Chapter 12: Antimicrobial Agent Mechanisms Flashcards
What are antimicrobial agents?
Chemical compounds to kill or suppress microorganisms.
Define antibiotics.
Natural (bacteria or fungi), semisynthetic, or synthetic molecules used to treat or prevent disease.
What is the difference between bacteriostatic and bactericidal?
Bacteriostatic inhibits growth, while bactericidal kills bacteria.
What is the difference between broad spectrum and narrow spectrum antibiotics?
Broad spectrum works on a wide variety of bacteria; narrow spectrum targets specific types.
What factors should be considered in the selection of antimicrobial agents?
- Lethal effects against the microorganism
- Toxicity toward the host
- Toxicity toward normal flora
- Pharmacological properties
- Host’s immune status
- Host’s organ function
- Solubility and distribution
- Site of infection
- Route of administration
- Cost-effectiveness
- Host allergies
What is intrinsic resistance?
Resistance naturally found in bacteria (chromosomal).
What is acquired resistance?
Resistance acquired from exogenous DNA (plasmid / through conjugation).
What are MDR microbes?
Multidrug-resistant microbes that are resistant to multiple antimicrobial agents.
What are the two basic activities of antibiotics?
- Disruption of cell envelope
- Interruption of metabolic functions.
What are β-lactam antibiotics?
Natural and semisynthetic antibiotics that inhibit transpeptidases (PBPs) involved in cell wall synthesis.
What role do glycopeptides play in antibiotic action?
They block the transpeptidation step in cell wall synthesis.
How do sulfonamides inhibit bacterial growth?
By competitively inhibiting dihydropteroate synthetase, disrupting folate synthesis.
What is the mechanism of action of rifampin?
It interferes with the production of mRNA, blocking RNA polymerase.
True or False: Aminoglycosides bind irreversibly to the 30S ribosomal subunit.
True.
What are the key points regarding antibiotic targets?
- Bacterial cell wall/envelope synthesis
- Folate synthesis
- DNA replication
- RNA transcription
- mRNA translation.
What is synergy in the context of antibiotic use?
Combined effect is greater than the additive effect.
What is antagonism in antibiotic therapy?
Combined effect is less than the additive effect, reducing or blocking activity.
What are the intrinsic mechanisms of antibiotic resistance?
- Lack of drug affinity
- Prevent access to action site
- Efflux pumps
- Enzymatic inactivation.
How can microorganisms acquire new targets?
Through mutations or transfer of mobile genetic elements that alter antibiotic targets.
What is lateral gene transfer (LGT)?
Transfer of genetic material between organisms, including conjugation, transformation, or transduction.
What are integrons?
Genetic elements that capture mobile gene cassettes through site-specific recombination.
Fill in the blank: Antibiotic mechanisms of resistance and their dissemination are not _______.
[static processes].
