Topic 16-Clindamycin. Streptogramins. Oxazolidinones

Question 1

What drug is part of the Lincosamide family?

Answer 1

Clindamycin

Question 2

What is the mechanism of action of Clindamycin?

Answer 2

Binds and inhibits the 50s ribosomal subunit

Question 3

Spectrum of Clindamycin

Answer 3

Narrow spectrum
Similar to macrolides
Effective against gram positive aerobes, gram negative anaerobes MRSA, staph, strep, clostridium (not dificile) fusibacterium, bacteroids fragilis
Intracellular- chlamydia and legionella (not mycoplasma)
protozoa- pneumocystis jirovecci (alternative compound)
plasmodium flaciparum (combination therapy
Toxoplasma (alternative) compound

NOT effective against gram negative aerobes or respiratory tract infections, and clostridium dificile

Question 4

Pharmacokinetics of Clindamycin
Administration
Absorption
Penetration
Excretion

Answer 4

IV, IM, or oral (every 8 hours)
good absorption
good penetration/distribution including bone, intracellularly, abscess (not CNS)
Excreted in bile

Question 5

Adverse effects of Clindamycin

Answer 5

ABX associated pseudomembrane colitis
Rash
Neutropenia
Maybe blocks neuromuscular junction

Question 6

Clinical use of Clindamycin

Answer 6

Staph infectins and mixed aerobic and anaerobic infections
toxic shock syndrome
odontogenic infection, osteomyelitis, skin, soft tissue infection (MRSA+strep+staph)
diabetic food (have to combine therapy with aminoglycosides to effectively treat gram negative aerobes)
aspiration pneumonia
secondary peritonitis, trauma wound
pneumocystis jiroveci (alternative

Question 7

What is the first and second choice drug in pneumocystis jiroveci?

Answer 7

1. )suphamexozale and trimethoprim

2. )Clindamycin

Question 8

What drug is used in combination therapy in plasmodium falciparum infection?

Answer 8

Clindamycin

Question 9

What is the first and second choice drug in toxoplasma infection?

Answer 9

1.)clindamycin?

Question 10

What is the resistance called for Clindamycin? Which bacteria is also resistant

Answer 10

MLS resistance. Enterococci.

Question 11

What is the rule about above and below the waist antibiotics?

Answer 11

Above the waist is gram positive anaerobes treated by clindamcyin
Below the waist is gram negative anaerobes treated by metronidazole

Question 12

What are the two Streptogramin drugs that are given together and potentiate each other

Answer 12

Dalfopristin and quinupristin

Question 13

What is the spectrum of dalfopristin and quinupristin?

Answer 13

Narrow spectrum
Gram positive cocci (multidrug resistanct)
Including MRSA, VRSA, enterococci, pneumococci (slow E. Faecium effectiveness)
Intracellular pathogens

Question 14

What is the mechanism of action for quinupristin?

Answer 14

Binds to a nearby site on the 50S ribosomal subunit and prevents elongation of the polypeptide

Question 15

What is the mechanism of action for dalfopristin?

Answer 15

binds to the 23S portion of the 50S ribosomal subunit, and changes the conformation of it, enhancing the binding of quinupristin by a factor of about 100. In addition, it inhibits peptidyl transfer.

Question 16

Pharmacokinetics of dalfopristin and quinupristin
Bactericidal or bacteriostatic
Administration
Half life
PAE
Metabolism
Interaction
Penetration
Distribution
Elimination

Answer 16

Bacteriostatic alone but together they are bactericidal
Administered parenterally (IV) every 8-12 hours
Half life is short
10 hour effectiveness after treatment(Post antibiotic effect)
Metabolized in liver
Inhibits CYP3A4
Penetrates 30-40 times higher concentration intracellularly
Good distribution
Eliminated in bile

Question 17

Clinical indications of dalfopristin and quinuprisitn

Answer 17

Vancomysin resistant E. faecium and multi-drug resistant bacteremia
Sepsis-life threatening infection
RESERVE DRUG

Question 18

Adverse effects of of dalfopristin and quinupristin

Answer 18

Phlebitis (given in central vein as precaution)

Athralgia-myalgia

Question 19

What are the two Oxazolidinones drugs

Answer 19

Linezolid and tedizolid

Question 20

What is the mechanism of action of linezolid

Answer 20

Special binding on the 23S rRNA of 50s subunit inhibiting the 70s initiation complex (NOT PART OF MLS resistance)

Question 21

Spectrum of Linezolid

Answer 21

Narrow spectrum, RESERVE
Gram positive rods and cocci (aerobe and anaerobe)
effective against enterococcus (both faecalis and faecium)-some resistance is building
VRSA, MRSA
pneumococci
cornybacteria
mycobacterium tuberculosis
pasteurella multocida

Question 22

Pharmacokinetics of Linezolid
Bactericidal or bacteriostatic
Administration
Absorption
Distribution
Concentration or time based effect
Elimination

Answer 22

Bacteriostatic, but bactericidal against streptococci
oral or parenteral 2 times a day
good oral absorption
Goes into CNS and intracellularly
Time based effect
Eliminated in kidney and bile (patient with kidney issue doesn’t need to switch does cause will also be excreted in bile)

Question 23

Adverse effect of Linezolid

Answer 23

Candidiasis
Bone marrow suppression
Weak MAO inhibitor (cheese effect, serotonin syndrome, and antidepressant effect)
Doesn’t inhibit CYP enzyme

Question 24

Indications for Linezolid

Answer 24

Reserve, life threatening severe infections
pneumonia, MRSA and VRSA
Enterococci