Micro-Bio Ch. 9-10

Sterilization

Destruction or removal of all viable microbes (including spores and virus)

Disinfection

Physical or chemical process to destroy vegetative pathogens (not endospores) and remove harmful microbial products (toxin) from material

Decontamination/Sanitization

Mechanical removal of microbes and other debris to reduce contamination to safe levels

Antisepsis/Degerimation

Reduces microbe numbers on human skin and form of decontamination but on living tissues

Aspesis

Free of pathogens or other contaminating organisms

\-static

To stand still

\-cide

Has ability to kill

Methods for Critical devices

Contact w/ sterile tissue (needles) must be sterilized before use

Methods for semi critical devices

Contact w/ mucosal membrane (endospore) High-level disinfection, perfectly sterilized

Methods for non critical devices

Doesn’t touch patient or only intact skin (blood pressure cuff) lower level disinfection unless contaminated w/ blood or bodily fluids

Cell Wall- Effects of Agents

Block wall synthesis or digest/degrade wall

Cytoplasmic membrane- Effects of Agents

Disrupt lipid layer, creates holes allowing damaging chemicals to enter and important ions

Cellular Synthesis- Effects of Agents

Interrupt synthesis of proteins, prevent replication, cause mutations

Proteins- Effects of Agents

Denature proteins (break bonds and disrupt structure) or block substrates from binding to active

The 6 Physical Methods of Microbial Control

1. Heat
2. Cold
3. Desiccation
4. Radiation
5. Filtration
6. Osmotic Pressure

True or False: Moist heat is more effective than dry heat

True

Primary effect of moist heat methods

Coagulation and denaturation of proteins (stops cellular metabolism)

Primary effect of dry heat methods

Dehydrates cell and denature proteins (stop cellular metabolism)

Methods of Moist heat Control

1. Boiling Water
2. Hot Water
3. Steam

Methods of Dry Heat Control

1. Pasteurization
2. Autoclaving
3. Incineration
4. Hot Air Oven (Dry Oven)

Autoclave Sterilize by

Steam under Pressure

Factors Affecting Germicidal Activity

1. Nature of microorganism being treated
2. Nature of material being treated
3. Degree of contamination
4. Time exposure
5. Strength and chemical action of germicide

Antibiotic

Substance produced by a microbe that, in small amounts, inhibit another microbe

Kirby-Bauer Test

Small disc containing a specific concentration of antibiotic are placed on the plate

E Test (epsilometers)

Plastic strip contains antibiotic at decreasing concentrations

E Test (epsilometers) determine

Minimal inhibitory concentration (smallest concentration of drug that inhibits growth)

Broth dilution test determine

minimum inhibitory concentration (MIC)

Therapeutic Index

Ratio of the dose of a drug that is toxic to humans compared to its minimum effective dose (therapeutic dose)

Broad-spectrum affects

Broad range of gram-positive or gram-negative bacteria

Narrow spectrum drugs affects

Limited range of microbial types

Superinfections

Overgrowth of pathogens that have developed antibiotic resistant and normal microbiota

Bactericideal

Kill microbes directly

Bacteriostatic

Prevent microbes from growing and host immune system destroys microbes

5 Antimicrobial modes of action

1. Inhibition of cell wall synthesis
2. Inhibition of nucleic acid (RNA and DNA) structure and function
3. Inhibition of the ribosome in protein synthesis
4. Interference with cytoplasmic membrane structure or function
5. Inhibition of folic acid synthesis

Antiviral Affects entry and fusion in virus reolication

Block host cell receptors, or fusion of virus with cell

Mechanism of resistance

1. Prevention of penetration
2. Enzymatic destruction of drug
3. Alteration of the Drug’s target site
4. Rapid ejection of the antibiotic