History of Antibiotics and Chemotherapy

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What is the main principle of selective toxicity in chemotherapy?

Selectively finding and destroying pathogens without damaging the host (correct)

Finding and destroying all types of cells in the body

Killing all microbes, including beneficial ones

Interfering with the growth of human cells

What is the therapeutic index of a medication?

The lowest dose of a medication that is effective

The highest dose of a medication that can be used

The number of microbes killed by a medication

The ratio of the lowest dose toxic to a patient to the dose used for therapy (correct)

Why are some medications too toxic for systemic use but used topically?

They have a narrow spectrum of activity

They interfere with essential structures or properties common in human cells (correct)

They are not effective against a wide range of pathogens

They have a high therapeutic index

What is the mechanism of action of penicillin G?

It interferes with bacterial cell wall synthesis Signup and view all the answers

What is the characteristic of antimicrobial medications that allows them to selectively target pathogens?

Their ability to interfere with essential structures or properties common in microbes but not in human cells Signup and view all the answers

What is the term for the use of chemicals to treat a disease?

Chemotherapy Signup and view all the answers

What is the primary mechanism by which Gram-negative bacteria are resistant to most β-lactam antibiotics?

Presence of β-lactamase Signup and view all the answers

Why is Mycobacterium tuberculosis intrinsically resistant to many antibiotics?

It has a cell waxy structure Signup and view all the answers

What is the term for microbes that are resistant to large numbers of antibiotics?

Superbugs Signup and view all the answers

What is the primary reason for the alarming rise in antimicrobial resistance?

Increasing use and misuse of antibiotics Signup and view all the answers

What is the name of the bacteria that is intrinsically resistant to antibiotics and has a new name, Clostridioides difficile?

Clostridium difficile Signup and view all the answers

What is the term for the concentration of antibiotic that inhibits the growth of bacteria?

Minimum Inhibitory Concentration (MIC) Signup and view all the answers

What is the primary mechanism of antibacterial drugs that target cell wall synthesis?

Interfering with cell wall formation Signup and view all the answers

Which test is used to determine the minimum inhibitory concentration (MIC) of an antibacterial drug?

Broth dilution test Signup and view all the answers

What is the primary difference between MIC and MBC?

MIC is the lowest concentration that inhibits growth, while MBC is the lowest concentration that kills bacteria Signup and view all the answers

What is the purpose of the zone of inhibition in the disk-diffusion method?

To determine the susceptibility of the organism to the antibiotic Signup and view all the answers

What is the advantage of the E-test over the disk-diffusion method?

It is more convenient to use with anaerobic pathogens Signup and view all the answers

What is the significance of selective toxicity in antibacterial therapy?

It allows antibiotics to target specific bacterial processes Signup and view all the answers