Chapter 11 Controlling Microbial Growth

Question 1

Sterilization

Answer 1

destruction of all microbial life

Question 2

disinfection

Answer 2

reduces contamination on inanimate surfaces, does not kill endospores

Question 3

asepsis

Answer 3

practices that prevent infection of sterile tissues

Question 4

decontamination

Answer 4

mechanical removal of most microbes from an animate or inanimate surfaces

Question 5

factors determining the effectiveness of a method

Answer 5

1 Number of m.o. present
2 Susceptibility of the m.o.
3 Temperature & pH of environment
4 Concentration of cleaning agent
5 Contact time
6 Presence of organic matter
7 Mode of action

Question 6

Bacteriostatic

Answer 6

stops bacteria from reproducing but not killing them

Question 7

Sepsis

Answer 7

growth of m.o. in the blood

Question 8

Autoclave

Answer 8

121 C at 15 psi for 15 minutes

Question 9

Pasteurization

Answer 9

Disinfects edible liquids with heat

Question 10

Filtration

Answer 10

pass liquid and gas through a filter

Question 11

Dessication

Answer 11

dehydration of vegetative cells when exposed ti normal room air

Question 12

Radiation

Answer 12

Cold sterilization with gamma rays, x rays, cathode rays

Question 13

Hardest agents to destroy

Answer 13

Prions - no way to reliably destroy
Bacillus & Clostridium - make endospores, infects immunocomp.
Pseudomonas - opportunistic and ubiquitous
Mycobacteria - waxy coat
Protozoan & Helminth cysts - resistant to chemical disinfectants

Question 14

Damage to Cell Membranes

Answer 14

Phenols, Lysol, Hexachlorophene, Triclosan
Chlorhexidene
Alcohol Isopropyl or Ethyl 70%
Quats, Quaternary Ammonium Compounds, Banzalkonium, sephiran

Question 15

Damage to Proteins

Answer 15

Denatures proteins, stops metabolic pathways by destroying enzymes, Heat (Autoclave)
Halogens - Iodine, Chlorine, chloramines
Alcohols Isopropyl or Ethyl 70%
Glutaraldehydes
Gases -Ethylene oxide
Heavy metals - Silver nitrate and silver ointment

Question 16

Damage to Nucleic Acid (DNA)

Answer 16

Prevents cell division
Hydrogen peroxide - toxic to living tissue
Ionizing radiation & gamma rays
Non-Ionizing radiation, UV produces thymine dimers