Intro to Antibacterial agents Flashcards Preview

Clinical Pathology > Intro to Antibacterial agents > Flashcards

Flashcards in Intro to Antibacterial agents Deck (31):
1

What are Antibiotics?

Chemical products of MICROBES that inhibit or kills other organisms

2

What are antimicrobial agents?

Encompasses antibiotics - synthetic/semi -synthetic with similar effect to antibiotics

3

Bacteriostatic?
Bactericidal?

Bacteriostatic - inhibits bacteria growth - protein synthesis inhibitor

Bactericidal - kills bacteria - cell wall-active agents

4

Minimum Inhibitory concentration

Minimum concentration of antibiotic/antimicrobial agent at which visible growth is inhibited

5

Antimicrobial interactions
Synergy?
Antagonism?
Indifference?

Synergy - activity of 2 antimicrobials are greater than if each one was given separately

Antagonism - activity of one animicrobial diminishes activity of other

Indifference - activity of antimicrobials is unchanged if given together

6

Antimicrobial Mechanism

Interrupt/inhibit critical intracellular processes/structures e.g. enzymes, molecules, structures

7

Selective Toxicity

Develop microbial so to target organisms without harming human host

8

Antibiotic targets

Cell wall
protein synthesis
DNA/RNA synthesis
Plasma membrane

9

Main constituent of Bacterial cell wall (gram positive and negative)

Peptidoglycan
- no cell wall in animal cells -> good for selective toxicity!

10

What are the main inhibitors of cell wall synthesisers?

- Beta Lactams e.g. penecillin
- Glycopeptides

11

Mechanism of Beta lactams

Beta lactam ring - blocks cell wall synthesis by blocking 'penicillin binding protein' (which constructs cel bacterial wall (NAG and NAM), not binds penicillin!)

12

Major classes of Beta lactams

Penecillin (-llin) - e.g. amoxicillin, flucloxacillin (for staph aureus)

Cephasporins e.g. cefuroxime, ceftazidime - broad spectrum (gram negative

Carbapenems e.g. meropenem, imipenem - EXTREMELY broad spectrum

Monobactams - Aztreonam - gram negative only (

13

Mechanisms of Glycopeptides

Prevents cross linking of peptideoglycans by binding directly to terminal D-Alanyl-D-Alanine on NAM pentapeptides

14

Example of Glycopeptides

Vancomycin

15

What class of bacteria are cell wall synthesis inhibitors ineffective?

Gram negative bacteria - unable to penetrate outer membrane porins

ONLY EFFECTS GRAM POSITIVE

16

Where does translation of RNA take place?

Ribosome

17

What constitutes a bacterial ribosome?

50s (large) and 30s (small) subunit; combine too form 70s initiation complex

18

Protein synthesis inhibitors - blocks 50s?


Macroslides, lincosamides and streptogramins (MLS)
- Erythromycin
- Clindamycin

Oxazolidinone's
- Linezolid - inhibits initiation of protein synthesis (50S) and assembly of initiation complex (70S)

19

Protein synthesis inhibitors - mechanism?

Bind to ribosome subunits, preventing translation

20

Protein synthesis inhibitor classes blocks 30S?
(Hint: AT)

AT
- Aminoglycosides e.g. gentamicin
- Tetracycline e.g. tetracycline

21

What classes inhibits DNA synthesis?
(Hint: QTF)

Trimethoprim - inhibits folate synthesis
Quinolone/Fluroquinolones - inhibit DNA gyrate and topoisomerase

22

RNA synthesis inhibitor?

Rifampicin

23

What do RNA synthesis inhibitors do?

RNA polymerase inhibitor and stops mRNA synthesis

24

What do plasma membrane agents do?

Destroy cell membrane

25

Main types of plasma membrane agents for both gram positive and negative bacteria?

Gram + = daptomycin (e.g. cyclic lipopeptides look like a frying pan!)

Gram- = colistin

26

Adverse effects of antibiotics?

- Nausea, vomiting, headache, rash etc
- generation of antibiotic resistance
- fungal infection (superficial and invasive candidiasis)
- C. diff infection

27

Name some specific antibiotic adverse effects

Beta lactams - allergies

-Amino glycosides - renal impairment

-Linezoid - bone marrow depression

28

What beta lactam antibiotic (and why) is suitable for people with penicillin?

Aztreonam - because it lacks bicyclic nucleus

29

4 most common precipitating antibiotics for C. Diff?

4 C's
- cephalosporins
- C - amoxiclav
- Clindamycin
- Ciprofloxin

30

Pharmacodynamic considerations - what are the time and concentration considerations?

How long and how much agents exceed minimum inhibitory concentration

31

What antibiotics are contradicted in pregnancy? (FATS)

Fluroquinilones
Amino glycosides
Tetracyclines
Sulfonamides

Decks in Clinical Pathology Class (50):