L22: Penicillins Flashcards
True or False: Penicillin G and Penicillin V/K are natural penicillins
True
Which four drugs are anti-staphylococcals?
1) Nafcillin
2) Oxacillin
3) Cloxacillin
4) Dicloxacillin
Ampicillin and Amoxicillin belong to which class?
A. Natural Penicillins
B. Anti-Staphylococcals
C. Anti-pseudomonals
D. Aminopenicillins
D. Aminopenicillins
Clavulanate, Tazobactam, and Avibactam belong to which group?
A. Natural Penicillins
B. Anti-Staphylococcals
C. Anti-pseudomonals
D. Aminopenicillins
E. Beta-lactamase Inhibitors
E. Beta-lactamase Inhibitors
True or False: Amoxicillin-clavulanate and Piperacillin-tazobactam are combination drugs
True
β-lactams antibiotics include which 4 major subgroups?
- Penicillins
- Cephalosporins
- Monobactams
- Carbapenems
Features shared by: 1) Penicillins, 2) Cephalosporins, 3) Monobactams, and 4) Carbapenems??
1) four membered lactam ring
2) can cause SJS
3) commonly used during pregnancy
What are two reasons for major resistance of β-lactams antibiotics?
1) Resistance to bacterial lactamase enzymes
2) Altered penicillin binding proteins
True or False: Lactamase inhibitors are co-formulated with penicillinsand other beta-lactams, to protect against degradation by lactamase enzymes
True
β-lactams inhibit _____ peptidoglycan cross-linking
transpeptidase-mediated
True or False: Transpeptidase reaction
site centers are found on D-alanyl-D-alanine, which β-lactam resembles
True
With β-lactam, transpeptidase mistakenly uses ___ as substrate, results in
irreversible inhibition
lactam
β-lactams inhibit transpeptidase-mediated peptidoglycan crosslinking.
Inhibition of peptidoglycan synthesis weakens ___, making it vulnerable to osmotic stress and rupture
cell well
β-lactams inhibit transpeptidase-mediated peptidoglycan crosslinking.
In this case, only ___ cells die – mechanism of cell death not completely understood
replicating
____: bacterial proteins that bind to penicillins & cephalosporins
penicillin binding proteins (PBP’s)
True or False: Only some bacteria with cell walls contain PBPs (penicillin binding proteins)
False - ALL bacteria with cell walls
contain PBPs (penicillin binding proteins)
True or False: Gram (-) strains contain B-lactamase while Gram (+) strains contain PBP
False –
Both Gram (+)/(-) contain PBP and B-lactamase
- However, B-lactamase is more externally located in Gram (+) while it is in more internal in Gram (-)
Structural differences & mutations in PBPs mean…?
They do not bind β-lactam drugs
- 4 of 5 PBPs in highly resistant Strep
pneumoniae have lower affinity for
penicillins
Alterations of PBP’s result in resistance typical of ___
MRSA
_____ commonly describes
organisms resistant to many beta-lactams
“Methicillin-resistant”
MRSA/ORSA refers to resistance to virtually all β-
lactams, including nearly all cephalosporins except 5th
gen agent ____
ceftaroline
___ is the leading cause of surgical site infection in
both tertiary and community hospitals
A. MRSA
B. ORSA
B. ORSA
____ is a β-lactamase with spectrum limited to
penicillins
Penicillinase
____ can hydrolyze a wide
variety of β-lactams; exclusive to gram(-) nosocomials
Extended Spectrum β-lactamases (ESBLs)
____: A few lactamase-producing individuals can protect an
entire community; this effect is commonly seen in Gram (+) microbes
Inoculum Effect
Which test uses substrate that changes color when degraded by lactamase?
Nitrocefin
Penicillins are more effective in ___ vs.
stationary growth phase
Logarithmic
Which four factors influence antibiotic efficacy?
1) Growth Phase
2) Population
3) Extracellular Biofilms
4) Location
True or False: Resistant minority microbes secrete lots of lactamase, which can protect neighbors
True
True or False: Bacteria persisting inside host cells are inaccessible to β-lactams + Adherent bacteria secrete polysaccharide
substrate
True
True or False: Penicillins are concentration-dependent, bacterialstatic agents
False - penicillins are TIME-DEPENDENT, BACTERICIDAL AGENTS
True or False: Penicillins kill power generally unaffected by low pH, low O2, or presence of proteins/constituents of pus
True
Where do penicillins distribute to? Where do they not distribute to?
Does: Joint, pleural, pericardial & bile fluids
Does NOT: Intraocular space, prostate, phagocytes, or CSF
when meninges are normal
When penicillins are used and meninges are inflamed, the drugs get into __
CNS
Penicillin dose is adjusted during renal failure. What is the exception?
Anti-staphylococcal penicillins are exceptions
- Rely on significant biliary elimination
____ organic acid transport
inhibitor; keeps drugs such as
penicillins in the circulation longer
Probenecid
True or False: Originally, Penicillin G was useful against many
gram-positive organisms
True
___ and ____ remain sensitive to Penicillin G
Gram (+) Cocci
Gram (-) Neisseria
True or False: Many anaerobes are sensitive to Penicillin V and K, which makes them useful for abscesses, gangrene,
tetanus
False - many anaerobes are sensitive to Penicillin G!!!! which makes them useful for abscesses, gangrene, tetanus
Treatment for syphilis?
Penicillin G
Why is penicillin is used more rarely now?
Due to resistance
True or False: Penicillin G can be administered via IM or IV. Penicillin G is acid instable while Penicillin V/K has greater acid stability
True
True or False: Penicillin G was the first of the “oral penicillins”
False - Penicillin V/K were
Anti-staphylococcal penicillins are stable toward Staph penicillinases. What type of infections do they treat?
