CPTP 3.11 - Pharmacology of Antimicrobials 2

Question 1

Name four antimicrobials which inhibit protein synthesis?

Answer 1

Tetracycline = Doxycycline
Macrolide = Clarithromycin//erythromycin
Clindamycin
Aminoglycoside = Gentamycin

Question 2

All antimicrobials which inhibit protein synthesis target which site?

Answer 2

Ribosome

Question 3

Name a tetracycline?

Answer 3

Doxycycline

Affect the binding of incoming tRNA onto the A-side and hence freeze protein synthesis

Question 4

Name an aminoglycoside?

Answer 4

Gentamycin
Cause the misreading of genetic code by tRNA, therefore inappropriate amino acids are incorporated into the growing chain = nonsense proteins formed

Question 5

Name two macrolides?

Answer 5

Erythromycin//Clarithromycin

Interfere with translocation (moving along the ribosome is inhibited)

Question 6

Describe how macrolides work (four things)?

Answer 6

Active against most gram positives and legionella and chlamydia
Act by inhibiting traslocation of growing peptide chain by binding to the 50S subunit protein within the ribsome
Found in prostatic fluid (DON’T cross BBB)
Excreted mainly in bile

Question 7

Describe how tetracyclines work?

Answer 7

Compete with tRNA for binding to A-side of ribosome

Wide spectrum of activity and also effective against mycoplasma/rickettsia//chlamydia

Question 8

Describe how aminoglycosides work?

Answer 8

Cause inappropriate amino acids to be incorporated into the proteins - mainly active against gram NEGATIVE
Administered IV//SC
DON’T cross the BBB
ADR = ototoxicity//nephrotoxicity//

Question 9

Describe clindamycin?

Answer 9

Active against gram positive bacteria - including penicillin resistant staphylococci
Administered orally however ADR = G.I disturbances are common

Question 10

Name a quinolone and describe how they work?

Answer 10

Ciprofloaxacin

Act by inhibiting bacterial DNA gyrase (Topoisomerase II) - preventing DNA repication

Question 11

How does metronidazole work?

Answer 11

Active against obligate anaerobic bacteria - electron transport proteins within these bacteria activate the drug to a from that initiates DNA damage

Question 12

Describe Nitrofurantoin?

Answer 12

Used only in UTI treatment

Question 13

What is a mycobacteria and give an example?

Answer 13

Only have a cell membrane (no cell wall)

TB

Question 14

What is rifampicin and how does it work?

Answer 14

Anti-TB drug
Binds to bacterial RNA polymerase and inhibits transcription
Induces cytochrome CYP34A = rapid excretion of other drugs

Question 15

What is Isoniazid?

Answer 15

Anti-TB drug

Inhibits the synthesis of mycolic acid (cell wall constituent ONLY found in mycobacteria)

Question 16

Name four anti-TB drugs?

Answer 16

Rifampicin
Isoniazid
Ethambutol
Pyrazinamide