Antibiotics

Question 1

How do beta-lactam antibiotics work?

Answer 1

They disrupt bacterial wall synthesis

Question 2

What is another name for phenoxymethylpenicillin?

Answer 2

Pen V

Question 3

What are the side effects of penicillins?

Answer 3

GI disturbance
- diarrhoea and vomiting

Question 4

What is Pen V used for?

Answer 4

• Otitis media
• Sinusitis
• Group A streptococcus
• Rheumatic fever

Question 5

What penicillin is prescribed for cellulitis?

Answer 5

Flucloxacillin

Question 6

Give examples of tetracycline antibiotics

Answer 6

Doxycycline
Lymecycline
Oxytetracycline

Question 7

How do tetracyclines work?

Answer 7

They block mRNA translating to stop replication of bacteria

Question 8

What are the side effects of tetracyclines?

Answer 8

• GI disturbance
• Tooth discolouration
• Enamel hypoplasia
• Deposits in bones
• Photosensitivity

Question 9

What are the contraindications for tetracyclines?

Answer 9

• Children under 12
• Teratogenic
• Secretes into breast milk
• Idiopathic intracranial hypertension

Question 10

What counselling needs to be given when prescribing tetracycline antibiotics?

Answer 10

• They’re prone to chelation making them less effective so shouldn’t be taken with antacids or iron supplements
• Requires loading doses, so the initial dose is higher than the rest

Question 11

Give examples of macrolide antibiotics

Answer 11

-Mycin ones

Azithromycin, clarithromycin, erythromycin

Question 12

How do macrolide antibiotics work?

Answer 12

They inhibit mRNA translation to stop bacterial replication

Question 13

When are macrolides commonly used?

Answer 13

As 2nd line in penicillin allergy

• Similar indications to penicillin’s

Question 14

What are the side effects of macrolides?

Answer 14

Usually well tolerated

• GI disturbance
• Causes prolonged GT interval

Question 15

What are the drug interactions of macrolide antibiotics?

Answer 15

Drygs metabolised by the CYP enzymes of the liver
Eg. Warfarin

Also increased risk of rhabdomyalysis if given with statins

Question 16

Which antibiotics are known to cause C.diff infection?

Answer 16

4 C’s:
- Co-amoxiclav
- Clindamycin
- Cephalosporins
- Ciprofloxacin

Question 17

How is C.diff infection treated?

Answer 17

Oral vancomycin for 10 days and hydration

Question 18

Give examples of quinolone antibiotics

Answer 18

Ciprofloxacin, levofloxacin

Question 19

How do quinolone antibiotics work?

Answer 19

They inhibit bacterial DNA synthesis

Question 20

What is ciprofloxacin used for?

Answer 20

(Drops) bacterial conjunctivitis, corneal ulcers, acute otitis externa

Pseudomonas in CF, meningococcal meningitis

Question 21

What are the side effects of quinolone antibiotics?

Answer 21

• GI disturbance
• Lowered seizure threshold
• damage to muscle tendons
• Prolonged QT interval

Question 22

What are the contraindications of quinolone antibiotics?

Answer 22

• G6PD deficiency
• Pregnancy/ breast feeding

Question 23

What is trimethoprim also known as?

Answer 23

Co-trimoxazole

Question 24

What are the indications for trimethoprim?

Answer 24

• Uncomplicated UTI, an alternative to nitrofurantoin and amoxicillin
• Acute pyelonephritis
• Acute prostatitis
• Acute diverticulitis
• Treatment and prophylaxis for PCP in HIV

Question 25

How does trimethoprim work?

Answer 25

It inhibits the enzyme dihydrofolate reductase inhibitor to reduce bacterial growth Bacteria require folate but it can't be external

Question 26

Give examples of sulflanomides

Answer 26

Sulphamethooxazole

Question 27

What are the side effects of folate synthesis inhibiting antibiotics?

Answer 27

Eg, trimethoprim and sulfonamides - Anaphylaxis - Drug fever - Impair haematopoiesis resulting in pancytopenia - Increased risk of hyperkalaemia and renal impairment - Teratogenic in first trimester or pregnancy

Question 28

What is nitrofurantoin used for?

Answer 28

Prophylaxis and treatment of UTI's

Question 29

How does Nitrofurantoin work?

Answer 29

It's reduced into an active form in acidic urine that impairs bacterial DNA

Question 30

What are the side effects of nitrofurantoin?

Answer 30

- Hypersensitivity reactions - Discolouration of urine to dark yellow or brown - Prolonged use can lead to hepatitis, pneumonitis, pulmonary fibrosis, and peripheral neuropathy - Teratogenic in 3rd trimester

Question 31

What class of antibiotic is metronidazole under?

Answer 31

Nitroimidazole

Question 32

What is metronidazole used to treat?

Answer 32

- Dental abscess - Trichomonas vaginalis - Bacterial vaginosis - H.pylori - PID - Rosacea

Question 33

How does metronidazole work?

Answer 33

It passively diffuses through the cell wall of bacteria and it reduced into into active form causing inhibition of DNA synthesis and DNA degradation Aerobic bacteria are not susceptible to it because they can't reduce the drug into the active form

Question 34

What are the side effects of metronidazole?

Answer 34

- GI disturbance - Metallic taste - Prolonged use can lead to optic neuritis, seizures, and peripheral neuropathy - Bad reaction when mixed with alcohol

Question 35

What is the management of cellulitis?

Answer 35

Class 1 (patient lacks systemic symptoms) - Oral antibiotics in outpatients Class2 (patient with comorbid condition that affects recovery) - Oral/IV antibiotics in outpatients Class 3 (limb-threatening condition and systemic symptoms) - Hospitalisation for IV antibiotics Class 4 (severe infection/sepsis) - Urgent hospitalisation and multiple therapy and specialist consultation

Question 36

When is ceftriaxone used?

Answer 36

Eg. meningitis It crosses the blood-brain barrier

Question 37

What is fusidic acid?

Answer 37

It's an antibiotic