Penicillin Resistance Mechanisms
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Questions and Answers

Which 5th generation antibiotic is noted for its effectiveness against MRSA?

  • Ceftaroline (correct)
  • Cefepime
  • Ceftobiprole (correct)
  • Cefpirome

    • Which combination of β-lactam drug and β-lactamase inhibitor maintains excellent anaerobic coverage?

  • Ampicillin-sulbactam (correct)
  • Piperacillin-tazobactam (correct)
  • Ceftolozane-tazobactam
  • Cefoperazone-sulbactam

    • What is a characteristic of Imipenem among the carbapenems mentioned?

  • Limited activity against gram-positive cocci
  • Narrowest range of activity compared to others
  • Broadest range of activity against most bacteria (correct)
  • Effective only on gram-negative rods

    • Which β-lactam + β-lactamase inhibitor has activity against β-lactamase producing bacteria?

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

    Which of the following statements regarding Cefepime is true?

    <p>It exhibits activity against gram-positive and negative bacteria including Pseudomonas</p> Signup and view all the answers

    Which of the following are characteristics of ampicillin?

    <p>It targets Enterococcus faecalis.</p> Signup and view all the answers

    What distinguishes the 2nd generation cephalosporins from the 1st generation?

    <p>They have increased anaerobic activity.</p> Signup and view all the answers

    Which of the following is an antipseudomonal penicillin?

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

    How does the activity of 3rd generation cephalosporins compare to that of the 1st and 2nd generations?

    <p>They have decreased activity against gram-positives.</p> Signup and view all the answers

    Which bacteria have shown reported resistance to amoxicillin?

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

    What is a key feature of ceftazidime among the 3rd generation cephalosporins?

    <p>It has activity specifically against Pseudomonas aeruginosa.</p> Signup and view all the answers

    What additional coverage do the antipseudomonal penicillins provide compared to aminopenicillins?

    <p>Effectiveness against Pseudomonas aeruginosa.</p> Signup and view all the answers

    Which of the following is true regarding decreased permeability in certain bacteria?

    <p>It is a mechanism of resistance seen in gram-negative bacteria.</p> Signup and view all the answers

    Which of the following statements accurately describes mutational drug resistance?

    <p>It usually represents a low level of resistance, developed to one drug at a time.</p> Signup and view all the answers

    How does transferable drug resistance differ from mutational drug resistance?

    <p>Transferable drug resistance cannot be overcome by combination therapies.</p> Signup and view all the answers

    What is a primary mechanism for the transfer of resistance in transferable drug resistance?

    <p>Conjugation.</p> Signup and view all the answers

    What term is used for the plasmid that carries multiple antibiotic resistance genes?

    <p>R plasmid.</p> Signup and view all the answers

    Which combination of drugs is commonly used in the multidrug therapy for tuberculosis?

    <p>Isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin.</p> Signup and view all the answers

    Which type of drug resistance is characterized by the inability to overcome resistance through combination therapy?

    <p>Transferrable drug resistance.</p> Signup and view all the answers

    What is the main disadvantage of using multidrug therapy in clinical practice?

    <p>It can increase the rate of adverse drug reactions.</p> Signup and view all the answers

    Which of the following best describes the level of resistance produced by mutational drug resistance?

    <p>Low-level resistance that can often be reversed.</p> Signup and view all the answers

    What is the role of sulfonamides in folic acid synthesis inhibition?

    <p>They block dihydrofolic acid production.</p> Signup and view all the answers

    Which enzyme is inhibited by trimethoprim in the folic acid synthesis pathway?

    <p>Dihydrofolate reductase</p> Signup and view all the answers

    Which of the following combinations is represented by co-trimoxazole?

    <p>Sulfamethoxazole and trimethoprim</p> Signup and view all the answers

    What types of infections is co-trimoxazole indicated for?

    <p>Urinary and respiratory tract infections</p> Signup and view all the answers

    What mechanism do lipopeptides like daptomycin employ against bacteria?

    <p>Leads to leakage from the cell membrane</p> Signup and view all the answers

    In addition to the production of insensitive targets, what is another key action of sulfonamides?

    <p>Blocking tetrahydrofolic acid synthesis</p> Signup and view all the answers

    What type of organisms are primarily targeted by gramicidin?

    <p>Gram-positive cocci and some gram-negatives</p> Signup and view all the answers

    What is a primary mechanism of action for polymyxins in treating infections?

    <p>Disruption of the lipid bilayer</p> Signup and view all the answers

    Which bacteria are intrinsically resistant to aztreonam?

    <p>Gram-positive bacteria</p> Signup and view all the answers

    Which additional antibiotic is recommended for treating Enterobacter species along with common guidelines for Enterobacteriaceae?

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

    What is unique about the Proteeae tribe's susceptibility compared to Enterobacteriaceae?

