Lecture 8. Antimicrobials

Question 1

What are three biocides?

Answer 1

Disinfectants, antiseptics and sterilisation

Question 2

What are disinfectants?

Answer 2

Products that are used on inanimate objects or surfaces

Question 3

What are antiseptics?

Answer 3

Products that destroy or inhibit the growth of microorganisms in or on living tissue

Question 4

What is sterilisation?

Answer 4

Physical or chemical process that completely destroys or
removes all microbial life, including spores

Question 5

What is an antibiotic?

Answer 5

A low molecular substance often produced by a microorganism that at a low concentration inhibits or kills other bacteria

Question 6

What is an antimicrobial?

Answer 6

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.

Question 7

Are all antibiotics antimicrobials?

Answer 7

Yes

Question 8

Are all antimicrobials antibiotics?

Answer 8

No

Question 9

What is antibiotic resistance?

Answer 9

Occurs when bacteria change in response to the use of these medicines

Question 10

What is antimicrobial resistance (AMR)?

Answer 10

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)

Question 11

What can antimicrobials be?

Answer 11

Plant-based, metal-based, nanotechnology-based, animal-based, microbe-based

Question 12

What is an example of a plant-based antimicrobial?

Answer 12

Isoquinoline alkaloid emetine obtained from the Cephaelis ipecacuanha

Question 13

What is isoquinoline alkaloid emetine used to treat?

Answer 13

Been used for many years to treat dysentery and the treatment of abscesses due to the spread of parasitic Entamoeba histolytica infections

Question 14

Where is Cephaelis ipecacuanha found?

Answer 14

Central America

Question 15

What is curcumin?

Answer 15

Yellow compound derived from turmeric
Turmeric is the spice from the rhizome of the plant Curcuma longa
Natural phenolic compound

Question 16

What is circumin used for?

Answer 16

Potent anti-tumour, anti-inflammatory, anti-oxidant, anti-microbial (bacteria, yeast, virus)

Question 17

What is circumin synergistic with?

Answer 17

Silver ions and antibiotics

Question 18

What are examples of metal ions?

Answer 18

Copper, silver, gold, platinum, palladium, zinc

Question 19

What are examples of animal-based antimicrobials?

Answer 19

Escapin (an L-amino acid oxidase) from the sea hare
Snake venom L-amino acid oxidases
Chitosan from shells of crustaceans

Question 20

Do AgNO₃ and Chitosan have synergism?

Answer 20

Yes

Question 21

What is an example of a microbe-based (non-antibiotic) antimicrobial?

Answer 21

Bacteriocins e.g Nisin

Question 22

When is escapin bacteriostatic and when is it bactericidal?

Answer 22

Bacteriostatic in minimal media
Bactericidal in rich media containing L-arginine and L-lysine

Question 23

How do L-amino acid oxidases (LAAO) function?

Answer 23

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

Question 24

What do snakes venom contain?

Answer 24

LAAOs

Question 25

What is chitosan derived from?

Answer 25

Deactylation of chitin

Question 26

What is chitosan’s antimicrobial activity based on?

Answer 26

The type of microorganism
The molecular weight
The degree of deacetylation

Question 27

What is Nisin a class of?

Answer 27

Antimicrobial termed Lantibiotics which contain an unusual amino acid: Lanthionine (Lan)