38 Questions
What is the main reason bacteria need to constantly produce new biomolecules?
To replace old worn-out ones and build new bacteria
What is the process by which mRNA is synthesized from DNA genes?
Transcription
What is the target of antibiotics that inhibit bacterial transcription and translation?
Bacterial growth and multiplication
What is the name of the antibiotic that is used to 'adorn' traditional treatment wardrobes?
Rifampin
What is the purpose of setting villages and isolated buildings on fire in the quote from Julius Caesar?
To starve the Romans by cutting off their forage and supplies
What are the rifamycins used to do?
Accentuate traditional treatment
What is the function of mRNA templates in bacteria?
To generate proteins
What is the term for the generation of proteins from mRNA templates?
Translation
What is the oldest aminoglycoside?
Streptomycin
Which aminoglycoside is commonly used?
Gentamicin
Which bacteria is tobramycin not effective against?
Enterococci
What is a characteristic of gentamicin?
It is spelled without a 'y'
Which aminoglycoside has better overall activity against aerobic gram-negative bacteria?
Amikacin
Which aminoglycoside is effective against some strains of enterococci?
Streptomycin
What is true about gentamicin-resistant strains?
They are not susceptible to tobramycin
Which aminoglycoside is not used for infections caused by enterococci?
Tobramycin
What type of bacterial infections is telithromycin approved for?
Respiratory infections
Which of the following strains of bacteria is telithromycin active against?
All of the above
Why are some strains of staphylococci resistant to telithromycin?
They are capable of modifying their ribosomes
Which of the following bacteria is NOT susceptible to telithromycin?
Enterobacteriaceae
What is the reason for telithromycin's effectiveness against more strains of staphylococci than macrolides?
Telithromycin can bind to modified ribosomes
What type of bacteria is telithromycin NOT active against?
Enterobacteriaceae
What is NOT mentioned about telithromycin's activity?
Activity against Neisseria spp.
What is the class of bacteria that includes Legionella pneumophila?
Atypical bacteria
What is the usual modification made to the peptidoglycan precursor by enterococci?
Change of d-alanyl–d-alanine to d-alanyl–d-lactate
What is the anticipated consequence of the transferability of the gene clusters that encode glycopeptide resistance in enterococci?
Increased resistance to glycopeptides in staphylococci
What was the origin of the soil sample that led to the discovery of vancomycin?
A missionary from Borneo
What is the meaning of the word 'vancomycin'?
Derived from the word 'vanquish'
What is the name of the journal that published the article about vancomycin use reviewed by Griffith RS?
Journal of Antimicrobial Chemotherapy
What is the result of the modification of the peptidoglycan precursor by enterococci?
Glycopeptides are no longer able to recognize and bind to the altered precursors
What is the name of the fatal condition in neonates caused by chloramphenicol?
Gray baby syndrome
What type of bacteria is Haemophilus influenzae?
Gram-negative
What is the term for the range of microorganisms that an antibiotic is effective against?
Spectrum of activity
What type of bacteria is Bacteroides fragilis?
Anaerobic
What is the name of the antibiotic shown in Figure 6-7?
Chloramphenicol
Which of the following is NOT typically affected by chloramphenicol?
Mycobacterium tuberculosis
What is a common neurologic abnormality associated with chloramphenicol?
Optic neuritis
What type of bacteria is Chlamydia trachomatis?
Atypical
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.
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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