PHRM 865 Exam 2 Latest Update
6 Characteristics of Beta Lactams - ANSWER 1. Same mechanism of action: inhibitors of
cell wall synthesis
2. Same mechanisms of resistance: destruction by beta-lactamase enzymes; alteration
in penicillin binding proteins (PBP), decreased permeability of outer cell membrane in
gram-negative bacteria
3. Pharmacodynamic properties: T>MIC dependent bactericidal activity (except for
Enterococcus spp. where it is only able to inhibit growth)
4. Short elimination half-life (<2 hours): Repeated, freqeunt dosing is needed for most
beta-lactams to maintain serum concentrations above the MIC of the infecting bacteria
for an adequate amount of time (except ceftriaxone, cefotetan, cefixime, ertapenem)
5. Renal elimination- primarily eliminated unchanged by glomerular filitration and
tubular secretion (except nafcillin, oxacillin, ceftriaxone, cefoperazone)
6. Cross-allergenicity-- All except aztreonam
Which 4 beta-lactams do not have a short elimination half-life?* - ANSWER Ceftriaxone
Cefotetan
Cefixime
Ertapenem
Which 4 beta-lactams do not require renal adjustment?* - ANSWER Nafcillin
Oxacillin
Ceftriaxone
Cefoperazone
Because they are not eliminated renally
Structure of Penicillins - ANSWER All penicillins share a beta-lactam ring attached to a
5-membered thiazolidine ring
'House with a garage'
Penicillins Mechanism of Action - ANSWER Interfere with cell wall synthesis by binding
to and inhibiting penicillin-binding proteins (PBPs) located in bacterial cell walls
Bactericidal (not against Enterococcus)
,Penicillins Mechanisms of Resistance* - ANSWER 1. Production of beta-lactamase
enzymes
--Enzyme hydrolyzes the beta-lactam ring inactivating the antibioitc
2. Alteration in structure of PBPs leading to decreased binding affinity--> MRSA and
penicillin-resistant streptococcus pneumoniae PRSP)
3. Alteration of outer membrane porin proteins leading to decreased penetration
Bacteria producing beta-lactamase enzymes* - ANSWER Gram + Aerobes: Staph
Aureus
Gram - Aerobes:
Haemophilus influenzae
Neisseria gonorrhoeae
Moraxella catarrhalis
Klebsiella pneumoniae
Eschericia coli
Enterobacter spp.
Proteus spp.
Psuedomonas aeruginosa
Serratia marcescens
Gram - Anaerobes:
Bacteroides fragilis
4 examples of natural penicillins - ANSWER Aqueous penicillin G (IV form)
Benzathine penicillin G (IM form)
Procaine penicillin G (IM form)
Phenoxymethyl penicillin (penicillin VK) (oral form)
First group of penicillins to be discovered and used clinically
Naturally derived from Penicillin notatum
Spectrum of activity of natural penicillins - ANSWER Gram +: Excellent activity vs
non-beta-lactamase producing gram + cocci and bacilli
--Very little activity vs Staphylcoccus spp. due to penicillinase production (one of the
, first beta lactamases found)
--Staph aureus most important bug to develop resistance
Gram -: Primarily used against some gram - cocci
-Neisseria meningitis
-Non-beta-lactamase producing neisseria gonorrhea (beta lactamase production occurs
in gonorrhoeae so it's not used as much)
-Pasteurella multocida
Anaerobes: good activity vs gram + anaerobes
Mouth anaerobes: (Gram + cocci, "above the diaphragm")
-Peptococcus Spp.
-Peptostreptococcus Spp.
Clostridium Spp. (Gram - bacilli, "below the diaphragm" (EXCEPT C. diff)
Other:
-Treponema pallidum
Penicillin G is still considered to be a potential drug of choice for?* - ANSWER Treatment
of infections due to viridans and group streptococci, Neisseria meningitidis,
Corynebacterium diphtheriae, Bacillus anthracis (anthrax), Clostridium perfringens and
tetani, and Treponema pallidum (syphilis)
Penicillinase-resistant penicillins (aka Antistaphlococcal penicillins) - ANSWER
Developed to address the emergence of penicillinase-producing staphlococcus aureus
that rendered the natural penicillins inactive.
Examples include: nafcillin* (iv), methicillin, oxacillin, cloxacillin , and dicloxacillin* (oral)
Gram +:
-Group streptococci
-Viridans streptococci
-MSSA (target organism!)
