Lecture 3 - Antibiotics & Resistance Flashcards Preview

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Flashcards in Lecture 3 - Antibiotics & Resistance Deck (36):
1

Disinfectants

For inanimate objects

2

Antiseptics

nontoxic, for living tissues (hand san)

3

Antibiotics

antimicrobials from bacteria and fungi exploited by humans

4

How was penicillin discovered

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

5

Best way to kill bacteria

Antibiotics

6

When are antibiotics absolutely required?

Surgery and essentially all forms of medicine

7

2 problems for antibiotics

No profit, less interest. Resistance always occurs

8

What are the 2 fates of antibiotics

Kill the bacteria or stunt the growth

9

MIC

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

10

How do we test MIC

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

11

5 Antibiotic Targets

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

12

How is cell wall synthesis stopped?

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

13

How does bacteria counteract b-lactam

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

14

What is used when penicillin resistance occurs?

Methicillin, can't be cleaved by lactamase

15

How does the bacteria counteract methicillin?

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

16

What is the main job of Vancomycin

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

17

How does vancomycin work?

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

18

How does bacteria counteract vancomycin?

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

19

What is the target for protein synthesis inhibition?

THE RIBOSOMES

20

What is used to inhibit folic acid synthesis

Trimethoprim and sulfonamides

21

Where is Folic Acid obtained from

Humans - diet, Bacteria - must synthesize on won

22

What is used to inhibit DNA/RNA synthesis?

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

23

What is used to alter the cell membrane?

Polymyxin B, binds to LPS and disrupts the membrane

24

What is horizontal transfer?

The gain of new genes from another organisms

25

What are the 3 methods of horizontal gene transfer?

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

26

Enterococci (VRE)

G+ cocci

27

What does enterococci infect?

The GI tract

28

What type of pathogen is Enterococci

Nosocomial pathogen

29

Enterococci causes?

UTI, Surgical infections and endocarditis

30

VRE stands for

Vancomycin resistant enterocci

31

Acinetobacter baumannil

G-, nosocomial, very resistant to all antibiotics

32

Klebsiella penumoniae

G-, nosocomial, pneumonia, highly resistnat

33

Costridia

G+ rod shapped, forms endospores

34

Clastridium difficile (C. diff) causes

pseudomembranous colitis - antibiotic caused diarrhea

35

How is C. diff transmitted?

Via the focal oral route

36

Toxins released by C. diff

A-B toxins, active and binding