Cell Wall Inhibitors in Antibiotics
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Questions and Answers

Which drugs are classified as aminopenicillins?

  • Nafcillin and oxacillin
  • Ampicillin and amoxicillin (correct)
  • Piperacillin and tazobactam
  • Methicillin and dicloxacillin

    • What is the role of β-lactamase inhibitors when co-formulated with aminopenicillins?

  • To prevent resistance in gram-positive bacteria
  • To enhance the antimicrobial spectrum (correct)
  • To weaken the bacterial cell wall
  • To reduce toxicity of the penicillins

    • Which penicillin is used to identify methicillin-resistant Staphylococcus aureus (MRSA)?

  • Methicillin (correct)
  • Amoxicillin
  • Piperacillin
  • Dicloxacillin

    • What specifically grants resistance to methicillin-sensitive Staphylococcus aureus (MSSA) against ampicillin and amoxicillin?

    <p>β-lactamase production</p> Signup and view all the answers

    Which of the following is an antipseudomonal penicillin?

    <p>Piperacillin</p> Signup and view all the answers

    What is the major mechanism of resistance to β-lactam antibiotics?

    <p>β-lactamase production</p> Signup and view all the answers

    What type of infections are antistaphylococcal penicillins primarily used to treat?

    <p>Infections caused by penicillinase-producing staphylococci</p> Signup and view all the answers

    How can β-lactamase be produced by bacteria?

    <p>Constitutionally from the bacterial chromosome or by plasmid transfer</p> Signup and view all the answers

    What is the primary mechanism of β-lactam resistance in gram-positive bacteria?

    <p>Secretion of β-lactamases extracellularly</p> Signup and view all the answers

    How do gram-negative bacteria primarily resist β-lactam drugs?

    <p>Inactivation of drugs in the periplasmic space</p> Signup and view all the answers

    What factor limits the penetration of β-lactam antibiotics in gram-negative bacteria?

    <p>Porin channels in the cell wall</p> Signup and view all the answers

    What characteristic of modified PBPs in bacteria contributes to antibiotic resistance?

    <p>Lower affinity for β-lactam antibiotics</p> Signup and view all the answers

    Which of the following β-lactam antibiotics can be administered orally?

    <p>Amoxicillin</p> Signup and view all the answers

    What happens to the absorption of dicloxacillin when taken with food?

    <p>Decreases due to increased gastric emptying</p> Signup and view all the answers

    Which of the following carbapenems can reach therapeutic levels in bacterial meningitis without inflammation?

    <p>Meropenem</p> Signup and view all the answers

    What is the primary route of administration for depot forms of penicillin?

    <p>Intramuscular</p> Signup and view all the answers

    What is true regarding the distribution of β-lactam antibiotics?

    <p>They generally distribute well throughout the body</p> Signup and view all the answers

    What is the primary route of administration for Imipenem?

    <p>Intravenously</p> Signup and view all the answers

    What adverse effect is more likely to occur at high levels of Imipenem?

    <p>Seizures</p> Signup and view all the answers

    Which of the following agents is exclusively a monobactam?

    <p>Aztreonam</p> Signup and view all the answers

    What type of pathogens does Aztreonam primarily target?

    <p>Gram-negative pathogens</p> Signup and view all the answers

    Which β-lactamase inhibitor contains a β-lactam ring but has no significant antibacterial activity by itself?

    <p>Clavulanic acid</p> Signup and view all the answers

    What effect does combining Imipenem with cilastatin have?

    <p>Prolongs activity in the body</p> Signup and view all the answers

    Which of the following is NOT a known side effect of aztreonam?

    <p>Nausea</p> Signup and view all the answers

    What is the primary route of excretion for penicillins?

    <p>Organic acid tubular secretion and glomerular filtration</p> Signup and view all the answers

    Which of the following is true regarding the metabolism of penicillin G?

    <p>It undergoes insignificant metabolism.</p> Signup and view all the answers

    What effect does probenecid have on penicillin levels in the blood?

    <p>It inhibits secretion, thereby increasing blood levels.</p> Signup and view all the answers

    What is a common adverse reaction associated with penicillin use?

    <p>Hypersensitivity reactions</p> Signup and view all the answers

    Which β-lactam antibiotic is known to cause nephritis?

    <p>Methicillin</p> Signup and view all the answers

    Which of the following statements is correct about cephalosporins?

    <p>They are produced semisynthetically via modification of amino acids.</p> Signup and view all the answers

    What is a potential hematologic toxicity associated with prolonged penicillin therapy?

    <p>Cytopenias</p> Signup and view all the answers

    In which condition are penicillin levels in the prostate deemed insufficient?

    <p>Non-inflamed state</p> Signup and view all the answers

    Which type of infection is primarily managed with oral vancomycin?

    <p>C.difficile infection in the colon</p> Signup and view all the answers

    What is a primary action of lipoglycopeptides like telavancin and oritavancin?

    <p>Inhibit bacterial cell wall synthesis</p> Signup and view all the answers

    What is a significant adverse effect associated with telavancin?

    <p>Nephrotoxicity</p> Signup and view all the answers

    What characteristic differentiates oritavancin and dalbavancin from telavancin?

