STUDY GUICE EXAM 2: Antibiotics

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Questions and Answers

What is selective toxicity in the context of antimicrobial drugs?

It specifically targets pathogens without harming the host. (correct)

It destroys all types of microbes indiscriminately.

It relies on the host's immune system to eliminate pathogens.

It enhances the immune response to all foreign substances.

Which type of toxin is a component of the outer membrane of gram-negative bacteria?

Endotoxin (correct)

Botulinum toxin

Exotoxin

Neurotoxin

What is a primary method by which bacteria cause direct damage to host cells?

Inducing inflammation through cytokine release.

Absorbing nutrients from the host cells.

Integrating their genetic material into the host genome.

Releasing enzymes that break down tissues. (correct)

What distinguishes bactericidal drugs from bacteriostatic drugs?

Bactericidal drugs kill microbes directly; bacteriostatic drugs prevent growth. Signup and view all the answers

Chronic viral infections can cause long-term damage primarily through which mechanism?

Integrating their nucleic acid into the host genome. Signup and view all the answers

Exotoxins are known for which of the following characteristics?

They can cause specific effects like nerve damage. Signup and view all the answers

What differentiates antibiotics from disinfectants?

Antibiotics specifically target bacterial infections, whereas disinfectants kill a broad range of pathogens. Signup and view all the answers

What is the primary characteristic that differentiates antibiotics from disinfectants?

Antibiotics can be used internally without harming the host cells, but disinfectants are toxic to internal use. Signup and view all the answers

Which of the following examples illustrates a narrow-spectrum antibiotic?

Penicillin G Signup and view all the answers

What can result from the overuse or misuse of antibiotics in treating bacterial infections?

Antibiotic resistance in bacteria Signup and view all the answers

What is one major challenge in treating fungal infections compared to bacterial infections?

Fungi are eukaryotic and similar to human cells, making treatments more toxic. Signup and view all the answers

What defines the 'spectrum of activity' of an antimicrobial agent?

The range of microorganisms that the agent can target. Signup and view all the answers

Which of these antibiotics is known to inhibit cell wall synthesis?

Penicillin Signup and view all the answers

Why is it important to understand the modes of action of antimicrobial drugs?

To target the pathogens without affecting human cells and avoid resistance. Signup and view all the answers

What is a superinfection?

A secondary infection occurring after treatment with broad-spectrum antibiotics. Signup and view all the answers

What characterizes antibiotic resistance?

Bacteria evolve mechanisms to survive antibiotics. Signup and view all the answers

Which of these antibiotics is a broad-spectrum antibiotic effective against a variety of bacteria?

Ciprofloxacin Signup and view all the answers

Which antibiotic is bacteriostatic and can inhibit the action of bactericidal antibiotics?

Tetracycline Signup and view all the answers

What possible outcome is a risk when using broad-spectrum antibiotics?

Increased risk of superinfections from opportunistic pathogens. Signup and view all the answers

How do bacteria commonly acquire resistance genes?

Via conjugation, transformation, or transduction. Signup and view all the answers

What is the function of beta-lactamase in bacteria?

It inactivates specific antibiotics. Signup and view all the answers

Which of the following factors contributes to antibiotic resistance?

Overprescription of antibiotics Signup and view all the answers

What are efflux pumps used for in bacteria?

To expel antibiotics from the cell. Signup and view all the answers

What serious consequence can result from antibiotic resistance?

Minor injuries could become life-threatening. Signup and view all the answers

What is one approach to addressing antibiotic resistance?

Researching for new antibiotic molecules. Signup and view all the answers

What is a significant challenge when using antifungal antibiotics?

Fungi are eukaryotic and similar to human cells. Signup and view all the answers

Which statement about MRSA is true?

It stands for Methicillin-Resistant Staphylococcus aureus. Signup and view all the answers

What distinguishes natural penicillin from synthetic penicillin?

Synthetic penicillin can resist degradation by bacterial enzymes. Signup and view all the answers

Why are bacteria with capsules more resistant to antibiotics?

Capsules provide a protective layer against antibiotics. Signup and view all the answers

In the broth-dilution test, what does the minimum inhibitory concentration (MIC) indicate?

Lowest concentration that prevents visible bacterial growth. Signup and view all the answers

How do synergism and antagonism differ in antibiotic action?

Synergism enhances effects while antagonism reduces it. Signup and view all the answers

What action does penicillin take against bacterial cells?

Inhibits peptidoglycan synthesis. Signup and view all the answers

Study Notes

Chemical Control Terms

Antimicrobial drugs are synthetic substances that inhibit microbial growth.
Antibiotics are substances produced by microbes that inhibit other microbes in small amounts.
Bactericidal drugs kill microbes directly.
Bacteriostatic drugs prevent microbial growth.
Selective toxicity is the ability of a drug to target pathogens without harming the host.

Microbial Damage to Cells

Direct Damage: Microbes disrupt host cell function and produce waste.
- Bacteria release enzymes that break down host tissue.
Using Host Nutrients: Microbes may trigger an excessive immune response, leading to inflammation and tissue damage.
- Certain bacteria bind iron more tightly than host cells.
Producing Toxins: Microbes release poisonous substances that cause various harmful effects.
- Endotoxins are part of the outer membrane of Gram-negative bacteria (LPS). They are released when bacteria die and cause intense immune responses.
- Exotoxins are proteins secreted by living cells, primarily Gram-positive bacteria. They are highly potent and cause specific effects.

