BACTE LAB MICROBIAL CONTROL

Aseptic Technique

Used to prevent contamination of surgical instruments, medical personnel, and the patient during surgery

Used to prevent bacterial contamination in food industry

Disinfection

Process of removing or killing microorganisms thru the use of chemical agents, not guaranteed to inactivate them all

Disinfectant

Applied to inanimate objects

Antiseptic

Applied to living tissue

Degerming

Mechanical removal of most microbes in a limited area

Sanitization

Use of chemical agent on food-handling equipment to meet public health standards and minimize chances of disease transmission

Sepsis

Comes from Greek for decay or putrid

Asepsis

Absence of significant contamination

Bacteriostatic Agent

An agent that inhibits the growth of bacteria, but does not necessarily kill them

Germicide

An agent that kills certain microorganisms

Bactericide

An agent that kills bacteria

Most do not kill endospores

Viricide

An agent that inactivates viruses

Fungicide

An agent that kills fungi

Sporocide

An agent that kills bacterial endospores of fungal spores

Time of Exposure

Chemical antimicrobials and radiation treatments are more effective at longer times.

In heat treatments, longer exposure compensates for lower temperatures

Bacillus subtilis

Clostridium sporogenes

Mycobacterium bovis

Nontuberculous mycobacteria

Poliovirus

Coxsackie

Rhinovirus

Trichophyton

Cryptococcus

Candida

Pseudomonas aeruginosa

Staphylococcus aureus

Salmonella choleraesuis

Enterococci

Herpes Simplex Virus

Cytomegalo Virus

Respiratory Synctial Virus

Hepa B Virus

Hepa C Virus

HIV

Hanta Virus

Ebola

Descending Order of Resistance to Germicidal Chemicals

Sterilization

Complete destruction or removal or killing of all living organisms

Ionizing Radiation

UV Light

DNA-Reactive Chemicals

3 Types of Damage to DNA

Bacillus pumilus

Ionizing Radiation quality control

Protein Denaturation

"Secondary"

Mode of action where hydrogen bonding occurs between amide groups

Disruption of Tertiary Structure

Mode of action where there is H2 bonding between side chains

Lysozyme

Enzyme that destroys the cell wall or prevents normal synthesis may bring about cell lysis

Removal of Free Sulfhydryl Group

Oxidizing agents transfers O2 atoms and heavy metals = does widespread damage

MnO4 - Permanganate

CrO4 - Chromate

Cr2O7 - Dichromate

HNO3 - Nitric Acid

H2SO4 - Sulfuric Acid

Examples of Oxidizing Agents

Heat

Kills the microbe by denaturing their enzymes

Thermal Death Point

Lowest temperature at which all the microbe in a liquid suspension will be killed in 10 mins

Thermal Death Time

Minimal length of time in which all bacteria in a liquid culture will be killed at the given temperature.

Decimal Reduction Time

Time in minutes at which 90% of bacteria at a given temperature will be killed. Used in canning industry

Coagulating the Protein

Principle of Moist Heat

Boiling

Used to sterilize surgical instruments, needle, syringes, glass, petri dishes

100C for 10-20mins.

Temperature and Time for Boiling

30 mins.

Hepatitis virus can survive up to how many minutes of Boiling?

20hrs or more

Endospores can survive up to how many hours of Boiling?

Autoclave

Sporicidal disinfection, steam under pressure

121C for 20-30mins at 15lbs psi

Time, Temp., and Pressure used in Autoclave

Kilit Ampule containing Bacillus stearothermophilus

Complete sterilization and quality control used for Autoclave

Arnold Sterilizer

Tyndallization, flowing steam, fractional/intermittent sterilization

100C for 30mins, 3 consecutive days

Temperature and Time used for Arnold Sterilizer

Inspissation

Thickening through evaporation

Usually used to sterilize high protein containing media that cannot withstand the high temperature of the autoclave

75-80C for 2 hrs, 3 consecutive days

Temperature and Time used in Inspissation

Lowenstein-Jensen Medium

Loeffler's Medium

Media that are used in Inspissation

Pasteurization

Partial sterilization, for milk and milk products

Low Temperature Holding

"Classic Pasteurization", Otherwise known as Batch Method

63-65C for 30 mins.

Low Temperature Holding temp. and time

High Temperature Short Time

Pasteurization that is a flash process

72C for 15 secs.

High Temperature Short Time, temp. and time

Ultra High Temperature

Pasteurization that can be stored without refrigeration

140C for 3-5 secs.

