Penicillins Flashcards
What are the 3 B-lactamase inhibitors?
Clavulonic Acid
Sulbactam
Tazobactam
What is the mehcanism of action for Penicillins?
Inhibit bacterial cell wall synthesis by blocking crosslinking of adjacent peptidoglycan strands with subsequent lysis.
What are Penicillin-binding proteins (PBPs)?
What enzymes fall into this classification?
Targets of B-lactam antibiotics; Include:
Transpeptidases
Transglycolases
D-alanine carboxykinase
-Peptidoglycan transpeptidase is one PBP that is inhibited.
T/F
Penicillins are bactericidal.
TRUE
What bugs exhibit Beta-lactamase Production?
Staph
H. flu
What bugs don’t allow antibiotic to penetrate to PBP targets?
Gram negative organisms (porin channel penetration)
What bugs exhibit low affinity binding of antibiotic to PBPs?
Pneumococcus, MRSA, Enterococcus
What feature allows Ampicillin and Amoxicillin to target some G– ?
What feature allows Piperacillin to target G– all the way through “SPACE bugs”?
Amine on side chain
long side chain with amines
When will a patient’s peak levels of penicillin be in reference to taking orally?
What effect does food have on penicillins?
1-2 hours after ingestion
Peak levels 2-3 hrs Decreases absorption (excet Pen V, Amoxicillin, and Carbenicillin)
Why is inflammation needed for PCNs distribution to brain, CSF, and prostate.
Insoluble in lipid
T/F
Some PCNs are acid stable; others are acid labile
TRUE
Are PCNs well distributed throughout the body?
What is their major route of Excretion and what does that make you take into consideration when prescribing?
Yes, but hydrophilic
Renal Excretion primarily; MUST ADJUST FOR RENAL INSUFFICIENCY
T/F
Hypersensitivity may not occur on re-exposure or may occur without previous reaction.
What two types of hypersensitivity are exhibited?
TRUE
-Immediate Reaction (anaphylaxis) - IgE mediated. -Delayed Reaction (i.e. rash) - IgM or IgG mediated.
Maculopapular rash is most common.
Why was methicillin removed from shelves?
Interstitial Nephritis
Besides Hypersensitivity, what 3 other adverse effects are associated with PCNs?
- Eosinophilia/Thrombocytopenia/Neutropenia
- Interstitial Nephritis
- Pseudomembranous colitis
What 2 kinds of salts do Pen G come in?
K+
Na+
Why is benzathine penicillin used to treat syphillis and phrphylaxis against rheumatic fever?
sustained release (21 days)
What bugs do PenG/VK cover?
Streptococcus
SOME Enterococcus
PS: Strep Pneumo PBP changes on rise causing more resistance
Why is Nafcillin great to use in patients with renal dysfunction?
hepatic elimination
What PCNs belong to the “Penicillinase Resistant Penicillins” (Antistaphylococcal penicillins)?
Which are IV only and which are PO only?
Methicillin, Oxacillin, Nafcillin
Cloxacillin, Dicloxacillin
Methicillin, Oxacillin, Nafcillin
Cloxacillin, Dicloxacillin
What bugs do Penicillinase Resistant Penicillins cover?
Staph
Strep
What PCNs belong to the “Aminopenicillins”?
What special ability is conferred by their structure?
Ampicillin (QID)/Amoxicillin(TID)
-Amino group allows for penetration into gram negative cell wall.
What bugs do Aminopenicillins cover?
-Streptococcous
-Enterococcus
-Haemophilus (non-b-lactamase producing)
Salmonella/Shigella (non-b-lactamase)
-Proteus mirabilis (watch sensitivity)
-E.coli (watch sensitivity, esp if GI is the source of E.coli)
-Klebsiella (watch sensitivity)
What is the drug of choice for Enterococcus?
Ampicillin (Amoxicillin if ampicillin is not available)
