Contemporary Antibiotics part 2

Question 1

cephalosporins have what type of configuration?

Answer 1

beta-lactam

Question 2

how does cephalosporins increase resistance to B-lactamase?

Answer 2

by addition of “R” groups

Question 3

T/F: cephalosporins are “custom” abx

Answer 3

true

Question 4

mechanism of action of cephalosporin

Answer 4

cell wall inhibition

Question 5

is cephalosporins bacterioCIDAL or bacterioSTATIC?

Answer 5

cidal

Question 6

T/F: cephalosporin has a more extensive spectrum in comparison to PCN and is more expensive than PCN

Answer 6

true

Question 7

spectrum of 1st generation cephalosporins

Answer 7

1. streptococcus
2. staphylococcus (MSSA, NOT MRSA)
3. E. coli
4. proteus mirabilis
5. klebsiella
6. oral anaerobes

Question 8

indications for 1st generation cephalosporins

Answer 8

1. community acquired staph infection
2. surgical wound prophylaxis with skin incision
3. odontogenic infection in PCN allergic patient
4. SBE and total joint replacement (TJR) prophylaxis

Question 9

what percent of the population with PCN allergy will have cephalosporin allergy?

Answer 9

1-10%

Question 10

T/F: avoid cephalosporin in patient with severe PCN allergy, probably okay if allergy is mild

Answer 10

true

Question 11

T/F: avoid any PCN when documented cephalosporin allergy is present

Answer 11

true

Question 12

macrolide abx mechanism of action

Answer 12

irreversibly bind 50s ribosomal unit

Question 13

what does macrolide abx inhibit?

Answer 13

RNA dependent protein syntehsis

Question 14

selective uptake by phagocytic cells serving as repository with macrolide use leads to what?

Answer 14

high levels at infection relative to blood levels

Question 15

T/F: macrolide abx don’t have post-antibiotic effect

Answer 15

false, has significant PAE because they’re bacterioSTATIC

Question 16

pros of clarithromycin (it’s a macrolide abx)

Answer 16

1. less resistance
2. better H. influenza coverage
3. BID dosing
4. less GI distress

Question 17

con of clarithromycin (it’s a macrolide abx)

Answer 17

1. need to take 1h before or 2h after eating

2. expensive

Question 18

indications for clarithromycin (it’s a macrolide abx)

Answer 18

1. sinus infection
2. mild to moderate odontogenic infection in PCN allergic pt
3. SBE prophylaxis in PCN allergic patient as alternative to Clindamycin
4. pneumonia/bronchitis

Question 19

which macrolide abx is better than clarithromycin to tx mild to moderate odontogenic infection in PCN allergic pt?

Answer 19

azithromycin

Question 20

azithromycin (also macrolide abx) has similar spectrum to clarithromycin but is better for what?

Answer 20

strep and gram negative anaerobes

Question 21

indications for azithromycin (also macrolide abx)

Answer 21

1. pneumonia/bronchitis

2. SBE prophylaxis

Question 22

pros of azithromycin (also macrolide abx)

Answer 22

1. daily dosing/improved compliance (i.e. Z-pack)
2. not require dosing around meals (unlike clarithromycin)
3. less GI distress

Question 23

cons of azithromycin

Answer 23

expensive

Question 24

macrolide abx adverse effects

Answer 24

1. GI distress
2. ototoxicity
3. cholestatic jaundice (hepatitis)
4. long Q-T interval/Torsades de Pointes
5. increased activity of digitalis
6. potentiation of oral anticoagulants such as coumadin
7. myopathy in patients taking statins for elevated cholesterol

Question 25

which macrolide abx has the worst GI distress?

Answer 25

erythromycin

Question 26

examples of lincosamides

Answer 26

1. clindamycin | 2. lincomycin

Question 27

which lincosamide abx is currently the only one used in US?

Answer 27

clindamycin

Question 28

mechanism of action of lincosamides

Answer 28

bind 50s ribosome leading to bacteriostatic inhibition of protein synthesis

Question 29

spectrum of bacteria treated by clindamycin

Answer 29

1. streptococcus 2. staphylcoccus 3. actinomyces 4. anaerobes

Question 30

clindamycin is bacteriostatic except when?

Answer 30

at high doses

Question 31

cons of clindamycin

Answer 31

1. higher toxicity than some (pseudomembranous colitis) | 2. expensive

Question 32

T/F: clindamycin can penetrate bone

Answer 32

true

Question 33

indications for clindamycin

Answer 33

1. chronic recurrent infection 2. osteomyelitiis 3. odontogenic infection in immunocompromised patient with severe PCN allergy 4. some increased use in routine odontogenic infection due to increasing resistance to PCN by oral anaerobes 5. total joint replacement (TJR) prophylaxis in PCN allergic patient 6. SBE prophylaxis in PCN allergic patient

Question 34

is metronidazole cidal or static?

Answer 34

cidal

Question 35

characteristics of metronidazole

Answer 35

1. oral dose equivalent to parenteral 2. mild toxicity 3. disulfuram effect 4. inexpensive

Question 36

mechanism of action of metronidazole

Answer 36

disrupts DNA in anaerobic environment

Question 37

indications for metronidazole

Answer 37

1. chronic anaerobic infection 2. particularly effective bone penetration 3. in combo with PCN or cephalosporin in serious odontogenic infection

Question 38

are tetracyclines cidal or static?

Answer 38

static

Question 39

mechanism of action of tetracyclines

Answer 39

30s ribosomal inhibition

Question 40

characteristics of tetracyclines

Answer 40

1. high resistance 2. inexpensive 3. broad spectrum

Question 41

indications for tetracycline

Answer 41

1. early adjunctive tx of peri-implantitis 2. resistant hospital acquired infections 3. helicobactor related gastric and peptic ulcer due to increasing resistance to metronidazole 4. topical therapy 5. dry socket prevention

Question 42

what happens when tetracycline is used to treat odontogenic infection

Answer 42

may result in deformity of developing teeth