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CA1 Extra Qns > Anti Microbial Extra Qns > Flashcards

Anti Microbial Extra Qns Flashcards

1
Q

How is penicillin V administered?

A

Oral (penicillin V has better absorption than pen G)

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2
Q

How does penicillinase resistant penicillin confer protection against beta lactamase catalysis?

A

Penicillinase resistant penicillin have bulky side groups that protect the beta lactam ring from beta lactamases

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3
Q

List 4 mechanisms of resistance to penicillin.

A
  1. Expression of efflux pumps -> pump antibiotics out
  2. Altered PBP -> reduce affinity for penicillins
  3. Production of beta lactamase -> destroys the beta lactam
  4. Bacteria decreases porin production -> prevents antibiotics from entering -> decreases intracellular drug concentration
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4
Q

What are the adverse reactions to penicillins?

A
  1. Allergy/hypersensitivity (SJS, TEN, Anaphylaxis)
  2. CDAD
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5
Q

How is piperacillin administered?

A

IV

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6
Q

How is augmentin (amoxicillin, clavulanic acid) administered?

A

Oral, IV

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7
Q

How is unasyn (ampicillin, sulbactam) administered?

A

IV

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8
Q

How is zosyn (piperacillin, tazobactam) administered?

A

IV

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9
Q

What is the coverage for Aztreonam?

A

Aztreonam covers gram negative bacteria only except ESBL

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10
Q

How is aztreonam administered?

A

IV

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11
Q

Does Aztreonam have cross-sensitivity with other penicillins?

A

No (only cephalosporins and carbapenams have cross sensitivity with penicillins)

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12
Q

How is vancomycin administered? What is the exception?

A

IV (only oral vancomycin is given for CDAD)

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13
Q

What is the action of mechanism of tetracycline/tigecycline?

A

Tetracycline binds to the 30S subunit. It prevents the binding of tRNA to the A site of the mRNA-ribosome complex, inhibiting protein synthesis.

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14
Q

Is tetracycline bacteriostatic or bactericidal?

A

Bacteriostatic (arrests cell growth)

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15
Q

Should tetracyclines be given with beta lactams?

A

No. Beta lactams are bactericidal that work in actively growing cells.

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16
Q

Are beta lactams bacteriostatic or bactericidal?

A

Bactericidal

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17
Q

How are the 3 tetracyclines administered?

A

Tetracycline (oral)
Doxycycline (oral, IV)
Minocycline (oral)

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18
Q

What is the action of mechanism for aminoglycosides?

A

They bind to 30S ribosome subunit, distorts structure of ribosome, causing misreading of mRNA

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19
Q

Are aminoglycosides bacteriostatic or bactericidal?

A

Bactericidal

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20
Q

What is the action of mechanism for macrolides?

A

Macrolides bind to 50S ribosomal subunit, inhibiting the translocation step, thus inhibiting protein synthesis

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21
Q

CSF penetration for macrolides?

A

Macrolides have poor CSF penetration

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22
Q

MACROLIDES HAVE Drug Drug Interactions

A

MACROLIDES HAVE Drug Drug Interactions

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23
Q

List the 2 mechanisms of resistance to macrolides.

A
  1. ERM gene expression -> ribosomal methylation -> reduced binding of macrolides to 50S ribosomal subunit
  2. Efflux pumps
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24
Q

CSF penetration for clindamycin?

A

Clindamycin have poor CSF penetration

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25
Q

What drug does clindamycin have cross-resistance with?

A

Erythromycin (ERM gene expression)

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26
Q

If erythromycin resistance is due to ERM gene, will clindamycin be effective?

A

If erythromycin resistance is due to ERM gene, clindamycin will NOT be effective

27
Q

If erythromycin resistance is due to increased expression of efflux pumps, will clindamycin be effective?

A

If erythromycin resistance is due to increased expression of efflux pumps, clindamycin is EFFECTIVE as it is not a substrate for the efflux pumps

28
Q

What does Azithromycin treat?

A

Atypical microbes

29
Q

FLUOROQUINOLONES have Drug Drug Interactions

A

FLUOROQUINOLONES have Drug Drug Interactions

30
Q

What are the 2 classes of drugs in nucleic acid synthesis inhibitors?

