Antimicrobials

Question 1

Which group of antibiotics cause yellowing of neonatal teeth?

Answer 1

Tetracyclines such as lymecycline

Question 2

What is the mechanism of action for penicillins?

Answer 2

penicillins are beta-lactam antibiotics which inhibit petidoglycan cross-link formation in bacterial cell wall

Question 3

What is the mechanism of action for cephalosporins?

Answer 3

beta-lactam antibiotics which inhibit petidoglycan cross-link formation in bacterial cell wall = bactericidal

Question 4

Give examples of cephalosporins

Answer 4

cefuroxime, ceftriaxone, cefalexin

Question 5

Give examples of penicillins

Answer 5

amoxicillin, phenoxymethylpenicillin, flucloxacillin

Question 6

What is the mechanism of action for macrolides?

Answer 6

bacteriostatic antibiotics, inhibit protein synthesis, inhibit petidlytransferase, bind to 5oS ribosome

Question 7

Give examples of macrolides

Answer 7

erythromycin, clarithromycin, azithromycin

Question 8

Give examples of quinolones

Answer 8

ciprofloxacin, levofloxacin

Question 9

What is the mechanism of action of quinolones

Answer 9

DNA gyrase inhibitor - stops DNA replication (ciprofloxacin and levofloxacin)

Question 10

What is the mechanism of action of ciprofloxacin?

Answer 10

DNA gyrase inhibitor - stops DNA replication - bacteriostatic

Question 11

What is the cross reactivity of cephalosporins and penicillins in pen allergic patients?

Answer 11

10%

Question 12

Which drugs interfere with folate metabolism?

Answer 12

dihydrofolate reductase inhibitors (trimethoprima nd methotrexate)
Sulphonamide inhibiting benzoic acid to folate conversion by inhibiting dihydropteorate synthetase (glizazide/thiazide diuretics;furosemide)

Question 13

Quinolones and breast feeding

Answer 13

should be avoided

Question 14

Risk of aminoglycoside use in pregnancy

Answer 14

risk of 8th cranial nerve ototoxicity

Question 15

Grey baby syndrome is caused by toxic levels of which anti-microbial?

Answer 15

Chloramphenicol - hypotension and cyanosis

Question 16

Which sterol is found in the cell membranes of fungi but not humans?

Answer 16

Ergesterol

Question 17

What is the main target of anti-fungal agents?

Answer 17

Ergesterol in fungi cell membranes

Question 18

What is amphotericin B?

Answer 18

An antifungal that disrupts fungal cell membranes by binding to ergesterol

Question 19

What is nystatin?

Answer 19

A polyene antifungal - inhibits ergesterol

Question 20

What are fluconazole, clotrimazole and ketonazole?

Answer 20

imidazole antifungals - inihbit ergesterol synthesis - should not be used in pregnancy

Question 21

Antibiotic prophylaxis in a patient who is chlamydia negative and has had an abortion

Answer 21

metronidazole 1g PR stat

Question 22

What base is aciclovir an analogue of?

Answer 22

guanine

Question 23

How does aciclovir work?

Answer 23

prodrug - converted to active form by thymidine kinase in viral cell to form guanine analogue - inhibits viral DNA polymerase

Question 24

What activates aciclovir?

Answer 24

aciclovir is a prodrug acitvated by thymidine kinase in viral cells

Question 25

What kind of antimicrobe is zidovudine?

Answer 25

nucleoside reverse transcriptase inhbitor - inhibits souble stranded DNA synthesis - used to treat HIV particularly in pregnancy as a monotherapy or in neonate for prophylaxis

Question 26

Which anti-malarial chemo-prophylaxis is safe for use in pregnancy?

Answer 26

mefloquine (larium) or malerone