Chapter 19 Pt 2 Flashcards
____ and ___ are peptides that act as ion-conducting antibiotics (ionophores) that allow uncontrolled movement of ions across the cell membrane
Valinomycin and gramicidin A
______ is a polypeptide antibiotic derived soil bacterium Bacillus polymyxa that operates within the cell membrane and shows a selective toxicity for bacterial cells over animal cells
Polymixin B
causes leakage of small molecules (e.g., nucleosides) from the cell
______ is a new class of antibacterial agents called the cyclic lipopeptides and is a natural product derived from Streptomyces roseosporus
Daptomycin
disrupts multiple functions of the bacterial cell membrane
______ act on the plasma membrane and result in the uncontrolled movement of ions across the cell membrane, leading to cell death.
Ionophores
______ operates selectively on the plasma membrane of bacteria and causes the uncontrolled movement of small molecules across the membrane.
Polymyxin B
True or False: Cyclic peptides are being designed which will self-assemble to form nanotubes in the cell membranes of bacteria.
True
What are the 5 actions that antibacterial agents which impair protein synthesis: through translation
Oxazolidinones bind to 50s subunit (prevents 70s)
tetracycline blacks tRNA binding
Chloramphenicol blocks peptide chain transfer
macrolides block translocation
aminoglycosides block translocation
______ was isolated from the soil microorganism Streptomyces griseus in 1944
streptomycin
True or False: aminoglycosides work best in slightly alkaline conditions
True
at pH 7.4 they have a positive charge that is beneficial to activity by aiding absorption through the outer membrane of Gram-negative bacteria
_____ bind specifically to the 30S ribosomal subunit and prevents the movement of the ribosome along mRNA
Aminoglycosides
_____inhibit protein synthesis by binding to the 30S subunit of ribosomes and preventing aminoacyl-tRNA from binding
Tetracyclines
isolated in 1948 from a mud-growing microorganism in Missouri called Streptomyces aureofaciens
_____ binds to the 50S subunit of ribosomes and appears to act by inhibiting the movement of ribosomes along mRNA, probably by inhibiting the peptidyl transferase reaction
Chloramphenicol
isolated from Streptomyces venezuela found in a field near Caracas, Venezuela
\_\_\_\_ binds to the 50S subunit to inhibit translocation and consists of a 14-membered macrocyclic lactone ring with a sugar and an amino sugar attached and is best-known example of this class of compounds is erythromycin
Macrolides
True or False: another method of increasing acid stability is to increase the size of the macrocycle to a 16-membered ring
True
____ are similar antibacterial properties to the macrolides and act in the same fashion but chemical modification led to the clinically useful clindamycin with increased activity
Lincosamides
____ are a relatively new class of synthetic antibacterial agents that inhibit protein synthesis at an earlier stage than previous agents and do not suffer the same resistance problems and bind to the 50S ribosome and prevent binding to 30S ribosome
Oxazolidinones
linezolid was the first of this class of compounds to reach the market in 2000
____ and _____ areuseful in the treatment of urinary tract infections (UTIs) and infections resistant to the more established antibacterial agents because they inhibit DNA gyrase and/or topoisomerase IV, depending on the type of infection
Quinolones and fluoroquinolones
True or False: in the 1980s with the development of enoxacin, improved broad-spectrum activity based on the discovery that a single fluorine atom at position 6 greatly increased both activity and cellular uptake
a basic substituent, such as a piperazinyl ring at position 7, was also beneficial for a variety of pharmacokinetic reasons due to the ability of the basic substituent to form a zwitterion with the carboxylic acid group at position 3
True
_____ was introduction of a cyclopropyl substituent at position 1 further increased broad-spectrum activity and replacement of the nitrogen at position 8 with carbon reduced adverse reactions and increased activity against S. aureus and the most active of the fluoroquinolones against Gram-negative bacteria
used in 2001 to treat many anthrax-infected patients after letters containing anthrax spores were sent through the U.S. postal service
ciprofloxacin
_____, ______, and ______ are third- and fourth-generation fluoroquinolones
ofloxacin, levofloxacin, moxifloxacin and besifloxacin
______ fluoroquinolones is active against streptococci
______ fluoroquinolones act at DNA gyrase and topoisomerase IV, this dual action slows development of resistance
third-generation
fourth-generation
______ inhibits Gram-positive bacteria and works by binding non-covalently to DNA-dependent RNA polymerase and inhibiting the start of RNA synthesis and its DNA-dependent RNA polymerases in eukaryotic cells are unaffected because the drug binds to a peptide chain not present in the mammalian RNA polymerase
rifampicin
In _____, a nitroimidazole structure which was introduced in 1959 as an antiprotozoal agent
began to be used as an antibacterial agent in the 1970s
the nitro group is reduced when the drug enters the bacterial cell, which lowers the concentration of metronidazole within the cell and sets up a concentration gradient down which more drug can flow
Nitroimidazoles and nitrofurantoin
metronidazole