    <p>Longer half-life enabling single-dose administration</p> Signup and view all the answers

    Daptomycin is primarily used for infections caused by which organisms?

    <p>Vancomycin-resistant Enterococcus (VRE)</p> Signup and view all the answers

    Which of the following is a unique feature of daptomycin?

    <p>It is inactivated by pulmonary surfactants</p> Signup and view all the answers

    What is a consequence of the combined actions of lipoglycopeptides?

    <p>Minimized selection of resistance</p> Signup and view all the answers

    Which property do lipoglycopeptides share with vancomycin?

    <p>Poor absorption after oral administration</p> Signup and view all the answers

    Which generation of cephalosporins is primarily resistant to staphylococcal penicillinase?

    <p>First generation</p> Signup and view all the answers

    What is a unique feature of the second generation of cephalosporins?

    <p>Activity against anaerobes, including Bacteroides fragilis</p> Signup and view all the answers

    Which third-generation cephalosporin is noted for its activity against Pseudomonas aeruginosa?

    <p>Ceftazidime</p> Signup and view all the answers

    What caution is associated with the use of third-generation cephalosporins?

    <p>Increased risk of C. difficile infection</p> Signup and view all the answers

    Which fourth-generation cephalosporin must be administered parenterally?

    <p>Cefepime</p> Signup and view all the answers

    What sets the advanced-generation cephalosporin Ceftaroline apart from others?

    <p>It is effective against MRSA</p> Signup and view all the answers

    Which of the following is not a characteristic of first-generation cephalosporins?

    <p>Broad activity against anaerobes</p> Signup and view all the answers

    What type of infections is Ceftaroline used to treat?

    <p>Complicated skin and skin structure infections</p> Signup and view all the answers

    Study Notes

    Cell Wall Inhibitors

    • Various classes of antibiotics inhibit bacterial cell wall synthesis

    • Penicillins:

      • Basic structure: core four-membered β-lactam ring, thiazolidine ring, and R side chain
      • Differ by the R substituent on the 6-aminopenicillanic acid residue
      • Side chain affects antimicrobial spectrum, stability to acid, cross-hypersensitivity, and susceptibility to β-lactamases

    • Cephalosporins:

      • Closely related to penicillins, both structurally and functionally
      • Mostly semisynthetic, chemically attaching side chains to 7-aminocephalosporanic acid
      • Structural changes on the acyl side chain alter antibacterial activity
      • More resistant than penicillins to some β-lactamases

    • Carbapenems:

      • Synthetic β-lactam antibiotics
      • Differing structure from penicillins: sulfur replaced by carbon in the thiazolidine ring
      • Examples: imipenem, meropenem, doripenem, ertapenem

    • Monobactams:

      • Disrupt bacterial cell wall synthesis
      • Unique: β-lactam ring not fused to another ring
      • Example: aztreonam

    • Other β-lactams:

      • Combinations exist (cephalosporin + β-lactamase inhibitor; carbapenem + β-lactamase inhibitor) to combat resistant bacteria or infections.
        • Examples: ceftolozane-tazobactam; ceftazidime-avibactam; meropenem-vaborbactam

    • Vancomycin:

      • Tricyclic glycopeptide
      • Active against aerobic and anaerobic gram-positive bacteria, including MRSA, MRSE, Enterococcus spp., and C. difficile
      • Binds to peptidoglycan precursors, disrupting polymerization and cross-linking, essential for cell wall integrity
      • Has a bactericidal effect
      • Used in skin and soft tissue infections, infective endocarditis, and nosocomial pneumonia

    • Lipoglycopeptides:

      • Telavancin, oritavancin, and dalbavancin
      • Bactericidal
      • Have a spectrum of similar activity against gram-positive bacteria
      • More potent than vancomycin
      • Inhibit bacterial cell wall synthesis, may also disrupt membrane potential

    • Daptomycin:

      • Cyclic lipopeptide antibiotic
      • Alternative for treating resistant gram-positive infections, including MRSA and VRE
      • Bactericidal, concentration-dependent
      • Used in complicated skin and skin structure infections, and bacteremia

    • Fosfomycin :

      • Synthetic antibacterial drug
      • Inhibits enolpyruvyl transferase, a key step in peptidoglycan synthesis
      • Active against E. coli and E. faecalis
      • First-line therapy for acute cystitis
      • Rapidly absorbed after oral administration
      • Excreted in the urine

    • Polymyxins:

      • Cationic polypeptides
      • Binds to phospholipids on gram-negative bacterial cell membranes, disrupting cell membrane integrity
      • Bactericidal agents, concentration dependent, used topically.
      • High risk of toxicity when used systemically

    Resistance Mechanisms

    • β-Lactamase production, decreased permeability, and altered PBPs are common resistance mechanisms for these antibiotics

    Pharmacokinetics

    • Administration routes depend on drug's stability to gastric acid and infection severity
    • Absorption, distribution, metabolism, excretion, and adverse reactions differ depending on specific drug class

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    Cell Wall Inhibitors PDF

    Description

    This quiz explores various classes of antibiotics that inhibit bacterial cell wall synthesis, including penicillins, cephalosporins, carbapenems, and monobactams. It covers their structures, mechanisms, and how modifications to their structures influence their effectiveness. Test your understanding of these essential components in pharmacology!

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