Clinical applications of antibacterials

Question 1

Drugs contraindicated in pregnancy

Answer 1

Tetracyclines: doxycycline, micocycline, tetracycline

Glycylcycline: tigecycline

Aminoglycosides: aminkacin, gentamycin, tobramycin, streptomycin, neomycin (contraindicated unless benefits outweigh risks - FDA category D)

Fluoroquinolones - cause connective tissue problems (also contraindicated to nursing mothers)

Metronidazole - generally not advised in 1st trimester

Trimethoprim –> antifolate

Cotriamoxazole –> antifolate

Nitrofurantoin —> cannot give in 38-42 weeks pregnancy

Question 2

Drugs contraindicated in children < 8yr

Answer 2

Tetracyclines: doxycycline, micocycline, tetracycline

Glycylcycline: tigecycline

Question 3

Drugs contraindicated in children <18y

Answer 3

Fidaxomicin - safety and effectiveness has not been established so only given to adults for C. difficile colitis

Fluoroquinolones - cause connective tissue problem (can only be given if benefits outweigh risks)

Question 4

Drugs that can penetrate intracellularly

Answer 4

Glycylcycline: tigecycline

Streptogramins: quinupristin, dalfopristin

Question 5

Antibacterial drugs that can inhibit CYP P450 enzymes

Answer 5

Macrolides - erythromycin, clarithromycin, telithromycin (but not azithromycin)

Chloramphenicol - inhibits CYP3A4 and CYP2C9

Streptogramins - quinupristin, dalfopristin –> inhibit CYP3A4

Question 6

Drugs with AE of QT prolongation

Answer 6

Macrolides - erythromycin, clarithromycin, telithromycin, azithromycin

Fluoroquinolones - 3rd and 4th generation

Question 7

Drugs used to treat C.difficile vs drugs that cause pseudomembranous colitis

Answer 7

To treat:
Metronidazole
Fidaxomicin
Vancomycin –> give oral

That cause pseudomembranous colitis:
Ampicillin
Clindamycin