L22: Penicillins - condensed Flashcards
What are the 4 subgroups of B-lactams?
- penicillins
- cephalosporins
- monobactams
- carbapenems
What causes resistance to b-lactams?
Lactamase enzymes; altered penicillin binding protein
Which group to: nafcillin, oxacillin, cloxacillin, and dicloxacillin belong to (NO CD)?
A. Aminopenicillins
B. Antipseudomonal
C. Natural
D. Antistaphylococcal
D. Antistaphylococcal
Ampicillin and Amoxicillin belong to which group?
A. Aminopenicillins
B. Antipseudomonal
C. Natural
D. Antistaphylococcal
A. Aminopenicillins
Piperacillin, carbencillin and tiracarcillin belong to which group?
A. Aminopenicillins
B. Antipseudomonal
C. Natural
D. Antistaphylococcal
B. Antipseudomonal
True or False: Lactamase inhibitors are co-formulated with penicillins and other b-lactams to protect against degradatin by lactamase enzymes
True
B-lactams inhibit _____ ____ ____ crosslinking
transpeptidase-mediated peptidoglycan crosslinking
Transpeptidase mistakenly uses lactam as substrate, which leads to ____ ____
irreversible inhibition
True or False: When B-lactams are used, cell wall is weakened, leaving it vulnerable to osmotic stress and rupture. As a result, all non-replicating cells die
False - all replicating cells die
______: bacterial proteins that bind to penicillins and cephalosporins
Penicillin binding proteins
True or False: All bacteria with cell walls contain PBP’s
True
Alteration in penicillin binding protein result in resistance typical of ___
MRSA
True or False: Structural differences and mutations in PBP’s mean that they do not bind B-lactam drugs
True
What does the term “methicillin resistant” describe?
Organisms resistant to many b-lactams
MRSA/ORSA refers to resistance to almost all B-lactams, including all cephalosporins, except 5th gen agent known as ___
ceftaroline
What is the leading cause of surgical site infection in both tertiary and community acquired hospitals?
ORSA
How can you identify B-lactamase production?
Nitrocefin test (uses substrate that changes color when degraded by lactamase)
When are penicillins more effective?
A. log stage
B. stationary growth stage
A. log stage
True or False: Bacteria that persist inside host cells are not accessible to B-lactams
True
True or False: Penicillins are time dependent, bactericidal agents
TRue
True or False: Probenacid keeps drugs like penicillins in circulation for longer
True
Which antibiotic is drug of choice for syphilis?
Penicilin G
Which was the first oral penicillin
Penicillin V/K
True or False: Anti-staphylococcal penicillins are stable towards Staph penicilinases
true
The bulky R group of ___ penicillins inhibits staph beta-lactamase enzymes
Anti-staphylococcal
True or False: Ampicillin and amoxicillin are effective against HELP ME
True
The amino group of aminopenicillins carries a ___ charge that facilitates passage through porins of gram (-)
positive
True or False: Ampicillins is better than Amoxicillin for oral therapy
False - Amox > Amp
B lactamase inhibitors protect penicillins from hydrolysis, thereby functioning as ____ inhibits of bacterial b-lactamase
irreversible suicide inhibitors
True or False: Piperaciiin is a better anti-pseudomonal penicillin
True
Although Piperacillin is inactive against most Staph, it is vulnerable to ___ lactamases
gram (+)
Piperacilin + _____ has widest spectrum of penicillins
Tazobactam
For S. aureus strain without resistance…..
Penicilin>oxacillin>vancomycin
When fetal B-lactam allergies involve ___ or ___ failure
respiratory; CV
How can you screen for a penicillin allergy?
Pre-Pen (major determinant)
True or False: All b-lactams can cause serum-sickness like reaction
True
true or false: failure rate for combo OC will go up after ABX
True
True or False: Amoxicillin/ampicillin rash may look serious, but its not
True
What may contribute to Amoxicillin/ampicillin rash?
Viral infection
- Not antibody mediate
- Does not increase risk of true penicillin allergy
