MMG Physical Control

+ inhibiting or limiting microbial growth

+ elimination of all viable microbes

+ elimination of microbes on inanimate objects, usually via chemical means

+ not necessarily sterilized

+ reduction of microbial numbers on fomites

+ chemical agent that kills or inhibits microbes externally on body

+ kills microbes
- bacteriocidal
- fungicidal
- viricidal

+ kills by lysing cells
- bacteriolytic
- fungilytic

+ reversibly inhibits growth;
- bacteriostatic
- fungistatic
- viristatic

+ chemical produced by microbe that can kill or inhibit another microbe. Naturally occurring

+ antimicrobial agent used internally to kill or inhibit a microbe; can be an antibiotic or chemically synthesized

- die at constant death rate
- rate varies by organism and conditions
- most susceptible cells die first
- must use antimicrobial agent until even hardier cells are dead.

- High-level: kills all pathogens including endospores
- Intermediate-level: kills fungal spores, protozoan cysts, viruses and pathogenic bacteria
- Low-level: kills vegetative bacteria, fungi, protozoa, and some viruses

+ External:
- Physical
- Chemical
+ Internal:
- Chemotherapeutic agents
- antibiotics

- Enveloped viruses
- Gram-positive bacteria
- Nonenveloped viruses
- Fungi
- Gram-negative bacteria
- Active stage protozoa
- Cysts of protozoa
- Mycotobacteria
- Bacterial endospores

Moist heat; Dry heat; Refrigeration; Freezing;
Desiccation; Lyophilization;
Filtration; Osmotic pressure;
Ionizing radiation;
Nonionizing radiation

- Boiling
- Autoclaving
- Pasteurization
- Ultra-high temperature sterilization

- Hot air
- Incineration

- Drying
- Conditions vary w/amount of water to be removed
- Inhibits metabolism
- Preserves food

- Freeze drying
- Minus 196 degrees for a few minutes while drying
- Inhibits metabolism
- Long term storage of bacterial cultures

- Separates microbes from air and liquids
- Sterilization of air and heat-sensitive ophthalmic and enzymatic solutions, vaccines, and antibiotics

- Exposure to hypertonic solutions
- Inhibits metabolism
- Used to preserve food

- Electron beams; gamma rays; x-rays
- Seconds to hours of exposure
- Destroys DNA
- Used to sterilize equipment and preserve food

- Ultraviolet light
- Irradiation w/260nm wavelength
- Inhibits DNA transcription and replication via formation of thymine dimers
- Used to disinfect/sterilize surfaces and transparent fluids/gases

- Moist Heat
- Dry Heat

- Moist
- steam heat (autoclave)
- high temps melts cellular membranes and denatures proteins
- efficacy depends on time/temp

- In a type of oven
- requires 160-180 degrees C for 1-2 hours
- only items not effected: metals; glass; powders; oils

- used for milk; ice cream; yogurt; fruit juices
- NOT sterilization; heat-tolerant and thermophilic microbes survive

- Viruses can pass through
- Not totally sterile
- Depth filters block larger particles
- Membrane filters block various sizes
- Nucleopore filters filter down to almost viral size

- natural or synthetic chemical
- selective toxicity

- smallest amount of antimicrobial agent needed to inhibit growth of organism
- usually performed w/tube dilution; looking for no growth; confirm w/viable cell count

- test various concentrations of antimicrobial agent
- diffuses outward from disc creating a zone of inhibition
- antibiotic may not diffuse in the chosen growth medium!

+ acts against surface microbes on inanimate objects
- dangerous if used parenterally

+ antimicrobial agents that are sufficiently non-toxic to tissues

- they are non-specific
- disrupt cell membranes
- alter proteins irreversibly

- Disinfectants and Antiseptics
- Phenol; Phenolics; Alcohols; Halogens; Oxidizing agents; Surfactents; Heavy metals; Aldehydes; Gaseous agents; Antimicrobials

- Carbolic acid
- Denatures proteins and disrupts cell membranes
- was a surgical antiseptic

- altered Phenol (biphenols)
- Denature proteins and disrupts cell membranes
- Disinfectants and antiseptics

- Denatures proteins and disrupts cell membranes
- Disinfectants, antiseptics, and a solvent in tinctures

- Presumably denature proteins
- Disinfectants
- antiseptics
- water purification

- Peroxides, ozone, peracetic acid
- Denatures proteins
- Disinfectants; deep wound antiseptics; water purification; sterilization of equipment

- Decrease surface tension of water
- Disrupt cell membranes
- soaps: degerming; detergents; antiseptic

- Arsenic; zinc; mercury; silver; copper; etc
- Denatures proteins
- Fungistats in paint, creams, surgical dressings; catheters; algicide

- Glutaraldehyde and Formaldehyde
- Denatures proteins
- Disinfectant and embalming fluid

- ethlyene oxide
propylene oxide
beta-propiolactone
- Denatures proteins
- Sterilizes heat and water sensitive objects

- Act against cell walls, membranes, protein synthesis, and DNA transcription and replication
- Disinfectants and treatment of infectious diseases

- denatures proteins
- one of the first disinfectants
- Too caustic by itself
- Phenol substitutes are used: hexachlorophene; Lysol; amphil; staphene

- Denatures proteins and disrupts cell membranes
- ethyl and isopropyl
- most effective as 70% solution
- effective against enveloped viruses, but not spores

- iodine, chlorine, bromine, fluorine
- used to treat water

- reduce surface tension of solvents to make them more effective
- helps soap remove oil & microbes
- used in detergents: amphipathic

- Peroxides, ozono, peracetic acids
- kill by oxidation of microbial enzymes
- Peroxide disinfects surfaces
- Ozone treats water
- Peracetic acid is a sporacide used to sterilize equipment

- Alter the 3D shape of proteins
- Silver nitrate can prevent blindness
- Thimerosal (mercury) used to preserve vaccines
- Copper controls algae growth (interferes with chlorophyll)

- Denature proteins and inactivates nucleic acids
- Formalin (37% solution for formaldehyde in water) used for embalming and disinfection