L2 Pharm: Penicillin Flashcards
B- Lactam (Penicillins):
- What is the MOA?
- Inhibit cell wall synthesis
- bind & inhibit PBPs in the bacterial cell membrane (penicillin binding proteins)
HYDROLYZES THE CYCLIC AMIDE BOND F THE B-LACTAM RING, inactivating the antibiotic
*Number, type and location of PBPs vary
between bacteria
- PBPs are only expressed during cell division
- Inhibition of PBPs leads to inhibition of final transpeptidation step of peptidoglycan synthesis
(inhibits cross-linking)
- What is the half life of B lactam?
- How is it eliminated?
- What are 4 drugs that are exceptions to this?
- True or False: Cross-Allergenicity is not present.
- SHORT - less than 2 hours
- Eliminated unchanged by KIDNEYS
- Except:
- nafcillin
- oxacillin
- ceftriaxone
- cefoperazone - FALSE: CROSS-ALLERGENICITY
- all except AZTREONAM
What structure do all penicillins share?
- Share a B lactam ring attached to a 5 membered thiazolidine ring
Penicillins:
What are the Mechanisms of Resistance? (3)
- a) B-lactamase degradation
(more effective in gram -)
b) PBP alteration, decreased binding affinity (MRSA, PRSP)
c) Alteration of outer membrane porin proteins –> decreased penetration (gram -)
Are penicillins bactericidal or bacteriostatic? (exception)
What is the function of the transpeptidase?
- Bactericidal (kill bacteria)
- EXCEPT against Enterococcus - Transpeptidase - cross-links the peptides in the membrane (B- lactase inhibit the transpeptidase)
How do gram positive bacteria destroy the B-Lactams?
Gram negative?
- B-lactamase destroys the B-Lactam antibiotics EXTRACELLULARLY
- Gram Negative:
- B - lactase produced in periplasmic space and inhibit the B-Lactam in this space
THEREFORE: cannot reach the PBP target due to poor penetration of the outer membrane
What are the mechanisms of resistance for Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP)?
2 mechanism:
Alteration in structure of PBPs leads to DECREASED BINDING AFFINITY
What mechanism of resistance is specific for gram NEGATIVE bacteria?
3 Mechanism:
Alteration of outer membrane PORIN PROTEINS leading to decreased
penetration
- or EFFLUX PUMPS that don’t
allow the bacteria to stay within the cell
Define Natural Penicillins.
What are some examples of natural penicillins?
- Parenteral (3)
- Oral (1)
Which is short acting?
Which is long acting?
- Aqueous penicillin G (IV)
- Benzathine penicillin G (IM, LONG-acting)
* given once a week for latent syphillis - Procaine penicillin G (IM)
* SHORT acting - Oral: Penicillin VK
* more bioavailable and better absorbed
Natural Penicillins:
Penicillin G and Penicillin VK have excellent activity against which
- Gram positive Cocci & Bacilli (6)
- Gram negative Cocci (2)
- Gram Negative Anaerobe (1)
- Other (1)
- Gram positive Cocci & Bacilli:
- Group Streptococci* (A, B, C, F, G)
- Viridans Streptococci*
- pen-susc. S. Aureus
- pen-suss. S. Pneumoniae
- Enterococcus spp.
- Bacillus Spp.
- Gram negative Cocci
- Neisseria Spp.*
- Pasteurella multocida - Gram Negative Anaerobe
- Clostridium Spp. *
- -> above the diaphragm - Other
- Treponema Pallidum (syphillis)
Penicillinase - Resistant Penicillins:
- Developed in response to the emergence
of penicillinase-producing ________. - Synthetic derivatives of natural
penicillin - contain an _____ side chain - What are some examples of Penicillinase resistance Penicillins?
- Parenteral (3)
- Oral (1)
- Staphylococcus
- Acyl
3. Parenteral: - Nafcillin - Oxacillin - Methicillin * Dicloxacillin (oral)
What is considered to be the drug of choice for the treatment of infections of the following bacteria? (7)
- Treponema Pallidum (syphillis)
- Neisseria Meningitidis
- Corynebacterium diphtheria
- Bacillus Anthracis (anthrax)
- Clostridium perfringens
& Tetani - Viridans
- Group Streptococci
Penicillin G
Why were Penicillinase Resistant Penicillins developed?
STATE 4.
To overcome the penicillinase enzyme of Staphylococcus Aureus, which inactivated NATURAL PENICILLIN
- containg an acyl side chain that streakily inhibits the action of penicillinase by preventing opening of the B lactam ring
- Nafcillin
- Methicillin
- Oxacillin
- Dicloxacillin * (oral)
What are the 3 gram positive bacteria susceptible to Penicillinase Resistant Penicillins?
What do these drugs have no activity against?
- Methicillin - susceptible S. Aureus (MSSA)
- Group Streptococci
- Viridians Streptococci
No gram negative activity & limited anaerobic activity
Antibiotic Resistance in Staphylococcus aureus:
First report of methicillin-
resistant S. aureus (MRSA)
caused by PBP alteration
mediated by _____ gene which confers resistance to all beta- lactams except what drug?
