Control of Microorganisms: Physical and Chemical Methods

formaldehyde

%) is used to inactivate viruses and toxins used in vaccines, it also destroys spores inbacteria and fungi.

Formaldehyde

* 8% *Reacts with NH₂, SH and COOH groups *Disinfectant, kills endospores

Ethylene oxide

* other agents for sterilization * is effective by carcinogenic (potential to cause cancer) and explosive gas

Chlorine

*****deoxides*** Forms hypochlorous acid (HClO), a strong oxidizing agent *Disinfect drinking water however one disadvantage is that it binds to organic matter and become inactive

Isopropanol

*50-70% *Denatures proteins and solubilizes lipids *Antiseptic used on skin

Dry heat (hot air oven)

*Good for glassware, metal, not plastic or rubber items

Boiling

*Moist heat *Denaturation *Kills vegetative cells but not spores *Equipment,dishes

Chemical Control important terms

Antiseptics are used to destroy pathogens on living tissue. • Sepsis refers to contamination by microorganisms. • Sanitizing means reducing microbial population to a safe level. • De-germing means removing organisms from an object's surface.

Autoclaving

Moist heat and pressure it Denaturation of portions Good method of Sterilization

qualities of a good disinfectant

No Damage to surface or person but penetratable and useful in all situations (heat/cold) and dissolvable in water and easy to obtain and has no odor.

uv light includeing x rays and gamma rays are used in what type of sterlization

This is only used for surface sterilization because it denatures proteins and dries cells cytoplasm. Dna absorbs ultraviolet radition and cause thymine dimmers who distort the dna and cause errors in them.

phenols

damage cell membranes and inactivate enzymes of microorganisms, while denaturing their proteins

ethyl alcohol used to

disinfect delicate instruments by killing bacteria and found in bactericides

Biguanides

disrupt plasma and effective at killing bacteria and fungi and used to contromicrobial growth on the skin and mucous membrane. It is the active ingredient in many surgical hand scrubs and is used to clean the skin of surgical patients before surgery.

Alcohol how is it disinfects/antiseptic

disrupts membranes by causing lipid dissolution denature proteins. they have solvent action on lipids and those in the plasma membrane

Ethylene oxide

disrupts proteins and can achieve complete sterilization in 4 hours and its has good penetration and can sterlize large items and kills endospores

Incineration over an naked flame

dry heat and it oxidizes many microbiol components

Halogen are

iodine bromine and fluorine are elements that are electronegative. They have the ability to oxidize molecules stealing electrons and disrupting cellular components

Disinfection

is killing of spores and viruses and is often achieved by the use of chemicals called disinfectants. It is used for inanimate objects

What does iodine disinfects

is used to disinfect wound, water, and resturant equipment

Autoclave and pressure cooker (steam under pressure)

kills all forms of life including bacterial endospores. *The substance being sterilized must be maintained at the effective Temp for the full time

Aldehydes

other agents for sterilization and causes cross-linking that inactivates proteins and nucleic acids

Idophores how is it disinfects/antiseptic

release iodine over a long period of time and disrupts protein function

Isopropyl alcohol is used in

rubbing alcohol

why are idophores used rather than Iodine

stains and causes allergic reaction

alcohol is not effective against

they are not effective against enveloped viruses or bacterial endospores. They effectively destroy bacteria and fungi by disrupting the lipids in the plasma membrane resulting in lysis, and denatures proteins.

Cold Boiling

ultrasonic device with container of cold solution to vibrate any form of life

Physical Methods of Control

• Heat is one of the most common physical control methods. uv light and pasteurization scrubbing and cold boiling are other types of physcial methods

Distinct properties of Antiseptics and Disinfectants

• They should be: • To kill/slow growth of microbes • Nontoxic to humans and animals • Soluble in water. • Storable. • Effective quickly •Even in low concentration. • Also important in choosing an agent are: • Temperature. • pH. • Duration of disinfection.

Pasteurization

A heating process that REDUCES the number of spoilage germs and eliminates pathogens in milk and other heat sensitive foods

Flash pasteurization or high temp short time pasteurization

A type of pasteuriation, using moist heat to reduce bacterial population, where the liquid is heated at 71.6 degrees C for 15 seconds.

Chlorine does what, where

Keeps bacterial population low in municipal water supplies and swimming

Sterilization

Kills or removes all forms of life, including bacterial endospores. it is which is commonly achieved by using heat combined with pressure and is more complete then disinfection

Germicide/Biocid

A chemical agent that demonstrates killing power against various microbes

types of alcohol are

Ethanol and isopropanol are widely used as skin antiseptics,

QUATS

Quaternary Ammonium Compounds: disinfectant that are considered nontoxic, odorless, and fast acting and are a good surface cleaner

Antisepsis

Refers to the killing or removal of microbes on living tissues

Dry and moist heat are applied differently

The dry heat changes microbial proteins and removes water, slowly burning the microbes. Moist heat (like boiling water) is faster and effective at a lower temperature thandry heat. It kills microbes by denaturing their proteins. Boiling water may not kill all spores or inactivate all viruses.

Sanitization

Usually used by the food industry. Reduces microbes on eating utensils to safe, acceptable levels for public health

X rays and gamma rays does what to microbes

X rays and gamma rays (ionizing radiations) force electrons out of microbial molecules. This affects cell metabolism and physiology

Gas sterilization is used for

a wide variety of hospital equipment especially those made of plastics that would be destroyed by heat

factors of disinfectant the killer provided more convincing tales

are time of exposure kind of organism ph of disinfectant materials nature concentration of disinfectant temperature of disinfectant

Phenols are not good for antiseptic use why?

are two toxic to the skin for antiseptic use so are used on feces and surfaces. They are however stable compound and are active in organic compounds. Poor against endospores, good at mycobacteria.

surface disinfection can use

biguanides and alcohol and isophone and QUATS

what two methods use moist heat

boiling and autoclave (both denature proteins) it is more effective then dry heat because water is heat is easier transferable between substances however does not kill spores