Antibiotics Flashcards
What is an infectious disease?
A disease caused by an organism.
What is a pathogen?
An organism that can cause disease.
What are anti-septics?
E.g. ethanol. Too toxic for ingestion, but not too toxic for skin.
What are disinfectants?
E.g. bleach. Too toxic for skin, but not for surfaces.
What are antibiotics?
An antibiotic is a naturally or synthetically derived substance antagonistic to growth of other microorganisms. Can also be used to describe drugs that target bacteria or microorganisms.
What are nosocomial-acquired infections?
Acquired in a hospital environment.
At what percent resistance are antibiotics considered to be unusable for a specific bacteria?
30-40% resistance.
What are the two types of resistance?
- Innate. 2. Acquired.
What is innate resistance?
Bacteria is innately never susceptible to the drug (ex. no cell wall to deplete).
What is acquired resistance?
Bacteria becomes resistant to drug.
How can bacteria undergo acquired resistance? (3)
- They can modify cell surface to prevent drug from getting in. 2. They can increase proteins that pump drug out of cell. 3. They could modify or degrade drugs.
What are three targets of antibiotics?
Bacteria cell wall, bacterial nucleic acid, and bacterial translation.
Why do antibiotics work well when bacteria are actively growing?
Because that is the time when they are growing cell walls.
What are two types of Beta-lactams?
- Penicillins. 2. Cephalosporins.
What is the site of action of B-lactams?
Inhibit enzymes (Penicillin binding protein, PBP) important for making cell wall.
What are some issues with B-lactams? (3)
Allergies, not effective against all bacteria, and resistance.
What are Beta-lactamases?
A series of enzymes that cleave the B-lactam ring.
What is an example of a drug that circumvents the resistance mechanism of beta-lactamases?
B-lactamase inhibitors with B-lactam drugs, such as Augmentin.
What is Augmentin?
Amoxicillin/clavulanate potassium. It is a B-lactamase inhibitor and a B-lactam.
How can drugs interrupt bacterial nucleic acids? (3)
- Interrupt pathways that make nucleic acid building blocks. 2. Interfere with DNA replication/maintenance. 3. Interfere with RNA production.
What are Quinolones/Fluoroquinolones?
They target bacterial type 2 DNA isomerases (DNA gyrase and DNA topoisomerases).
What is an example of a Quinolone/Fluoroquinolone?
Ciprofloxacin.
What do DNA gyrase and DNA topoisomerases do?
They provide DNA maintenance and help finish DNA replication.
Are Quinolones/Fluoroquinolones recommended for children and those who are pregnant?
No. Concerns for cartilage development and absence of data documenting safety.
Do Quinolones/Fluoroquinolones have a black box warning?
Yes, for possible Achilles tendon rupture.
What drug is an example of Macrolides?
Azithromycin (Zithromax) is an example.
What are the benefits of using Azithromycin (Zithromax)?
Drugs slowly released from tissues, resulting in once-daily dosing and shortening of treatment duration.
How do Macrolides work?
They interrupt bacterial translation.
How do Tetracyclines works?
They interrupt bacterial translation.
What drug is an example of Tetracyclines?
Minocycline. At low doses, it can treat acne.
What is a negative of using Tetracyclines?
They bind calcium and get deposited with it, causing an interfere in bone development (limits use in children and pregnant women).
How does antibiotic-associated diarrhea occur?
Antibiotics kill off ‘good bacteria’.
What combination of antibiotics and birth control pills results in lower efficacy of the birth control?
Rifamptin decreases the efficacy of birth control pills and any other birth control using hormones. It may increase enzymes that break down the hormones.
What is Rifamptin used for?
Tuberculosis.
How can we make new antibiotics? (2) What are some problems with developing new drugs? What has helped that problem?
- Chemically modify existing antibiotics. 2. Identify new drug targets. Drugs are expensive to develop. The GAIN act may influence more antibiotic development.
Why is TB hard to treat? (4)
- Different cell walls (waxy). 2. Slow growth. 3. Intracellular pathogen. 4. quickly develops resistance.
What is Bedaquiline (Sirturo)? How does it work?
A drug used for multi-drug resistant TB. It works by targeting ATP synthase (but not mammalian version).
How was Bedaquiline (Sirturo) developed?
By screening chemical libraries to find compounds with activity against mycobacterium smegmatis.