Viral Damage to Cells

Invasion: Viruses infect cells by binding and inserting their genetic material (DNA or RNA).
- Infected cells produce more viral particles.
Cell Lysis: New viral particles are released, killing the host cell.
Chronic Infection: Some viruses cause long-term damage by integrating into the host genome or creating persistent infections.

Antibiotics

Antibiotics are natural or synthetic compounds that kill or inhibit bacterial growth.
Bacteria and fungi are the main producers of antibiotics
Antibiotics target prokaryotic or fungal cell characteristics
Disinfectants are chemicals used on non-living surfaces to kill microbes, but are too toxic for internal use.

Problems of Chemical Treatment

Bacterial infections: Overuse or misuse of antibiotics can lead to antibiotic resistance and disrupt the body's normal flora.
Viral infections: Antiviral drugs may have limited effectiveness because viruses utilize host cells for replication.
Fungal infections: Treating fungal infections is challenging because fungi are eukaryotic, similar to human cells, making antifungal drugs potentially toxic to humans.

Spectrum of Activity

Spectrum of activity refers to the range of microorganisms an antimicrobial agent can target.
Broad-spectrum antibiotics are effective against a wide range of bacterial species.
Narrow-spectrum antibiotics target specific types of bacteria.
Superinfection is a secondary infection caused by resistant pathogens after broad-spectrum antibiotics kill off normal flora.

Broad vs. Narrow-Spectrum Antibiotics

Broad-spectrum antibiotics are effective against unknown or mixed infections but can kill beneficial bacteria and promote resistance.
Narrow-spectrum antibiotics target specific bacteria, reducing the risk of disrupting normal flora and resistance in unrelated species.

Dangers of Broad-Spectrum Antibiotics

Superinfections: Broad-spectrum antibiotics can kill beneficial bacteria and promote the growth of opportunistic pathogens.
Antibiotic Resistance: Broad-spectrum antibiotics contribute to the development of resistance in a wide range of bacteria.

Understanding Modes of Action

It is important to understand how antimicrobial drugs work to:
- Avoid inappropriate use that leads to resistance.
- Ensure the drug targets pathogens without harming the host.
- Inform the development of new drugs to target resistant strains.

Modes of Action of Antibiotics

Inhibition of Cell Wall Synthesis: Antibiotics like penicillin block the synthesis of peptidoglycan, causing bacterial cell lysis.
Inhibition of Nucleic Acid Synthesis: Antibiotics target bacterial enzymes involved in DNA and RNA synthesis, which differ from those in human cells.
Inhibition of Essential Metabolites: Antibiotics block metabolic pathways in bacteria that are not present in human cells.
Inhibition of Protein Synthesis: Antibiotics target bacterial ribosomes, inhibiting protein synthesis.
Transcription Inhibitor: Antibiotics target bacterial RNA polymerase, blocking the transcription of DNA into RNA.

Antifungal Antibiotics

Inhibition of Ergosterol Synthesis: Antifungal drugs target the synthesis of ergosterol, a component of fungal cell membranes.

Challenges of Using Antifungal Antibiotics

Eukaryotic Similarity: Fungi are eukaryotic, like human cells, making it difficult to target fungi without harming humans.
Toxicity: Antifungal drugs often have higher risks of toxicity and side effects.
Resistance: Fungi can develop resistance to antifungal drugs.

Penicillin and its Mode of Action

Penicillin contains a beta-lactam ring crucial for its antibacterial activity.
Penicillin inhibits penicillin-binding proteins (PBPs) involved in bacterial cell wall synthesis.

Natural vs. Synthetic Penicillin

Natural penicillin is derived directly from the mold Penicillium.
Synthetic penicillin is chemically modified for improved stability, broadened spectrum of activity, and resistance to bacterial enzymes.

Penicillinase

Penicillinase (beta-lactamase) is an enzyme produced by some bacteria that breaks down penicillin.
Natural penicillins are sensitive to penicillinase because they lack structural modifications found in synthetic penicillins.

Bacterial Resistance to Antibiotics

Capsules: Capsules provide a protective outer layer that shields bacteria from antibiotics and the immune system.
Mycobacteria: These bacteria have a thick layer of mycolic acids that makes them impermeable to many antibiotics.

Antibiotic Resistance Mechanisms:

Enzymatic Destruction or Inactivation: Bacteria produce enzymes to breakdown or modify the antibiotic.
Prevention of Penetration: Bacteria alter their cell walls or membranes to prevent antibiotic entry.
Alteration of Target Site: Bacteria alter the target molecule within the cell so the antibiotic cannot bind.
Rapid Efflux: Bacteria use efflux pumps to actively transport the antibiotic out of the cell.

Spread of Antibiotic Resistance

Antibiotic resistance genes can be spread through horizontal gene transfer methods:
- Conjugation: Transfer of genes through direct cell-to-cell contact.
- Transformation: Uptake of free DNA from the environment.
- Transduction: Transfer of genetic material by bacteriophages.

Making Antibiotic Resistance Worse

Overprescription of antibiotics.
Incomplete courses of antibiotic treatment.
Use of antibiotics in agriculture and animal farming.

Consequences of Antibiotic Resistance

Infections become difficult to treat.
Common infections could become life-threatening.
Medical procedures become riskier due to the increased risk of untreatable infections.

Addressing Antibiotic Resistance

Removing some antibiotics from circulation.
Researching and developing new antibiotic molecules.

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Description

This quiz covers key terms related to microbial control, including antimicrobial drugs, antibiotics, and the mechanisms of microbial damage to host cells. Understand the differences between bactericidal and bacteriostatic drugs, as well as the implications of selective toxicity. Test your knowledge on how microbes affect host tissues and their means of damaging cells.