-NOT ACTIVE against MRSA
Gram -: no activity
Anaerobes: limited, to no activity
6 Characteristics of Beta Lactams - ANSWER 1. Same mechanism of action: inhibitors of
cell wall synthesis
2. Same mechanisms of resistance: destruction by beta-lactamase enzymes; alteration
in penicillin binding proteins (PBP), decreased permeability of outer cell membrane in
gram-negative bacteria
3. Pharmacodynamic properties: T>MIC dependent bactericidal activity (except for
Enterococcus spp. where it is only able to inhibit growth)
4. Short elimination half-life (<2 hours): Repeated, freqeunt dosing is needed for most
beta-lactams to maintain serum concentrations above the MIC of the infecting bacteria
for an adequate amount of time (except ceftriaxone, cefotetan, cefixime, ertapenem)
5. Renal elimination- primarily eliminated unchanged by glomerular filitration and
tubular secretion (except nafcillin, oxacillin, ceftriaxone, cefoperazone)
6. Cross-allergenicity-- All except aztreonam
Which 4 beta-lactams do not have a short elimination half-life?* - ANSWER Ceftriaxone
Cefotetan
Cefixime
Ertapenem
Which 4 beta-lactams do not require renal adjustment?* - ANSWER Nafcillin
Oxacillin
Ceftriaxone
Cefoperazone
Because they are not eliminated renally
Structure of Penicillins - ANSWER All penicillins share a beta-lactam ring attached to a
5-membered thiazolidine ring
'House with a garage'
Penicillins Mechanism of Action - ANSWER Interfere with cell wall synthesis by binding
to and inhibiting penicillin-binding proteins (PBPs) located in bacterial cell walls
Bactericidal (not against Enterococcus)
,Penicillins Mechanisms of Resistance* - ANSWER 1. Production of beta-lactamase
enzymes
--Enzyme hydrolyzes the beta-lactam ring inactivating the antibioitc
2. Alteration in structure of PBPs leading to decreased binding affinity--> MRSA and
penicillin-resistant streptococcus pneumoniae PRSP)
3. Alteration of outer membrane porin proteins leading to decreased penetration
Bacteria producing beta-lactamase enzymes* - ANSWER Gram + Aerobes: Staph
Aureus
Gram - Aerobes:
Haemophilus influenzae
Neisseria gonorrhoeae
Moraxella catarrhalis
Klebsiella pneumoniae
Eschericia coli
Enterobacter spp.
Proteus spp.
Psuedomonas aeruginosa
Serratia marcescens
Gram - Anaerobes:
Bacteroides fragilis
4 examples of natural penicillins - ANSWER Aqueous penicillin G (IV form)
Benzathine penicillin G (IM form)
Procaine penicillin G (IM form)
Phenoxymethyl penicillin (penicillin VK) (oral form)
First group of penicillins to be discovered and used clinically
Naturally derived from Penicillin notatum
Spectrum of activity of natural penicillins - ANSWER Gram +: Excellent activity vs
non-beta-lactamase producing gram + cocci and bacilli
--Very little activity vs Staphylcoccus spp. due to penicillinase production (one of the
, first beta lactamases found)
--Staph aureus most important bug to develop resistance
Gram -: Primarily used against some gram - cocci
-Neisseria meningitis
-Non-beta-lactamase producing neisseria gonorrhea (beta lactamase production occurs
in gonorrhoeae so it's not used as much)
-Pasteurella multocida
Anaerobes: good activity vs gram + anaerobes
Mouth anaerobes: (Gram + cocci, "above the diaphragm")
-Peptococcus Spp.
-Peptostreptococcus Spp.
Clostridium Spp. (Gram - bacilli, "below the diaphragm" (EXCEPT C. diff)
Other:
-Treponema pallidum
Penicillin G is still considered to be a potential drug of choice for?* - ANSWER Treatment
of infections due to viridans and group streptococci, Neisseria meningitidis,
Corynebacterium diphtheriae, Bacillus anthracis (anthrax), Clostridium perfringens and
tetani, and Treponema pallidum (syphilis)
Penicillinase-resistant penicillins (aka Antistaphlococcal penicillins) - ANSWER
Developed to address the emergence of penicillinase-producing staphlococcus aureus
that rendered the natural penicillins inactive.
Examples include: nafcillin* (iv), methicillin, oxacillin, cloxacillin , and dicloxacillin* (oral)
Gram +:
-Group streptococci
-Viridans streptococci
-MSSA (target organism!)
-NOT ACTIVE against MRSA
Gram -: no activity
Anaerobes: limited, to no activity
