microbial growth

Question 1

Asepsis vs sepsis

Answer 1

asepsis: absence of significant contamination
sepsis: microbial contamination

Question 2

Sterilization

Commerical sterilization

Disinfection

Antisepsis

Answer 2

Removal of all microbial life

Kills C. Botulinum endospores

removal of pathogen

removal of pathogens from living tissue

Question 3

Degerming

Sanitization

Biocide/Germicide

Bacteriostasis

Answer 3

Removal of microbes from a limited area

Lowering the number of micrbial counts on utensils

Kills microbes

Inhibits microbes (does not kill)

Question 4

Microbial control Agent

Answer 4

Alters membrane permeability

damages proteins

damages nucleic acids

Question 5

Heat

TDP vs TDT

Answer 5

Kills by denaturing enzymes

TDP (Thermal death point): lowest temperature in which all cell culture will be killed within 10 min

TDT (Thermal death time): The time it takes the cell culture to die at a specific temperature

Question 6

Autoclave

Answer 6

121C at 15 psi

moist/heat denatures proteins

Question 7

Pasteurization

Answer 7

Reduces spoilage organisms and pathogens

Treatment: 63C for 30 minutes

High Temp for short time: 72C for 15 sec

ultra High temp: 140C for 1 sec

Except: thermoduric organisms. wil survive

Question 8

Dry Heat Sterilization

Answer 8

Kills by oxidation

• dry heat
• flaming
• incineration
• hot air sterilization

Hot air: 170C for 2 hr

Autoclave: 121C for 15 min.

Question 9

Filtration

Hepa vs membrane filtration

Answer 9

HEPA: Removes microbes > 0.3um

Membrane Filtration: Removes Microbes > 0.22um

Question 10

Microbial Control

Low temp

High Pressure

Desiccation

Osmotic Pressure

Chemicals

Answer 10

Low temperature: Inhibits microbial growth

• Refrigeration
• Deep Freezing
• Lyophilization

High Pressure: Denatures proteins

Desiccation: Prevents Metabolism

Osmotic pressure: causes Plasmolysis (Shrinkage from loss of water)

Chemicals: controls growth by reducing population to safe levels on living and inanimate objects.

Question 11

Radiation

Answer 11

Ionizing radiation - damages DNA & ionizes water to release OH

• X-rays
• gamma rays
• electron beams

Nonionizing radiation - Damages DNA

• UV
• 260nm

Microwaves - kills by heat except antimicrobial

Question 12

Disinfectants

Answer 12

Phenol & Phenolics (Carbolic acid) - Disrupt plasma membranes

Bisphenols (Hexacholorphene & Triclosan) - Disrupt plasma membranes

Biguanides (Chlorhexidine) - Disrupt plasma membranes

• High specificity to bacterial cell membrane
• has broad spectrum activity (Both gram - and gram + bacteria)

Halogens (Iodine & Chlorine)

Alcohol (Ethanol & Isopropanol) - Dentaures protein, dissolves lipids. Requires water

Question 13

Heavy Metals

Answer 13

Ag (Silver), Hg (Mercury) & Cu (Copper)

Silver Nitrate: Prevents gonorrheal ophthalmia neonatorum

Silver Sulfadiazine: Toopical cream used on burns

Copper sulfate: an algicide

Oligodynamic action: Denature proteins

Question 14

Surfactant

Answer 14

Soap: Degerms

Acid-anionic detergents: sanitizing

Quarternary Ammonium Compounds: bactericidal, denatures proteins & distrupts plasma membrane

Question 15

Food Preservative

Answer 15

Organic Acids (Sorbic acid, benzoic acid, calcium propionate)

• Inhibits metabolism
• controls mod and bacteria in food & cosmetics

Nitrite

• Prevents endospore germination

Antibiotics (Nisin & Natamycin)

• Prevents spoilage of cheese

Question 16

Aldehydes

Answer 16

Inactivates protein by cross linking w/ functional groups

Use: Medical Equipment

Glutaraldehyde

formaldehyde

Orthophthalaldehyde

Question 17

Gas Sterilants

Answer 17

Denatures proteins

Use: Heat-sensitive material

Ethylene oxide

Question 18

Peroxygens

Answer 18

Oxidizing agents

Use: Contaminated surfaces

Question 19

Microbial characteristics

Answer 19

most resistant to least

Prions

endospores

mycobacteria

vegetative protozoa

Gram -

Fungi

viruses w/o envelope

gram +

viruses w/ lipid envelopes

Question 20

Chemotherapy

Answer 20

Paul Ehrlich, Chemist: methylene blue for staining bacteria. Dyed rabbit ear vein

Koch: Alkaline methylene blue w/ heat to stain waxy envelope

Alexander Fleming: Discovered mold, penicillium notatum

Question 21

Anitmicrobial Drugs

Answer 21

Chemotheraphy - The use of drug to treat disease

Antimicrobial drugs: Interferes with microbial growth in host

Antibiotic: inhibits microbes using substance produced by a microbe

Selective toxicity: Kills microbes w/o damaging host

Question 22

Antimicrobial spectrum

Answer 22

Broad spectrum

Narrow spectrum

Superinfection

Question 23

Penicillin

Answer 23

Natural

Penicillin G (injection)

Penicillin V (Oral)

Semisynthetic

Oxacillin (Narrow - Gram +)

Ampicillin (Extended - many Gram -)

Question 24

Cell wall synthesis

Answer 24

1st Generation: Narrow spectrum

2nd generation: Extended spectrum

3rd Generation: includes psudeomonads

4th generation: Broadest spectrum

Question 25

Polypeptide antibiotics

Answer 25

_Bacitracin (topical)_ against Gram + _Vancomycin_ Glycopeptide Last Line against anitibiotic resistant S. aureus

Question 26

Antibiotic Resistance

Answer 26

* Enzymatic destruction of drug * Prevention of penetration of drug * Alteration of drug's target site * Rapid ejection of the drug

Question 27

Causes of antibiotic resistance

Answer 27

* Using outdated or weakened antibiotics * Using antibiotics for the common cold and other inappropriate conditions * Using antibiotics in animal feed * Failing complete the prescribed regimen * Using someone else's leftover prescription