MB2020 TOPIC 1 LECTURE 2 Antimicrobial Agents

What are chemotherapeutic agents

Non-toxic compounds used internally to treat infections

What are disinfectants?

Toxic chemicals that kill microorganisms and are used for non living objects

What are antiseptics?

Chemical substances that kill microorganisms/inhibit their growth and are applied to living tissue

What are antimicrobials

Natural or synthetic compounds that kill microorganisms or inhibit their growth

What are antibiotics?

Chemical compounds produced by microorganisms to inhibit or kill other microorganisms.

What are synthetic antimicrobials?

Chemical synthesised compounds that kill or inhibit microorganisms

What are the five things that chemotherapeutic agents should be?

1. Non-toxic for human or animals

2. Effective against pathogenic microorganisms

3. Relatively stable in vivo

4. Active at relatively low concentrations

5. Easy and non-expensive to manufacture

What is bacteriostatic?

When bacteria stops growing and multiplying but bacteria is not killed.

What is bacteriolytic?

When bacteria is killed due to bacteria cells breaking open.

What does bactericidal mean?

Agent that causes bacteria death but total cell count plateaus.

What is antimicrobials susceptibility testing?

Used to determine wether a particular microorganism is sensitive or resistant to a particular antimicrobials.

What is minimum inhibitory concentration?

The lowest concentration of an antimicrobial agent that results in inhibition of visible growth of the test organism under standard conditions

What is minimum bactericidal concentration?

The lowest concentration of an antimicrobial agent that kills 99.9% of original inoculum in given time.

What are the three antimicrobial susceptibility testing methodology?

1. microdilution test - determines MIC in liquid media

2. solid media methods - measure inhibition zone (disc assay, kirby-bauer and E-test(a strip containing a drug at exponentially increasing concentrations))

3. Indirect Molecular methods (e.g PCR)

In the microdilution method, if there is growth, what colour would be shown ?

PINK

What is the treatment for influenza and what does it do?

Amantadine - prevents virus entry

What is the treatment for herpes virus and what does it do?

Acyclovir - inhibits DNA polymerase

What is the treatment for HIV and what does it do?

Abacavir - a nucleoside reverse transcriptase inhibitor.

What is the purpose of Zanamivir?

Inhibits the release of viruses

What are the three advantages of multiple drug therapy?

1. prevents the development of drug resistance

2. more effective

3. suits for the long-term treatment

What are some drugs used to treat tuberculosis?

1. isoniazid

2. ethambutol

3. pyrazinamide

4. rifampicin

What does indifference mean?

Two drugs do not interact, their combined effect is not different from the effect of one more potent drug alone

EXAMPLE a drug gives 90% effectivity, a second drug comes along and there is still 90% effectivity, therefore that second drug is of no use

What does additivity mean?

The combined activity of two or more agents is the sum of their individual activities

EXAMPLE one drug gives 50% effectivity , another drug give 30% effectivity together they give 80% effectivity

What does synergism mean

The combined effect of two drugs is greater that the sum of two individual effects

EXAMPLE One drug gives an effectivity of 20% another give effectivity of 50% together they give effectivity of 90%

What does antagonism mean?

The combined effect is less than the sum of two individual effects ( one antimicrobial prevents the full effect of another)

EXAMPLE one drug gives 50% effectivity, another gives 30% together they give 20% effectivity.