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Questions and Answers
What was the cause of John McCrae's death?
What was the cause of John McCrae's death?
- Wounded in World War I
- Blood infection
- Streptococcal pneumonia/meningitis (correct)
- Died in the Second Boer War
In which war did Norman Bethune serve and get wounded?
In which war did Norman Bethune serve and get wounded?
- Spanish Civil War
- World War I (correct)
- Second Boer War
- Second Sino-Japanese War
What led to the miraculous revolution in medicine and the curing of infectious diseases?
What led to the miraculous revolution in medicine and the curing of infectious diseases?
- Treatment with a new experimental drug (correct)
- Brought western medicine to China
- Served in the Second Sino-Japanese War
- Graduated from U of T in Medicine
Which enzyme is inhibited by trimethoprim in the folic acid biosynthesis pathway?
Which enzyme is inhibited by trimethoprim in the folic acid biosynthesis pathway?
What is the synergistic effect observed when trimethoprim and sulfonamide are used in combination?
What is the synergistic effect observed when trimethoprim and sulfonamide are used in combination?
What is the substrate of the enzyme involved in folic acid biosynthesis that is structurally similar to sulfa drugs?
What is the substrate of the enzyme involved in folic acid biosynthesis that is structurally similar to sulfa drugs?
What type of inhibition is exemplified by the action of sulfa drugs on the enzyme involved in folic acid biosynthesis?
What type of inhibition is exemplified by the action of sulfa drugs on the enzyme involved in folic acid biosynthesis?
Which antibiotic irreversibly binds to the 30S ribosomal subunit, causing it to malfunction and blocking initiation of translation?
Which antibiotic irreversibly binds to the 30S ribosomal subunit, causing it to malfunction and blocking initiation of translation?
Which antibiotic class is often the drug of choice for patients allergic to penicillin?
Which antibiotic class is often the drug of choice for patients allergic to penicillin?
Which antibiotic class interferes with protein synthesis at various steps?
Which antibiotic class interferes with protein synthesis at various steps?
Which antibiotic is crucial for treating Gram-positive bacteria resistant to β-lactam drugs?
Which antibiotic is crucial for treating Gram-positive bacteria resistant to β-lactam drugs?
Which antibiotic class has low affinity for Gram-positive bacteria?
Which antibiotic class has low affinity for Gram-positive bacteria?
Which antibiotic class is effective against a wide range of bacteria and resists β-lactamases?
Which antibiotic class is effective against a wide range of bacteria and resists β-lactamases?
Which antibiotic class has greater activity against Pseudomonas species?
Which antibiotic class has greater activity against Pseudomonas species?
Which antibiotic class is bacteriostatic and reversibly binds to the 30S subunit, blocking tRNA attachment?
Which antibiotic class is bacteriostatic and reversibly binds to the 30S subunit, blocking tRNA attachment?
Which antibiotic inhibits topoisomerases and is bactericidal against a wide variety of bacteria?
Which antibiotic inhibits topoisomerases and is bactericidal against a wide variety of bacteria?
Which antibiotic blocks prokaryotic RNA polymerase from initiating transcription and is used to treat tuberculosis, Hansen’s disease, and meningitis?
Which antibiotic blocks prokaryotic RNA polymerase from initiating transcription and is used to treat tuberculosis, Hansen’s disease, and meningitis?
Which type of antimicrobial drug can be 'static' or 'cidal'?
Which type of antimicrobial drug can be 'static' or 'cidal'?
Who isolated Streptomycin from S. griseus?
Who isolated Streptomycin from S. griseus?
What test is commonly used to determine the susceptibility of bacterial strains to drugs?
What test is commonly used to determine the susceptibility of bacterial strains to drugs?
What is the main concern in the industry regarding antimicrobial drugs?
What is the main concern in the industry regarding antimicrobial drugs?
'Antimicrobial drugs exhibit selective toxicity' - how is relative toxicity expressed?
'Antimicrobial drugs exhibit selective toxicity' - how is relative toxicity expressed?
'Determining susceptibility of bacterial strains involves minimum inhibitory and bactericidal concentrations' - what does MIC stand for?
'Determining susceptibility of bacterial strains involves minimum inhibitory and bactericidal concentrations' - what does MIC stand for?
'Antimicrobials differ in behavior in the body, with some requiring multiple doses per day' - what term describes this behavior?
'Antimicrobials differ in behavior in the body, with some requiring multiple doses per day' - what term describes this behavior?
Which antimicrobial drug was identified as most suitable for treating humans post-1960?
Which antimicrobial drug was identified as most suitable for treating humans post-1960?
What term describes combinations of antimicrobial drugs that can be antagonistic, synergistic, or additive?
What term describes combinations of antimicrobial drugs that can be antagonistic, synergistic, or additive?
'Adverse effects of antimicrobial drugs include toxicity, allergic reactions, and suppression of normal microbiota' - what are normal microbiota also known as?
'Adverse effects of antimicrobial drugs include toxicity, allergic reactions, and suppression of normal microbiota' - what are normal microbiota also known as?
