Heat treatment, irradiation, filtration and mechanical removal.

use of any one of a variety of antimicrobial chemical.

(1). Destroy Pathogens and Prevent Transmission

(2). Reduce or eliminate MOs responsible for contamination of water, food, and other etc.

Decontamination

Destroy or remove contaminants.

Contaminants

Microbes present at a given time that are undesirable or unwanted

Decontaminated

Sterilization

(latin: sterilis) – unable to produce offspring - barren

Parts of the body that are naturally free of microbes

Brain, muscles and liver

Cide

substances that kill (Latin for cida-kill)

Static

do not kill, but prevent growth, if removed growth will resume

Disinfection and Antisepsis

 Reduces the total microbial population

Soap

removal of bacterial

Nosocomial infections

hospital-acquired infections

Weakened conditions of the patients

Heating – alters the flavor

 Chemicals – FDA

More Resistant Microbes are

Bacterial Endospores:

Bacillus and Clostridium most resistant forms of life.

Only extreme heat or chemical treatment ensures their destruction

Mycobacterium Species

Waxy cell walls makes them resistant to many chemical treatments.

Need stronger more toxic disinfectants must be used

Mycobacterium tuberculosis – causes tuberculosis

Pseudomonas Species

Common environmental organisms, resistant to some chemical disinfectant and can grow

income.

Most common causes of nosocomial infections

Naked viruses

Lack a lipid envelope and more resistant to disinfectant

Critical items

Semicritical items

body tissue. Mucous membranes are effective barriers against entry into deeper tissues.

Gastriointestinal endoscopes and endotracheal tubes.

Non-critical instruments

poses little risk of infection bc only come in contact

unbroken skin. Countertops, stethoscopes, and blood pressure cuffs

1. Population Size

2. Population Composition

shortest time needed to kill all organisms in a microbial suspension at a specific

temperature under defined conditions.

The increase in the temp. required to reduce D to 1/10 its value

Time in minutes at a specific temperature needed to kill a population of cells or spores.

 Usually 250°C or 121.1° C

Moist heat sterilization – carried out at temp above 100° C to destroy bacterial

Autoclave

Saturated Steam under pressure.

o Developed in 1884 by Chamberland

autoclave’s chamber.o Air in initially in chamber is forced out, until the chamber is filled with saturated steam and outlets are closed.

o Hot saturated steam will fill the chamber until it reaches 121° C and 15 pounds of pressure. (saturated steams destroys all vegetative cells and endospores within 10 to 12 minutes - 15 minutes is the standard time to provide a margin of safety).

Degrading nucleic acids

63° C for 30 minutes

(high temperature short term (HTST)

Large quantities of milk at 72° C for 15 seconds, then rapid cooling.

o Milk and Milk products are treated at 140 to 150 ° C for 1 to 3 seconds.

o Does not require refrigeration

o Example: small coffee creamers

Retort: uses pressurized steam in an industrial-sized autoclave

Conditions designed to destroy Clostridium botulinum are destroyed

well above normal storage.Commercially sterile

Factors determine time and temperature

Higher temp, shorter the time needed to kill all organisms

�� Higher bacteria concentration, the longer heat treatment required to kill all organisms

�� Designed to kill 1012 C. botulinum endospores

Sterilization in the absence of water.Oven heated at 160 to 170 ° C for 2 to 3 hours.

Used by inhibiting growth and reproduction by freezing and refrigeration.

Most pathogens are mesophilic and do not grow well at temp above 4° C. Refrigerated items may be ruined by growth of psychrophilic and psychrotrophic mos,especially if water is present.

Good for short term storage.

Reduces the microbial population in solutions that are heat-sensitive and sometimes can be used to sterilize solutions and media.Does not directly destroy mos, rather removes them.

Fibrous or granular materials that have been bonded into a thick layer filled with twisting

channels of small diameter.

Circular and porous membrane, A little over 0.1mm thick

Made of cellulose acetate ,or other synthetic material

 many different sizes, but 0.2um in diameter are used for the removal of most vegetative cells, but not viruses.

particles from small ones. Have replaced depth filters.

Used to: sterilize [pharmaceuticals, ophthalmic solutions, culture media, oils, antibiotics,and other heat-sensitive solutions.

Air can be sterilized by filtration

�� Example: surgical masks and cotton plugs on culture vessels.

Employs high-efficiency particulate air filters which

radiation if very short wavelengths or high energy

Gamma Rays

emitted during radioisotope decay

First widely used antiseptic and disinfectant

 Lister (1867) used to reduce the risk of infections during operations.

disinfectants.

Cresols, xylenols, and etc. Act by denaturing proteins and disrupting cell membranes.

Bacterial and fungicidal, but not sporicidal

Any of the five elements (fluorine, chlorine, bromine, iodine, and astatine) in group VIIA

and most other metals.Iodine and chlorine are important antimicrobial agent

skin antiseptic and kills by oxidizing cell constituents and iodinating cell

protein.Higher concentrations kills spores

disinfectant for water supplies and swimming pools, also used in dairy and food industry. o Destroys all types of mos and viruses but is too irritating to skin and mucous membranes to be used as an antiseptic

Mercury, silver, arsenic, zinc, and copper were used as germicides. Now there are other less toxic and more effective germicides. Many are bacteriostatic than bactericidal

A 1% Silver nitrate is stilled used in the eyes of infants to prevent ophthalmic gonorrhea) Silver sulfadiazinc is used on burns Copper sulfate is an effective algicide in lakes and swimming pools.

Most popular disinfectants are quaternary ammonium compounds that have a positive charged quaternary nitrogen and a long hydrophobic aliphatic chain.

Common – formaldehyde and glutaraldehyde – are highly reactive molecules that

combine with nucleic acids and proteins and inactive them.

o Sporicidal and can be used as chemical sterilants.

o Glutaraldehyde an effective disinfectant in hospitals and laboratory equipment.

Ethylene Oxide (EtO)

Used on plastic petri dishes and syringes (heat sensitive, heart-lung machines components, sutures, and catheters.

Both microbial and sporicidal

Kills by combining with cell proteins.Effective sterilizing agent bc rapidly penetrates materials.

Best known disinfectant screening test

Where the potency of a disinfectant is compared with that of phenol.

dilutions of phenol and the experimental disinfectant inoculated with the test bacteria Salmonella typhi and Staphylococcus aureus, placed in a 20 or 37º C water bath. The inoculated disinfectant tubes are next subcultures to fresh medium at 5 minute intervals and the subcultures are incubated for two or more days. highest dilution that kills the bacteria after 10 min exposure, but not after 5 min are used to calculate the phenol coefficient. reciprocal of the appropriate test disinfectant dilution is divided by that of phenol to obtain the coefficient. higher the phenol coefficient value, more effective the disinfectant. value greater than 1 means that the disinfectant is more effective than phenol.