Antimicrobials IV

Question 1

mechanism of chloramphenicol

Answer 1

blocks peptidyltransferase at 50S ribosomal subunit (bacteriostatic) –> protein synthesis inhibition

Question 2

what changes causes resistance to chloramphenicol

Answer 2

• production of chloramphenicol acetyltransferase which inactivates drug
• changes in membrane permeability

Question 3

clinical application of chloramphenicol

Answer 3

topical treatment of ear and eye infections (no systemic adverse effects)

Question 4

drug interaction of chloramphenicol

Answer 4

it is a CYP450 inhibitor

Question 5

adverse effects of chloramphenicol

Answer 5

Aplastic Anemia
Gray Baby Syndrome (cyanosis): newborns do not have effective glucuronic acid conjugation mechanism needed for breakdown of chloramphenicol –> vomiting, flaccidity, hyperthermia, gray color, shock and collapse

Question 6

mechanism of clindamycin

Answer 6

blocks peptide transfer (translocation) at 50S ribosomal subunit (bacteriostatic) -> inhibition of protein synthesis

Question 7

clinical applications of clindamycin

Answer 7

• Pneumocystis Jiroveci pneumonia in AIDs pts
• Toxoplasmosis in AIDS pts
• Prophylaxis for endocarditis for those who are undergoing a dental procedure

Question 8

adverse effects of clindamycin

Answer 8

Fatal Pseudomembrane Colitis
diarrhea, nausea, skin disease
Impaired liver function and neutropenia

Question 9

what is the streptogramins

Answer 9

Dalfopristin-Quinupristin

Question 10

mechanism of dalfopristin-quinupristin

Answer 10

cause protein synthesis inhibition by binding to separate sites on 50S ribosome (mainly bacteriocidal)

Question 11

clinical application of streptogramins

Answer 11

dalfopristin-quinupristin

infections caused by staph or vancomycin resistant strain of e. faecium (not e. faecalis)

Question 12

mechanism of linezolid

Answer 12

binds to 23S ribosomal RNA of 50S subunit -> inhibition of protein synthesis

weak, reversible inhibitor of monoamine oxidase

Question 13

main use of linezolid

Answer 13

treat multi drug resistant infections

Question 14

what drug is 100% bioavailable after oral administration

Answer 14

linezolid

Question 15

adverse effect of linezolid

Answer 15

• inhibitor of MOA –> increased serotonin in brain
• Lactic acidosis
• Optic and Peripheral Neuropathy
• Myelosuppression

Question 16

mechanism of Fidaxomicin

Answer 16

binds to sigma subunit of RNA polymerase hence inhibiting it –> protein synthesis inhibition

Question 17

main clinical application for Fidaxomicin

Answer 17

C. difficile colitis

Question 18

mechanism of Mupirocin

Answer 18

binds to bacterial isoleucyl transfer-RNA synthetase –> inhibition of protein synthesis

Question 19

clinical use of mupirocin

Answer 19

MSSA or MRSA

Question 20

adverse effects of mupirocin

Answer 20

not used systemically so well tolerated

burning
edema
tenderness
dry skin
pruritis

Question 21

drugs that affect nucleic acid synthesis

Answer 21

Fluoroquinolones
Sulfonamides
Trimethoprim

Question 22

what are the fluoroquinolones

Answer 22

1st gen: Nalidixic acid
2nd gen: Ciprofloxacin
3rd gen: Levofloxacin
4th gen: Moxifloxacin and Gemifloxacin

Question 23

mechanism of fluoroquinolones

Answer 23

direct inhibitor of bacterial DNA synthesis

inhibits bacterial enzymes, DNA gyrase (topoisomerase II) and topoisomerase IV –> damage to bacterial DNA –> bacterial cell death

Question 24

mechanism of resistance in fluoroquinolones

Answer 24

mutation in genes that

• encode DNA gyrase (II) and topoisomerase IV
• regulate expression of efflux pumps

Question 25

name and use of first generation fluroquinolones

Answer 25

Nalidixic acid uncomplicated urinary tract infection

Question 26

name and use of second generation fluoroquinolones

Answer 26

Ciprofloxacin traveler's diarrhea (e. coli) pseudomonas aeruginosa (in CF patients) prophylaxis for meningococcal infection

Question 27

name and use of third generation fluororquinolones

Answer 27

Levofloxacin ``` CA pneumonia (most common) prostatitis caused by e. coli STDs (not syphilis) skin infections acute sinusitis chronic bronchitis tuberculosis ```

Question 28

name and use of fourth generation fluoroquinolones

Answer 28

Moxifloxacin and Gemifloxacin together with levofloxacin are referred to as respiratory fluoroquinolones -used for pneumonia

Question 29

adverse effect of fluroquinolones

Answer 29

Connective tissue problems QT prolongation GI disturbances (most common) Superinfections

Question 30

what drugs can enhance the toxicity of fluroquinolones

Answer 30

theophyllines, corticosteroids, NSAIDs,

Question 31

Levofloxacin, Gemifloxacin, and Moxifloxacin can increase the serum levels of what drugs

Answer 31

warfarin, caffeine, and cyclosporine

Question 32

contraindications of fluroquinolones

Answer 32

- pregnancy and nursing mothers | - children under 18 - due to erosion of cartilage in weigh bearing joints