Ultra High Temperature, temp. and time

Autoclave

Arnold Sterilizer

Inspissation

Moist Heat that are Sporicidal

Direct Flaming/Aseptic Technique

Flaming the mouth of tubes, wire loops and needles, forceps, and petri dishes

Oven (Hot Air Sterilization)

Sterilize glasswares, cotton swabs, metallic instruments, oils, powders

160-180C for 1hr & 30 mins. to 2 hrs

Temperature and Time needed for the Oven

Bacillus subtilis var. niger

Quality control used for the Oven

Incineration

Effective way to sterilize disposable items and biological wastes, most common method for infectious wastes

300-400C

Temperature needed for Incineration

Cremation

Burning of dead human bodies to ashes, control communicable diseases

300-400C

Temperature needed for Cremation

Gaseous Sterilizer: Ethylene Oxide

Heat labile machine instruments

Chemicals that sterilize in a chamber similar to an autoclave

Denature proteins, by replacing functional groups with alkyl groups

Toxic and explosive in pure form, Highly penetrating.

Cold Sterilization

Ethylene Oxide type of sterilization

Bacillus subtilis var. globigii

Ethylene Oxide quality control

4-18 hrs

Ethylene Oxide requires how many hours of exposure to kill all microbes and endospores?

Cold Temperature

Slow freezing is most harmful to bacteria

Ice crystals that form and grow disrupt the cellular and molecular structure of the bacteria

Treponema pallidum

Bacteria in blood bags that are killed at refrigerator temp. within 3 days

Gamma Rays

X-rays

Electron Beams

Higher Energy Rays

Examples of Ionizing Radiation

Penetrates human tissues

Disadvantage of Ionizing Radiation

UV Light (Non-Ionizing Radiation)

Radiation that reduces airborne infection

Damages skin and eyes

Disadvantage of UV light

Microwave Radiation

Heat is absorbed by water molecules.; May kill vegetative cells in moist foods

Solid foods are unevenly penetrated

Filtration

Used to sterilize heat labile substances such as serum, plasma and certain carbohydrate solution, enzymes, vaccines, antibiotic solutions and some culture media.

Method of choice for antibiotic solutions, radioisotopes, vaccines, toxic chemicals and carbohydrates

High Efficiency Particulate Air Filter

Removes almost all microbes larger than about 0.3 um in diameter

Seitz Filter

Filter that is 98% effective

Cellulose Diacetate

Best filter used

0.015 to 12 microns

Pore diameter of Cellulose Diacetate filter

0.22mm and 0.45mm

Pore diameter need to filter most bacteria

Lyophilization or Freeze-Drying

Water is removed by high vacuum at low temp.

Most effective method for long term preservation of microbial cultures

Between 50C and 93C

Temperature of cultures that are quick-frozen

Dessication

Microbes cannot grow or reproduce in the absence of water but can remain viable for years; to grow and multiply, microbes require H2O; removal of water

1 hr

How long is Dessication needed for Neisseria gonorrhoeae

Several months

How long is Dessication needed for Mycobacterium tuberculosis?

Viruses

Fairly resistant to Dessication

Clostridium spp.

Bacillus spp.

Bacteria that can survive decades

Osmotic Pressure

Use of high concentration of salts and sugars in foods

High concentration of these substance create a hypertonic environment that causes water to leave the microbial cell causing plasmolysis/bacteriolysis

Alcohol

Acids

Alkalies

Halogens

Aldehydes

All non-selective methods of chemical destruction

Alcohol

Kill bacteria, fungi, but not endospores or naked viruses.

Act by denaturing proteins and disrupting cell membranes

Used to mechanically wipe microbes off skin before injections or blood drawing

Not good for open wounds, because cause proteins to coagulate

Ethanol

Drinking alcohol. Optimum concentration is 70%

Isopropanol

Rubbing alcohol. Better disinfectant than ethanol

Alkalies

CaCO3 (limewater)

NaOH (caustic soda)

KOH (caustic potash)

Halogens

Effective alone or in compounds

Combines with amino acid tyrosine in proteins and denatures proteins

Stains skin and clothes, somewhat irritating

Iodophors (5-10%)

Compounds with iodine that are slow releasing, takes several minutes to act.

Not effective against bacterial endospores

Chlorine

Alters cellular component

Easily inactivated by organic materials

Sodium Hypochlorite

When mixed in water forms hypochlorous acid

Chloramines

Consists of chlorine and ammonia

Aldehydes (Alkylating Agents)

Includes some of the most effective antimicrobials

Inactivate proteins by forming covalent crosslinks with several functional groups

Glutaraldehyde

Less irritating and more effective than formaldehyde

Used in surgical equipment

Bactericidal, Tuberculocidal, and Viricidal in 10 min.

A 2% solution of glutaraldehyde (Cidex) is what and in how many mins.?

3-10 hrs

Glutaraldehyde is sporicidal in how many hours?

8% Formaldehyde Gas

Commonly used as formalin, a 37% aqueous solution

Irritates mucous membranes, strong odor

Formalin

Was used extensively to preserve biological specimens and inactivate viruses and bacteria in vaccines

Also used in mortuaries for embalming

Crede's Prophylaxis

Used on babies with mothers who have gonorrhea

Oligodynamic Action

Very tiny amount are effective