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Questions and Answers
Streptomycin binds to the 50S subunit of the bacterial ribosome.
Streptomycin binds to the 50S subunit of the bacterial ribosome.
False
Chloramphenicol exerts a bactericidal effect by destroying bacterial cells.
Chloramphenicol exerts a bactericidal effect by destroying bacterial cells.
False
Animal cells can synthesize their own folic acid.
Animal cells can synthesize their own folic acid.
False
Sulfonamides competitively inhibit the synthesis of folic acid by mimicking para aminobenzoic acid (PABA).
Sulfonamides competitively inhibit the synthesis of folic acid by mimicking para aminobenzoic acid (PABA).
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Fluoroquinolones affect the synthesis of RNA in bacterial cells.
Fluoroquinolones affect the synthesis of RNA in bacterial cells.
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Broad spectrum antibiotics are effective only against Gram-positive bacteria.
Broad spectrum antibiotics are effective only against Gram-positive bacteria.
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Narrow spectrum antibiotics target a wide range of bacterial species.
Narrow spectrum antibiotics target a wide range of bacterial species.
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Beta lactam antibiotics require that bacterial cells be actively growing to exert their toxicity.
Beta lactam antibiotics require that bacterial cells be actively growing to exert their toxicity.
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Penicillins contain a four-membered beta lactam ring in their chemical structure.
Penicillins contain a four-membered beta lactam ring in their chemical structure.
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Glycopeptides like vancomycin work by binding to the end of peptide chains in peptidoglycan precursors.
Glycopeptides like vancomycin work by binding to the end of peptide chains in peptidoglycan precursors.
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Polymyxin is an antibiotic that specifically targets bacterial nucleic acids.
Polymyxin is an antibiotic that specifically targets bacterial nucleic acids.
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A clinically-useful antibiotic should have characteristics that include being inexpensive and easy to produce.
A clinically-useful antibiotic should have characteristics that include being inexpensive and easy to produce.
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All antibacterial agents are toxic to the host cells.
All antibacterial agents are toxic to the host cells.
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Dihydrofolate reductase is responsible for the conversion of Dihydrofolic acid to Thymidine.
Dihydrofolate reductase is responsible for the conversion of Dihydrofolic acid to Thymidine.
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Alteration of membrane permeability can prevent an antimicrobial agent from entering a bacterial cell.
Alteration of membrane permeability can prevent an antimicrobial agent from entering a bacterial cell.
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Multiple drug resistance can only occur through chromosomal genes, not plasmids.
Multiple drug resistance can only occur through chromosomal genes, not plasmids.
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Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to traditional antibiotic therapies.
Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to traditional antibiotic therapies.
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Efflux pumps actively remove drugs from the cell, contributing to bacterial resistance.
Efflux pumps actively remove drugs from the cell, contributing to bacterial resistance.
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The mechanism of infection prevention states that only one type of antimicrobial should be used for every infection.
The mechanism of infection prevention states that only one type of antimicrobial should be used for every infection.
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Hydrogen peroxide is more stable and less expensive than chlorine.
Hydrogen peroxide is more stable and less expensive than chlorine.
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Bacteria can become resistant by developing a new metabolic pathway that bypasses the actions of an antimicrobial agent.
Bacteria can become resistant by developing a new metabolic pathway that bypasses the actions of an antimicrobial agent.
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Beta-lactamases are a type of efflux pump that prevents antimicrobial drugs from entering bacteria.
Beta-lactamases are a type of efflux pump that prevents antimicrobial drugs from entering bacteria.
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Quaternary ammonium compounds are effective sporicides.
Quaternary ammonium compounds are effective sporicides.
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Aldehydes can inactivate nucleic acids and proteins.
Aldehydes can inactivate nucleic acids and proteins.
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Organic acids, such as benzoic acid, can stimulate microbial metabolism.
Organic acids, such as benzoic acid, can stimulate microbial metabolism.
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Ethylene oxide is used to sterilize heat-sensitive equipment.
Ethylene oxide is used to sterilize heat-sensitive equipment.
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Pharmacodynamics refers to the study of what the drug does to the body.
Pharmacodynamics refers to the study of what the drug does to the body.
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Combination therapy is only used to reduce the duration of treatment.
Combination therapy is only used to reduce the duration of treatment.
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Pharmacokinetics studies what the body does to the drug, including its absorption and excretion.
Pharmacokinetics studies what the body does to the drug, including its absorption and excretion.
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Beta-lactamase is a type of antibacterial agent.
Beta-lactamase is a type of antibacterial agent.
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Phenol is commonly used today as a skin disinfectant due to its effectiveness.
Phenol is commonly used today as a skin disinfectant due to its effectiveness.
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Alcohols are effective against endospores.
Alcohols are effective against endospores.
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Hypochlorous acid is formed when chlorine is mixed with water.
Hypochlorous acid is formed when chlorine is mixed with water.
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Heavy metals exert their biocidal effect through a process called oligodynamic action.
Heavy metals exert their biocidal effect through a process called oligodynamic action.
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Chemical agents that are bacteriostatic completely eliminate pathogenic bacteria.
Chemical agents that are bacteriostatic completely eliminate pathogenic bacteria.
