Pharmacology Lecture 10_Intro to antimicrobials Flashcards
What is the mechanisium of action of Lipopeptides like daptomycin (what are they most effective against?)
Lipopeptides have nonpolar tails that insert into the cell membrane. These bind with Ca which helps them complex together and form a channel that disrupts the cells electrochemical gradient. Mostly effective against gram possitive bacteria
What is the mechanisium of action of Beta Lactam antibacterials
Transpeptidase is the bacterial enzyme that catalyzes the crosslinking of peptidoglycan in the formation of cell walls. Beta lactams have a 4 member ring that reacts with the transpepdidase and froms an inactive complex. This prevents the bacteria from forming a cell wall which causes them to lyse.
What are five of the methods of resistance bacteria use against antibacterial agents
- Reduced entry of drug into microbe
- Enhanced export of the drug by efflux pumps (Multi Drug resistant Protein [MDR])
- Microbial enzymes that alter or destroy the antimicrobial
- Alteration of target proteins
- Alteration of metabolic/signaling pathways targeted by drug
What are three areas of the body that are difficult to deliver drugs
Bone, CNS, adiapose tissue
Describe the method of action of Polymyxins. What are they effective against?
They are short possitivly charged peptides. This attracts them to the negativly charged cell membrane. This disrupts the cell membrane structure. They are toxic to human and can only be used topically. They are effective against gram negative bacteria
How do quinolones work.
They inhibit topoisomerase which prevents transcription and the creation of mRNA by causing super coiling in the DNA
How do beta lactam allergic responses work
the beta lactam binds to a human protein to form a protein haptn complex. That complex can be identified by antibodies. This can result in anaphylaxis and cytolytic anemia. It is typicall a class wide allergy
What does Sulfonamides target, what does Trimethoprim target, and how do they prevent bacterial replication
Sulfonamides inhibits dihydropteroate synthase. Trimethoprim inhibits dihydrofolate reductase. Both of these enzymes are part of the folic acid synthesase pathway. Without folic acid cells cannot replicate thus these medications are bacteriostatic. Humnas do not have a folic acid pathway thus we are relativly unaffected. They are indirect DNA synthesis inhibitors
How does metronidazole work?
It attacks bacterial DNA directly
What is the one beta lactam that is typically exluded from the class wide allergy?
aztreonam, becasue it is a monobactum and the and the lack of the second ring makes it less allergenic
what are • Penicillins • Cephalosporins • Carbapenems • Monobactams
The 4 sub classes of beta lactam antibacterials
Define “Minimum Bacteriacidal Consentration” (MBC)
Minimum consentration of antibiotic required to kill bacteria.
What is a common glycopeptides. What is it effective against. What is it not effective against?
Vancomycin is typical. It is often effective against MRSA. it is not effective against gram negative bacteria.
What is the method of action of Bacitracin
It prevents peptidoglycan subunits from being transported to the cell surface. It is also toxic to humans and can only be used topically.
Bactericidal vs Bacteriostatic
Bactericidal antibacterial agents activly kill bacteria while bacteriostatic just inhibits their growth.
