PHM203 - ID Spectrum: Questions And Complete
Answers
What organisms does penicillin cover? Right Ans - Beta-lactamase negative
GPC
Oral anaerobes
N. meningitis
Syphilis
List 4 mechanisms of resistance to penicillin Right Ans - 1 - inactivation by
beta-lactamase
2 - modification of target PBP's
3 - impaired penetration of drug to reach target PBP
4 - presence of an efflux pump
What are the gaps in penicillin coverage? Right Ans - Atypicals
Beta-lactamase positive GPC
aerobic GNB
anaerobic GN
What additional coverage does aminopenicillins have? Right Ans -
Everything penicillin covers +
increase activity against GN organisms
Enterococcus spp.
What do Penicillinase-resistant penicillins (cloxacillin, methicillin) cover?
Right Ans - Everything penicillin covers +
increased GP activity
Staphylococcus except MRSA
What do Extended-spectrum penicillins (ureidopenicillins, piperazine
penicillin) cover? Right Ans - Everything penicillin covers +
more GN activity
What do penicillin + BL inhibitor (piperacillin/tazobactam) cover? Right
Ans - Everything penicillin covers +
GP + enterococcus
GN
, anaerobes
Cephalosporins have no activity against? Right Ans - No activity against
Enterococcus
1st generation Cephalosporins (cefazolin, cephalexin) coverage? Right Ans
- Everything penicillin covers +
easy to kill GNB (Proteus, E. coli, Klebsiella, H. flu)
2nd generation Cephalosporins (cefoxitin, cefuroxime, cefaclor) coverage?
Right Ans - Everything penicillin covers +
cefoxitin IV:
Gut anaerobes (B. fragilis - GNB - resistance rate is too high; no longer used)
cefuroxime PO/IV:
H. flu (GNB)
M. catarrhalis (GNC)
3rd generation Cephalosporins (ceftriaxone, cefotaxime, ceftazidime)
coverage? Right Ans - Everything penicillin covers +
broader GNB
Ceftazidime (IV) only: P. aeruginosa
Loses:
Ceftazidime: GPC
Cefotaxime, ceftriaxone: decreased staph activity but good Strep activity
decreased gut anaerobe coverage
4th generation Cephalosporins (Cefepime) coverage? Right Ans -
Everything penicillin covers +
more GN including ampC (BL producing SPICE organisms) but not ESBL
P. aeruginosa
decreased Staph but good Strep activity.
New cephalosporin agent (Ceftolozane/tazobactam) coverage? Right Ans -
GN including P. aeruginosa and anaerobes, ESBL (E. coli & Klebsiella)
Answers
What organisms does penicillin cover? Right Ans - Beta-lactamase negative
GPC
Oral anaerobes
N. meningitis
Syphilis
List 4 mechanisms of resistance to penicillin Right Ans - 1 - inactivation by
beta-lactamase
2 - modification of target PBP's
3 - impaired penetration of drug to reach target PBP
4 - presence of an efflux pump
What are the gaps in penicillin coverage? Right Ans - Atypicals
Beta-lactamase positive GPC
aerobic GNB
anaerobic GN
What additional coverage does aminopenicillins have? Right Ans -
Everything penicillin covers +
increase activity against GN organisms
Enterococcus spp.
What do Penicillinase-resistant penicillins (cloxacillin, methicillin) cover?
Right Ans - Everything penicillin covers +
increased GP activity
Staphylococcus except MRSA
What do Extended-spectrum penicillins (ureidopenicillins, piperazine
penicillin) cover? Right Ans - Everything penicillin covers +
more GN activity
What do penicillin + BL inhibitor (piperacillin/tazobactam) cover? Right
Ans - Everything penicillin covers +
GP + enterococcus
GN
, anaerobes
Cephalosporins have no activity against? Right Ans - No activity against
Enterococcus
1st generation Cephalosporins (cefazolin, cephalexin) coverage? Right Ans
- Everything penicillin covers +
easy to kill GNB (Proteus, E. coli, Klebsiella, H. flu)
2nd generation Cephalosporins (cefoxitin, cefuroxime, cefaclor) coverage?
Right Ans - Everything penicillin covers +
cefoxitin IV:
Gut anaerobes (B. fragilis - GNB - resistance rate is too high; no longer used)
cefuroxime PO/IV:
H. flu (GNB)
M. catarrhalis (GNC)
3rd generation Cephalosporins (ceftriaxone, cefotaxime, ceftazidime)
coverage? Right Ans - Everything penicillin covers +
broader GNB
Ceftazidime (IV) only: P. aeruginosa
Loses:
Ceftazidime: GPC
Cefotaxime, ceftriaxone: decreased staph activity but good Strep activity
decreased gut anaerobe coverage
4th generation Cephalosporins (Cefepime) coverage? Right Ans -
Everything penicillin covers +
more GN including ampC (BL producing SPICE organisms) but not ESBL
P. aeruginosa
decreased Staph but good Strep activity.
New cephalosporin agent (Ceftolozane/tazobactam) coverage? Right Ans -
GN including P. aeruginosa and anaerobes, ESBL (E. coli & Klebsiella)
