Peptidoglycan Precursor Modification in Bacteria
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Questions and Answers

What is the main reason bacteria need to constantly produce new biomolecules?

  • To maintain their shape
  • To replace old worn-out ones and build new bacteria (correct)
  • To fight off antibiotics
  • To undergo photosynthesis

    • What is the process by which mRNA is synthesized from DNA genes?

  • Translation
  • Mutagenesis
  • Transcription (correct)
  • Replication

    • What is the target of antibiotics that inhibit bacterial transcription and translation?

  • Bacterial cell wall
  • Bacterial growth and multiplication (correct)
  • Bacterial DNA replication
  • Bacterial metabolism

    • What is the name of the antibiotic that is used to 'adorn' traditional treatment wardrobes?

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

    What is the purpose of setting villages and isolated buildings on fire in the quote from Julius Caesar?

    <p>To starve the Romans by cutting off their forage and supplies</p> Signup and view all the answers

    What are the rifamycins used to do?

    <p>Accentuate traditional treatment</p> Signup and view all the answers

    What is the function of mRNA templates in bacteria?

    <p>To generate proteins</p> Signup and view all the answers

    What is the term for the generation of proteins from mRNA templates?

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

    What is the oldest aminoglycoside?

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

    Which aminoglycoside is commonly used?

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

    Which bacteria is tobramycin not effective against?

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

    What is a characteristic of gentamicin?

    <p>It is spelled without a 'y'</p> Signup and view all the answers

    Which aminoglycoside has better overall activity against aerobic gram-negative bacteria?

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

    Which aminoglycoside is effective against some strains of enterococci?

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

    What is true about gentamicin-resistant strains?

    <p>They are not susceptible to tobramycin</p> Signup and view all the answers

    Which aminoglycoside is not used for infections caused by enterococci?

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

    What type of bacterial infections is telithromycin approved for?

    <p>Respiratory infections</p> Signup and view all the answers

    Which of the following strains of bacteria is telithromycin active against?

    <p>All of the above</p> Signup and view all the answers

    Why are some strains of staphylococci resistant to telithromycin?

    <p>They are capable of modifying their ribosomes</p> Signup and view all the answers

    Which of the following bacteria is NOT susceptible to telithromycin?

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

    What is the reason for telithromycin's effectiveness against more strains of staphylococci than macrolides?

    <p>Telithromycin can bind to modified ribosomes</p> Signup and view all the answers

    What type of bacteria is telithromycin NOT active against?

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

    What is NOT mentioned about telithromycin's activity?

    <p>Activity against Neisseria spp.</p> Signup and view all the answers

    What is the class of bacteria that includes Legionella pneumophila?

    <p>Atypical bacteria</p> Signup and view all the answers

    What is the usual modification made to the peptidoglycan precursor by enterococci?

    <p>Change of d-alanyl–d-alanine to d-alanyl–d-lactate</p> Signup and view all the answers

    What is the anticipated consequence of the transferability of the gene clusters that encode glycopeptide resistance in enterococci?

    <p>Increased resistance to glycopeptides in staphylococci</p> Signup and view all the answers

    What was the origin of the soil sample that led to the discovery of vancomycin?

    <p>A missionary from Borneo</p> Signup and view all the answers

    What is the meaning of the word 'vancomycin'?

    <p>Derived from the word 'vanquish'</p> Signup and view all the answers

    What is the name of the journal that published the article about vancomycin use reviewed by Griffith RS?

    <p>Journal of Antimicrobial Chemotherapy</p> Signup and view all the answers

    What is the result of the modification of the peptidoglycan precursor by enterococci?

    <p>Glycopeptides are no longer able to recognize and bind to the altered precursors</p> Signup and view all the answers

    What is the name of the fatal condition in neonates caused by chloramphenicol?

    <p>Gray baby syndrome</p> Signup and view all the answers

    What type of bacteria is Haemophilus influenzae?

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

    What is the term for the range of microorganisms that an antibiotic is effective against?

    <p>Spectrum of activity</p> Signup and view all the answers

    What type of bacteria is Bacteroides fragilis?

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

    What is the name of the antibiotic shown in Figure 6-7?

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

    Which of the following is NOT typically affected by chloramphenicol?

    <p>Mycobacterium tuberculosis</p> Signup and view all the answers

    What is a common neurologic abnormality associated with chloramphenicol?

    <p>Optic neuritis</p> Signup and view all the answers

    What type of bacteria is Chlamydia trachomatis?

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

    Study Notes

    Peptidoglycan Precursor Modification

    • Some bacteria modify the structure of peptidoglycan precursor, changing the d-alanyl-d-alanine dipeptide, often to d-alanyl-d-lactate.
    • This modification prevents glycopeptides from recognizing and binding to the altered precursors.

    Glycopeptide Resistance

    • The gene clusters that encode this modification activity are transferable and have been found in S. aureus.
    • It is anticipated that glycopeptide resistance will increase in frequency in staphylococci.

    Vancomycin History

    • Vancomycin was discovered from a soil sample sent by a missionary from Borneo to an organic chemist at Eli Lilly and Company.
    • The soil sample harbored a bacterium that produced a compound with potent activity against gram-positive bacteria.
    • The compound was purified and named vancomycin, derived from the word "vanquish".

    Bacterial Protein Production

    • Bacteria constantly produce new biomolecules to replace old ones and build new bacteria.
    • This process involves transcription (synthesis of mRNA from DNA genes) and translation (generation of proteins from mRNA templates).
    • Antibiotics can target these processes to inhibit bacterial growth and multiplication.

    Rifamycins

    • Rifamycins are "accessory" antibiotics that enhance the effect of traditional treatments.
    • They consist of rifampin (rifampicin), rifabutin, rifapentine, and rifaximin.

    Aminoglycosides

    • Streptomycin is the oldest aminoglycoside and is rarely used today, but remains effective against some enterococci strains.
    • Gentamicin is the most commonly used aminoglycoside, active against both aerobic gram-negative and gram-positive bacteria.
    • Tobramycin has a similar spectrum of activity to gentamicin, but lacks activity against enterococci.
    • Amikacin is effective against strains of aerobic gram-negative bacteria that are resistant to gentamicin and tobramycin.

    Telithromycin

    • Telithromycin is approved for use in patients with bacterial respiratory infections.
    • It is active against most strains of S. pneumoniae, including penicillin-resistant and macrolide-resistant strains.
    • It is also active against more strains of staphylococci and other streptococci than macrolides, but some strains are resistant.

    Chloramphenicol

    • Chloramphenicol has a broad spectrum of activity that includes many aerobic gram-positive, gram-negative, anaerobic, and atypical bacteria.
    • Its use is limited by its toxicity profile, which can cause gray baby syndrome and neurologic abnormalities.
    • It is effective against many bacteria, including Streptococcus pyogenes, Haemophilus influenzae, and anaerobic bacteria.

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    Description

    This quiz covers how bacteria modify peptidoglycan precursors to resist glycopeptides, including the alteration of d-alanyl–d-alanine dipeptide to d-alanyl–d-lactate. It also touches on the transferability of the gene clusters encoding this activity.

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