ICWS I - Handout Flashcards
What is the main structure that confers antibacterial activity to penicillins?
The β-lactam ring
The β-lactam ring is essential for the antibacterial action of penicillin antibiotics.
What are the four groups of penicillins?
- Natural penicillins
- Penicillinase Resistant Penicillins
- Extended spectrum penicillins
- Antipseudomonal penicillins
Each group has distinct characteristics and uses.
What is the mechanism of action of penicillins?
Penicillins inhibit the final stage of bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)
This binding prevents cross-linking of peptidoglycan, leading to cell lysis.
What role do autolysins play in the effectiveness of penicillin antibiotics?
Autolysins cleave peptidoglycan bonds during cell growth, and in the presence of penicillin, they lead to cell wall weakness and lysis
Cells must be actively growing for penicillin to be bactericidal.
Which penicillin is the drug of choice (DOC) for Neisseria meningitides?
Penicillin G
Penicillin G is effective against several Gram-positive bacteria.
What is the primary bacterial resistance mechanism against penicillin antibiotics?
Inactivation of penicillin by bacterial β-lactamase (penicillinase)
This enzyme splits the penicillin molecule, rendering it inactive.
Fill in the blank: The backbone of peptidoglycan is composed of two alternating sugars: N-acetylglucosamine (NAG) and _______.
N-acetylmuramic acid (NAM)
These sugars form the structure of bacterial cell walls.
What is the significance of the β-lactam ring in penicillin antibiotics?
The β-lactam ring forms an irreversible covalent acyl-bond with transpeptidase, preventing cross-linking
This action is crucial for the bactericidal effect of β-lactam antibiotics.
True or False: Methicillin-resistant Staphylococcus aureus (MRSA) resistance is associated with penicillinase production.
False
MRSA resistance is due to an alternate PBP, not penicillinase.
What are the adverse side effects associated with penicillin drugs?
- Allergy
- Electrolyte imbalances
- GI disturbances
- Superinfections
Allergic reactions are particularly notable among penicillins.
What is the primary use of antipseudomonal penicillins?
Treatment of Pseudomonas aeruginosa infections
Antipseudomonal penicillins are specifically designed to target this resistant organism.
What is the pharmacokinetic property of penicillin G?
Good tissue penetration but poor CNS penetration
Renal elimination is the primary route for penicillin G.
Fill in the blank: Fosfomycin inhibits one of the first steps in the synthesis of _______.
peptidoglycan
It blocks the condensation of uridine diphosphate-N-acetylglucosamine with phosphoenolpyruvate.
What is the mechanism of action of Bacitracin?
Inhibits the conversion to its active form of the lipid carrier for peptidoglycan transport
This leads to accumulation of cell-wall subunits in the cytoplasm.
Which penicillins can be combined with a penicillinase inhibitor?
- Ampicillin
- Amoxicillin
- Piperacillin
- Ticarcillin
The combination extends the spectrum of these agents.
What is the most common allergic reaction associated with penicillins?
Anaphylaxis
Allergic reactions to penicillins can be life-threatening.
What is the mechanism of action of glycopeptides like vancomycin?
They bind to the terminal D-alanine-D-alanine of the stem peptide, inhibiting subunit addition to peptidoglycan
This prevents cell wall synthesis.
True or False: Extended spectrum penicillins have good activity against Gram-positive bacteria.
True
They also provide extended coverage against Gram-negative organisms.
What are the properties of beta-lactamase inhibitors?
- Resemble beta-lactam molecules
- Weak antibacterial action
- Inhibit many β-lactamases
These properties enable them to extend the spectrum of coverage of penicillins.
What are the foremost antibiotics used in hospitalized patients?
Penicillins
Followed by sulfa drugs and cephalosporins.
Are all penicillins cross-allergic?
Yes
All penicillins are cross-allergic and cross-sensitizing.
What is the prototype of penicillin?
Penicillin G
What is the renal elimination method for penicillin G?
Filtration and tubular excretion
What inhibits the renal elimination of penicillin G?
Probenecid
