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Flashcards in Treatment of Infections Deck (52)
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Superficial fungal infections usually give rise to what infections?

Tineas infections


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


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!!


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

Block lanosterol 14(a)-demethylase


Which prevents ergosterol biosynthesis


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





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


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

Tetracyclines such as doxycycline


How do Polyenes (Nystatin and Amphotericin B) work?

Target ergosterol --> increasing membrane permeability


Are fungi eukaryotic or prokaryotic?



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


How do Allyamines and Thiocarbamates (like Terbinafine) work?

They block squalene epoxidase


And so prevents ergosterol biosynthesis


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)


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


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




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


How do Echinocandins (Caspofungin and Micafungin) work?

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


Which in turn prevents cell-wall biosynthesis


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


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


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)


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


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


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


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


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


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 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


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


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

Prevent RNA/DNA biosynthesis by being incorportated instead during replication


What type of drugs are usually given IV?

Those with a low bioavaliability


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


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





So monitoring is very important


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