Antibiotics and Bacterial Resistance
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Questions and Answers

What is the primary mechanism of resistance to β-lactam antibiotics in bacteria such as Escherichia coli and Haemophilus influenzae?

  • alteration of the bacterial cell wall
  • development of efflux pumps
  • production of β-lactamase enzyme (correct)
  • formation of a biofilm

What is the purpose of combining a β-lactamase inhibitor with a β-lactam antibiotic?

  • to enhance the distribution of the antibiotic to the site of infection
  • to increase the absorption of the antibiotic from the gut
  • to reduce the risk of allergic reactions
  • to protect the antibiotic from enzymatic hydrolysis (correct)

Which of the following bacteria is NOT susceptible to piperacillin?

  • Escherichia coli
  • Bacteroides fragilis
  • Pseudomonas aeruginosa
  • Klebsiella pneumoniae (correct)

What is the primary indication for the use of antipseudomonal penicillins such as piperacillin and ticarcillin?

<p>Infections caused by Pseudomonas aeruginosa (B)</p> Signup and view all the answers

Which of the following infections is NOT typically treated with β-lactam antibiotics?

<p>Fungal infections (A)</p> Signup and view all the answers

What is the effect of combining a β-lactamase inhibitor with a β-lactam antibiotic on its antimicrobial spectrum?

<p>broadening of the antimicrobial spectrum (C)</p> Signup and view all the answers

What is the primary function of beta-lactamase inhibitors in antibiotic therapy?

<p>To protect hydrolyzable penicillins from inactivation (B)</p> Signup and view all the answers

Which of the following is a mechanism of penicillin resistance in bacteria?

<p>Alterations in the target enzyme, transpeptidase (C)</p> Signup and view all the answers

What is the primary concern regarding the use of beta-lactam antibiotics in patients with impaired renal function?

<p>Accumulation of the drug leading to increased toxicity (A)</p> Signup and view all the answers

Which of the following drug interactions is a concern when using beta-lactam antibiotics?

<p>Increased risk of bleeding when combined with warfarin (B)</p> Signup and view all the answers

What is the primary target of beta-lactam antibiotics in bacterial cells?

<p>The peptidoglycan cell wall (B)</p> Signup and view all the answers

In which stage of bacterial growth are bacteria most susceptible to the action of beta-lactam antibiotics?

<p>Log phase (C)</p> Signup and view all the answers

What is the mechanism by which high doses of bacteriostatic drugs can act as bactericidal agents?

<p>By preventing the growth of bacteria (D)</p> Signup and view all the answers

Which of the following bacteria is intrinsically resistant to β-Lactam antibiotics?

<p>Mycoplasma (C)</p> Signup and view all the answers

What is the postantibiotic effect (PAE) of β-Lactam antibiotics?

<p>The delay in bacterial growth after antibiotic treatment (C)</p> Signup and view all the answers

What is the common mechanism of action of Penicillins, Cephalosporins, Carbapenems, and Monobactams?

<p>Inhibition of cell wall synthesis (A)</p> Signup and view all the answers

What is the reason for the limited use of Penicillins despite being the most widely effective antibiotics?

<p>Increased resistance (B)</p> Signup and view all the answers

What is the function of Penicillin Binding Proteins (PBPs) in bacterial cell membrane?

<p>To synthesize cell wall (B)</p> Signup and view all the answers

What is the effect of β-Lactam antibiotics on susceptible bacteria?

<p>Death due to imbibition of water (A)</p> Signup and view all the answers

What is the structural characteristic of β-Lactam antibiotics?

<p>Heteroatomic ring structure with 3 carbon and 1 nitrogen atom (A)</p> Signup and view all the answers

Flashcards

Bactericidal Antibiotics

Antibiotics that kill bacteria.

Bacteriostatic Antibiotics

Antibiotics that prevent bacterial growth.

Bacteriostatic to Bactericidal

High doses of some antibiotics that normally stop bacteria from growing can actually kill them.

β-Lactam Antibiotics

A class of antibiotics that all kill bacteria by interfering with their cell wall synthesis.

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β-Lactam Mechanism

The mechanism of action of β-lactam antibiotics involves binding to specific bacterial proteins called Penicillin Binding Proteins (PBPs).

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Beta-Lactamases

Bacterial enzymes that break down the β-lactam ring of some antibiotics, making them ineffective.

