Contemporary Antibiotics part 2 Flashcards
cephalosporins have what type of configuration?
beta-lactam
how does cephalosporins increase resistance to B-lactamase?
by addition of “R” groups
T/F: cephalosporins are “custom” abx
true
mechanism of action of cephalosporin
cell wall inhibition
is cephalosporins bacterioCIDAL or bacterioSTATIC?
cidal
T/F: cephalosporin has a more extensive spectrum in comparison to PCN and is more expensive than PCN
true
spectrum of 1st generation cephalosporins
- streptococcus
- staphylococcus (MSSA, NOT MRSA)
- E. coli
- proteus mirabilis
- klebsiella
- oral anaerobes
indications for 1st generation cephalosporins
- community acquired staph infection
- surgical wound prophylaxis with skin incision
- odontogenic infection in PCN allergic patient
- SBE and total joint replacement (TJR) prophylaxis
what percent of the population with PCN allergy will have cephalosporin allergy?
1-10%
T/F: avoid cephalosporin in patient with severe PCN allergy, probably okay if allergy is mild
true
T/F: avoid any PCN when documented cephalosporin allergy is present
true
macrolide abx mechanism of action
irreversibly bind 50s ribosomal unit
what does macrolide abx inhibit?
RNA dependent protein syntehsis
selective uptake by phagocytic cells serving as repository with macrolide use leads to what?
high levels at infection relative to blood levels
T/F: macrolide abx don’t have post-antibiotic effect
false, has significant PAE because they’re bacterioSTATIC
pros of clarithromycin (it’s a macrolide abx)
- less resistance
- better H. influenza coverage
- BID dosing
- less GI distress
con of clarithromycin (it’s a macrolide abx)
- need to take 1h before or 2h after eating
2. expensive
indications for clarithromycin (it’s a macrolide abx)
- sinus infection
- mild to moderate odontogenic infection in PCN allergic pt
- SBE prophylaxis in PCN allergic patient as alternative to Clindamycin
- pneumonia/bronchitis
which macrolide abx is better than clarithromycin to tx mild to moderate odontogenic infection in PCN allergic pt?
azithromycin
azithromycin (also macrolide abx) has similar spectrum to clarithromycin but is better for what?
strep and gram negative anaerobes
indications for azithromycin (also macrolide abx)
- pneumonia/bronchitis
2. SBE prophylaxis
pros of azithromycin (also macrolide abx)
- daily dosing/improved compliance (i.e. Z-pack)
- not require dosing around meals (unlike clarithromycin)
- less GI distress
cons of azithromycin
expensive
macrolide abx adverse effects
- GI distress
- ototoxicity
- cholestatic jaundice (hepatitis)
- long Q-T interval/Torsades de Pointes
- increased activity of digitalis
- potentiation of oral anticoagulants such as coumadin
- myopathy in patients taking statins for elevated cholesterol
which macrolide abx has the worst GI distress?
erythromycin
examples of lincosamides
- clindamycin
2. lincomycin
which lincosamide abx is currently the only one used in US?
clindamycin
mechanism of action of lincosamides
bind 50s ribosome leading to bacteriostatic inhibition of protein synthesis
spectrum of bacteria treated by clindamycin
- streptococcus
- staphylcoccus
- actinomyces
- anaerobes
clindamycin is bacteriostatic except when?
at high doses
cons of clindamycin
- higher toxicity than some (pseudomembranous colitis)
2. expensive
T/F: clindamycin can penetrate bone
true
indications for clindamycin
- chronic recurrent infection
- osteomyelitiis
- odontogenic infection in immunocompromised patient with severe PCN allergy
- some increased use in routine odontogenic infection due to increasing resistance to PCN by oral anaerobes
- total joint replacement (TJR) prophylaxis in PCN allergic patient
- SBE prophylaxis in PCN allergic patient
is metronidazole cidal or static?
cidal
characteristics of metronidazole
- oral dose equivalent to parenteral
- mild toxicity
- disulfuram effect
- inexpensive
mechanism of action of metronidazole
disrupts DNA in anaerobic environment
indications for metronidazole
- chronic anaerobic infection
- particularly effective bone penetration
- in combo with PCN or cephalosporin in serious odontogenic infection
are tetracyclines cidal or static?
static
mechanism of action of tetracyclines
30s ribosomal inhibition
characteristics of tetracyclines
- high resistance
- inexpensive
- broad spectrum
indications for tetracycline
- early adjunctive tx of peri-implantitis
- resistant hospital acquired infections
- helicobactor related gastric and peptic ulcer due to increasing resistance to metronidazole
- topical therapy
- dry socket prevention
what happens when tetracycline is used to treat odontogenic infection
may result in deformity of developing teeth