- mecA
- ceftaroline
- only antibiotic for Staph. Aureus
Aminopenicillins:
- were developed in response to what?
- Semisynthetic derivative of NATURAL penicillin by adding what?
- State 3 examples
(1 parenteral, 2 oral)
WHAT ARE THEY INEFFECTIVE AGAINST BECAUSE OF PENICILLINASE?
AMINOPENICILLINS:
- Gram negative Aerobes
- Adding an amino group
- Parenteral: AMPICILLIN
Oral: Ampicillin
& Amoxicillin
- Staph Aureuas
What are gram positive bacteria that are susceptible to Aminopenicillins? (2 really important, 4 others)
Gram negatives? ( 5 )
**KNOW THESE **
AMINOPENICILLINS
(Ampicillin, Amoxicillin)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Gram Positive: 1. Enterococcus Spp.* 2. Listeria Monocytogenes - pen-susc. S. aureus - pen- suss. S. Pneumo - Group Streptococci - Viridans Streptococci
_____________________
Gram negative:
- Proteus mirabilis
- some E. coli
- Salmonella
- Shigella
- βL- H. influenzae
- (only B-lactamase negative strains)
CARBOXYPENICILLINS:
- Developed in response to the need for what?
- Semisynthetic derivatives of natural
penicillin – addition of _____ group - What is the only drug for this??
- Agents with ENHANCED activity against gram negative bacteria & increasing frequency of Pseudomonas Aeriginosa as a nosocomial pathogen
- Carboxyl
- TICARCILLIN
- Parenteral ONLY
(not available anymore anyways)
Carboxypenicillins:
- state the activity against Gram Negative bacteria
- Are there any gram positives bacteria it eradicates?
- PSEUDOMONAS AERUGINOSA
- Proteus mirabilis
- Salmonella, Shigella
- some E. coli
- βL+ H. influenzae
- Enterobacter spp - Marginal activity for gram positives
- streptococcus spp. (less active)
- NOT ACTIVE against Enterococcus or Staphylococcus
- NOT active against Klebsiella spp., Serratia spp., or Actinobacter spp.
UREIDOPENICILLINS:
- Developed in response to the need for agents with MORE enhanced activity against what?
- Semisynthetic derivatives of the amino-
penicillins with ____. - State an example (parenteral? oral?)
- In response to enhanced activity against GRAM NEGATIVE bacteria
- acyl side chain adaptations
- NO ORAL
- Parenteral: PIPERACILLIN**
What class of penicillins are the broadest spectrum penicillins available without B-Lactamase Inhibitors?
UREIDOPENICILLINS
Ureidopenicillins have fairly good activity against ___
State the Gram Negative Bacteria it works against.
- Anaerobes
- a) Pseudomonas Aeriginosa*
b) Enterobacter sp
c) Klebsiella spp.
d) Serratia Marcescens
+
- Proteus Mirabilis
- Salmonella
- Shigella
- E.Coli
- Bl+ H influenza
Gram Positives:
-Viridians strep
-Group strep
Enterococcus
B- Lactamase Inhibitors:
- Combination product of B-Lactamase & Penicillins
- Protect penicillins from being hydrolyzed by
some β-lactamases by doing what? - Very weak to no _______ activity
- Examples? (4)
- by irreversibly binding
to catalytic site of β-lactamase enzyme - Antibacterial
- Clavulanate (+Amoxi)
- Sulbactam (+Ampic)
- Tazobactam (+Piperacil.)
- Avibactam (used in combo with cephalosporins)
- Why were B- Lactamase Inhibitor Combinations developed?
Examples? Parenteral a) What makes Unasyn b) What makes Timentin c) what makes Zosyvn
Enteral (1)
- To enhance the activity of Penicillins against B lactase produce bacteria
a) Ampicillin- Sulbactam (Unasyn)
b) Ticarcillin - Clavulunate (Timentin)
c) Piperacillin/Taxobactam (Zosyn)
Oral: Amoxicillin - Clavulanate (Augmentin)
What Gram positive bacteria is killed by B-Lactamase Inhibitor combos? (1)
Gram Negative? (2 important, 4 others)
Anaerobe? (1)
What is ticarcillin/clavulanate extremely active against?
- S. Aureus (NOT MRSA)*
- H. Influenzae *
Moraxella Catarrhalis*
E. Coli
Proteus Spp.
Klebsiella Spp.
Neisseria Gonorrhea
- Anaerobe:
- Bacteroides spp. *
** TICARCILLIN/CLAVULANATE is active against STENOPHTROPHOMONAS MALTOPHILIA
Anaerobes:
- increased activity against B. Fragilis & B. Fragilis group (DOT) organisms
- Penicillins display ____ dependent bacterial killing
- Time above MIC correlates with what?
- All penicillins are bactericidal, but display bacteriostatic activity against ENTEROCCOCUS & STAPHYLOCOCCUS with the addition of what?
- What can this be used in the treatment of?
- Time dependent
- Efficacy
- no significant PAE for gram negative bacteria
(post-antibiotic effect)
HOWEVER significant for gram +
- AMINOGLYCOSIDE
(gentamicin, streptomycin) - used in treatment of Enterococcal Endocarditis