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Beta-Lactam Inhibitors

Drugs that block the activity of beta-lactamases, protecting antibiotics from being destroyed.

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Penicillin-Binding Proteins (PBPs)

Bacterial proteins that are the targets of β-lactam antibiotics.

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Peptidoglycan

A network of sugar and protein molecules that forms the rigid outer layer of bacteria.

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Transpeptidases

Enzymes that join together peptidoglycan chains, forming the bacterial cell wall.

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Selective Toxicity

The idea that a drug is more toxic to a pathogen than to the host.

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Penicillins

The most widely used and least toxic antibiotics, characterized by their β-lactam ring and variations in their side chain.

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β-Lactam Subclasses

Penicillins, cephalosporins, carbapenems, and monobactams are all types of β-lactam antibiotics.

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Penicillin Side Chain Impact

The side chain on a penicillin molecule influences its effectiveness against different bacteria, how easily it's broken down, and its stability in the body.

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Cell Wall-less Resistance

Bacteria like Mycoplasma lack a cell wall, making them resistant to cell wall-targeting antibiotics like β-lactams and vancomycin.

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Clinical Uses of Penicillins

Penicillins are effective against a broad range of bacteria, including those causing urinary tract infections, respiratory infections, and meningitis.

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Penicillin Sensitivity

Penicillins are often prescribed to treat infections caused by bacteria that are sensitive to penicillin.

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Penicillins: Infections

Penicillins can be used to treat a variety of infections, including those affecting the urinary tract, respiratory system, and skin.

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Beta-Lactamase Resistance

Bacteria that can break down penicillin have enzymes called beta-lactamases.

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Study Notes

Antibiotic Classification

  • Bacteriocidal: kill bacteria
  • Bacteriostatic: prevent growth of bacteria
  • High doses of bacteriostatic drugs may act as bacteriocidal agents

β-Lactams

  • All β-lactam antibiotics are bactericidal in nature
  • Mechanism of action: bind to specific receptors on bacterial cell membrane (Penicillin Binding Proteins, PBPs) → inhibit transpeptidase enzyme → prevent cross-linking of peptidoglycan chains
  • Bacteria formed in the presence of β-lactams lack cell-wall, causing imbibition of water and leading to cell death
  • Bacteria like Mycoplasma are intrinsically resistant to β-lactams and vancomycin due to lack of cell-wall

β-Lactam Subclasses

  • Penicillins
  • Cephalosporins
  • Carbapenems
  • Monobactams

Penicillins

  • Most widely effective antibiotics and also the least toxic drugs known
  • Members of this family differ from one another in the R substituent attached to the 6-aminopenicillanic acid residue
  • The nature of this side chain affects the antimicrobial spectrum, stability to stomach acid, and susceptibility to bacterial degradative enzymes (β-lactamases)
  • Mechanism of action:
    • Penicillin (or other cell wall synthesis inhibitor) is added to the growth medium
    • The cell begins to grow, but is unable to synthesize new cell wall

Definitions

  • Beta-lactamases: bacterial enzymes that hydrolyze the beta-lactam ring of certain penicillins and cephalosporins
  • Beta-lactam inhibitors: potent inhibitors of some bacterial beta-lactamases used in combinations to protect hydrolyzable penicillins from inactivation
  • Penicillin-binding proteins (PBPs): bacterial cytoplasmic membrane proteins that act as the initial receptors for penicillins and other beta-lactam antibiotics
  • Peptidoglycan: chains of polysaccharides and polypeptides that are cross-linked to form the bacterial cell wall
  • Transpeptidases: bacterial enzymes involved in the cross-linking of linear peptidoglycan chains, the final step in cell wall synthesis
  • Selective toxicity: more toxic to the invader than to the host

Clinical Uses

  • Urinary tract infections
  • Respiratory tract infections
  • Meningitis
  • To treat Gonorrhea, Syphilis, typhoid, bacillary dysentery
  • Sub acute bacterial endocarditis
  • Bone and joint infections
  • Bronchitis, Pneumonia
  • Skin and Soft tissue infections

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Related Documents

Beta-Lactams PDF

Description

This quiz covers the basics of antibiotics, their types and mechanisms of action. It includes bacteriocidal and bacteriostatic drugs, and the properties of β-LACTAMS antibiotics.

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