'Antimicrobials differ in behavior in the body' - what term describes the study of the action of drugs within the body?
'Antimicrobials differ in behavior in the body' - what term describes the study of the action of drugs within the body?
'Antimicrobial drugs are classified as antibiotics, antifungals, antiparasitics, and antivirals' - what term describes their ability to affect only microbial cells while causing little or no harm to host cells?
'Antimicrobial drugs are classified as antibiotics, antifungals, antiparasitics, and antivirals' - what term describes their ability to affect only microbial cells while causing little or no harm to host cells?
Who discovered the first successful antimicrobial chemical in 1910?
Who discovered the first successful antimicrobial chemical in 1910?
Which discovery marked the finding of the first 'sulfa' drug?
Which discovery marked the finding of the first 'sulfa' drug?
Who discovered the effectiveness of penicillin against bacterial species in 1928?
Who discovered the effectiveness of penicillin against bacterial species in 1928?
Who led the efforts in 1941 to purify and test penicillin?
Who led the efforts in 1941 to purify and test penicillin?
'Sulfa' drugs are derivatives of which antimicrobial chemical?
'Sulfa' drugs are derivatives of which antimicrobial chemical?
'Ampicillin' and 'Methicillin' are chemical derivatives of which antimicrobial drug?
'Ampicillin' and 'Methicillin' are chemical derivatives of which antimicrobial drug?
Which method uses a strip with a gradient of drug to determine MIC?
Which method uses a strip with a gradient of drug to determine MIC?
What is the primary target of β-lactam drugs in bacteria?
What is the primary target of β-lactam drugs in bacteria?
Which antibiotic interferes with the transport of peptidoglycan precursors across the cytoplasmic membrane?
Which antibiotic interferes with the transport of peptidoglycan precursors across the cytoplasmic membrane?
Which type of cells are weakened by penicillins, cephalosporins, and other β-lactam drugs?
Which type of cells are weakened by penicillins, cephalosporins, and other β-lactam drugs?
What is the mode of action of vancomycin in bacteria?
What is the mode of action of vancomycin in bacteria?
Diffusion bioassay is used for comparing known concentrations with patient samples to yield drug concentration through:
Diffusion bioassay is used for comparing known concentrations with patient samples to yield drug concentration through:
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Study Notes
Antimicrobial Drugs: Features and Susceptibility Testing
- Penicillin, initially difficult to purify, was proven effective in humans by a police officer
- Penicillin G identified as most suitable for treating humans post-1960
- Streptomycin isolated by Selman Waksman from S. griseus, prompting further antibiotic screening
- Few new antibiotics being developed, leading to a concern in the industry
- Antimicrobial drugs exhibit selective toxicity, with relative toxicity expressed as therapeutic index
- Antimicrobial drugs are classified as antibiotics, antifungals, antiparasitics, and antivirals
- Antimicrobial drugs can be "static" (inhibit growth) or "cidal" (kill microbes), with varying spectra of activity
- Combinations of antimicrobial drugs can be antagonistic, synergistic, or additive
- Antimicrobials differ in behavior in the body, with some requiring multiple doses per day
- Adverse effects of antimicrobial drugs include toxicity, allergic reactions, and suppression of normal microbiota
- Determining susceptibility of bacterial strains involves minimum inhibitory and bactericidal concentrations
- The Kirby-Bauer disc diffusion test is commonly used to determine the susceptibility of bacterial strains to drugs
Commercial Modifications of Susceptibility Testing
- Commercial modifications of susceptibility testing aim to be less labor-intensive and provide faster results.
- One automated system uses turbidity in cards to determine growth rate and interprets results to determine minimum inhibitory concentrations (MICs) in 6–15 hours.
- E test, a modification of the disc diffusion test, uses a strip with a gradient of drug to determine MIC. The intersection of the zone of inhibition indicates MIC.
- Measuring concentration of antimicrobial drugs in blood or other body fluids is important to determine blood toxicity and achievable levels for new drugs.
- Diffusion bioassay compares known concentrations with patient samples and produces a standard curve to yield drug concentration.
- Drug targets of bacteria include cell wall synthesis, nucleic acid synthesis, cell membrane integrity, metabolic pathways, and protein synthesis.
- β-lactam drugs competitively inhibit enzymes that help form peptide bridges between adjacent glycan chains in cell walls.
- Vancomycin binds to the amino acid side chain of NAM molecules, blocking peptidoglycan synthesis.
- Bacitracin interferes with the transport of peptidoglycan precursors across the cytoplasmic membrane.
- Penicillins, cephalosporins, and other β-lactam drugs competitively inhibit enzymes that catalyze formation of peptide bridges between adjacent glycan strands, disrupting peptidoglycan synthesis.
- These drugs weaken cell walls, leading to cell lysis and are only effective against actively growing cells.
- Penicillins have a basic structure and side chain and are grouped into narrow-spectrum, penicillinase-resistant, and broad-spectrum categories based on their activity against Gram-positive and Gram-negative bacteria.
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