Antibiotics Flashcards
What are the four shapes of bacteria?
Bacillus, coccus, spiral, other.
What are the two types of bacterial cell walls?
Gram-negative and gram-positive.
What are gram-positive walls?
Consist of thick layers of peptidoglycan.
What are gram-negative walls?
Cell walls that do not contain much peptidoglycan and instead contain two separate membrane layers.
What is the structure of peptidoglycan?
Glycan strands made of alternating N-acetylglucosamine and N-acetylmuramic acid cross-linked by peptides.
How are individual glycan strands polymerized into a chain?
By glycosyltransferase (GT)
How are the glycan strands CROSS-LINKED?
Transpeptidase (TP)
What are the four types of diseases caused by pathogenic bacteria?
Food borne illnesses
Sexually transmitted diseases.
Skin infections
Highly infectious diseases
What four characteristics are antibiotic efficacies described by?
- Spectrum of acitivity.
- Bacterial sensitivity.
- Therapeutix index.
- Ability to penetrate.
What are bacteriocidal antibiotics?
Leads to a permanent loss of replicative ability.
What are bacteriostatic antibiotics?
Leads to a temporary loss of growth and replication that returns following removal of antibiotics.
What are the four classes of antibiotics?
Cell wall inhibitors, folic acid, DNA synthesis inhibitors, protein synthesis inhibitors.
What is the mechanism of cell wall inhibitors?
Inhibit enzyme DD-transpeptidase responsible for crosslinking components of the cell wall.
What is DD transpeptidase also known as?
Penicillin binding protein.
What are cell wall inhibitors most effective against?
Gram-positive bacteria.
What are beta-lactamases?
Bacterial enzymes made by staphylococci that confer resistance against cell wall inhibitors.
What are beta-lactamase inhibitors?
Used in combination with cell wall inhibitors to prevent bacterial resistance.
What is vancomycin?
Inhibits peptidoglycan cross-linking, produced in other bacteria.
What is the mechanism of folic acid inhibitors?
Drugs that resemble PABA (folic acid precursor) interfere with folic acid synthesis, inability to synthesize purines.
What are three examples of protein synthesis inhibitors?
Chloramphenicol, tetracyclines, macrolides.
What ribosomal complex does bacteria use to synthesize protein?
70s complex composed of 50s and 30s subunits.
What is the mechanism of chloramphenicol and macrolides?
Bind to 50s subunit to block transpeptidation.
What is the mechanism of tetracyclines?
Bind to 30s subunit to prevent binding of incoming tRNA.
How does aminoglycoside inhibit protein synthesis?
Bind to the 30s subunit to block initiation, cause misreading, inhibit translocation.
