Antibiotics Flashcards
Define Antibiotics
These are natural products of fungi and bacteria -soil dwellers
Natural antagonism and selective advantage
Kill or inhibit the growth of other micro-organisms
Most derived from natural products through fermentation then get modified chemically
This tends to increase their pharmacological properties and antimicrobial effects
What is a main principle of antibiotics being used as a therapeutic agent ?
Being selectively toxic
Due to differences in structure and metabolic pathways between host and pathogen
Harm micro-organisms not the host
Target in microbe not host
Difficult for viruses (intracellular ),fungi and parasites
The effect it will have on commensal flora
What is therapeutic margin ?
The active dose (MIC) versus toxic effect
This is narrow for toxic drugs such as
aminoglycosides,vancomycin
(ototoxic and nephrotoxic)
There are no safe drugs so the therapeutic imperative is balanced with host damage
What does MIC stand for ?
Minimum inhibitory concentration
What is ototoxic ?
the property of being toxic to the ear
What is nephrotoxic ?
This is the toxicity to the kidneys
Define microbial antagonism
Maintains flora-complex interactions
Competition between flora
Limits the growth of competitors and pathogens
What is antibiotic associated colitis?
This occurs when broad spectrum highly potent antibiotics damage the flora leading to an overgrowth of pathogen /bacteria.
This means that clostridium dificile will over grow
What are some factors which may cause immunosuppression ?
SLIDE
What are the three categories through which antibiotics are classified ?
Activity
Structure
Target site
What are bactericidal antibiotics ?
These kill bacteria
Used when the host defence mechanism are impaired
Required in endocarditis, kidney and infection
What are bacteriostatic antibiotics ?
These will inhibit bacteria
These are used when the host defence mechanism are intact
Used in infectious diseases
What are the two antibiotic spectrum types ?
Broad specturm antibiotics
Effective against many types
e.g. Cefotaxime
Narrow spectrum antibiotics
Effective against very few types
Penicillin G
What are the different structures of antibiotics ?
SLIDE
Dont need to learn
What are some targets on bacteria for selective toxicity ?
SLIDE