Antibiotics and Beta-Lactamase Inhibitors

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Questions and Answers

What is the mechanism of action of Vancomycin?

Inhibition of cell wall synthesis (correct)

Inhibition of protein synthesis

Inhibition of folic acid synthesis

Inhibition of DNA replication

Which of the following antibiotics is effective against Gram +ve and -ve organisms and anaerobes?

Ertapenem

Penicillin

Aztreonam

Imipenem (correct)

What is the main advantage of Meropenem over Imipenem?

Less renal degradation (correct)

Narrower spectrum of activity

Greater risk of convulsions

Less risk of hypersensitivity

Why is cilastatin often given with Imipenem?

To inhibit its renal metabolism Signup and view all the answers

What is the main indication for the use of Vancomycin?

MRSA infections Signup and view all the answers

Which of the following antibiotics is considered safe in patients with a history of hypersensitivity to penicillin?

Aztreonam Signup and view all the answers

What is the advantage of Ertapenem over Imipenem?

Less risk of convulsions Signup and view all the answers

What is the purpose of combining clavulanic acid with amoxicillin in Augmentin?

To irreversibly inhibit β-lactamase Signup and view all the answers

What is the main side effect of Imipenem?

All of the above Signup and view all the answers

Which of the following is NOT a combination of a β-lactam antibiotic with a β-lactamase inhibitor?

Cefoperazone + tazobactam Signup and view all the answers

What is the mechanism by which probenecid increases the duration of action of penicillin?

By inhibiting the renal tubular secretion of penicillin Signup and view all the answers

What is the primary mechanism of hypersensitivity reactions to penicillin?

Immune reaction to penicilloic acid Signup and view all the answers

Which of the following routes of administration is dependent on the stability of the antibiotic to gastric acidity?

Oral Signup and view all the answers

What is the primary mechanism of action of β-lactam antibiotics?

Inhibition of cell wall formation Signup and view all the answers

Which of the following is a characteristic of depot IM preparations of penicillin?

Slow absorption into the circulation Signup and view all the answers

What is the primary site of excretion of penicillin?

Kidneys Signup and view all the answers

What is the primary goal of antimicrobial therapy after a pathogen is cultured?

To choose an antimicrobial based on the pathogen's susceptibility Signup and view all the answers

What is the difference between bactericidal and bacteriostatic antimicrobial drugs?

Bactericidal drugs kill the organism, while bacteriostatic drugs stop the growth of the organism Signup and view all the answers

What is the classification of antimicrobial drugs based on their effect on bacteria?

Bactericidal vs. bacteriostatic Signup and view all the answers

What is the primary consideration for choosing an antimicrobial agent?

The site of infection Signup and view all the answers

What is the significance of the minimum inhibitory concentration (MIC) in antimicrobial therapy?

It is the concentration of the antimicrobial that inhibits the growth of the pathogen Signup and view all the answers

What is the primary mechanism of action of cell wall inhibitors?

Inhibition of cell wall formation Signup and view all the answers

What is the classification of antimicrobial drugs based on their spectrum of activity?

Narrow spectrum vs. extended spectrum Signup and view all the answers

What is the primary consideration for dosing of β-lactam antibiotics in patients with impaired renal function?

Dose adjustment based on the patient's renal function Signup and view all the answers

Study Notes

Irreversible Inhibitors of β-Lactamase

Combine with β-lactam antibiotics to protect against β-lactamase-producing organisms
Examples:
- Amoxicillin + clavulanic acid (Augmentin)
- Ampicillin + sulbactam (Unasyn) (IV)
- Ticarcillin + clavulanic acid (Timentin) (IV)
- Piperacillin + tazobactam (Zosyn) (IV)
- Cefoperazone + sulbactam (Sulperazone)

Pharmacokinetics of Penicillins

Absorption: oral, IV, or IM, depending on stability to gastric acidity and severity of infection
Depot IM preparations: procaine penicillin G and benzathine penicillin G
Can cross the placenta, but are not teratogenic
Can cross the blood-brain barrier (BBB) in inflamed meninges (e.g., meningitis)
Excretion: primarily renal, with probenecid inhibiting renal tubular secretion
Distribution: bone, with low levels persisting over a long time period

Adverse Effects of Penicillins

Hypersensitivity:
- Most important adverse effect
- Caused by penicilloic acid, a metabolite that reacts with proteins and serves as a hapten
- May cause rashes, angioedema, and anaphylaxis
- Allergic cross-sensitivity may occur between penicillins and 1st-generation cephalosporins

Other β-Lactam Antibiotics

Carbapenems:
- Imipenem (given IV)
- Meropenem and ertapenem (broader spectrum and less renal toxicity)
Monobactams:
- Aztreonam (given IV and IM)
- Narrow spectrum, effective against aerobic Gram-negative organisms
- No cross-allergy with penicillins

Vancomycin

Mechanism of action: inhibits synthesis of bacterial cell wall phospholipids
Spectrum and uses:
- Effective against Gram-positive organisms (e.g., MRSA and enterococcal infections)
- Used in severe infections in patients allergic to β-lactams
- Used in antibiotic-associated colitis due to C. difficile (e.g., clindamycin)
Pharmacokinetics:
- Given by IV infusion
- May require dose adjustment in pregnancy and lactation

Choosing an Antimicrobial Agent

Factors to consider:
- Organism's identity
- Site of infection
- Patient factors
- Safety of the agent
- Cost of therapy
Classification of antibacterial drugs:
- Bactericidal (kill the organism)
- Bacteriostatic (stop the growth of the organism)
According to the antibacterial spectrum:
- Narrow spectrum: effective against single or limited group of microorganisms
- Extended spectrum: effective against Gram-positive and a significant number of Gram-negative organisms

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Description

This quiz covers the combination of antibiotics with beta-lactamase inhibitors to protect against inactivation by beta-lactamase-producing organisms. It includes examples of antibiotic combinations and their pharmacokinetics.