Lecture 8. Antimicrobials Flashcards
What are three biocides?
Disinfectants, antiseptics and sterilisation
What are disinfectants?
Products that are used on inanimate objects or surfaces
What are antiseptics?
Products that destroy or inhibit the growth of microorganisms in or on living tissue
What is sterilisation?
Physical or chemical process that completely destroys or
removes all microbial life, including spores
What is an antibiotic?
A low molecular substance often produced by a microorganism that at a low concentration inhibits or kills other bacteria
What is an antimicrobial?
Any substance of natural, semisynthetic or synthetic origin that kills or inhibits the growth of microorganisms but causes little or no damage to the host – more general encompassing parasites etc.
Are all antibiotics antimicrobials?
Yes
Are all antimicrobials antibiotics?
No
What is antibiotic resistance?
Occurs when bacteria change in response to the use of these medicines
What is antimicrobial resistance (AMR)?
A broader term, encompassing resistance to drugs to treat infections caused by other microbes as well as parasites (e.g. malaria), viruses (e.g. HIV) and fungi (e.g. Candida)
What can antimicrobials be?
Plant-based, metal-based, nanotechnology-based, animal-based, microbe-based
What is an example of a plant-based antimicrobial?
Isoquinoline alkaloid emetine obtained from the Cephaelis ipecacuanha
What is isoquinoline alkaloid emetine used to treat?
Been used for many years to treat dysentery and the treatment of abscesses due to the spread of parasitic Entamoeba histolytica infections
Where is Cephaelis ipecacuanha found?
Central America
What is curcumin?
Yellow compound derived from turmeric
Turmeric is the spice from the rhizome of the plant Curcuma longa
Natural phenolic compound
What is circumin used for?
Potent anti-tumour, anti-inflammatory, anti-oxidant, anti-microbial (bacteria, yeast, virus)
What is circumin synergistic with?
Silver ions and antibiotics
What are examples of metal ions?
Copper, silver, gold, platinum, palladium, zinc
What are examples of animal-based antimicrobials?
Escapin (an L-amino acid oxidase) from the sea hare
Snake venom L-amino acid oxidases
Chitosan from shells of crustaceans
Do AgNO₃ and Chitosan have synergism?
Yes
What is an example of a microbe-based (non-antibiotic) antimicrobial?
Bacteriocins e.g Nisin
When is escapin bacteriostatic and when is it bactericidal?
Bacteriostatic in minimal media
Bactericidal in rich media containing L-arginine and L-lysine
How do L-amino acid oxidases (LAAO) function?
Convert L-amino acids into pyruvic acid and H₂O₂
The intracellular concentration of H₂O₂ is tightly controlled by various enzymatic and nonenzymatic antioxidant systems and is assumed to vary between 1 and 700nM
Intracellular steady-state concentrations of H₂O₂ above 1μM are considered to cause oxidative stress inducing growth arrest and cell death
What do snakes venom contain?
LAAOs
What is chitosan derived from?
Deactylation of chitin
What is chitosan’s antimicrobial activity based on?
The type of microorganism
The molecular weight
The degree of deacetylation
What is Nisin a class of?
Antimicrobial termed Lantibiotics which contain an unusual amino acid: Lanthionine (Lan)
