Antimicrobial Drugs- BIOL 2320

What is selective toxicity?

The ability of antimicrobials to target mechanisms unique to pathogens without harming host cells.

How do anti-cancer drugs utilize selective toxicity?

They target features of cancerous cells that non-cancerous cells lack to minimize damage to healthy cells.

What are the two categories of antibiotic spectrum?

Broad spectrum and narrow spectrum.

What is a broad spectrum antibiotic?

An antibiotic that targets multiple pathogens and has low selectivity.

What is a narrow spectrum antibiotic?

An antibiotic that targets only one or a few pathogens and has high selectivity.

What is the effect of broad spectrum antibiotics on normal microbiota?

They can harm beneficial bacteria, potentially leading to antibiotic resistance.

What is the purpose of bacteriostatic drugs?

To inhibit microbial growth without killing them, allowing the immune system time to respond.

What is the difference between bacteriostatic and bactericidal drugs?

Bacteriostatic drugs inhibit growth, while bactericidal drugs kill microbes.

What are the common modes of action of antibacterials?

Inhibition of cell wall synthesis, plasma membrane injury, inhibition of protein synthesis, inhibition of nucleic acid synthesis, and anti-metabolite action.

What is the role of penicillin in antimicrobial therapy?

It prevents cell wall synthesis by inhibiting peptidoglycan production, effective against gram-positive bacteria.

How do polypeptide and ionophore antibiotics injure the plasma membrane?

By creating holes or manipulating osmolarity, leading to leakage of cell contents.

What is the significance of targeting 70S ribosomes in bacteria?

It allows antibiotics to inhibit protein synthesis selectively in bacteria without affecting human cells.

What is nalidixic acid used for?

It prevents DNA replication in gram-negative bacteria.

What is the action of sulfanilamide?

It competes with PABA to inhibit folic acid synthesis, essential for bacterial metabolism.

What challenges do antiviral drugs face?

They must target viral processes without harming host cells, as viruses are intracellular parasites.

What are entry and fusion inhibitors in antiviral therapy?

Drugs that prevent viruses from entering host cells by blocking receptors or fusion of viral envelopes.

What is the function of nucleoside analogs like acyclovir?

They inhibit nucleic acid synthesis by mimicking nucleotides, halting DNA production in viruses.

What is the role of protease inhibitors in antiviral treatment?

They block the cleavage of protein precursors, crucial for the viral life cycle.

How do exit inhibitors like Tamiflu work?

They inhibit neuraminidase, preventing viruses from detaching from host cells to spread.

What is the primary function of antibacterial drugs?

To specifically target and inhibit or kill bacterial pathogens.

How are narrow-spectrum antibiotics more selective?

They are designed to act on specific pathogens, requiring identification of the pathogen for use.

What is the consequence of using broad-spectrum antibiotics indiscriminately?

Increased risk of developing antibiotic resistance and disruption of normal microbiota.

What is the impact of inhibiting protein synthesis in bacteria?

It is bactericidal, as bacteria cannot survive without protein production.

What is the significance of the suffix 'cillin' in antibiotics?

It indicates that the drug targets bacterial cell wall synthesis.

What is the role of ionophores in antibacterial action?

They alter osmolarity, causing plasmolysis in bacterial cells.

What is the mechanism of action for antiviral drugs targeting genome integration?

They prevent viruses from integrating their DNA with the host genome.

How do antiviral drugs prevent nucleic acid synthesis?

By inhibiting the synthesis of viral DNA and RNA.

When is Tamiflu most effective?

When taken early in the disease cycle.

What do type 1 interferons do?

They are antimicrobials produced by viral-infected host cells that provide immunity to nearby uninfected cells.

What is the role of Imiquimod?

It promotes the production of interferon to enhance immunity.

What is the function of reverse transcriptase in retroviruses?

It converts viral RNA to DNA and integrates it into host cell chromosomes.

What is AZT used for?

It is an antiretroviral drug used to treat HIV which inhibits reverse transcriptase.

What causes antibiotic resistance?

Natural selection where resistant microbes proliferate after sensitive ones die.

What are persister bugs?

Bacteria that survive antibiotic exposure by stopping reproduction.

How do superbugs differ from persister bugs?

Superbugs are resistant to multiple antibiotics, while persister bugs are resistant to a single antimicrobial.

What is a superinfection?

The overgrowth of antibiotic-resistant normal microbiota due to antibiotic use.

What mechanisms do pathogens use to resist antimicrobials?

Enzymatic destruction, prevention of penetration, alteration of target sites, and rapid efflux.

How do bacteria inactivate penicillin?

Using an enzyme called beta-lactamase.

What is one consequence of using outdated antibiotics?

They may not be effective against prevalent strains and encourage resistance.

Why should antibiotics not be used for the common cold?

Most colds are caused by viruses, which are not affected by antibiotics.

What happens when antibiotics are used in animal feed?

It can lead to antibiotic resistance in humans when the animals are consumed.

What is the effect of failing to complete an antibiotic regimen?

It can lead to the development of resistant bacteria and treatment relapse.

What is a synergistic effect in drug combinations?

When two drugs work better together than separately.

Give an example of synergistic antibiotics.

Streptomycin and Penicillin.

What is an antagonistic effect in drug combinations?

When two drugs work worse together than individually.

Give an example of antagonistic antibiotics.

Penicillin and Tetracycline.

What is the role of disk-diffusion tests?

To test the synergy of antibiotics based on their zones of inhibition.

What is the impact of antibiotic misuse?

It creates selective pressure for resistant bacteria to proliferate.

What are resistance genes often spread on?

Plasmids or transposons via conjugation and transduction.

What is the primary target of anti-retrovirals?

Reverse transcriptase in retroviruses.

How do bacteria alter their target binding sites?

To prevent antibiotics from binding and continuing their metabolic processes.

What happens to persister cells after antibiotic treatment ends?

They can start growing again and proliferate without being affected by the antibiotic.

What is the relationship between antibiotic misuse and superbugs?

Misuse creates conditions that favor the development of superbugs.

What is the effect of overuse of broad-spectrum antibiotics?

They can create selective pressure for multiple resistant targets.

The most selective antimicrobial activity would be exhibited by a drug that

inhibits cell wall synthesis.

3 multiple choice options

Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses.

How can this result best be explained?

A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency.

3 multiple choice options