Antibiotics and Penicillin Quiz

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Questions and Answers

Who first discovered that Staphylococcus aureus could not grow near the mold Penicillium notatum?

Howard Florey

Alexander Fleming (correct)

Ernst Chain

Pfizer

What year did Pfizer achieve mass production of Penicillin using deep-tank fermentation techniques?

1942 (correct)

1950

1945

1940

What was the yield of wild-type Penicillium notatum in 1929?

100-150 units/mL

2-20 units/mL (correct)

40-80 units/mL

80-100 units/mL

Which strain of Penicillium was found to produce 100 times more penicillin than the original strain?

Penicillium chrysogenum Signup and view all the answers

Which event occurred in 1945 regarding Penicillin?

Nobel Prize awarded to Fleming, Florey, and Chain Signup and view all the answers

Which type of microorganism is responsible for producing approximately 70% of known antibiotics?

Streptomyces bacteria Signup and view all the answers

What was the first antibiotic discovered and what organism produced it?

Penicillin, produced by Penicillium notatum Signup and view all the answers

How many known antibiotics are there approximately?

8000 Signup and view all the answers

In the context of antibiotic resistance, which statement is true?

Bacterial strains can develop resistance to antibiotics through mutation. Signup and view all the answers

What is the significance of antibiotic resistance in microorganisms?

It creates challenges in treating infections. Signup and view all the answers

What is the mechanism through which MRSA effectively resists methicillin?

By using a different protein in their cell walls Signup and view all the answers

Which factor contributed to the emergence of resistance to penicillin in Staphylococcus aureus?

The development of beta-lactamase genes Signup and view all the answers

In which year did Staphylococcus aureus first show resistance to methicillin after its introduction?

1961 Signup and view all the answers

What is a principal reason MRSA is now resistant to many antibiotics?

It produces beta-lactamase Signup and view all the answers

How did the bacterial resistance to antibiotics primarily evolve?

Via selective pressure from antibiotic use Signup and view all the answers

What is the primary purpose of the Disk-Diffusion Method in drug discovery?

To identify suitable antibiotics by checking for inhibition zones Signup and view all the answers

Which term describes the process when the combined effect of two drugs is less than the effect of either drug alone?

Antagonism Signup and view all the answers

What is the role of potassium clavulanate in antibiotic treatment?

It inhibits the activity of penicillinase Signup and view all the answers

What type of antibiotics are referred to as bactericidal?

Antibiotics that kill microbes directly Signup and view all the answers

Which of the following approaches was used for strain selection in 1970?

Strain selection with a focus on colony characteristics Signup and view all the answers

What is one form of misuse of antibiotics that can lead to antibiotic resistance?

Using antibiotics that are outdated or weakened Signup and view all the answers

Which type of penicillin is designed to have a broader range of activity?

Extended-spectrum penicillins Signup and view all the answers

What is a significant consequence of using antibiotics in animal feed?

Increased growth rates of livestock Signup and view all the answers

Study Notes

Course Information

Course code: MICR20010
Course title: Agricultural Microbiology
Instructor: Dr. Tadhg Ó Cróinín

Exam Schedule

Practical Exam: November 22nd, 2-3 PM. 30 multiple-choice questions (MCQs) over 1 hour. Focuses on practical material (manual and online). Worth 15% of the final grade.
Final Exam: December 12th, 9:30-11:30 PM. Confirm time on official schedule. 60 MCQs over 2 hours. Questions will cover lecture material. Worth 70% of the final grade.
Practice materials for both exams are available on Brightspace.

Remaining Lectures

Lecture 10: Microorganisms and Disease
Lecture 11: The Immune System
Lecture 12: Pathogenic Bacteria
Lecture 13: Pathogenic Fungi and Viruses
Lecture 14: Antibiotic Resistant Microorganisms
Lecture 15: Microbiology in the Food Industry - The Fungi
Lecture 16: Microbiology in the Food Industry - Fermentations
Lecture 17: The Nitrogen Cycle

Antibiotic Discovery and Resistance

What are Antibiotics?
- Compounds produced by microorganisms.
- Kill or inhibit the growth of other microorganisms.
- Approximately 70% are produced by Streptomyces bacteria
- Penicillin was first and produced by Penicillium notatum
- Approximately 8000 known antibiotics.
Discovery of Penicillin:
- 192: Alexander Fleming discovered that the bacterium Staphylococcus aureus failed to grow in areas contaminated by Penicillium notatum.
- 1940: Howard Florey and Ernst Chain purified penicillin, injected into mice, and initiated human trials.
- 1942: Pfizer achieved mass production of Penicillin using deep-tank fermentation techniques.
- 1950: Penicillin was available orally to the public without a prescription.
- 1945: Nobel Prize in Physiology & Medicine jointly awarded to Fleming, Florey, and Chain for the discovery of Penicillin.

