Antimicrobials Flashcards

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1
Q

List the 3 types of Antibiotic Resistance

A
  • Multi-drug Resistant (MDR)
  • Extensively-drug Resistant (XDR)
  • Pan-drug Resistant (PDR)
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2
Q

How do the Beta-lactam antibiotics work?

List 3 types

A
  • Interfere with the synthesis of the cell wall (peptidoglycan)
  • Penicillins
  • Cephalosporins
  • Carbapenems
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3
Q

What is Beta-lactamase?

Name a Beta-lactamase resistant drug

A
  • Enzyme used by some bacteria to break down Beta-lactam Antibiotics
  • Flucloxacillin
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4
Q

Why is Clavulanic Acid added to Amoxicillin to produce Co-amoxiclav?

A

Clavulanic Acid is a Beta-lactamase Inhibitor

Thus inhibits bacterial action of Beta-lactamase

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5
Q

What kind of Antibiotics are;

  • Cefalexin
  • Ceftriaxone
  • Cefuroxime
  • Cefotaxime
A

Cephalosporins (a type of beta-lactams)

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6
Q

List 4 types of Antibiotic that interfere with Protein synthesis

A
  • Tetracyclines (prevent tRNA binding to Ribosomes)
  • Aminoglycosides
  • Macrolides
  • Nitrofurans
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7
Q

Tetracyclines can be used in treating Respiratory infections, Acne, Chlamydia and Lyme disease

Why shouldn’t they be given to Children <12, Pregnants and Breastfeeding women?

A

Cause staining of developing teeth

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8
Q

List 3 Macrolides

A
  • Clarithromycin
  • Erythromycin
  • Azithromycin
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9
Q

List common features of Pencillins and Macrolides

A
  • Individual sensitivity testing required

- Similar clinical applications (Macrolides are also active against aytpical respiratory organisms)

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10
Q

List 7 common clinical applications of Macrolides and Penicillins

A
  • Bacterial Meningitis
  • Bone/ Joint infections
  • Skin/ Soft tissue infections
  • Otitis Media
  • Pneumonia
  • UTIs
  • STIs
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11
Q

Describe why Nitrofurantoin is one of the 1st line treatments for UTIs?

A
  • Up to 50% of an oral dose of Nitrofurantoin is excreted in urine in an unchanged form
  • Allows Nitrofurantoin to concentrate in urine, increasing its effectiveness in the bladder (compared to other tissue compartments)
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12
Q

How do Quinolones work?

Name 2

A
  • Inhibit Topoisomerase II (Bacterial DNA Gyrase), the enzyme permits Transcription/ Replication
  • Ciprofloxacin
  • Levofloxacin
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13
Q

Quinolones often require individual sensitivity testing.

List their clinical applications and antimicrobial properties

A
  • Complicated UTIs
  • Gonorrhoea
  • Pseudomonas aeruginosa cover
  • Very good cover of Gram(-ve)s as well atypical organisms and Gram (+ve)s
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14
Q

List ADRs of Quinolones

A
  • Tendinitis +/- rupture
  • Aortic dissection (Aortic aneurysm bursts)
  • CNS effects (E.g Convulsions)
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15
Q

Sulfonamides are a type of AB that interfere with Folate Synthesis/ Action.

State another AB agent that acts in the same way
How does it work?

A
  • Trimethoprim

- Folate antagonist, reversibly inhibits Dihydrofolate Reductase (stronger affinity for Bacterial DHFR than human)

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16
Q

State the clinical application for Trimethoprim

List an ADR

A
  • UTIs

- Teratogenic effects on fetus (so caution when prescribing to females of reproductive age)

17
Q

Why must patients avoid drinking alcohol when using Metronidazole?

A

Has Disulfiram-like action

build up of Acetaldehyde so hangover effects

18
Q

Why is Acyclovir predominantly activated in infected cells?

How does it work?

List 2 clinical applications

A
  • The viral enzyme Thymidine Kinase is more effective at phosphorylating and thus activating it
  • Fully phosphorylated form inhibits viral DNA Polymerase
  • Herpes simplex infections (Genital herpes, Encephalitis)
  • Varicella Zoster (Chicken Pox, Shingles)
19
Q

Herpes Simplex Virus (HSV) has 2 serotypes.

Compare their presentations

A

HSV1: Mouth/ lips/ eye infections

HSV2: Genital infection

20
Q

Describe the use of Acyclovir to treat Oral herpes (HSV1)

A
  • Do NOT prescribe Topical Antivirals (limited evidence supporting use)
  • NICE DOES NOT recommend routine prescription of Oral Antivirals for healthy people with Herpes Labialis
21
Q

Describe the use of Acyclovir to treat Genital herpes (HSV2)

A

1st episode;
- Oral Acyclovir within 5 days of start of episode OR while new lesions forming

Recurrent episodes;

  • Episodic Antiviral treatment (Attacks infrequent at <6/year)
  • Suppressive Antiviral treatment (Attacks frequent/ causing psychological distress/ affecting social life)
22
Q

How does Metronidazole affect Warfarin metabolism?

A

Inhibits CYP2C9-> Reduced metabolism of Warfarin so greater effect

23
Q

Verpamil and Simvastatin are metabolised by CYP3A4.

How do Macrolides affect their levels?

A

Macrolides inhibit CYP3A4 so increased effect

24
Q

Describe Enterohepatic Circulation/ Recycling

A
  • Drugs absorbed in intestines and taken into hepatocytes

- Drug/ metabolites secreted into bile and returned to intestine where more drug is absorbed into circulation

25
Q

How do lower rates of Enterohepatic Recycling affect oral contraceptive effectiveness?

How do oral ABs play a role in this?

A
  • Lower EHR rates-> Lower blood concentrations of Oestrogen/ Progesterone-> Increased risk of getting pregnant
  • Oral ABs reduce gut flora-> Lowered EHR rates