40 Questions
What is the primary function of chemotherapeutic agents?
To selectively act against microbes or malignant cells
What is true about all antibiotics?
They are produced from microbes
What is the term for the destruction or dissolution of bacterial cells?
Bacteriolytic
What is characteristic of Gram positive bacterial cell walls?
Thick cell wall
Who is considered the 'Father of Chemotherapy'?
Paul Ehrlich
What was discovered by Fleming, Chain, and Florey?
Penicillin
In what year were sulphonamides discovered?
1935
What is true about the outer membrane of Gram negative bacteria?
It is a barrier to the diffusion of antibiotics
What is the mechanism of action of β-lactams?
Inhibitors of cell wall synthesis
Which of the following antibiotics is an inhibitor of cell membrane leakage?
Polypeptides
What is the mechanism of action of sulfonamides?
Inhibitors of folate synthesis
What is the classification of Ampicillin based on its spectrum of activity?
Extended spectrum
Why are human cells not affected by β-lactams?
Human cells do not have a cell wall
What is the characteristics of penicillins that make them ideal antibiotics?
Low direct toxicity and broad spectrum of activity
Which of the following antibiotics is an inhibitor of DNA-dependent RNA polymerase?
Rifampicin
What is the difference between human and bacterial cells that makes antibacterial therapy possible?
All of the above
What is the name of the first penicillin available?
Penicillin G
Which type of bacteria is Penicillin G active against?
Most gram-positive bacteria, gram-negative cocci, anaerobic bacteria, and spirochetes
What is the preferred drug for pharyngitis caused by Streptococcus pyogenes?
Penicillin G
What is the preferred drug for infections caused by Bacillus anthracis?
Penicillin G
What is the primary treatment for meningitis caused by Neisseria meningitidis?
Ceftriaxone
What is the drug of choice for syphilis?
Penicillin G
What is the name of the spirochete that causes syphilis?
Treponema pallidum
What is the characteristic of Penicillin G?
Narrow-spectrum agent
What is the main difference between penicillin V and penicillin G?
Penicillin V is stable in stomach acid
What is a common side effect of penicillins?
All of the above
What is the purpose of β-lactamase resistant penicillins?
To treat infections caused by penicillinase-producing staphylococci
What is the term used to describe staphylococcal strains that are resistant to methicillin and other penicillinase-resistant penicillins?
Methicillin-resistant Staphylococcus aureus
What is the treatment of choice for methicillin-resistant Staphylococcus aureus?
Vancomycin
How is nafcillin usually administered?
Intravenously
Which of the following is not a broad-spectrum penicillin?
Nafcillin
Which of the following is formulated for oral dosing?
Dicloxacillin
Why is an antipseudomonal aminoglycoside added to the regimen?
To increase killing of Pseudomonas
What is a side effect of piperacillin?
Bleeding secondary to disrupting platelet function
Why is piperacillin administered parenterally?
Because it is acid labile
What is the purpose of beta-lactamase inhibitors?
To inhibit bacterial beta-lactamases
Which of the following is a beta-lactamase inhibitor?
Sulbactam
What is the characteristic of cephalosporins?
They are bactericidal, often resistant to beta-lactamases, and active against a broad spectrum of pathogens
What is the structure of cephalosporins?
A ß-lactam ring fused to a six-membered S-containing dihydrothiazine ring
Who discovered the 1st cephalosporin?
Guiseppe Bortzu
Study Notes
Antimicrobials and Antineoplastic Agents
- Chemotherapeutic agents selectively act against microbes or malignant cells, without affecting body cells.
- Antimicrobials are used to treat infectious diseases caused by microbes, and antibiotics are a type of antimicrobial produced by microbes to inhibit or kill other microbes.
Terminologies
- Bacteriostatic: stops the growth of bacteria
- Bactericidal: kills bacteria
- Bacteriolytic: destruction or dissolution of bacterial cells
Gram Positive and Gram Negative Bacteria
- Gram positive bacteria have a thick cell wall and peptidoglycan directly accessible from the environment.