Antibiotic Producing Organisms

(Table 30.2)

Various microorganisms, including bacteria (e.g., Bacillus licheniformis, Streptomyces species), fungi (e.g., Cephalosporium spp., Penicillium griseofulvin), and actinomycetes, produce antibiotics.

Development of Penicillin Strains

The original Penicillium mould (notatum) produced much less penicillin (less than 10 units per mL of broth) in 1943.
A new strain, Penicillium chrysogenum, produced 100 times more penicillin.
Strain improvement continued over the next 30 years.

Industrial Evolution of Penicillin Production

Various methods and developments in penicillin production are detailed, showing increases in yield over time.

Drug Discovery

A method of initial strain screening is described.

Check Antibiotic Spectrum

A method of determining antibiotic efficiency on different microorganisms
Streaking a sample of suspected antibiotic-producing microorganisms and testing for the zone of growth and inhibition.

Disk-Diffusion Method

Use of the Disk-Diffusion Method for identifying effective antibiotics.

Testing a Strain - Examples

Staphylococcus albus
Micrococcus luteus

The Action of Antimicrobial Drugs

Bactericidal: Directly kills microbes.
Bacteriostatic: Prevents microbes from growing.

Effects of Drug Combinations

Synergism: Combined drug effect is greater than individual drug effects. Example: Combination of penicillin with potassium clavulanate (inhibitor of penicillinase). This combination with broad-spectrum penicillin - amoxicillin is Augmentin.
Antagonism: Combined drug effect is less than individual drug effects.

Synergism between Two Different Antibiotics

Demonstrated visually by the effect of two different antibiotics on the growth of specific microorganisms.
Shows antibiotic synergy, resulting in a larger zone of inhibition.

The Action of Antimicrobial Drugs: Mechanism of Action

Cell wall synthesis
Protein synthesis inhibition
Nucleic acid replication inhibition
Plasma membrane injury
Essential metabolite synthesis inhibition

Inhibitors of Cell Wall Synthesis - example: Penicillin

Naturally occurring penicillins.
Semisynthetic penicillins (improved from natural forms, overcoming weaknesses).
Extended-spectrum penicillins (effective against a broader range of bacteria).
Penicillin G (requires injection).
Penicillin V (taken orally).

However...

A cartoon about bacteria developing resistance to penicillins.

Antibiotic Resistance

Misuse of antibiotics selects for resistant mutants.
Includes factors like outdated antibiotics, using them inappropriately, or not completing a full course.
Using antibiotics in animal feed.

Antibiotics and Animal Feed

Data shows a correlation of increasing resistance to antibiotics in poultry by use in animal feed over time.

Resistance to Penicillin

Gene for beta-lactamase (an enzyme that breaks down penicillin) carried by plasmids.
Methicillin introduced, relatively resistant to beta-lactamases.
Methicillin-resistant Staphylococcus aureus (MRSA) is a consequence

The Evolution of Drug-Resistant Bacteria

Staphylococcus aureus (commonly found on people).
MRSA (methicillin-resistant S. aureus) is a serious pathogen.
S. aureus resistance to penicillin emerged within two years of its widespread use.
Resistance to methicillin emerged shortly after its widespread use.

Methicillin

Methicillin mechanism for inhibiting bacteria.
Different protein used by MRSA strains.
MRSA strains' higher survival rate compared to non-resistant S. aureus strains when exposed to methicillin.
Current resistance to multiple drugs in the MRSA strain.

Resistance Mechanisms

Mechanisms of resistance to antibiotics: Blocking entry, inactivation of enzymes (eg: beta lactamases), altering the target molecule, and efflux.

Finding new Antibiotics

Teixobactin, a new discovery, signals a new antibiotic class.
Importance in finding new ways to combat resistance.
Exploring new environments for discovering new antibiotics.

Next Time:

Microbiology in the food industry, Part 1: The Fungi

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Description

Test your knowledge on the history and discovery of antibiotics, particularly penicillin. Explore key events like the discovery of Staphylococcus aureus's resistance and the advancements in antibiotic production. This quiz covers significant statistics, events, and concepts in the field of microbiology and antibiotic resistance.