A

Fluroquinolones (Ciprofloxacin, Levofloxacin, Moxifloxacin)
Anti-folate drugs (Sulfonamides, Trimethoprim, Co-trimoxazole)

31
Q

How are fluoroquinolones administered?

A

IV / Oral (good oral availability, taken 2h before or 6h after dairy food)

32
Q

How are anti folate drugs administered?

A

ORAL

33
Q

Where are sulfa drugs acetylated and conjugated?

A

sulfa drugs are acetylated and conjugated in the liver which leads to crystaluria

34
Q

List the adverse effects of sulfonamides.

A
  1. Crystaluria -> Nephrotoxicity
  2. Hematological disturbances
  3. Kernicterus (avoid in newborns and infants)
35
Q

Contrindications of Nitrofurantoin

A
  1. Pregnant women in their last trimester
  2. Patients with G6PD deficiency
  3. Patients with upper tract UTIs
36
Q

What is nitrofurantoin active against?

A

E. coli and Enterococcus

37
Q

CSF penetration for 5-Flucytosine?

A

Good CSF penetration

38
Q

CSF penetration for Echinocandins?

A

Poor CSF penetration

39
Q

What are the 4 triazoles?

A

Fluconazole, Posaconazole, Itraconazole, Voriconazole

40
Q

CSF penetration of fluconazole

A

good CSF penetration

41
Q

CSF penetration of itraconazole

A

poor CSF penetration

42
Q

CSF penetration of voriconazole

A

good CSF penetration

43
Q

List the adverse effects of imidazoles

A
  1. Contact dermatitis
  2. Vulvar irritation
  3. Oedema
44
Q

What drug treats tinea infections?

A

Miconazole, Oral Terbinafine treats tinea capitis

45
Q

What is an anti-protozoal agent?

A

Metronidazole

46
Q

How is metronidazole administered?

A

Oral

47
Q

What is the mechanism of action for Metronidazole?

A

Nitro group of metronidazole serves as an electron acceptor forming cytotoxic free radicals, leading to protein and DNA damage

48
Q

What amebicide is metronidazole?

A

Mixed amebicide (acts on both parasite in the lumen and act on amoebas in intestinal wall)

49
Q

What metabolism does metronidazole undergo?

A

Hepatic metabolism (moxifloxacin also)

50
Q

Adverse effects of metronidazole.

A
  1. Unpleasant metallic taste
  2. GI effects (nausea, vomiting)
51
Q

Can metronidazole be used in pregnancy?

A

Yes but avoid use in first trimester

52
Q

What drugs have poor CSF penetration?

A

Itraconazole, Echinocandins, Macrolides, Aminoglycosides

53
Q

What drugs have drug-drug interactions?

A

Fluoroquinolones, Macrolides, Triazoles, Rifampicin (given with vitamin K)

54
Q

Can beta-lactams be used in pregnancy?

A

Yes

55
Q

What drug is useful for empirical treatments?

A

Aminoglycosides

56
Q

What does co-trimoxazole do?

A

It interferes with tetrahydrofolate synthesis

57
Q

Which 2 NRTIs are safe to use in pregnancy?

A

Emtricitabine and Tenofovir

58
Q

How are all NRTIs administered?

A

Oral

59
Q

What does Ganciclovir treat?

A

All herpesvirus, especially active against cytomegalovirus

60
Q

What does Acyclovir treat?

A

Herpes simplex virus types 1 and 2, varicella-zoster virus (acyclovir is more active against HSV than VZV)

61
Q

What is the advantage of using pro-drugs valacyclovir and valganciclovir for treatment?

A

It has much better oral bioavailability and administered with lesser dosing frequency (but its COSTLY)

62
Q

Adverse effect of NNRTI

A

CNS effects

63
Q

What is integrase inhibitor active against?

A

HIV-1 and HIV-2

64
Q

What is NNRTI?

A

It is a non-competitive inhibitor of HIV-1 RT. (NOT used against HIV-2)

CA1 Extra Qns (5 decks)

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