- Gram negative bacteria have a thin cell wall, surrounded by an inner and outer membrane, with lipopolysaccharides, phospholipids, and proteins, making it a barrier to antibiotic diffusion.
Historical Perspectives
- 1877: Louis Pasteur discovered the phenomenon of antibiosis.
- 1906: Paul Ehrlich coined the term "chemotherapy" and is considered the father of chemotherapy.
- 1935: Domagk discovered sulfonamides (Prontosil to sulphanilamide).
- 1929, 1939, 1941: Fleming, Chain, and Florey discovered penicillin from penicillium.
- Waksman discovered streptomycin from actinomycetes and coined the term "antibiotic".
Antimicrobial Classification
- Classification by chemical structure (e.g., β-lactams, aminoglycosides)
- Classification by mechanism of action (e.g., inhibitors of cell wall synthesis)
- Classification by activity against organisms (e.g., anti-bacterial, anti-fungal)
- Classification by spectrum of activity (e.g., narrow, broad, extended)
- Classification by origin/source of antimicrobials
Classification by Organism Affected
- Anti-viral
- Anti-bacterial
- Anti-fungal
- Anti-protozoal
- Anthelmintic
Classification by Spectrum
- Narrow spectrum: e.g., penicillin G, streptomycin, erythromycin
- Broad spectrum: e.g., tetracycline, chloramphenicol
- Extended spectrum: e.g., ampicillin, amoxicillin
Classification by Mechanism of Action
- Cell wall synthesis inhibition: e.g., β-lactams, vancomycin, cycloserines
- Cell membrane leakage: e.g., polypeptides, polyenes
- Folate synthesis inhibition: e.g., sulfonamides, pyrimethamine, cotrimaxazole
- DNA gyrase and topoisomerase inhibition: e.g., fluoroquinolones
- RNA polymerase inhibition: e.g., rifampicin
- Protein synthesis inhibition: e.g., aminoglycosides, tetracyclines, chloramphenicol, macrolides
Differences in Human and Bacterial Cell Components
- Human cells lack a cell wall (peptidoglycans = peptides + sugar)
- Human cell membrane is different (bacteria contain hypanoids in place of sterol)
- Human cells take preformed dihydrofolic acid (no need for PABA in humans)
- Dihydrofolic acid reductase enzyme is different (thousand-time affinity)
- Topoisomerase II are different (in bacteria, DNA gyrase)
- DNA-dependent RNA polymerase is different
- Ribosome 60S subunit for human (in bacteria, 50S)
- Ribosome 40S subunit for human (in bacteria, 30S)
Penicillins
- Penicillins are bactericidal and active against a variety of bacteria, with low direct toxicity.
- Examples: ampicillin, amoxicillin, carbenicillin, ticarcillin
- Spectrum: narrow spectrum to broad spectrum
- Pharmacokinetics: vary depending on the specific penicillin
β-Lactamase Resistant Penicillins
- Examples: flucloxacillin, methicillin, nafcillin, oxacillin, dicloxacillin
- Spectrum: very narrow, active against penicillinase-producing staphylococci
- Pharmacokinetics: vary depending on the specific penicillin
Broad-Spectrum Penicillins
- Examples: ampicillin, amoxicillin
- Spectrum: broad spectrum, active against a variety of bacteria
- Pharmacokinetics: vary depending on the specific penicillin
Cephalosporins
- Cephalosporins are beta-lactam antibiotics, similar in structure and actions to penicillins.
- They are bactericidal, often resistant to beta-lactamases, and active against a broad spectrum of pathogens.
- Classification: 1st generation, 2nd generation, 3rd generation
- Examples: cephalexin, cefuroxime, cefamandole
This quiz covers the basics of antimicrobials and chemotherapeutic agents, including their selective action against microbes or malignant cells.
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