EXAM 2 Antibiotics II Cont'd

Question 1

what is the mechanism of chloramphenicol?

Answer 1

inhibits 50S peptidyltransferase

Question 2

describe the spectrum of chloramphenicol

Answer 2

broad spectrum

mostly bacteriostatic to all bacteria, except h. influenzae (bacteriocidal)

Question 3

what is the clinical use of chloramphenicol?

Answer 3

restricted to life-threatening infections of h. influenzae, bacteriodes, rickettsia, and meningitis (serious infections where penicilin can’t be used due to allergy)

Question 4

the utility of chloramphenicol is limited due to its severe ___

Answer 4

toxicity

Question 5

does chloramphenicol cross the BBB?

Answer 5

yes

Question 6

what are the adverse effects of chloramphenicol?

Answer 6

• hemolytic anemia, aplastic anemia (fatal), anemia, teratogenic, gray baby syndrome in premature infants

Question 7

what are the serious drug interactions of chloramphenicol?

Answer 7

inhibits CYP450s to slow metabolism of warfarin, phenytoin (toxicity risk)

Question 8

the mechanism of clindamycin is the same as ___

Answer 8

macrolides

it blocks peptide bond formation at the 50S subunit of bacterial ribosome (inhibits translocation step of protein synthesis)

Question 9

___ is antagonistic if co-administered with macrolides

Answer 9

clindamycin

Question 10

what is the spectrum of clindamycin?

Answer 10

• active against infections caused by non-enterococcal, gram + cocci
• no gram - activity
• bacteriostatic

Question 11

urine levels of clindamycin are ___

Answer 11

non-therapeutic, so it is not good for UTIs

Question 12

clindamycin can accumulate in patients with ___ or ___ failure

Answer 12

renal or liver

Question 13

what are the adverse effects of clindamycin?

Answer 13

• pseudomembranous colitis - treated with oral vancomycin or metronidazole
• hematological disorders
• fever
• diarrhea
• cellulitis

Question 14

what are the clinical uses for clindamycin?

Answer 14

• bone and joint infections
• anaerobes above the diaphragm
• gram + microbes

Question 15

for patients with ___, clindamycin can be prescribed orally for months as an outpatient therapy

Answer 15

anaerobic aspiration pneumonia

Question 16

what is the mechanism of linezolid?

Answer 16

binds to 50S subunit of bacterial ribosomes and blocks protein synthesis

Question 17

what is the spectrum of linezolid?

Answer 17

• bactericidal (streptococci)
• bacteriostatic (enterococci and staphylococci)

Question 18

what antibiotic has the following clinical uses?

treatment of vancomycin-resistant E. faecium

nosocomial pneumonia (both meth-susceptible and MRSA)

community acquired pneumonia

complicated skin infections caused by strep, staph, and MRSA

Answer 18

linezolid

Question 19

what are the adverse effects of linezolid?

Answer 19

• generally well-tolerated with rare side effects
• hematologic (2.4% of patients)
• chronic treatment has resulted in reversible neurotoxicity

Question 20

patients receiving adrenergic or serotinergic agents while taking linezolid may develop ___

Answer 20

serotonin syndrome

Question 21

quinuprostin/dalfopristin is in what ratio?

Answer 21

30:70

Question 22

the synergistic effect of quinuprostin/dalfopristin causes ___ to enhance quinuprostin binding

Answer 22

conformation change

Question 23

what is the spectrum of quinuprostin/dalfopristin?

Answer 23

bacteriostatic

Question 24

how should quinuprostin/dalfopristin be administered?

Answer 24

slow IV infusion only

no dose adjustment needed in renal insufficiency

Question 25

what are the clinical uses for quinuprostin/dalfopristin?

Answer 25

• reserved for serious infections by multidrug resistant gram + organisms
• life threatening bacteremia VRE, enterococcus faecium, and complicated skin infections caused by MRSA and meth-resistant s. pyogenes

Question 26

what are the adverse effects of quinuprostin/dalfopristin?

Answer 26

• local effects
• arthralgia and myalgia
• hyperbilirubinemia

Question 27

what is the unique mechanism of mupirocin?

Answer 27

reversibly inhibits isoleucyl transfer-RNA synthetase enzyme which inhibits protein transaction

Question 28

what is the spectrum of mupirocin?

Answer 28

bactericidal

Question 29

how is mupirocin administered?

Answer 29

topically, but only small areas at a time

Question 30

what are the clinical uses for mupirocin?

Answer 30

MRSA and meth-resistant s. pyogenes skin lesions

Question 31

what are the adverse effects of mupirocin?

Answer 31

• application to large skin areas should be avoided in patients with renal insufficiency to avoid accumulation of polyethylene glycol used in ointment perparations