Microbiology 20: Antimicrobials 1 Flashcards

1
Q

What coverage do Glycopeptides antibiotics have ?

A

Gram +ve

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2
Q

When would Glycopeptide antibiotics be indicated ?

A

Gram +ve bacteria resistant to Beta lactams

E.g MRSA

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3
Q

Why are beta lactams considered bactericidal ?

A

They dont kill existing bacteria, they inhibit cell wall synthesis so stop new bacteria from forming their cell walls and hence causing lysis.

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4
Q

Give 3 examples of classes of beta lactams ?

A

Penicillins
Cephalosporins
Carbapenems

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5
Q

Give an example of a drug that is a beta lactamase inhibitor ?

A

Clavulanic acid

tazobactam

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6
Q

As you go up the generations of cephalosporins what happens to their activity against gram +ve and -ve bacteria ?

A

As you go up the generations the activity against gram -ve goes up and +ve goes down.

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7
Q

What complications can glycopeptides cause ?

A

Nephrotoxicity

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8
Q

Give 2 examples of Glycopeptides ?

A

Vancomycin

Teicoplanin

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9
Q

Which Glycopeptide is often used to treat C.difficile infection ?

A

Vancomycin

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10
Q

Which antibiotic is commonly used to treat meningitis ?

A

Ceftriaxone (cephalosporin)

Can’t normally penetrate blood brain barrier but does so when there is inflammation ie in meningitis

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11
Q

List 5 classes of Protein synthase inhibitors ?

A
Aminoglycosides
Tetracyclines
Macrolides
Chloramphenicol
Oxazolidinones (Linezolid)
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12
Q

Why are Proteinase inhibitors selective for bacteria and not hum an cells ?

A

They bind to the ribosomal subunit which is a different size in bacteria (30S) compared to human cells

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13
Q

What antibiotic coverage do Aminoglycosides (gentamicin) have ?

A

Good gram -ve activity

Poor gram +ve and anaerobe activity

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14
Q

what antibiotic coverage do Tetracyclines (doxycycline) have ?

A

Mostly gram +ve

Very good for intracellular pathogens e.g chlamydia and mycoplasma

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15
Q

Which class of Protein synthesis inhibitors are contraindicated in children and pregnant women ?

A

Tetracyclines

Deposit in bone and also cause discolouration of teeth

Chloramphenicol is contraindicated in the 3rd trimester as it can cause “grey baby syndrome”

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16
Q

What is a dangerous complication of giving babies chloramphenicol ?

A

Grey baby syndrome

Aplastic anaemia

17
Q

What is the antibiotic coverage of Linezolid ?

A

Very active against gram +ve bacteria

Poor activity against gram -ve bacteria

18
Q

In which infection is Linezolid particularly useful ?

A

MRSA

19
Q

Give 2 side complications you can get with Linezolid ?

A

Optic neuritis

Thrombocytopenia

20
Q

Give 2 classes of DNA synthesis inhibitors ?

A

Quinolones

Nitroimidazoles

21
Q

What antibiotic coverage do quinolones (ciprofloxacin) have ?

A

very active against gram -ves

New quinolones: moxifloxicin and levofloxacin have more gram +ve cover than gram -ve

22
Q

Give one example of a Nitroimidazole ?

A

Metronidazole

23
Q

Which bacteria is Metronidazole particularly effective against ?

A

Anaerobes (C.Difficile)

24
Q

Give one example of a class of RNA synthesis inhibitors ?

A

Rifampicins

25
Q

Which antibiotic turns your secretions (urine, tears etc) an Orange colour ?

A

Rifampicin

26
Q

What is the antibiotic treatment for Pneumocystis jirovecii pneumonia ?

A

Septrin (Sulphonamides + Trimethoprim) (co-trimoxazole)

27
Q

Which antibiotic is commonly used to treat skin infections such as cellulitis or impetigo ?

A

Flucloxacillin

28
Q

List 2 serious side effects of gentamicin ?

A
  • Ototoxic

- Nephrotoxic

29
Q

Which antibiotic is often given in the case of penicillin allergy ?

A

Erythromycin (macrolide)

30
Q

List 2 mechanisms of resistance that MRSA uses against Beta lactams ?

A
  • Beta lactamses (inactivation)
  • PBP2a (altered target) - Normally beta lactams bind to penicillin binding proteins in the cell wall to cause their effect. Binding To PBP2a means the cell wall is not affected.