Topic 3d: Controlling growth

Question 1

biocide

Answer 1

-chem/phys agent that inactivates microbes (decreases # of cells)
-use decimal reduction time (D) = time req’d to kill 90% of microbes

Question 2

sterilization

Answer 2

all cells, spores destroyed or removed

Question 3

disinfection

Answer 3

killing or severly lim’g growth that may cause disease (not sterile!!)

Question 4

decontam

Answer 4

treat object to make it safe to handle

Question 5

sanitization

Answer 5

like disinfection, level of microbes reduced

Question 6

antiseptics

Answer 6

chem agents to kill pathog microbes in tissue

Question 7

chemotherapy

Answer 7

use chem agents to kill or inhibit growth of microbes on host tissue

Question 8

what factors effect efficiency of biocide

Answer 8

-pop size
-pop composition
-[] /intensity of antimicrobial agent
-contract time
-temp
-env

Question 9

using heat to control

Answer 9

moist heat kills lots
boiling does not sterilize
–must autoclave
–pasteurization (short blast of high temo, not ster, but remove pathogens/bact that could spoil food)
–tyndallization (ster, and let sit, let endospores germ, then boil, repeat to get rid of spores)

Question 10

using radiation to control

Answer 10

-UV - low amnt of penetration
-like disinfectant to decrease microbe load
-only good for surface

-ionizing (deep penetration, destroys spores)
-good for food treatment, not viruses

Question 11

using filtration to control (4 ways)

Answer 11

1) depth filters - thick layer w small diam channels (not sterile)
2) Hepa filt - high eff air filt, 0.3 um retention)
3) Membrane filt -porous mems w variety of pore sizes
4) Nucleopore filt - polycarbonate film irradiated and chemically etched (control pore size); good for e mic

Question 12

using chems

Answer 12

-for disinfection (for inanimate) and antisepsis (for live) to decrease mic load
-effective against wide range or orgs at low []s
-overuse can lead to resistance

Question 13

chem - alc and phenolics

Answer 13

-alcs: dont ster/kill spores, just denature prots
-phenolics: denat prots and disrupt mems; Lister used; disinfectant
–dif than alc bc remains active for longer periods of time
—can be used to kill agents of TB

Question 14

chem - halogens

Answer 14

F, Cl, Br, I = common biocides
I - ox’s part of cell and mods prots
—tincture = KI in water/ethanol used as antiseptic
—idophor = I w organic carrier is water sol to reduce irritation (used in hosps)

Cl - ox’s cell material, kills almost all microorgs; also reacts w organic compounds

Question 15

chem - heavy metals and detergents

Answer 15

Hm - rare; s/t use silv nitrate or copper sulfate

dets - good for disinfect; amphiphilic, can disrupt mems and denat prots

Question 16

chem - aldehydes and sterilizing gases

Answer 16

ald - highly reactive, inactive nu acids and prots, fixative, sporicidal

sterilizing agents - ethylene oxide both microbicial and sporocidal; alkylating agents react w dna prots

Question 17

bacteriostatic

Answer 17

component added puts e/t on hold, bact cant grow anymore

Question 18

bacteriocidal

Answer 18

cells being killed but no drop in total cell count bc even though dying, not breakinf apart

Question 19

bacteriolytic

Answer 19

kills cells and bust them open

Question 20

what are the methods to test effectiveness (3)

Answer 20

1) dilution tests
2) diffusion test
3) phenol coefficient test