

preserve food, media, cultures

autoclave (a type of moist heat control ) + (sterilization with steam under pressure)

what it is?

pressure = increase steam temperature > sterilizes surface of item

• denaturation or proteins, destruction of membranes and DNA

• items cant be heat + moisture sensitive

what can an autoclave control: endospores?, prions?,  viruses?, etc. 

YES

• endospores

• viruses

• bacteria

• fungi

• protozoa cyst / oocycst

CANT CONTROL

• prions

• extreme thermophiles archaea

pasteurization

Heat is applied to kill potential agents of infection and spoilage > DOES NOT DESTROY FOOD FLAVOR/VALUE

• BUT DOES NOT KILL ALL > MORE LIKE REDUCE TO SAFER LEVEL

types of pasteurization

and the differences

Flash method: aka High Temp Short - Time

• DOES not Sterilize BUT lowers overall microbe count

  • cant kill endospores ONLY non-spore

Ultra pasteurized: Ultra-high temperature

• 134 Celsius for 2-5 seconds

• kills nearly all microbes

Know what and what can’t be killed by simply boiling contaminated water

killed

• most bacteria and viruses

• protozoa

• fungi

• yeast

• Helminths + eggs

NOT KILLED

• bacterial endospores

• prions

Be familiar with the differences between micro biostatic and microbicidal

Micro biostatic: Prevents microbes from growing or multiplying

microbicidal: Directly kills microorganisms.

ionizing radiation > what it is and the types

Deep penetrating power sufficient energy to cause electrons to leave their orbit

• gamma rays

• x rays

• cathode rays

non-ionizing radiation

little penetrating power

• Ultra Violet Light creates pyrimidine dimers

• interferes with replication

Know what a thymine dimers is and how it is formed, and its biological effect

type of DNA damage (lesion) where two adjacent thymine bases for an abnormal covalent bond disrupting DNA structure

Caused by ultraviolet (UV) radiation

effects

• DNA Replication Disruption

• mutations

• cell death

• cancer risk

Halogens (a germicidal category)

Examples are

• chlorine

• Iodine

Chlorine (a type of Halogen)

• denatures proteins due to disruption of disulfide bonds

• Unstable in sunlight

Iodine (a type of Halogen)

• interferes with disulfide bonds of proteins

• degerming agent for medical and dental

• can be use for disinfectants or ointments

Germicidal

something that is capable of killing or preventing the growth of germs

Phenols (a germicidal category)

a carbolic acid that is poisonous >

• disrupts cell walls + membranes

• precipitate proteins (make proteins insoluble)

• Bactericidal, fungicidal, virucidal

• IS TOXIC for antiseptics

Alcohols (a germicidal category)

Ethyl + isopropyl suitable for microbial control

• concentration of 50% and higher dissolve membrane lipids + coagulate proteins of vegetative bacterial cells and fungi

  • NEED water to coagulate > GOOD IS 70% alcohol concentration

hydrogen peroxide

(a germicidal category)

reactive hydroxyl-free radicals that damages protein and DNA

• can be antiseptic at low concentration

• strong solution = sporicidal

Detergents

(a germicidal category)

quaternary ammonia compounds > act as surfactants that alter membrane permeability of some bacteria and fungi

Soaps (a germicidal category)

mechanically removes soil + grease contain microbes

• antibacterial additives are LYSOL AND TRICLOSAN

Heavy metals (a germicidal category)

ability to denature proteins and disrupt microbial metabolism using silver and mercury

surfactant def

caused by detergents

• are compounds in detergents that lower surface tension, allowing water to mix with oils, grease, and dirt.

• disrupting microbial membranes

organic mercury > type of heavy metal germicidal

weak antiseptics + infection preventatives

• use for Ophthalmic solutions (eye drops) / cosmetics

Soaps with respect to microbial control

• weak microbicides (prevent the transmission of sexually transmitted infections)

• can treat gonorrhea, meningitis, and syphilis

Alcohols with respect to microbial control

alcohol gel hand cleansing good for antisepsis

Chlorine with respect to microbial control

• use for drinking water, sewage, wastewater, inanimate objects

Iodophors (a form of iodine) with respect to microbial control

• antiseptic prep for surgery + injections

• surgical hand scrubs

• disinfect equipment + surfaces

Elemental iodine: aqueous or tinctures

(a form of iodine)

• topical antiseptic prior to surgery

• used on burned or injured skin

• disinfection for plastic instruments/thermometers

• tablet form for contaminated water

Silver Sulfadiazine ointment applications with respect to microbial control

added to dressing > precent infection for second + third degree burn

Silver Nitrate applications with respect to microbial control

topical germicide for mouther, ulcers (stomach/intestine), root canals

Metallic silver applications with respect to microbial control

catheters > prevent UTI

paint, plastics, steels, walls, floors > control microbial survival

Colloidal silver applications with respect to microbial control

mild germicidal ointment

rinse for mouth, nose, eyes, vagina

Know what lyophilization is; what is it and why is it used?

Freeze drying > for preservation

• by removing water under low temperature and vacuum condition