Types of Disinfectants

1st Group: Phenols; disrupt plasma membranes

2nd Group: Biguanides; used for microbial control on skin.

3rd Group: Halogens; Iodine and Chlorine

Autoclave

Pasteurization

Reduces spoilage organisms and pathogens

How does dry heat sterilization kill by?

Oxidation

High Pressure

denatures protiens

Filtration

Removes Microbes

Disiccation

Prevents metabolism

Osmotic Pressure

Causes plasmolysis, used to preseve foods

Low Temperature

Inhibits microbial growth

refrigeration

deep freezing

slow freezing

lyophilization

Radiation

Damages DNA

*Ionizing radiation (x-rays, gamma, electron) carry more energy shorter wavelengths

*Non-ionizing (UV) damages the DNA of the cell

*Microwaves kill by heat

Peroxygens

exert antimicrobial activity by oxidizing cellular components of the treated microbes.

Aldehydes

the most effective antimicrobials

Most Resistant to Least Resistant

(Microbial Control)

Prions

Endospores

Mycobacteria

Cysts of protozoa

Vegetative protozoa

Gram-negative Bacteria

Fungi

Viruses

Gram-positive Bacteria

Viruses with Lipid envelopes

Sepsis

presence of microorganisms, microbial contamination

Asepsis

do not have significant contamination. Pose no medical threats, in food are below challenged levels.

Aseptic Surgery

Techniques to prevent microbial contamination of wounds. Cleaning and preparing the wounded area.

*Clean from inside out

*From top to bottom

*swab in only one direction, inside out

Sterilization

ther removal of destruction of all forms of microbial life. Heating is the most common method used for killing microbes.

Effectiveness of antimicrobial treatments depends on the following.

1. Number of microorganisms present at location.

2. Environment

3. Time of exposure

4. Microbial Characteristics

Actions of Microbial Control Agents

(three modes of action)

*Alternation of membrane permeability

*Damage to Proteins

*Damage to Nucleic Acids

Thermal Death Point

(TDP) the lowest temperature at which all cells in a culture are killed in 10 minutes

Thermal Death Time

Time to kill all cells in a culture

Decimal Reduction Time

Minutes to kill 90% of a population at a given temperature

Disinfection

Removal of pathogens from non living items, non living tissue, works well in room temperature

Antisepsis

Removal of pathogens from living tissues

Degerming

Removal of microbes from a limited area, washing hands, brushing teeth, rinsing with Listerine

Sanitation

Lower microbial counts on eating utensils

Biocide/Germicide

Kills Microbes

Bacteriostasis

Inhibiting, not killing microbes

Alternation of Membrane Permeability

can rupture or make holes. Microorganisms will leak out, or outsides will leak in.

Damage to Proteins

Cell will just die, apply chemical, microorganisms take in chemical denature=death

Damage to Nucleic Acids

Nucleic acid is the brain of the cell. If altered the microorganism will die

Nitrates Prevent __________ germination.

Endospore

Anitbodies, Nisin and Natamycin prevent

_____________________

of cheese.

spoilage

Aldehydes are among the most effective

__________________________.

Antimicrobials

Peroxygens

exert antimicrobial activity by oxidating cellular components of the treated microbes.

Toxic Oxidants

*ozone, hydrogen peroxide, and peracetic acid

Hydrogen Peroxide

is an antiseptic found in many household medicine cabinets and hospital supply rooms.

Gaseous Sterilants

Denature Agents