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Flashcards in Treatment of Infections Deck (52)
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1

Superficial fungal infections usually give rise to what infections?

Tineas infections

 

Such as athletes foot (tinea pedis) and ringworm of the scalp (tinea capitis)

2

What is a carbapenem?

An inhibitor of cell wall synthesis

 

These are highly resistant to B-lactamases, and have a very broad spectrum of activity, including anaerobes

 

These are last resort!!

3

How do Azoles and Triazole (like Fluconazole and Itraconazole) work?

Block lanosterol 14(a)-demethylase

 

Which prevents ergosterol biosynthesis

4

What are the 2 major proteins that are in HIVs envelope?

gp120

 

gp41

5

What is the HAART therapy?

Highly Active Anti-Retroviral Therapy

 

Taking 3 different anti-retroviral drugs, with at least 2 different classes

 

This decreases the chance of resistance build up

6

What type of drug can be depositied into the teeth and bone of growing children/foetus?

Tetracyclines such as doxycycline

7

How do Polyenes (Nystatin and Amphotericin B) work?

Target ergosterol --> increasing membrane permeability

8

Are fungi eukaryotic or prokaryotic?

Eukaryotic

9

How do tetracyclines like doxycycline work?

 

How does resistance occur?

Bind reversibly to the A site on the 16rRNA unit. This interferes with translocation in the tRNA (A --> P)

 

Their effects are bacteristatic, and they have a great level of selective

 

The induction of efflux pumps.....

Intrinsic - The basal activity of the pumps

Acquired - The upregulation in the presence of the antibiotic

10

How do Allyamines and Thiocarbamates (like Terbinafine) work?

They block squalene epoxidase

 

And so prevents ergosterol biosynthesis

11

Explain the differences between a isomotic, hyper/hypo osmotic solutions

Isomotic - Where the osmolality of the solution is equal to that of the intracellular fluid

 

Hyper-osmotic - When the osmolality of the solution if greater than that of the intracellular fluid (so movement out)

 

Hypo-osmotic - When the osmolality of the solution if less than that of the intracellular fluid (so movement in)

12

What are NNRTIs, and how do they work?

Non-Nucleoside Reverse Transcriptase Inhibitors

 

These inhibit DNA replication by binding to the allosteric site of reverse transcriptase, causing a conformational change

13

How does the Varicella-Zoster Virus (VZV) work?

It gains entry via the respiratory tract, and moves through the lymph to the skin (its target organ) after 14 days incubation

 

This can stay latent after the initial infection in the cerebral/posterior root ganglia. Later on it can then move down a sensroy nerve and back to the skin

 

 

14

What is the difference with Endotoxin, and exotoxins?

Endotoxin - A structual feature of lipopolysaccharides

 

Exotoxins - These are toxins that are actively secreted during normal growth

15

How do Echinocandins (Caspofungin and Micafungin) work?

Block 1,3-(B)-D-glucan synthase

 

Which in turn prevents cell-wall biosynthesis

16

How does Nitrofuratonin work?

It is broken down into many different active metabolites

 

Broad spectrum of activity

 

Cannot be used on people with urinary cathaters, due to drug accumulation in the bladder

17

How do glycopeptides such as Vancomycin work?

 

And how does resistance build up?

These bind to the d-ala - d-ala on the peptide side chain of the peptidoglycan monomer, preventing this from being added to the peptidoglycan chain

 

Only work against gram positive bacteria

 

There is an alteration in the terminal AA of the peptide chain, reducing hydrogen bonding, and so prevents stable binding of vancomycin

18

What is the difference between osmolarity and osmolality?

Osmolarity - The number of osmoles (particles) per litre of solution

 

Osmolality - The number of osmoles (particles) per Kg of solvent (eg, water)

19

How does HIV enter the cell?

HIV approaches a CD4(+) T-cell

 

Their gp41 and gp120 proteins vind to the CD4 and chemokine receptors

 

Binding of co-receptors causes a conformational change in gp120, exposing gp41 which has two domains (HR1 and HR2)

 

Zipping occurs, which is where HR2 coils into the grooves that have been exposed on HR1

 

This punches a hole in the membrane, allowing the HIV capsid to pass through the cell membrane

20

Explain the 2 different types of acquired resistance with respect to antibiotics

Genetic - This is irreversible, and comes about due to mutations or plasmids

 

Phenotypic - This is reversible, eg, E.coli is more resistant to antibiotics in a biofilm than on its own

21

What are the 3 routes of parenteal administration?

Intravenous - Into a large proximal vein

Intramuscular - Small amount of liquid into the muscle

Subcutaneous - Liquid added to the subcutaneous tissue

22

Describe the different herpes viruses

HSV1 - Oropharyngeal Sores in children, usually spread from kissing

 

HSV2 - Genital infections that are common in young adults, which can increase the chance of HIV infection

 

 

Both are part of the alpha sub-family of herpes, are enveloped, and have DS DNA

23

How do macrolides, like erythromycin and clarithromycin, work?

Bind to the 23S rRNA in the 50S subunit, inhibiting translocation

 

Mainly used in the treatment of gram-positive bacteria

 

Used for strep infections when penicillin allergies are present

24

Explain Vapour Point Depression

Boiling point elevation and Freezing point depression

Vapour Point Depression - Where the addition of a non-volatile solute to the solvent will decrease the vapour pressure.....so less moleucle will evaporate

 

Boiling Point Elevation - The dissolution of a non-volatile solute in a solvent will increase the boiling point

 

Freezing Point Depresson - The dossolution of a non-volatile solute in a solvent will decrease the freezing point

25

How are Benzylpenicillin (Pen G) and Amoxicillin similar and different?

Can pass through the BBB --> can be used to treat meningitis

 

Excreted in the urine

 

Is absorbed and distributed quickly

 

Difference = Amoxicillin is oral, whilst Pen G is given IV/IM

26

How does Fluorinated pyrimidine analogues (5-Flucytosine) work?

Prevent RNA/DNA biosynthesis by being incorportated instead during replication

27

What type of drugs are usually given IV?

Those with a low bioavaliability

28

Explain how Acyclovir works

A pro-drug, that is phosphorylated 3 times, the first by viral thymidine kinase....which gives the drug specificity

 

ACV-TP is then incorporated into the DNA strand being created, acting as a chain terminator

29

What are the major side effects of aminoglycosides such as gentamicin?

Nephrotoxicity

 

Ototoxicity

 

So monitoring is very important

30

Define Colligative Properties

This is known as the properties of solutions that are dependent on the ratio of solute particles to solvent particles in the solution, not the identity of the solute