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Zinc chloride is commonly used in mouthwashes.
Zinc chloride is commonly used in mouthwashes.
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Ozone is used to produce hydroxyl-free radicals that damage proteins and DNA.
Ozone is used to produce hydroxyl-free radicals that damage proteins and DNA.
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Study Notes
Antimicrobial Agents
- Antimicrobials interfere with vital structures and processes of microorganisms to kill or inhibit their growth.
- Broad-spectrum antibiotics act against a wide range of Gram-positive and Gram-negative bacteria.
- Narrow-spectrum antibiotics are effective against either Gram-positive or Gram-negative bacteria.
- Limited-spectrum antibiotics target a single organism or disease.
- A clinically useful antibiotic should have a wide spectrum of activity, be non-toxic and non-allergenic to the host.
- It should not eliminate the normal flora of the host, reach the area of infection and be easy to produce and stable.
- Microbial resistance to the antibiotic should be uncommon and unlikely to develop.
Classification of Antibacterials
- Antibacterials can be categorized based on their site of action and molecular structure.
-
Cell wall synthesis inhibitors: Inhibit steps in bacterial peptidoglycan synthesis.
- Generally effective against eubacteria, as human cells lack rigid cell walls
- Beta-lactams (e.g., penicillins, cephalosporins, carbapenems):
- Contain a 4- or 6-membered ring.
- Inhibit carboxypeptidase and transpeptidase enzymes.
- Bactericidal and require active bacterial growth.
- Glycopeptides (e.g., vancomycin): Block cell wall synthesis by binding to the end of peptide chains.
Other Inhibitors
- Cell membrane inhibitors: Disrupt bacterial membrane structure or function, example: Polymyxin.
-
Protein synthesis inhibitors: Target 70S ribosomes (bacterial)
- Tetracyclines, chloramphenicol, macrolides (e.g., erythromycin), and aminoglycosides (e.g., streptomycin).
- Nucleic acid inhibitors: Affect DNA or RNA synthesis or binding, example: Fluoroquinolones (e.g., ciprofloxacin).
- Competitive inhibitors: These agents compete with essential metabolites for bacterial enzymes responsible for folic acid synthesis (e.g., sulfonamides, trimethoprim).
Mechanisms of Antimicrobial Resistance
- Mechanisms of bacterial resistance mechanisms include:
- Altering the target site to decrease antibiotic affinity.
- Destroying or inactivating the antibiotic.
- Limiting antibiotic uptake into the cell.
- Developing alternative metabolic pathways.
- Using efflux pumps to remove the antibiotic from the cell.
- Producing a bacterial protein to shield the target site.
Prevention of Antimicrobial Resistance
- To prevent resistance:
- Prescribe the correct antibiotic for the infection.
- Identify the causative organism.
- Choose narrow-spectrum instead of broad-spectrum antimicrobials.
- Maintain correct treatment duration.
- Use appropriate dosages.
Chemical Methods of Microbial Control
- Chemicals can be bacteriostatic (preventing growth) or bactericidal (killing).
- Factors influencing effectiveness include population size, type of organism, concentration, duration of exposure, temperature, pH, organic matter, and biofilm formation.
Disinfectants and Antiseptics
- Phenol (carbolic acid): Disrupts cell membranes and precipitates proteins; rarely used today due to skin irritation.
- Alcohols: Kill most bacteria, fungi, but not endospores; dissolve membrane lipids and coagulate proteins.
- Halogens (e.g., iodine, chlorine): Denature proteins; iodine used as tincture, chlorine used to disinfect water.
- Heavy metals (e.g., silver, copper, zinc): Oligodynamic action, precipitate proteins.
- Oxidizing agents (e.g., ozone, hydrogen peroxide): Produce free radicals that damage proteins and DNA.
- Quaternary ammonium compounds: Alter cell permeability; used as disinfectants and antiseptics.
- Aldehydes (e.g., formaldehyde, glutaraldehyde): React chemically with nucleic acids and proteins, inactivating them.
- Organic acids (e.g., benzoic acid): Inhibit microbial metabolism, commonly used as food preservatives.
- Gaseous sterilization (e.g., ethylene oxide): Used to sterilize heat-sensitive equipment and materials; inactivates nucleic acids and proteins.
Prophylaxis and Pharmacology
- Prophylaxis: Treatment given to prevent disease or infection.
- Chemoprophylaxis: Use of medication to prevent a disease or infection.
- Alternative medicine: Treatments outside conventional medicine.
- Complementary medicine: Use of alternative therapies with conventional treatments.
- Combination therapy (polytherapy): Use of more than one medication to treat an infection.
- Pharmacology: Study of drug action, divided into pharmacodynamics and pharmacokinetics.
- Pharmacodynamics: Study of the drug's effect on the body.
- Pharmacokinetics: Study of how the body processes a drug (absorption, distribution, metabolism, elimination).
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Description
This quiz covers various antibiotics, their mechanisms of action, and the types of bacteria they target. Understand the differences between broad-spectrum and narrow-spectrum antibiotics and learn about specific compounds like penicillins and glycopeptides. Test your knowledge on how these medications affect bacterial growth and metabolism.
