8.5

Question 1

What is the difference between ketolides and macrolides?

Answer 1

Ketolides bind to 2 RNA domain vs macrolides bind to only 1.

= kotolides bind tighter, harder to efflux

Question 2

What are ketolides used for? Spectrum?

Answer 2

Respiratory infections
strep, staph
H. flu, Pertussis
Atypical: Chlamydia, Mycoplasma, and Legionella

Question 3

What are the toxicities of ketolides?

Answer 3

Erythromycin – GI – N/V/D; Phlebitis
QT prolongation
Erythromycin and Clarithromycin – Cyp 3A4 inhibitors
Blurred vision, diplopia, difficulty focusing
Severe liver damage

Question 4

What is the mechanism of tetracyclines and Glycylcyclines?

Answer 4

Bind to 30s and prevent protein synthesis

Question 5

How do bugs become resistant to TCN?

Answer 5

Efflux pumps

Ribosomal mutation

Question 6

What is the spectrum of TCN?

Answer 6

Strep pneumo, staph aureus
H. flu, Neisseria
Atypical: Rickettsia, Chlamydia, Mycoplasma, Borrelia, Treponema

Question 7

What TCN is PO and IV?

Answer 7

Doxycycline

Question 8

What does minocycline treat?

Answer 8

MRSA

Leprosy

Question 9

How are Glycylcyclines different than TCNs?

Answer 9

Glycl amide group- prevents recognition by efflux pump

Question 10

What is the coverage of glycylcyclines?

Answer 10

G+: Strep, Staph (including MRSA), Enterococci (including VRE)
G-: H. Flu, Neisseria, Enterobacteriacea
Anarobes: B. fragilis and many other
Atypical: Mycoplasma

Question 11

What are the toxicities of TCNs?

Answer 11

Rings structure – a potent chelator of metal ions gray to yellow discoloration of growing teeth and bone
Contraindicated for pregnant women
Cautious for children <8y.o
Rashes, anaphylaxis
Blue-black hyperpigmentation – minocycline
Photosensitivity
N/V
Hepatoxicity

Question 12

What is the mechanism of Choramphenicol?

Answer 12

Binds to 50s, blocks formation of peptide bonds

Question 13

If a bug is resistant to Choramphenicol, what else is it likely resistant to?

Answer 13

also resistant to macrolides/ketolides, clindamycin ***

**These drugs are all similar, if resistant to one, likeley resistant to all

Question 14

How do bugs become resistant to Choramphenicol?

Answer 14

Producing enz acetylates chloramphenicol  prevent binding to target
Efflux pumps

Question 15

What is the spectrum of chloramphenicol?

Answer 15

Strep
H. Flu, Neisseria, Salmonella, Shigella
**Anaerobes – B fragilis and other
**Atypical – Mycoplasma, Chlamydia, Rickettsia

Question 16

What are the toxicities of chloramphenicol?

Answer 16

Reversible bone marrow suppression – dose dependent
Bind to mitochondrial ribosome
Irreversible aplastic anemia – occurs after completion a of therapy
Neonates – caused “gray baby syndrome”
Not fully functional liver enz (i.e UDP-glucuronyl transferase) accumulation of unmetabolized chloramphenicol
Optic neuritis

Question 17

What is the mechanism of clindamycin?

Answer 17

Binds to 50s, inhibits protein synthesis

Similar to macrolides

Question 18

If a bug is resistant to clindamycin, what else is it likely resistant to?

Answer 18

macrolides

Question 19

What is the spectrum of clindamycin?

Answer 19

G+: Strep, staph
Anaerobes: B. Fragilis, Clostridium, and most other

**Most G- intrinsically resistant

Question 20

What are the toxicities of clindamycin?

Answer 20

Induce C diff colitis – 0.01 -10%
Diarrhea
Rashes

Question 21

What is the mechanism of Streptogramins?

Answer 21

2 different macrocyclic compounds
Binds to 50S prevent protein synthesis
Each compound has moderate antibacterial effects
Dalfopristin binds to ribosome -> induce conformational change -> enhance binding of quinupristin

Question 22

What other Abx binding sites do streptogramins overlap with?

Answer 22

Macrolides

Clindamycin

Question 23

What is the coverage of streptogramins?

Answer 23

Covers G+ only (i.e. strep, staph, and enterococcus)

Question 24

What are the toxicities of streptogramins?

Answer 24

CYP450 inhibitor

Phlebitis – should be given via central line
Arthralgia, myalgias
Hyperbilirubinemia

Question 25

What is the mechanism of linezolid?

Answer 25

Prevents 30s from joining with 50s= ribosome can’t form

Question 26

How do bugs become resistant to linezolid?

Answer 26

Mutation of ribosome

Efflux pumps

Question 27

What is the spectrum of linezolid?

Answer 27

G(+) – strep, staph including MRSA and VRE

Question 28

When is linezolid used? How dosed?

Answer 28

Reserved for VRE, MRSA

PO/IV = bioavalibility

Question 29

What are the toxicities of linezolid?

Answer 29

N/V/D
Thrombocytopenia
Anemia, leukopenia – reversible
Not be given with MAO inhibitors
Together with SSRI serotonin syndrome

Question 30

What is the spectrum for nitrofuratonin/macrobid?

Answer 30

Staph enterococcus

UTI only, need good renal fxn

Question 31

What are the toxicities of nitrofuratonin/macrobid?

Answer 31

N/V, rash, interstitial pneumonitis, hepatitis, hemolytic anemia, and neuropathy