Intro to Antibacterial Agents Flashcards
Definition of Antibiotics
Chemical products of microbes that kill or inhibit other organisms.
Definition of Antimicrobials agents
(usually) synthetic compounds that kill or inhibit organisms - includes, antibiotics, antifungal, antiviral ect…
* *Antimicrobial and Antibiotic are terms used interchangeably
Definition of Bacteriostatic
Inhibit bacterial growth (protein synthesis inhibitors)
Definition of Bactericidal
Kill Bacteria (Cell wall active agents)
Definition of Minimum Inhibitory Concentration (MIC)
The minimum conc of antibiotic at which visible growth is inhibited.
Definition if Synergism
Activity of two antimicrobials given together is greater than the sum of their activity if given separately.
Definition of Antagonism
One agent that diminishes the activity of another
Definition of Indifference
Activity unaffected by the addition of another agent
The combination of which 2 drugs is used in the treatment of streptococcal endocarditis?
Synergism of:
- beta lactam
- aminoglycoside
*Streptococcal endocarditis is the infection of the endocardial surface of the heart.
Name 5 targets of antibacterial agents
- Cell wall (only present in bacteria not in eukaryotes so ideak for selective toxicity)
- Protein Synthesis
- DNA synthesis
- RNA Synthesis
- Plasma Membrane
What is the major component of a bacterial cell wall?
Peptidoglycan :
- it is present in both Gram positive and Gram negative bacteria
- it is a polymer of glucose derivatives.
(N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG) )
What makes up peptidoglycan?
N-acetyl muramic acid (NAM)
N-acetyl glucosamine (NAG)
what drugs inhibit cell wall synthesis?
- beta-Lactams
- Glycopeptides
what type of drug is Benzylpenicillin?
beta-lactam antibiotic
*was the first true antibiotic in clinical practice
How do beta-lactam antibiotics work?
The are characterised by the beta-lactam ring.
They interfere with the function of “penicillin binding proteins”.
(inhibit with transpeptidase enzymes involved in peptidoglycan cross linking)
Name 4 types of beta-lactam antibiotics
- Penicillins (narrow spectrum)
- Cephalosporins (broad spectrum)
- Carbapenems (extremely broad spectrum)
- Monobactams (gram negative bacteria only)
Give an example of a penicillin
- Benzylpencillin (PEN)
- Amoxicillin
- Flucloxacillin
(penicillin is a relatively narrow spectrum beta-lactam antibiotic)
Give an example of a cephalosporin
- Cefuroxime (CXM)
- ceftazidime
(cephalosporin is a relatively broad spectrum beta-lactam)
give an example of a carbapenem
- Meropenem (MER)
- Imipenem
(Carbapenem is an extremely broad spec beta-lactam antibiotic)
give an example of a Monobactam
-Aztreonam (AZT)
Monobactams are a beta-lactam that are effective only on gram negative bacteria
How do glycopeptides work?
they are large molecules that inhibit the binding of transpeptidades and therefore prevents peptideoglycan cross-linking
*effective on gram positive bacteria (can’t penetrate gram negative bacteria)
give an example of glycopeptides
- Vancomycin
- Teicoplanin
describe how protein synthesis takes place in bacteria
Translation of RNA takes place on a ribosome.
Ribosome complexes catalyse peptide bond formation and synthesise polypeptides in 4 stages:
-INITIATION (ribosome attaches to mRNA)
- ELONGATION (amino acids join to form polypeptide chain)
- TERMINATION (stop codon reached and ribosome releases polypeptide)
- RIBOSOME RECYCLING (70S ribosome splits into 50S and 30S subunits)
Name 4 Protein synthesis inhibitors
- Aminoglycosides
- Macrolides, Lincosamides, Streptogramins (MLS)
- Tetracyclines
- Oxazolidinones
