Chapter 14 Review Sheets - Antimicrobial Drugs

Who produces Antibiotics?

Bacteria

Why do antibiotics exist in nature?

Because of natural competition between microbes (provide competitive advantages)

What was the contribution of paul Ehrlich to antimicrobial therapy?

Would this be considered an antibiotic?

Discovered Compound 606, an antimicrobial agent that proved to be an effective treatment for Syphilis

Yes, it is considered the first modern antibiotic

What is Prontosil?

Is this an antibiotic?

What is the actual active ingredient of Prontosil?

Dye discovered to have antimicrobial activities

Active ingredient was Sulfanilamide

Yes, it was the first commercially available antibiotic

Who is Alexander Fleming?

How did he contribute to modern medicine?

First to discover a naturally produced Antimicrobial, Penicillin, in 1928

Penicillin was antibacterial against many different causative agents of diseases

What type of organism produces Penicillin?

Mold (Penicillium notatum)

Which group of bacteria are responsible for the majority of antibiotics in prodiction today?

Actinobacteria

Explain the difference between Broad Spectrum and Narrow Spectrum antibiotics.

Broad Spectrum — drug that targets many types of microbes

Narrow Spectrum — drug that targets on a specific subset of microbes

What are the potential consequences of choosing a broad spectrum antibiotic over a narrow spectrum antibiotic?

Broad spectrum antibiotic will also target a broad spectrum of the normal microbiota

• Can cause a superinfection because the antibacterial intended for the preexisting infection kills the protective microbiota

Why might one choose to use a broad spectrum antibiotic?

Can be used when a narrow spectrum drug fails because of development of drug resistance by target pathogen

What is a Superinfection?

Why does it occur?

Secondary infection that may develop as a result of long-term, broad spectrum antimicrobial use

What are some potential routes of administration for an antibiotic?

Why are these different routes preferred?

Just any way you take meds, basically

Different ones preferred over others based on:

• Bactericidal vs. Bacteriostatic

• Spectrum of Activity

• Dosage

• Side Effects

• Potential Interactions

How does the route of administration affect the amount of the antibiotic present in the patients plasma?

What is the difference between a Synergistic and an Antagonistic drug interaction?

Synergistic —> combined effect of a combination of drugs is LARGER than the additive effect of each individual drug

Antagonistic —> combined effect of a combination of drugs is SMALLER than the additive effect of each individual drug

Understand that not all antibiotics persist for the same length of time in the system.

How does the length of a half-life affect the frequency of when you take the antimicrobial?

Longer half-life means you take the antimicrobial less frequently and vice versa (inverse relationship between half-life and taking of dose)

What does it mean if an antimicrobial compound is selectively toxic?

It selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host

What are the major targets of antimicrobial compounds?

• Cell Wall

• Plasma Membrane

• DNA and RNA Synthesis

• Ribosomes

• Metabolic Pathways

What is the common characteristic between Penicillins, Cephalosporins, Monobactams, and Carbapenems?

Contain a Beta-Lactam ring

What do the Beta-Lactam Antibiotics inhibit?

Cell wall synthesis

What are the benefits of chemically modifying antimicrobial compounds, such as Penicillin, to create variations of that compound (e.g. Methicillin)?

Can change the spectrum of action, improve absorption, and make it resistant to enzymes

What is the difference between Natural, Semisynthetic, and Synthetic antimicrobial compounds?

Natural —> produced naturally by microorganisms in nature

Semisynthetic —> chemically modified derivative of a natural antibiotic

Synthetic —> developed from a chemical not found in nature

What is the function of Aminoglycosides?

What is an example of an Aminoglycoside antibiotic?

Bind to the 30S subunit and interfere with the ribosome’s proofreading ability, leading to the generation of faulty proteins that insert into and disrupt the bacterial cytoplasmic membrane

Streptomycin

What is the function of Tetracyclines?

Binds to the 30S subunit, blocking the association of tRNAs with the ribosome during Translation

What is the function of Chloramphenicols?

Binds to the 50S subunit, inhibiting peptide bond formation

What is the function of Polymyxins?

Targets the lipopolysaccharide component of Gram-Negative bacteria and ultimately disrupt the integrity of their outer and inner membranes

Why might general toxicity be an issue with Polymyxins?

Can just be toxic in general and kill cells that it shouldn’t

Why would nucleic acid synthesis be an appropriate target for antibiotic compounds if Eukaryotes also synthesize nucleic acids?

Because the RNA Polymerase enzymes in bacteria are structurally different from those in Eukaryotes, allowing for selective toxicity against bacterial cells

What are the targets of Rifamycin and Fluoroquinolones like Ciprofloxacin?

Bacteria and their nucleic acid synthesis

How do Sulfanilamide and Trimethoprim inhibit bacterial cell growth?

Why does this affect bacteria but not Eukaryotes?

Interfere in the bacteria synthesis of folic acid by blocking Purine and Pyrimidine biosynthesis (inhibiting bacterial growth)

Does not affect Eukaryotes because they do not create folic acid (obtain it through nutrition sources instead)

Isoniazid inhibit Mycolic Acid synthesis. Which group of organisms would be targeted by this treatment?

Mycobacteria — prevents the synthesis of Mycolic Acid, which is essential for Mycobacterial cell walls

What is the challenge associated with treating diseases caused by Eukaryotic organisms?

Eukaryotes have cells very similar to human cells, making it more difficult to develop drugs with selective toxicity

What are the cellular targets that provide specificity to the treatment of fungal infections?

Chitin, Ergosterol, microtubules, etc.

Acyclovir is an analog of Guanosine.

How does this work to combat viral infections?

It is activated by the herpes simplex viral enzyme Thymidine Kinase and, when added to a growing DNA strand during replication, causes chain termination

What are the main areas used to target viral infections?

Nucleic acid and protein synthesis

What Polymerase is unique to RNA viruses, such as HIV, that is a target of some anti-viral medications?

RNA-Dependent RNA Polymerase (RdRp)

How does inhibiting Neuraminidase help to treat viral infections?

The specifically target influenza viruses by blocking the activity of the influenza virus Neuraminidase, preventing the release of the virus from infected cells