Staph infections (skin, osteomyelitis, endocarditis)
Anti-staphylococcal penicillins have bulky ____ group that inhibits Staph ___ ___ enzymes
R group; beta lactamase
True or False: Anti-staphylococcal penicillins have significant biliary clearance, meaning NO need for dosing adjustments in
renal failure
True
True or False: Anti-staphylococcal penicillins are superior to penicillin against penicillin-sensitive strains
False - Anti-staphylococcal penicillins are INFERIOR to penicillin against penicillin-sensitive strains
True or False: Anti-staphylococcals have been
weakened by altered PBP resistance schemes: MRSA/ORSA
organism
True
Aminopenicillins extend penicillin spectrum
to include ____ organisms
gram-negative
True or False: Ampicillin & amoxicillin have nearly
identical spectrum
True
Ampicillin & amoxicillin are effective against…. HELPS ME?
Haemophilus influenzae
E. coli
Listeria;
Proteus mirabilis
Salmonella
Moraxella
E. faecalis
True or False: Aminopenicillins are not effective for gram(-)
nosocomials, which frequently possess β-lactamases that destroy aminopenicillins
True
Klebsiella, Enterobacter, P. aeruginosa
The amino group of aminopenicillins carries a
___ charge that facilitates passage through porins of
gram negatives
A. neutral
B. positive
C. negative
B. positive
Amoxicillin is better than ___ for oral therapy
Ampicillin
True or False: Both Amoxicillin and Ampicillin are adjusted in renal failure + can be combined with β-lactamase
inhibitors to prevent β-lactamase breakdown
True
True or False: There is a current shortage of amoxicillin suspension – using pills, penicillin, or cephalosporins
True
β-lactamase inhibitors protect penicillins from ___
hydrolysis
Some β-lactamase inhibitors mimetics lack antibacterial activity – instead, function as _____ _____ of bacterial β-lactamase
irreversible “suicide” inhibitors
_____: A β-lactamase inhibitor that is useful for UTI’s and infections of respiratory tract, ear, skin (not affected by current shortage)
A. Clauvulanic Acid
B. Augmentin
B. Augmentin = amoxicillin + clavulanate
True or False: β-lactamase inhibitors inhibit many plasmid encoded beta-lactamases, but usually do
not inhibit chromosomal beta lactamases
True
_____ is an example of a non-beta lactam, beta-lactamase inhibitors
Avibactam
Other new non-beta lactam, beta
lactamase inhibitors include
____ and _____ (also: Avibactam)
vaborbactam; relebactam
____ is an antipseudomonal carboxypenicillin, works to treat Pseudomonas (known for drug resistance) – but also good for penicillin-resistant anaerobes (B. fragilis)
Ticarcillin
Ticarcillin can lead to high sodium, which is bad for __ and cause ___ ___
heart; kidney failure
True or False: Ticarcillin is good for penicillin-resistant
anaerobes, e.g. B. fragilis, and mixed aerobic/anaerobic infections
True
Ticarcillin can interact with platelets, leading to increased __
bleeding
True or False: Penicillin is a better anti-pseudomonal than Piperacillin
False - Piperacillin is a better anti-pseudomonal than Penicillin
What advantage does piperacillin have over ticarcillin?
Greater activity against: Pseudomonas aeruginosa, Klebsiella
Piperacillin is inactive against most ___, but it is vulnerable to
_____
Staph; Gram (+) β-lactamases
____ + _____ (Zosyn®) has the
widest spectrum of the penicillins
Piperacillin + Tazobactam
True or False: Piperacillin + Tazobactam can treat: bacteremia, pneumonias, burn infections
True
True or False: Zosyn may not work on piperacillin-resistant P. aeruginosa
True
For S. aureus strain without resistance
schemes….
Penicillin > oxacillin > vancomycin
Incidence of penicillin are common cause of drug allergy and are influenced by route of administration.
What is the order?
topical > IM > IV > oral
Penicillin allergies can manifest in ___, ____, ____, _____
skin (90%) ; respiratory (70%) ; GI (45%); cardiovascular (45%)
When fatal, β-lactam allergies involve
___ or ____ failure
respiratory; cardiovascular
Penicilloyl-polylysine (Pre-Pen) is ____ while several minor determinants include: ____, ____
major determinant; penicilloate, penilloate
True or False: All beta lactams can cause
serum sickness-like reaction
True
- May involve deposition of antigen or
drug immune complexes, causing
inflammation
Amoxicillin and ampicillin may cause
non-allergic ___
rash
- Also associated with viral infection; very common in
those receiving amoxicillin who are also infected
with cytomegalovirus
True or False: Amoxicillin and ampicillin may cause
non-allergic rash - This phenomenon IS
antibody-mediated, and DOES increase risk of
true penicillin allergy
False - this phenomenon is NOT
antibody-mediated, and does NOT increase risk of
true penicillin allergy
Why should you generally avoid avoid combination of penicillins with bacteriostatics (especially tetracyclines or chloramphenicol)???
True or False: The transfer of plasmid DNA between different strains of bacteria can transfer resistance to different microbes
True
- Example: resistant Strep sanguis + Strep viridans acquired PBP’s from S. pneumo
True or False: In IV solution, penicillins can inactivate aminoglycosides
True
- sometimes combo still given though
- beta lactams can “help” aminoglycosides enter target bacteria
____ and ___ are classes associated with C. Diff
Cephalosporins
Penicillins
Why will failure rate for combination oral contraceptives go up after anti-biotic therapy?
Enterohepatic recirculation of OTC’s
True or False: Failure rate for combination oral contraceptives will go up after antibiotic therapy
True
