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Medsci 202 > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

What is the traditional definition of an antibiotic and why is this flawed?

A

The traditional definition of an antibiotic is a substance produced by a microorganism which is effective in killing or inhibiting other microorganisms
This definition is flawed as many modern day antibiotics are either modified in the lab or completely made in the lab

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2
Q

What are the three classes of antibiotics with regards to their production?

A

Synthetic, Semisynthetic, organic

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3
Q

What tends to be the term utilized for these modern day antibiotics that are entirely synthesized?

A

Antimicrobial agent, anti-fungal agent etc.

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4
Q

What modern, entirely synthesized agents are never called antibiotics?

A

Antiviral agents

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5
Q

What are the desirable qualities in an antibiotic?

A

Kill or inhibit bacterial growth
No damage caused to host or allergic reaction created
Stable storage
Remains specific tissue long enough to help host
Quickly kills pathogens to reduce changes of antibiotic resistance developing

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6
Q

What is the antibacterial spectrum?

A

The range of activity against bacteria

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7
Q

Give an example of a narrow spectrum antibiotic

A

Vancomycin which only effects gram positive bacteria

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8
Q

Give an example of a broad spectrum antibiotic

A

Ampicillin or tetracycline which is effective against both gram positive and gram negative bacteria

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9
Q

What is bacteriostatic activity?

A

The level of antimicrobial acitvity that inhibits pathogen growth allowing the immune system to overcome the infection

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10
Q

What is bactericidal activity?

A

The level of antimicrobial technology that kills the pathogen

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11
Q

What is an antibiotic combination and what is its purpose?

A

Broaden the antibiotic spectrum and to allow for the ability to kill any of the microbes that have mutated quickly resulting in the ability to kill an resistant organisms that emerge, can also be used to treat polymicrobial infections

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12
Q

What is antibiotic synergism?

A

When two antibiotics combine to enhance antimicrobial activity

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13
Q

What is antibiotic antagonism?

A

When two antibiotics interfere with each other resulting in less antimicrobial activity than that of the most active drug

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14
Q

What is the minimum inhibitory concentration?

A

The minimum concentration of the antibiotic required to inhibit growth of the pathogen

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15
Q

What is the minimum bactericidal concentration?

A

The minimum concentration required to kill the pathogen

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16
Q

What are the two ways of calculating the minimum inhibitory concentration?

A
  1. Lawn agar plate with antibiotic discs, the concentration can be calculated from the diameter
  2. Use of a dilution series
17
Q

What is a dilution series?

A

A series of broth cultures with the same concentration of bacteria, treated with different antibiotic concentrations, the results of the broth culture growth can be then be used to determine the minimum inhibitory concentration and the minimum anti bactericidal concentration

18
Q

What is an antibacteriogram?

A

A lawn agar with antibiotic discs

19
Q

What are the 5 main targets of anti biotics?

A

Cell wall Synthesis, DNA replication, RNA synthesis, Antimetabolites, Protein Synthesis

20
Q

What are the two different types of antibiotics that target cell wall synthesis?

A

Beta Lactam antibiotics and glycopeptides

21
Q

What are beta lactam antibiotics?

A

Bacteriacidal antibiotics which inhibit peptidyl transferase such as penecillin, amoxycillin and ampicillin

22
Q

How are gram negative bacteria made susceptible to beta lactam anti biotics?

A

Penecillins are altered in the lab to produce compounds such as amoxycillin which can pass through membrane pores on the bacterial outermembrane

23
Q

What are Glycopeptides?

A

Bactericidal compounds such as vancomycin which binds to the monomers of peptidoglycan preventing their polymerisation

24
Q

What are antibiotics that target RNA transcription?

A

Rifamycins which bind to bacterial RNA polymerase causing a change in the conformation of the active site preventing RNA transcription
Bactericidal compounds used against mycobacteria

25
Q

What are the antiobiotics that target DNA replication?

A

Quinones and fluoroquinones which bind to topoisomerases preventing DNA replication as they prevent supercoiling, acting as bactericidal agents

26
Q

What is the difference between fluoroquinones and quinones?

A

Fluorquniones are more active and are typically used due to antibiotic reistances

27
Q

What are the antibiotics that target antimetabolites?

A

Sulfonamides are bacteriostatic compounds which prevents parabenzoic acid from being converted to tetrahydrofolic acid which prevents the formation of nucleic acids as this is a required co-factor

28
Q

What are the antibiotics that target protein synthesis?

A

Antibiotics that target the large ans small (50S and 30s) components of the bacterial ribosome

29
Q

What antibiotics target the 30S ribosome unit?

A

Aminoglycosides and tetracyclines

30
Q

How to aminogylcosides target protein synthesis?

A

Freeze the 30S complex resulting in the misreading of mRNA causing nonsense proteins, is a bacteriocidal compound affective agains gram negative bacteria, synergistic with penecillins

31
Q

How do tetracyclines inhibit protein synthesis?

A

Inhibits the binding of amino acyl-tRNA to accceptor site, broad spectrum, bacteriostatic compounds which are typically not used for children

32
Q

What antibiotics bind to the 50S subunit?

A

Macrolides, Lincosamides and Chloramphenicol

33
Q

How do Macrolides work?

A

inhibit translocation of tRNA from A to P site, bacteriostatic and act against gram positives

34
Q

How do Lincosamides work?

A

inhibit peptidyl transferase activity, bacteriostatic broad spectrum compounds

35
Q

How do Chloramphenicols work?

A

Broad spectrum, bacteiostatic which is rarely used due to strong side effects

36
Q

What are the 4 antibiotic resistant mechanisms?

A

Exclusion of antibiotic from site of action,
New or modified antibiotic insensitive target,
Efflux pump for the removal of antibiotics,
Enzymatic modification or degradation of the antibiotic

37
Q

What are the two major forms of resistance?

A

Non-genetic and genetic

38
Q

How does an organism gain genetic antibiotic resistance?

A

Transformation, transduction or conjugation

Medsci 202 (16 decks)

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