Antibiotics

Question 1

If a patient presents with a staphylcoccus infection what would be the most appropriate antibiotic to use and why?

Answer 1

So Staphylococus is a gram posotive bacteria meaning it has a more simple cell wall structure witha thick layer of peptidoglycan which retains gram stain during staining procedure.

Staphlycoccus often has resistantce to amoxicillin due to its ability to produce a beta lactamase which is an enzyme that brakes down these antibiotics.

Staphlycococus has got growing resistance to erythromycin so i wouldnt use that.

I’d supply the patient with Flucloxacillin becase its on the POM S list and its a narrow spectrum antibiotic with specific effectivness on staph infections

In supplying the patient with Flucloxacillin were also promoting antibiotic stewardship because we know its got specifc effectiveness against this particular bacteria so theres less chance of inducing antibiotic resistance.

Question 2

If a patient presents with a streptocci infection which antibiotic would be the most appropriate to use in order to fight the infection?

Answer 2

I’d supply the patient with Amoxiciliin.

Amoxicillin is considered a broad spectrum antibiotic when reffering to sterp infections as its effective agasint a wide range of different steptocci strains. It works by interfering with penecillin binding proteins and transpeptidase enzyme which effectivley inhibits cell wall synthesis and results in lysis.

Question 3

If the patient was taking statins how would this effect your supply of antibiotics

Answer 3

So we know that theres an drug interaction between macrolide antibiotics and statins.

So erythromycin is a macrolide antibiotic meaning it has a macrocylic lactone ring in its chemical structure and it works by inhibitng bacterial protien synthesis.

So erythromycin is also a potent inhibitor of the cyp450 enzymes in the liver. CYP450 is the main metabolism pathway for statins so the metabolism of the statins would be compromised.

That can lead to increased plasma concentration of statins in the blood and that could cause the patient to suffer with myopathy so muscle fatigue and weakness. It could also result in rhamdomyolsis which is when the muscle tissue breaks down releasing myglobin into the blood stream which can cause organ damage.

Question 4

What is Warfirin and what is it’s mechanism of action

Answer 4

It’s an anticoagulant that interferes with the proteins that are responsible for coagulation.

It works by inhibting an enzyme called vitamin K reductase which is crucial for the synthesis of clotting factors in the liver, so it prolongs the time it takes for blood to clot.

So it binds to Vitamin K reductase receptor in the liver and inhibits its activity.

Question 5

Describe gram posotive bacteria

Answer 5

• Gram posotive bacteria are charecterised by the cell wall structure
• They have a less complex cell wall consisting of a thick layer of petidoglycan which provides support and structrue.
• The peptidoglycan is what retains the gram stain during the tesing process

They include the following types of bacteria:
Staphlycoccus
Stepttococus
Clostridium

Question 6

What is the mode of action of Antibiotics

Answer 6

Fall into 2 categories:
* Bacterioistic = Inhibt bacterial growth
* Bactreiocidal = Destroy bacteria

Penecillins are Bacteriocidal, they inhibit cell wall synthesis by intefering with penecillin binding protiens which prevent cross linking of the peptidoglycan chains leading to cell death.

Erythromycin is Bacterioistic, It inhibits bacterial protein synthesis by binding to the 50s subunit of bacterial ribosome.

Question 7

What is the drug interaction between warfarin and antibiotics

Answer 7

So for the Antibiotics contained within the POM S list youve got Penecillins so amoxicillin and Flocloxicillin and youve got a macrolide antibiotic in Erythromycin

So all of these 3 antibiotics Inhibits warfarin metabolism
* So warfarin is metabolised by Cytochrome P450 enzymes in the liver, when those enzymes are inhibted warfrin metabolism decreases so the amount of free unbound warfrin in the blood circulation increases leading to an increase in the theraputic effect so increased increased anticoagulant effect increase INR

Question 8

What does INR stand for and what does it mean

Answer 8

International Normalized Ratio
Its basically a blood test to determine the clotting tendency of blood comparing it to an average