Final: Anitbiotics Flashcards
What was the death rate of children (below the age of 5) around 100 years ago, prior to the advent of today’s modern drugs (such as vaccinations of penicillin teach scientists about new potential medicinal drugs?
1 of every 3 children
Who discovered penicillin and how?
Alexander Fleming
It was discovered accidentally when a plate of bacteria was contaminated by mold
What did the discovery of penicillin teach scientists about new potential medicinal drugs?
This revolution showed that Mother Nature holds the clues to combat infection.
What a the characteristics of an ideal antimicrobial drug?
1) easy to administer
2) toxic only to the infectious agent and not the host
3) able to reach the infectious agent anywhere in the body
4) remains active in the body only as long as needed
5) safely and easily broken down and excreted naturally
Microbes are easily killed in laboratory conditions, why is it much more difficult when attempting to kill them in living organisms?
Sometimes the drug will accidentally interact with the host’s cells, tissue, and organs. For example, fungal cell actually have similar features to human cells and drugs that affect fungal pathogen can affect the host a well.
What is the principle behind selective toxicity?
The ability of a drug to only effect the pathogen ailing the host and not the host itself.
Why is it important for drugs, such as antibiotics, to be selectively toxic?
If not then they would have lots of side effects due to their unintended interaction with the host’s cells, tissues, and organs
Why is penicillin selectively toxic to only bacteria?
They react with one or more enzymes involved in this process, causing weak points at growth sites, making the cell become is osmotically fragile and subject to lysis.
When does selective toxicity become a more difficult task?
Typically the more closely related the infectious agent becomes to its host, the difficult selective toxicity becomes, and the more likely side effects are to occur.
Antimicrobial drugs are divided into what 5 categories based on the metabolic targets they affect?
1) cell wall synthesis
2) nuclei acid (DNA and RNA) structure and function
3) protein synthesis
4) membrane structure or function
5) folic acid synthesis
What does the size of a zone of inhibition tell the observer about the effectiveness of an antibiotic? What about the absence of a zone of inhibition?
They are the areas around the disks where the antibiotics have diffused into the media effectively inhibiting the growth of the bacteria in that area. No zone inhibition around a disk indicates that particular bacteria is resistant to the antibiotic.
What is antibiotic sensitivity testing and why is it useful whenever practical?
Usually carried out to determine which antibiotic will be most successful in treating a bacterial infection in real life.
