Antibacterial Therapy II

Question 1

Glycopeptides MOA

Answer 1

• Vancomycin
• inhibit bacterial CW synthesis
• earlier point than beta lactams
• prevent incorporation of subunits into peptidoglycan

Question 2

Lipopeptides MOA

Answer 2

• Daptomycin
• disrupt bacterial cell membrane
• cause depolarization of cell membrane
• calcium dependent
• bactericidal

Question 3

Glycopeptides/Lipopeptides Special Considerations

Answer 3

• bactericidal
• vancomycin is slowly tidal
• vancomycin not well absorbed orally
• daptomycin inactivated by lung surfactant - not effective vs. pneumonia

Question 4

Vancyomycin

Answer 4

Glycopeptide
S: Enterococci, Penicillin R Streptococci, MRSA, CNS, C. diff
CI: Bacteremia, pneumonia, endocarditis, bone & joint ix’s, SSTI’s, C. diff ix’s (orally)

Question 5

Daptomycin

Answer 5

Lipopeptide
S: Enterococci, Penicillin R. Streptococci, MRSA, CNS, vancomycin R organisms
CI: Bacteremia, endocarditis, SSTI, bone and joint ix’s

Question 6

Aminoglycosides MOA

Answer 6

• inhibit protein synthesis

- bind 30S subunit

Question 7

Aminoglycosides Special Considerations

Answer 7

• bactericidal
• renally eliminated
• nephrotoxicity
• ototoxicity
• Gentamicin synergy w/ beta lactams vs. Enterococci

Question 8

Gentamicin

Answer 8

Aminoglycoside
S: G-, Pseudo, Enterococci and Streptococci (w/ beta lactams)
CI: bacteremia, G- sepsis, drug resistant UTI

Question 9

Tobramycin

Answer 9

Aminoglycoside
S: G-, Pseudo (better than gentamicin)
CI: combo therapy vs. Pseudo, drug R UTI

Question 10

Macrolides MOA

Answer 10

• inhibit protein synthesis

- bind 23S subunit

Question 11

Macrolides Special Consideration

Answer 11

• bacteriostatic
• active vs IC organisms
• azithromycin has long half life

Question 12

Azithromycin

Answer 12

Macrolide
S: Mycoplasma, Chlamydophila, Moraxella catarrhalis, Legionella, Neisseria gonorrhea, MAC, Chlamydia trachomatis
CI: combo tx for MAC, MAC prophylaxis in HIV pt’s, second line for STI’s, combo w/ beta lactams vs. CAP

Question 13

Azithromycin preferred over erythromycin and clarithromycin. Why?

Answer 13

• fewer drug interactions
• once daily oral dosing
• broader spectrum

Question 14

Lincosamide MOA

Answer 14

• inhibit protein synthesis

- binds 50S subunit

Question 15

Lincosamide Special Considerations

Answer 15

• bacteriostatic
• high bioavailability
• high risk of C. diff

Question 16

Clindamycin

Answer 16

Lincosamide
S: Streptococci, MRSA, S. aureus, anaerobes
CI: abscesses, SSTI, bone and joint ix’s, polymicrobial ix’s, combo w/ penicillin for NF

Question 17

Tetracyclines and Glycylcyclines MOA

Answer 17

• inhibit protein synthesis

- bind 30S and 50S subunits

Question 18

Tetracyclines and Glycylcyclines Special Considerations

Answer 18

• active vs. IC organisms

- bacteriostatic

Question 19

Doxycycline

Answer 19

Tetracycline
S: Legionella, M. catarrhalis, Chlamydophila, C. trachomatis, Mycoplasma, S. pneumo, H. influenzae
CI: CAP, COPD, chlamydial STI’s

Question 20

Tigecycline

Answer 20

Glycylcycline
S: Broad spectrum, G+, G-, anaerobes
CI: last line of polymicrobial, MDR ix’s if susceptible

Question 21

Tetracycline

Answer 21

• requires QID dosing on empty stomach
• poorly tolerated
• narrower spectrum than doxycycline

Question 22

Fluoroquinolones MOA

Answer 22

-inhibit DNA gyrase and topoisomerase

Question 23

Fluoroquinolones Special Considerations

Answer 23

• high bioavailability
• bactericidal
• increasing levels of resistance
• levo and moxi active vs. IC organisms
• high risk of C. diff

Question 24

Ciprofloxacin

Answer 24

Fluoroquinolone
S: G-, Pseudo
CI: not first line (increasing resistance), UTI’s, combo w/metronidazole or clindamycin vs. polymicrobial ix’s

Question 25

Levofloxacin

Answer 25

Fluoroquinolone S: Streptococci, Mycoplasma, Chlamydophila, Legionella, G- CI: suspected drug resistant respiratory ix's

Question 26

Moxifloxacin

Answer 26

- respiratory quinolone - others preferred - high risk of C. diff - active vs. MDR tuberculosis

Question 27

Trimethoprim-Sulfamethoxazole MOA

Answer 27

- inhibits folate production, purine synthesis | - inhibits dihydropteroate synthase and dihydrofolate reductase

Question 28

Nitrofurantoin

Answer 28

- reduced IC'ly into reactive intermediates that damage proteins, RNA - complex mechanism, minimal resistance

Question 29

TMP-SMX Special Considerations

Answer 29

- bacteriostatic - high oral bioavailability - increasing S. pneumo and E. coli resistance

Question 30

Nitrofurantoin resistance

Answer 30

- only reaches therapeutic levels in urine - bactericidal - effective for cystitis, not pyelonephritis

Question 31

TMP-SMX

Answer 31

Anti-folate S: S. pneumo, S. aureus (MRSA), PJP, G- CI: PJP prophylaxis, UTI, purulent cellulitis

Question 32

Nitrofurantoin

Answer 32

Anti-folate S: E. coli, E. faecalis, Klebsiella CI: 1st line for cystitis

Question 33

Nitroimidazole MOA

Answer 33

-inhibit DNA synthesis

Question 34

Nitroimidazole Special Considerations

Answer 34

- high bioavailability - high CNS penetration - disulfram reaction with alcohol

Question 35

Metronidazole

Answer 35

Nitroimidazole S: anaerobes, including C. diff, protozoa (eg. Giardia) CI: C. diff ix's, polymicrobial ix's, trichomoniasis

Question 36

Oxazolidinone MOA

Answer 36

- inhibit protein synthesis | - binds 30S subunit

Question 37

Oxazolidinone Special Considerations

Answer 37

- activity vs. beta lactam and vancomycin resistant organisms - high bioavailability - bacteriostatic - cytopenias with prolonged therapy

Question 38

Linezolid

Answer 38

Oxazolidinone S: Streptococci, Enterococci, Staphylococci, anaerobes CI: failure w/ vancomycin therapy

Question 39

Anti-tuberculous drugs Special Considerations

Answer 39

- four drug combo therapy due to increasing resistance - bactericidal - well absorbed - rifampin induces CYP 3A4 - monitor for hepatotoxicity

Question 40

Four Anti-tuberculous drugs

Answer 40

Rifampin* Ethambutol* Pyrazinamide Isoniazed *active vs. MAC as well