Lecture 3 - Antibiotics & Resistance

Question 1

Disinfectants

Answer 1

For inanimate objects

Question 2

Antiseptics

Answer 2

nontoxic, for living tissues (hand san)

Question 3

Antibiotics

Answer 3

antimicrobials from bacteria and fungi exploited by humans

Question 4

How was penicillin discovered

Answer 4

Was on a plate withs staph, and no growth around the penicillin

Question 5

Best way to kill bacteria

Answer 5

Antibiotics

Question 6

When are antibiotics absolutely required?

Answer 6

Surgery and essentially all forms of medicine

Question 7

2 problems for antibiotics

Answer 7

No profit, less interest. Resistance always occurs

Question 8

What are the 2 fates of antibiotics

Answer 8

Kill the bacteria or stunt the growth

Question 9

MIC

Answer 9

Minimum inhibitory concentration - how much antibiotic is needed to stop growth

Question 10

How do we test MIC

Answer 10

Various test tubes with varying conc and the bacteria. Which everyone shows a visible change is the MIC. NEW: strips used on plate with different antibiotics, as the strip moves towards to centre concentrate increases. Measure conc where growth of bacteria stops

Question 11

5 Antibiotic Targets

Answer 11

• cell wall synthesis
• protein synthesis
• DNA/RNA synthesis
• folate synthesis
• changes in cell membrane

Question 12

How is cell wall synthesis stopped?

Answer 12

• Using B-lactam rings that will bind to penicillin binding proteins (PBP) and will stop the cross linking

Question 13

How does bacteria counteract b-lactam

Answer 13

Production of b-lactamase which destroys the lactam ring and thus no binding to peptide

Question 14

What is used when penicillin resistance occurs?

Answer 14

Methicillin, can’t be cleaved by lactamase

Question 15

How does the bacteria counteract methicillin?

Answer 15

Makes different Protein Binding Penicillin which won’t bind lactam or methicillin

Question 16

What is the main job of Vancomycin

Answer 16

Stops cell wall synthesis for gram positives (can’t get through the outer membrane of g-)

Question 17

How does vancomycin work?

Answer 17

Binds the terminal d-ala-d-ala and stops transcription

Question 18

How does bacteria counteract vancomycin?

Answer 18

Changes terminal end to d-ala-d-lac so that vancomycin cannot bind

Question 19

What is the target for protein synthesis inhibition?

Answer 19

THE RIBOSOMES

Question 20

What is used to inhibit folic acid synthesis

Answer 20

Trimethoprim and sulfonamides

Question 21

Where is Folic Acid obtained from

Answer 21

Humans - diet, Bacteria - must synthesize on won

Question 22

What is used to inhibit DNA/RNA synthesis?

Answer 22

Fluoroquinolones which stop the coiling, and Rifampicin which stop RNA polymerase from working

Question 23

What is used to alter the cell membrane?

Answer 23

Polymyxin B, binds to LPS and disrupts the membrane

Question 24

What is horizontal transfer?

Answer 24

The gain of new genes from another organisms

Question 25

What are the 3 methods of horizontal gene transfer?

Answer 25

Transformation - floating dna
Transduction - bacteriophage
Conjugation - direct passing of plasmid

Question 26

Enterococci (VRE)

Answer 26

G+ cocci

Question 27

What does enterococci infect?

Answer 27

The GI tract

Question 28

What type of pathogen is Enterococci

Answer 28

Nosocomial pathogen

Question 29

Enterococci causes?

Answer 29

UTI, Surgical infections and endocarditis

Question 30

VRE stands for

Answer 30

Vancomycin resistant enterocci

Question 31

Acinetobacter baumannil

Answer 31

G-, nosocomial, very resistant to all antibiotics

Question 32

Klebsiella penumoniae

Answer 32

G-, nosocomial, pneumonia, highly resistnat

Question 33

Costridia

Answer 33

G+ rod shapped, forms endospores

Question 34

Clastridium difficile (C. diff) causes

Answer 34

pseudomembranous colitis - antibiotic caused diarrhea

Question 35

How is C. diff transmitted?

Answer 35

Via the focal oral route

Question 36

Toxins released by C. diff

Answer 36

A-B toxins, active and binding