    <p>They are susceptible to tetracyclines.</p> Signup and view all the answers

    Which of these bacteria is listed with the additional treatment recommendation of aminoglycosides?

    <p>Salmonella species</p> Signup and view all the answers

    Acinetobacter baumannii has intrinsic resistance to which of the following antibiotics?

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

    Which of the following bacteria's treatment may include first and second generation cephalosporins?

    <p>Shigella species</p> Signup and view all the answers

    What is a shared treatment characteristic of Salmonella and Shigella species?

    <p>Both require aminoglycosides and first generation cephalosporins for treatment.</p> Signup and view all the answers

    Which of these options applies to non-fermentative gram-negative bacteria (NF-GNB)?

    <p>They are intrinsically resistant to daptomycin.</p> Signup and view all the answers

    Which type of bacteria include Pseudomonas aeruginosa in its resistance characteristics?

    <p>Non-fermentative gram-negative bacteria</p> Signup and view all the answers

    Which additional treatment is required for Burkholderia cepacia along with NF-GNB guidelines?

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

    Study Notes

    Penicillin Resistance: Mechanisms and Examples

    • Decreased Permeability: Gram-negative bacteria can become resistant to penicillins like oxacillin and methicillin due to altered outer membrane porins, reducing the drug's entry into the cell.
    • β-Lactamase Production: Many bacteria produce enzymes called β-lactamases that break down the penicillin molecule, rendering it ineffective. This resistance can be overcome by using penicillin combined with a β-lactamase inhibitor like sulbactam or clavulanate.
    • Mutational Drug Resistance: Can develop over time, usually resulting in low-level resistance to a single drug.
    • Transferable Drug Resistance (R Plasmid): Bacteria can acquire resistance genes through plasmids, which can code for resistance to multiple classes of antibiotics. This leads to high-level resistance that cannot be overcome by combination therapy.
    • Examples of Penicillin Resistance:
      • Enterococcus faecalis: Resistant to most penicillins except for ampicillin and amoxicillin.
      • Escherichia coli: Can develop resistance to ampicillin and amoxicillin.
      • Pseudomonas aeruginosa: Intrinsically resistant to many penicillins, requiring specific antipseudomonal penicillins like carbenicillin, ticarcillin, and piperacillin.
      • Staphylococcus aureus (MRSA): Resistant to methicillin and other penicillin-based antibiotics.

    Cephalosporin Resistance

    • 1st, 2nd, and 3rd Generation Cephalosporins: Have differing levels of activity against gram-positive and gram-negative bacteria.
      • 1st Generation: Effective against Staphylococcus aureus and some gram-negative bacteria like Escherichia coli and Klebsiella.
      • 2nd Generation: Increased activity against gram-negative bacteria and some anaerobes.
      • 3rd Generation: Increased activity against gram-negative bacteria, but decreased activity against gram-positives. Some are active against Pseudomonas aeruginosa.
    • ESBL (Extended-Spectrum β-Lactamase) Production: A significant resistance mechanism for cephalosporins, leading to resistance to a wide range of β-lactam antibiotics.
    • Efflux Pumps: Can remove cephalosporins from bacterial cells before they can exert their effect.
    • Carbapenems: A class of antibiotics with broad-spectrum activity, typically used as last-resort treatments when other antibiotics fail.
    • Carbapenemase Production: A significant resistance mechanism for carbapenems, resulting in high-level resistance to these drugs.

    Other Antibiotic Resistance Mechanisms

    • Folic Acid Synthesis Inhibitors (Sulfonamides and Trimethoprim): Target two enzymes involved in folic acid synthesis, ultimately inhibiting bacterial growth.
    • Gramicidin: Forms pores in bacterial cell membranes, disrupting cell function.
    • Lipopeptides (Daptomycin): Bactericidal against gram-positive bacteria including VRE and MRSA.
    • Polymyxins (Polymyxin B and Colistin): Bind to LPS of gram-negative bacteria, disrupting their cell membranes.
    • Alteration of LPS: Some bacteria develop resistance to polymyxins by modifying their LPS, reducing binding affinity.

    Summary

    • Resistance mechanisms vary depending on the antibiotic class and the bacterial species.
    • Understanding these mechanisms is crucial for developing effective antibiotic therapies and preventing further spread of resistance.
    • Continued research is needed to address the growing challenge of antibiotic resistance.

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    Related Documents

    Essentials of Medical Microbiology: Antimicrobial Agents and Resistance (PDF)

    Description

    Explore the various mechanisms of penicillin resistance in bacteria, including decreased permeability, β-lactamase production, and mutational drug resistance. Learn about the significance of R plasmids in the transfer of resistance genes and examine examples of resistant organisms like Enterococcus faecalis. This quiz provides insights into the ongoing challenges in antibiotic treatment.

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