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Clinical Pathology > Intro to Antibacterial agents > Flashcards

Intro to Antibacterial agents Flashcards

1
Q

What are Antibiotics?

A

Chemical products of MICROBES that inhibit or kills other organisms

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2
Q

What are antimicrobial agents?

A

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

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3
Q

Bacteriostatic?

Bactericidal?

A

Bacteriostatic - inhibits bacteria growth - protein synthesis inhibitor

Bactericidal - kills bacteria - cell wall-active agents

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4
Q

Minimum Inhibitory concentration

A

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

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5
Q

Antimicrobial interactions
Synergy?
Antagonism?
Indifference?

A

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

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6
Q

Antimicrobial Mechanism

A

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

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7
Q

Selective Toxicity

A

Develop microbial so to target organisms without harming human host

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8
Q

Antibiotic targets

A

Cell wall
protein synthesis
DNA/RNA synthesis
Plasma membrane

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9
Q

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

A

Peptidoglycan

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

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10
Q

What are the main inhibitors of cell wall synthesisers?

A
  • Beta Lactams e.g. penecillin

- Glycopeptides

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11
Q

Mechanism of Beta lactams

A

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

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12
Q

Major classes of Beta lactams

A

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 (

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13
Q

Mechanisms of Glycopeptides

A

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

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14
Q

Example of Glycopeptides

A

Vancomycin

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15
Q

What class of bacteria are cell wall synthesis inhibitors ineffective?

A

Gram negative bacteria - unable to penetrate outer membrane porins

ONLY EFFECTS GRAM POSITIVE

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16
Q

Where does translation of RNA take place?

17
Q

What constitutes a bacterial ribosome?

A

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

18
Q

Protein synthesis inhibitors - blocks 50s?

A

Macroslides, lincosamides and streptogramins (MLS)

  • Erythromycin
  • Clindamycin

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

19
Q

Protein synthesis inhibitors - mechanism?

A

Bind to ribosome subunits, preventing translation

20
Q

Protein synthesis inhibitor classes blocks 30S?

Hint: AT

A

AT

  • Aminoglycosides e.g. gentamicin
  • Tetracycline e.g. tetracycline
21
Q

What classes inhibits DNA synthesis?

Hint: QTF

A

Trimethoprim - inhibits folate synthesis

Quinolone/Fluroquinolones - inhibit DNA gyrate and topoisomerase

22
Q

RNA synthesis inhibitor?

A

Rifampicin

23
Q

What do RNA synthesis inhibitors do?

A

RNA polymerase inhibitor and stops mRNA synthesis

24
Q

What do plasma membrane agents do?

A

Destroy cell membrane

25
Q

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

A

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

Gram- = colistin

26
Q

Adverse effects of antibiotics?

A
  • Nausea, vomiting, headache, rash etc
  • generation of antibiotic resistance
  • fungal infection (superficial and invasive candidiasis)
  • C. diff infection
27
Q

Name some specific antibiotic adverse effects

A

Beta lactams - allergies

  • Amino glycosides - renal impairment
  • Linezoid - bone marrow depression
28
Q

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

A

Aztreonam - because it lacks bicyclic nucleus

29
Q

4 most common precipitating antibiotics for C. Diff?

A

4 C’s

  • cephalosporins
  • C - amoxiclav
  • Clindamycin
  • Ciprofloxin
30
Q

Pharmacodynamic considerations - what are the time and concentration considerations?

A

How long and how much agents exceed minimum inhibitory concentration

31
Q

What antibiotics are contradicted in pregnancy? (FATS)

A

Fluroquinilones
Amino glycosides
Tetracyclines
Sulfonamides

Clinical Pathology (50 decks)

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