Lecture 49 Flashcards
Tetracyclines are usually used to treat H. pylori and community acquired pneumonia, and intracellular bacterial infections. It works by blocking the attachement of amino acyl ____ to mRNA-ribosome complexes. So is it effective against static or rapidly growing bacteria? I
amino acyl tRNA
it is effective against rapidly growing bacteria that are producing a lot of proteins.
_______ is a bacteriostatic antibiotic that is broad spectrum, particularly useful in treating bacterial meningitis because it accumulates in the ____. It blocks the ______ transferase activity of the 50S ribosomal subunit. The most common method of resistance is induction of ________ acetyl transferase encoded on a plasmid –> acetylation prevents binding to ribosome.
Chloramphenicol
CSF
Peptidyl transferase
Chloramphenicol
Macrolides including ______ are particularly good for treating respiratory infections like Whooping cough. They too block the action of the 50S ribosomal subunit.
Erythromycin
Quinolones and Fluroquinolones inhibit bacterial DNA replication by inhibiting ________ and gyrase. They are active against BOTH gram + and gram -. Resistance is due primarily to mutations in the enzymes they inhibit. Ciprofloxacin is an example.
Topoisomerase
______ is an RNA pol inhibitor that blocks mRNA synth and is used in the treatment of TB. Mutations in the RNA pol occur frequently, thus resistance is a big issue here.
Rifampin
Fidaxomicin is a bcateriocidal antibiotic that also blocks RNA synth and is newly approved for treatment of ______ ______.
Clostridium difficile
Sulfonamides and Trimethoprim disrupt _____ metabolism, inhibiting Dihydopterase synthase and Dihydrofolate reductase, respectively. Keep in mind disrupting this metabolism inhibits production of ______ and ______ acids. Sulfonamides act as analogs for ______, which is different than the action of Trimethoprim. What might this mean about the effect of combining them for a treatment?
Folate
Nucleotides
Amino acids
PABA (para-aminobenzoic acid)
They have a synergistic effect, in that they both result in disruption of folate metabolism, but because they do so in different ways, their combined effect would be greater.
______ is the class of antibiotics that disrupt cell membranes. It is typically used for treating infection with Gram ____ bacteria, but these bacteria can alter their LPS to become less negative, and thus more resistant to the drug. Keep in mind this class of drugs is especially toxic because it can have the same (but to a lesser degree) effect of eukaryotic cells.
Polymixins
Gram -
Bacteriocidal (killer) drugs mnemonic: PC VAC
Bacteriostatic drug mnemonic: Stop The Colonies
Penicillin Cephalosporin Vancomycin Aminoglycoside Ciprofloxacin
Sulphanomides Tetracyclines Chloamphenicol
_______-mediated resistance results in resistance to a class of drug that is STRUCTURALLY related, and is limited to a single species of bacteria.
Chromosomal-mediated
_______-mediated resistance can affect multiple drug classes and is not limited to one species of bacteria. Keep in mind ______ with resistance can be present on plasmids, and these can “jump” into the bacteria’s chromosome –> Enterococcus resistance to _______ is a good example of this.
Plasmid-mediated
Transposons
Vancomycin
The vancomycin resistance genes on the plasmid acquired by enterococci are HAX.
H –> is a reductase that converts pyruvate to _____.
A –> is a D-Ala-D-lactate _____
X –> is a D-Ala-D-Ala _______.
All of this results in a D-Ala-D-Lactate structure of peptidoglycan, so Vancomycin cannot bind D-Ala-D-Ala and inhibit the transpeptidase reaction required for cross-linking.
Lactate
Ligase
Dipeptidase
