Microbe Growth Control (short)

Question 1

BSL 2

Answer 1

• (usually) not highly transmissible by respiratory route

- PPE can include lab coat and gloves

Question 2

BSL 3

Answer 2

• can include more transmissible agents (e.g., mycobacterium tuberculosis, Brucela spp.)
• organisms may be transmissible via the respiratory route
• routine use of Biosafety Cabinet, masks

Question 3

BSL 4

Answer 3

handling of microbes for which there is no vaccine or effectve tx

Question 4

thermolabile

Answer 4

altered/killed by easily by heat

Question 5

thermostable

Answer 5

not altered easily by heat

Question 6

Microbial resistance to killing in order of toughest

Answer 6

1. Bacterial endospores
2. Mycobacterium
3. Protozoan cysts
4. Non-enveloped virues
5. Vegetative bacteria
6. Fungi
7. Enveloped viruses

Question 7

Strong/weak acid killing capacity

Answer 7

Strong can kill directly

Weak may enable chemicals to inactivate microbes faster (facilitate)

Question 8

Damage to cell wall (mode)

Answer 8

block synthesis, digest, or break down it surface

Ex. abx, lysozyme, detergent

Question 9

Disrupt CM (mode)

Answer 9

Loss of membrane integrity or selective permeability

Ex. surfactants, heat

Question 10

Inhibit synthesis of protein/nucleic acids

Answer 10

Interfere with gene translation

Ex. abx, radiation, formaldehyde

Question 11

Alter fx of proteins/nucleic acids

Answer 11

alter bonds of secondary/tertiary structures

Ex. heat, strong organic solvents, penolics, metallic ions, abx

Question 12

Heat causes cell membranes to become more fluid, thus losing their

Answer 12

selective permeability

Question 13

Moist heat is more energetic/effective than dry heat but boiling doesn’t kill

Answer 13

bacterial endospores

Question 14

Boiling (#s)

Answer 14

100 C @ 10 mins kills vegetative
100 C @ 30 mins kills resistant bacteria

No kilings of bact. spores

Question 15

Dry heat

Answer 15

160-180C for 2 hours

Question 16

Pressurized staem (autoclave)

Answer 16

121C for 15 min (more than 15 lb of press)

Effective but limited by cost and volume

Question 17

Filtration

Answer 17

micropore size: 0.05 - .45 um (.22um common for bacteria)

Difficult to use with fluids and viruses pass through most filters

Question 18

HEPA

Answer 18

Effective @ bacteria, less so against viruses

Air only (doesn’t remove chemicals)

Question 19

Ultraviolet

Answer 19

260nm wavelength

Question 20

Danger to humans but useful on bulk medical items and food preservation

Answer 20

Gamma rays

Question 21

WHITEBOARD THE TABLE ON PAGE 11

Answer 21

do it

Question 22

High Disinfectant
Sterilant

DIsrupts structural proteins and enzymes

Kills vegetative bact. w/in minutes and spores in 3-10 hours (but active solution is unstable)

Answer 22

Glutaraldehyde 2-5% aqueous

not corrosive, not antiseptic, not inactivated by organic material

Question 23

HIgh disinfecctant
Sterilant

Formation of hydroxyl free radicals (toxic to cells)

Stable for weeks

6 hours sterilization

Answer 23

Hydrogen peroxide, vaproized 25%

Question 24

INtermediate disinfectant
NOT a sterilant

Formation of Hydroxyls (toxic)

(2-30 minutes for disinfection)

Answer 24

Hydrogen peroxide, aqeuous 3%

Question 25

Int. disinfectant NOT a sterilant Disrupts cell walls/membranes and precipitates proteins Kills vegetative bacteria within a few minutes (stable) (2-30 minutes for disinfection)

Answer 25

Phenolic compounds (0.4-5.0%) | Amphyl/Lysol

Question 26

Inhibitors of cell synthesis

Answer 26

Beta lactam abx

Question 27

Inhibits peptidoglycan synthesis by inhibiting crosslinks of polymers (NAG/NAM)... These abx bind to PBPs to inhibit synthesis Results in weakened cell wall and increased phagocytosis

Answer 27

Beta lactam abx

Question 28

Acts poorly against existing peptigoG (so more effective against growing bacteria) More effective at Gram Pos Low toxicity Generally bacteriocidal

Answer 28

Beta lactam abx

Question 29

Inhibit accurate translation of mRNA or polypeptide chain at bacterial ribsome

Answer 29

Inhibitors of protein synthesis | chloramphenical, clinda, macrolides, aminoglycosides, tetracyclines

Question 30

Inhibit polypeptide elongations in translaton by binding to 50S

Answer 30

chloramphenicol, clinda bacteriostatic broad spectrum resistance is due to chemical alteration of abx or ribosome

Question 31

binds to 50s subunit, prevents translaocation

Answer 31

macrolides

Question 32

inhibit translation by binding to 30s (causing a misreading of mRNA and incomplete synthesis

Answer 32

aminoglycosides bacteriocidal broad spectrum

Question 33

inhibits translation by blocking binding of tRNA to 30S

Answer 33

tetracyclines bacteriostatic broad spectrum