Control of Microbial Growth

Question 1

Koch’s postulates (1)

Answer 1

Suspected pathogen should be present in all cases of disease and absent in healthy animals

Question 2

Koch’s postulates (2)

Answer 2

Suspected organism should be grown in pure culture

Question 3

Koch’s postulates (3)

Answer 3

Cell from pure culture of suspected organism should cause disease to healthy animals

Question 4

Koch’s postulates (4)

Answer 4

Organism should be reisolated and shown to be the same as the original one

Question 5

What the first vaccine against?

Answer 5

Anthrax

Question 6

How Pasteur made anthrax vaccine?

Answer 6

• Weaken anthrax bacteria by heating it until it cannot cause disease.
• Inject that weakened anthrax bacteria to healthy sheep
• The sheep’s immunity recognize the bacteria and produce antibody to against it.
• Inject anthrax bacteria to vaccinated sheep and normal sheep
• Result: vaccinated sheep survive while other can’t

Question 7

What cause death in surgery?

Answer 7

Nosocomial infections

Question 8

Liset’s surgical protocol for disease control

Answer 8

• Wash hands before surgery
• Heat sterilization of surgical instrument
• Apply phenol to wound

Question 9

Carrier

Answer 9

People recover from disease but still carry the bacteria

Question 10

Control measure for Salmonella typhi

Answer 10

• Water chlorination
• Milk pasteurization
• Sewage treatment plant design improvement
• Transmission control (flies, carries)
• Preventive vaccinate and antibiotic therapy

Question 11

Aseptic

Answer 11

Environment or procedure free of microbial contaminants

Question 12

Sterillaztion

Answer 12

killing all living organism, including spores

Question 13

Disinfection

Answer 13

killing most organism from inanimate object

Question 14

Antisepsis

Answer 14

killing pathogen from surface of living tissues

Question 15

Sanitation

Answer 15

reducing microbial population to safe level

Question 16

Pasteurization

Answer 16

Heat to destroy pathogen and reduce spoilage microorganism in food

Question 17

Antimicrobial treatment result facts

Answer 17

Microbial death does not occur at once, but in constant rate determined by D-value

Question 18

D-value

Answer 18

how long it take to reduce bacteria by 90%

Question 19

Effectiveness of treatment depend on

Answer 19

• Size of population
• Exposure time of agent
• Concentration, temperature, pH
• Characteristics
• Interaction and protective features of environment

Question 20

The most resistant microbial charcteristic

Answer 20

Prion: naked protein against most chemical method, cooking, and autoclaving

Question 21

How mycobacterium resist antimicrobial treatment?

Answer 21

Waxy mycolic acid prevent chemical entry

Question 22

How endospore and cyst resist antimicrobial treatment?

Answer 22

Thick coat prevent chemical entry

Question 23

Surprising fact of enveloped virus

Answer 23

Enveloped virus more easily damaged than non-enveloped one

Question 24

What antibiotic cannot do?

Answer 24

Cannot fight injection caused by virus

Question 25

How antibiotic work?

Answer 25

Inhibit the bacterial process by killing them or keeping them from reproducing

Question 26

Key targets of antimicrobials

Answer 26

Cell wall synthesis (Penicillin) DNA replication (flouroquinolones) RNA synthesis (rifampicin) Protein synthesis (tetracyclines, macrolides) Folic acid synthesis (sulfonamides) Membrane disruption (daptomycin for Gram-positives, colistin for Gram-negative)

Question 27

How penicillin disrupt cell wall synthesis?

Answer 27

Inhibit crosslinking of peptidolycan

Question 28

How rifampicin inhibit RNA sysnthesis?

Answer 28

Inhibit RNA polymerase (expect eukaryotic)

Question 29

Types of antibiotic resistances

Answer 29

- Intrinsic resistance: innate | - Acquired resistance: develop the ability to resist over time

Question 30

Mechanisms of HGT

Answer 30

Transduction Conjugation Transformation

Question 31

Germ Theory of Disease

Answer 31

Disease is made of small microscopic entities that replicated within the disease

Question 32

Bactericidal agent

Answer 32

Compound kill bacteria

Question 33

Bactericidal vs bacteriostatic

Answer 33

Bacteriostatic just slow down the growth while bactericidal completely kill all

Question 34

Antimicrobial Efficacy Test

Answer 34

Incubate challenge organism with antimicrobial agent then draw the kill curves Or use dilutions

Question 35

Broad-spectrum

Answer 35

Antimicrobial's ability to affect large variety of microbes

Question 36

SOS response

Answer 36

Bacterium's coordinated response to DNA damage

Question 37

Problems with antibiotic resistance

Answer 37

- Overuse/misprescribing - Non-adherence to antibiotics regiments - Wide-spread use in agriculture

Question 38

How tetracycline inhibit protein synthesis

Answer 38

Bind to A site to block tRNA come in, so new amino acid cannot add to growing peptide chain so synthesis of peptide is aborted

Question 39

How macrolide inhibit protein synthesis

Answer 39

Target the 23s large subunit so peptide bond formation cannot catalyze

Question 40

How sulfonamide inhibit folic acid synthesis

Answer 40

Target enzyme dihydropteroate so the thyme synthesis cannot be done

Question 41

How daptomycin disrupt membrane in Gram-positive

Answer 41

Attach into membrane and form large pores that result in leakage of ions and electrolytes

Question 42

How colistin disrupt membrane in Gram-negative

Answer 42

Disrupt outer membrane and then inner membrane

Question 43

Why using antibiotics in long term can link to C. diff?

Answer 43

Antibiotic destroy normal microflora. Normal microflora cannot eat primary bile salt in intestine and make them turn to secondary bile salt. Primary bile salt activate C. diff pore.

Question 44

Ways of acquired resistance

Answer 44

Acquiring mutation | Acquiring new genes by HGT

Question 45

HGT

Answer 45

donor - receipt

Question 46

Gene mutation cause antibiotic resistance

Answer 46

Most bacteria killed by antibiotic. Only drug resistance bacteria survive and multiple