Chapter 10: AntiMicrobial Treatment (Down to before Primary sites of action)

What are the characteristics of the ideal antimicrobial drug?

• Selective toxicity: Toxic to the microbe but nontoxic to host cells

• Microbicidal rather than microbistatic

• Relatively soluble; functions even when highly diluted in body fluids

• Remains potent long enough to act and is not broken down or excreted prematurely

• Does not lead to the development of antimicrobial resistance

• Complements or assists the activities of the host’s defenses

• Remains active in tissues and body fluids

• Readily delivered to the site of infection

• Does not disrupt the host’s health by causing allergies or predisposing the host to other infections

What is prophylaxis?

Use of a drug to prevent infection of a person at risk

• Not treatment but it’s prevention

What is Antimicrobial chemotherapy?

The use of drugs to control infection

What are antimicrobials? What are the 5 sub categories of antimicrobials?

All-inclusive term for any antimicrobial drug, regardless of its origin

1. Antibiotics

2. Semisynthetic drugs

3. Synthetic drug drugs

4. Narrow-spectrum (limited spectrum)

5. Broad-spectrum (extended spectrum)

What are antibiotics? It is a type of what?

• Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms; generally, the term is used for drugs targeting bacteria and not other types of microbes

• It is a type of antimicrobial

Are all antimicrobial antibiotics? And are all antibiotics antimicrobial?

Antibiotics are always antimicrobial, but antimicrobial are not always antibiotics

What are semisynthetic drugs?

• Drugs that are chemically modified in the laboratory after being isolated from natural sources

• They are part natural and parts synthetic

• It is like modifying antibiotics to get these

What are synthetic drugs? Are they hundred percent synthetic?

• Drugs produced entirely by chemical reactions

• They are 100% synthetic

What are Narrow-spectrum (Limited spectrum) antimicrobials? what is an example?

Their antimicrobial was effective against a limited array of microbial types

• For example, a drug effective mainly against gram-positive bacteria.

What are Broad-spectrum (Extended spectrum) antimicrobials? what is an example? Does it kill pathogens and healthy cells or just pathogens?

Antimicrobial effective against the variety of microbial types

• For example, a drug effective against both gram-positive and gram-negative bacteria

• Can kill pathogens and healthy cells because it’s broad

For the origin of antimicrobial drugs, Antibiotics are originally metabolic products of what? Why do they produce antibiotics?

• Antibiotics are originally metabolic products of bacteria and fungi:

• Produced to inhibit the growth of competing microbes in their habitat

Between bacteria and fungi, what are the greatest numbers of antibiotic metabolic products from? which two do most antibiotics come from? are microbes affected by the anabiotic’s that they produce?

Greatest numbers derived from:

• Bacteria in the genera (plural genus) Streptomyces and Bacillus

• Fungi in the genera (plural genus) Penicillium and Cephalosporium

• most antibiotics come from the two bacteria and microbes are not affected by the antibiotics that they produce

What is the minimum inhibitory concentration (MIC)? What is the useful for determining? Does the MIC mean killing?

• Minimum inhibitory concentration (MIC): the smallest concentration (highest dilution) of drug that visibly inhibits growth

• Useful in determining the smallest effective dosage and providing a comparative index against other antimicrobials

• It does not necessarily mean killing it is just inhibiting growth

What is the therapeutic index? What does a small and large ratio mean? What are the numerical values for a therapeutic index and what do they mean?

• Therapeutic Index: The ratio of the dose of the drug that is toxic to humans compared to its minimum effective (therapeutic) dose:

• The smaller the ratio, the greater the potential for toxic drug reactions

• TI = 1.1 is a risky choice

• TI = 10 is a safer choice

• The drug with the highest therapeutic index has the widest margin of safety

How do you calculate the therapeutic index? Provide a image.

Take the toxicity concentration (Like at what concentration would it be toxic?) And divided by the MIC

What is selectively toxic mean?

kill or inhibit microbial cells without damaging host

tissues

What are drugs with excellent selective toxicity? and provide a example.

• Drugs with excellent selective toxicity block the synthesis of the bacterial cell wall (ex: penicillins):

• Human cells lack the chemical peptidoglycan and are unaffected by the drug

What drugs are most toxic to humans? provide an example of what a target. when does selective toxicity become more difficult to achieve?

• Drugs that act upon a structure common to both the infective agent and the host cell (ex: cytoplasmic membrane)

• As characteristics of the infectious agent are more and more similar to the host cell, selective toxicity becomes more difficult to achieve