14 Questions
What are chemotherapeutic agents?
Chemical agents that combat disease in the body.
Define antimicrobial drugs.
Chemical agents that destroy microorganisms.
How are antimicrobial drugs classified according to their spectrum of activity?
Broad spectrum and narrow spectrum
Which category of antimicrobial drugs acts on cell wall synthesis?
Drugs acting on cell wall
Antimicrobial drugs that inhibit protein synthesis in bacterial ribosomes include _____.
Chloramphenicol, erythromycin, clindamycin, tetracyclines, and aminoglycosides
Active replication of bacteria is not required for most antibacterial drug actions.
False
Match the following mechanisms of drug resistance with their examples:
Enzymes that destroy drug activity = Staphylococcus B-lactamase Altered metabolic pathways = Sulfonamides Altered enzymes = Trimethprim resistant bacteria
What are chemotherapeutic agents?
Chemotherapeutic agents are chemical agents which combat disease in the body.
Define antimicrobial drugs.
Antimicrobial drugs are chemical agents that destroy microorganisms.
What is the classification of antimicrobial drugs based on spectrum of activity?
Broad spectrum antibiotics
Antimicrobial drugs that directly kill microorganisms are known as __________.
bactericidal
Antimicrobial drugs that inhibit growth of microorganisms are bacteriostatic.
True
What is the mechanism of action of Quinolones?
Quinolones inhibit microbial DNA synthesis by blocking DNA gyrase.
Match the following mechanisms of drug resistance with their descriptions:
Enzymes that destroy drug activity = Microorganisms produce enzymes that destroy drug activity. Altered metabolic pathways = Microorganisms develop altered metabolic pathways to bypass drug reactions. Mutations in gene controlling susceptibility = Chromosomal mutation due to spontaneous mutations in drug susceptibility control genes. Plasmid mediated resistance = Resistance carried by plasmids with genes encoding resistance to antimicrobial drugs.
Study Notes
Chemotherapeutic Agents and Antimicrobial Drugs
- Chemotherapeutic agents are chemical agents that combat disease in the body.
- Antimicrobial drugs are chemical agents that destroy microorganisms, and may be synthetic or natural.
Classification of Antimicrobial Drugs
- Classified according to spectrum of activity:
- Broad spectrum antibiotics: act against both gram negative and gram positive bacteria (e.g. amoxicillin, ciprofloxacin)
- Narrow spectrum antibiotics: act against certain microorganisms (e.g. penicillin)
- Classified according to mechanism of action:
- Drugs acting on cell wall (e.g. penicillin)
- Drugs acting on protein synthesis (e.g. aminoglycosides)
- Drugs acting on cell membrane (e.g. polymyxin)
- Drugs acting on nucleic acid biosynthesis (e.g. rifampicin)
- Classified according to bactericidal or bacteriostatic activity:
- Bactericidal: eliminate bacteria (e.g. aminoglycosides)
- Bacteriostatic: inhibit growth of bacteria (e.g. chloramphenicol)
Action of Antimicrobial Drugs
- Directly kill microorganisms (bactericidal)
- Inhibit growth of microorganisms (bacteriostatic)
Mechanism of Action
- Inhibition of cell wall synthesis (e.g. cephalosporins, penicillins, vancomycin)
- Inhibition of cell membrane function (e.g. clostin, polymyxin B)
- Inhibition of protein synthesis (e.g. chloramphenicol, erythromycin, clindamycin, tetracyclines, aminoglycosides)
- Inhibition of nucleic acid synthesis (e.g. quinolones, rifampin, sulfonamides, trimethoprim)
Mechanisms of Drug Resistance
- Microorganisms produce enzymes that destroy the activity of the drug
- Microorganisms develop an altered metabolic pathway that bypasses the reaction inhibited by the drug
- Microorganisms develop an altered enzyme
Origins of Drug Resistance
- Non-genetic origin:
- Active replication of bacteria is required for most antibacterial drug action
- Microorganisms may lose specific target structure and become resistant
- Intracellular microorganisms are not affected by drugs as long as they stay inside cells
- Genetic origin:
- Chromosomal mutation: develops as a result of spontaneous mutation in a locus that controls susceptibility to a given drug
- Extrachromosomal "plasmid mediated resistance": carries genes for resistance to one or several antimicrobial drugs
- R-factor composed of two parts: resistant-transfer factor (RTF) and R-determinant
- Dissemination by bacterial conjugation mainly
- Genetic material and plasmid can be transferred by transformation, transduction, and conjugation
Chemotherapeutic Agents and Antimicrobial Drugs
- Chemotherapeutic agents are chemical agents that combat disease in the body.
- Antimicrobial drugs are chemical agents that destroy microorganisms, and may be synthetic or natural.
Classification of Antimicrobial Drugs
- Classified according to spectrum of activity:
- Broad spectrum antibiotics: act against both gram negative and gram positive bacteria (e.g. amoxicillin, ciprofloxacin)
- Narrow spectrum antibiotics: act against certain microorganisms (e.g. penicillin)
- Classified according to mechanism of action:
- Drugs acting on cell wall (e.g. penicillin)
- Drugs acting on protein synthesis (e.g. aminoglycosides)
- Drugs acting on cell membrane (e.g. polymyxin)
- Drugs acting on nucleic acid biosynthesis (e.g. rifampicin)
- Classified according to bactericidal or bacteriostatic activity:
- Bactericidal: eliminate bacteria (e.g. aminoglycosides)
- Bacteriostatic: inhibit growth of bacteria (e.g. chloramphenicol)
Action of Antimicrobial Drugs
- Directly kill microorganisms (bactericidal)
- Inhibit growth of microorganisms (bacteriostatic)
Mechanism of Action
- Inhibition of cell wall synthesis (e.g. cephalosporins, penicillins, vancomycin)
- Inhibition of cell membrane function (e.g. clostin, polymyxin B)
- Inhibition of protein synthesis (e.g. chloramphenicol, erythromycin, clindamycin, tetracyclines, aminoglycosides)
- Inhibition of nucleic acid synthesis (e.g. quinolones, rifampin, sulfonamides, trimethoprim)
Mechanisms of Drug Resistance
- Microorganisms produce enzymes that destroy the activity of the drug
- Microorganisms develop an altered metabolic pathway that bypasses the reaction inhibited by the drug
- Microorganisms develop an altered enzyme
Origins of Drug Resistance
- Non-genetic origin:
- Active replication of bacteria is required for most antibacterial drug action
- Microorganisms may lose specific target structure and become resistant
- Intracellular microorganisms are not affected by drugs as long as they stay inside cells
- Genetic origin:
- Chromosomal mutation: develops as a result of spontaneous mutation in a locus that controls susceptibility to a given drug
- Extrachromosomal "plasmid mediated resistance": carries genes for resistance to one or several antimicrobial drugs
- R-factor composed of two parts: resistant-transfer factor (RTF) and R-determinant
- Dissemination by bacterial conjugation mainly
- Genetic material and plasmid can be transferred by transformation, transduction, and conjugation
This quiz covers the classification of antimicrobial drugs, including chemotherapeutic agents, anti-microbial drugs, and their spectrum of activity.
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