Exam II: Antibiotics Flashcards
Streptomyces, Bacillus, and Escherichia are examples of bacteria that produce what?
They produce antibiotics
What are 2 molds that can produce antibioltics?
Penicillum, Cephalosporum
What is selective toxicity?
Drugs that specifically target microbial processes, and do not harm the host cellular processes
What are 5 mechanisms of action/sites of selective toxicity?
Bacterial cell wall Nucleic acid synthesis Protein synthesis Cell membrane Folic acid synthesis
Why does interruption of folic acid synthesis work in targeting bacteria?
We bring our own folic acid into ourselves, but bacteria have to make it.
How do penicillins and cephalosporins work in regard to cell wall synthesis?
Inhibits cross-linking by blocking peptidases within the NAG/NAM/pentapeptide stucture to weaken the cell wall and cause it to burst. No new crosslinks
How does vancomycin work in regard to cell wall synthesis?
Hinders peptidoglycan elongation, which inhibits NAG/NAM linking
How does cycloserine work in regard to cell wall synthesis?
Prevents the cell from making NAG/NAM subunits
What happens when antibiotics weaken the cell wall?
The cell lyses
What is Penicillin chrysogenum?
The mold where PCN was first discovered
What generations of PCN are there?
1st, 2nd, 3rd
What are natural forms of penicillin?
Penicillin G and V
Ampiccilin and carbenicillin are examples of what?
Synthetic penicillin
How are synthetic penicillins made?
A base unit penicillin undergoes a structure change in a lab.
The basic structure of a penicillin consists of which 3 parts?
Thiazolidine ring
Beta-lactam ring
Variable side chain (R group)
Which portion of the penicillin structure is responsible for the activity of the drug?
R group
What portion of the penicillin structure is necessary to make the penicillin active?
Beta-lactam ring
What does an active penicillin do to combat a microbe?
Inhibits peptidoglycan activity
What does a penicillin resistant organism do to become resistant to make the penicillin ineffective?
B-lactamase (exoenzyme) secreted outside of cell and cleaves to the B-lactam ring. This inactivates the penicillin (since the B-lactam ring is necessary to be active).
Penicillins (such as ampicillin) are ineffective on mycobacteria. Why?
Mycoplasmas lack a cell wall, which is how a penicillin works.
What are cephalosporins similar to? What are 2 structural differences that cephalosporins have from the other?
Similar to penicillin. Differences include the main ring is different, and there are 2 sites for R groups.
From what is cephalosporins made, and what kind of organism is it?
Cephalosporium acremonium (mold)
How do aminoglycosides, tetracyclines, and chloramphenicol work?
They interfere with the process of translation
How does tetracycline work? What is is commonly used for? What are benefits to its use? Side effects?
Inhibits protein synthesis. Used for STDs. It is broad spectrum and low cost. Can be used on both Gram + and Gram - organisms. May cause gastrointestinal disruption.
