Antimicrobial Chemotherapy Flashcards
What is meant if an organism is termed sensitive?
organism is sensitive if it is inhibited or killed by the antimicrobial
What is meant if an organism is termed resistat?
organism is resistant if it is not killed or inhibited by the antimicrobial available at the site of infection.
What are antibiotics active against?
Bacteria
What is meant by a Bactericidal?
antimicrobial that kills bacteria.
What is mean by a Bacteriostatic?
Antimicrobial that inhibits growth of bacteria.
what is meant by MIC?
Minimal inhibitory concentration minimum concentration of antimicrobial needed to inhibit growth of a given
How can antiobiotics be administrated?
Topical
Systemic
Parenteral
How is an antibiotic administered topically?
Applied to a surface (skin or to mucous membranes )
How is an antibiotic administrated systematically?
Taken internally, (orally or parenterally)
Hpw is an antibiotic administered Parenterally?
Administered intra-venously (i.v.) or intra-muscularly (i.m.), occasionally subcutaneously.
What do antibiotics do to bacteria?
By inhibiting or killing bacteria.
Name the three areas of metabolic activity of antibiotics.
Inhibition of cell wall synthesis
Inhibition of protein synthesis
Inhibition of nucleic acid aynthesis.
Why are human cells not affacted by antibiotics?
Human cells do not have cell walls, so they are not affected by antibiotics that inhibit cell wall synthesis
Name two Bactericidal antibiotics which are effective against gram positive bacteria.
Penicillins and Cephalosporins (β-lactams).
Macrolides are considered either bactericidal orbacteriostatic antibiotics. depending on what?
Depending on concentration and bacterial species,
Oxazolidinones are considered either bactericidal orbacteriostatic antibiotics. depending on what?
Depedning on the bacteria being treated.
Measurement of the antibiotic sensitivity of an organism in the laboratory is designed to do what?
Predict whether an infection will respond to treatment with that antibiotic.
In some cases, all strains of a given species are naturally resistant to an antibiotic.
What are streptococci always resitant to?
aminoglycosides
Gram negative organims are always resistant to??
Why?
Vancomycin
Usually due to inability of the drug
to penetrate the bacterial cell wall to exert its action)
If a bacertia is known to be resitant, what becomes irrelevant.
Laboratory Sensitivity Testing
What is aquired resistance?
Resistance may be present in some strains of bacteria but not in others.
Laboratory sensitivity testing is ued to?
Esablish the sensitivity of any bacteria isolate from a patient
What does the widespread use of antibiotics encourage and cause?
causes selective pressure and encourages new resistant organisms to outgrow sensitive strains.
How is resistance aquired?
Spontaneous mutation
Spread of resistance.
