Pre Lab 5

How many microliters of a safe bacteria will you use to inoculate a Petri dish?

150 µl

Which of the following best describes a bacterial Co-Culture?

A culture containing two or more different species of bacteria grown together in the same environment.

Which of the following antibiotics inhibit protein synthesis?

An antibiotic that blocks the binding of tRNA's, An antibiotic that prevents peptide formation, An antibiotic that causes mismatches between codons and anticodons

Match the ribosomal subunits to their cell type: 60S subunit and 40S subunit:

Animal cells

Where will you patch colonies from your Master Plate onto the inoculated Petri dish?

At your table

What is the definition of multidrug-resistant (MDR) bacteria?

Bacteria resistant to more than three antibiotic classes.

Match the ribosomal subunits to their cell type: 50S subunit and 30S subunit:

Bacterial cells

Why is Bacitracin, an antibiotic found in topical ointments like Neosporin, considered a broad-spectrum' antibiotic?

Because it kills both Gram-positive and Gram-negative bacteria

Which of the following antibiotics block the synthesis of peptidoglycan molecules that form the bacterial cell wall?

Beta-lactams

Explain why an antibiotic that targets bacterial ribosomes is an example of selective toxicity.

Both the ribosomal units in bacteria are entirely different from those in animal and therefore human cells. Because the antibiotics would only inhibit the function of the bacterial ribosomes, there would be minimal harm done to the human patient.

The enzyme DNA gyrase is necessary for DNA replication in bacteria (we have different topoisomerases). Which antibiotic targets this enzyme?

Ciproflaxin

What is the name of the group of pathogens designated as 'priority status' by the WHO for urgent antimicrobial development?

ESKAPE

Why is there an increased death rate for patients infected with an ESKAPE pathogen?

ESKAPE bacteria have acquired antibiotic resistance genes.

During lab this week you will screen the soil bacterial colonies growing on your Co-Culture plates for antibiotic production. Which of the following is a species of Gram-positive bacteria that you will use to determine whether your bacterial colonies are producing an antibiotic?

Enterococcus raffinosus

During lab this week you will screen the soil bacterial colonies growing on your Co-Culture plates for antibiotic production. Which of the following is a species of Gram-negative bacteria that you will use to determine whether your bacterial colonies are producing an antibiotic?

Escherichia coli

Which of the following bacteria is NOT officially classified as one of the ESKAPE pathogens, but is recognized as a multidrug resistant pathogen that is of great concern to the healthcare community?

Escherichia coli

What has contributed to the increased representation of bacterial species with drug resistance mechanisms in hospital-acquired infections?

Genetic mutation and mobile genetic elements (gene transfer among bacterial species)

Several antibiotics target the bacterial cell wall. Why does this antibiotic lyse bacterial cells and not our own cells?

Human cells do not produce peptidoglycan

Where will you inoculate Petri dishes?

In the fume hood

If you discover that none of your soil isolates inhibit the growth of E. raffinosus or E. coli, you still have results! Explain why this is the case, and what other questions you could potentially explore with your soil isolates.

It is possible that even if our soil isolates do not inhibit the growth of E. raff or E. coli, they could be effective in inhibiting the growth of other bacteria. Several antibiotics are simply narrow-spectrum and only inhibit the growth of a select few species of gram-positive or gram-negative bacteria

Will you use an ESKAPE pathogen to test for antibiotic production by your soil isolates?

No, instead we will use non-pathogenic, related bacteria.

We have provided you with one Gram-positive species and one Gram-negative species to test your soil isolates for antibiotic production. This is to determine whether a soil isolate might be:

Producing a broad-spectrum antibiotic

Which biomolecule is synthesized by ribosomes?

Proteins

Which of the following terms can be used to describe the quality of an antimicrobial drug that selectively kills a microbial target while causing minimal harm to the patient?

Selective toxicity

An antibiotic that binds to the 30S subunit and is produced naturally by species of Streptomyces bacteria:

Tetracycline

The polymyxins are natural antibiotics produced by the bacterial species Bacillus polymyxa. They are very effective at killing Gram negative bacteria because they target which cellular structure? (think about the structure of Gram negative bacteria!)

The outer and inner membrane

What does the Zone of Inhibition really tell us about the soil bacteria in Colony A?

The soil bacteria in Colony A produce an antibiotic that inhibits the growth of E. raffinosus.

What do we really know about the soil bacteria in Colony B?

The soil bacteria in Colony B do not produce an antibiotic that inhibits the growth of E. raffinosus.

True of False: The use of antibiotics has selected for the spread of AMR genes among bacteria.

True