What is a mutation?
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A change in a gene.
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What is a mutation?
A change in a gene.
What are the two main mechanisms through which bacteria develop antibiotic resistance?
Mutations and natural selection.
What does the Zone of Inhibition (ZI) indicate?
The effectiveness of the antibiotic against bacteria.
What do antibiotics do?
Kill bacteria or impair their growth.
Which bacteria is a mannitol fermenter on MSA?
Staphylococcus aureus.
What can a mutation in a gene produce?
Larger shield.
What does the Kirby Bauer Sensitivity Test determine?
The sensitivity of microbes to antibiotics.
How do you determine which antibiotic is most resistant?
Check the table in the book against the diameters you measure.
What are two main factors that inflate antibiotic resistance?
Over-prescription of antibiotics and improper use of antibiotics (by patients and livestock).
What was the first natural antibiotic to be discovered?
Penicillium notatum (fungus).
Who discovered Penicillium notatum and when?
Alexander Fleming in 1928.
What are antiseptics?
Substances that kill or inhibit microbes (not endospores) and are gentle enough for use on the skin.
What are disinfectants?
Substances that kill or inhibit microbes and may kill spores, but are only for use on surfaces and objects.
What role does gene transfer play in antibiotic resistance?
Bacteria can transfer resistance genes to each other through processes like conjugation, transformation, and transduction.
How is the colony picked up?
With a swab, then stirred into saline.
What happens to a survivor in an environment with no competition?
The survivor reproduces and its population becomes antibiotic resistant.
What is the outcome of natural selection in the context of antibiotic resistance?
The population becomes antibiotic resistant.
Why are antibiotics given to livestock?
Antibiotics are given to livestock to promote growth and prevent disease.
What is a major consequence of giving antibiotics to livestock?
It contributes to the development of antibiotic-resistant bacteria.
How can bacteria evolve antibiotic resistance?
Through mutations and natural selection.
What does a zone of inhibition smaller than 19mm around S. epidermidis indicate?
The bacteria are resistant to the antibiotic toadicilin.
What does a zone of inhibition greater than 20mm around S. epidermidis indicate?
The bacteria are sensitive to the antibiotic toadicilin.
What should you measure around the antibiotic disc?
The diameter of the Zone of Inhibition (ZI).
What are antimicrobials?
Compounds that kill or inhibit microbial growth.
Do different species or families of bacteria have the same thresholds for resistance and sensitivity?
No, different species/families have different thresholds for resistance and sensitivity.
What do antibiotics do?
Kill or inhibit the growth of bacteria.
What is the primary function of sanitizers?
Sanitizers reduce microbes to limits deemed acceptable by health and safety standards but do not eliminate all microbes.
What is a potential consequence of continued overuse of antibiotics?
The creation of super resistant pathogens that we cannot kill.
What do antifungal agents do?
Kill or inhibit the growth of fungi.
What type of bacteria can grow on Mannitol Salt Agar (MSA)?
Salt-tolerant bacteria.
What does a bacteriostatic agent do?
A bacteriostatic agent prevents new microbial growth but does not kill existing cells.
What happens to resistant strains when exposed to antibiotics?
Resistant strains are not killed by antibiotics.
What is the function of a bactericidal agent?
A bactericidal agent kills microbes.
Can you name an example of a resistant strain?
MRSA (Methicillin-resistant Staphylococcus aureus).
Why should you never open a plate with S. aureus?
Because it can be pathogenic and pose a health risk.
How does penicillin inhibit bacterial growth?
By inhibiting peptidoglycan formation.
Why can penicillin kill bacteria without harming human cells?
Because peptidoglycan, which penicillin inhibits, is a bacterial cell wall component not found in human cells.
What type of plate is used in the experiment?
A nutrient agar (NA) plate.
Which bacterium is used to inoculate the nutrient agar plate?
E. coli.
How should the bottom of the plate be labeled?
With 4 circles where you will place discs.
How should the plates be kept to ensure the discs don't fall?
Keep the plates right side up.
At what temperature and for how long should the plates be incubated?
Incubate at 37°C for 24 hours.
Can antiseptics be used on the skin?
Yes, they are gentle enough for use on the skin.
Which bacteria does not ferment mannitol on MSA?
Staphylococcus epidermidis.
Where are many resistant strains commonly found?
Many resistant strains are nosocomial or healthcare-associated infections (HAI).
What should be done with the discs before placing them on the plates?
Impregnate the discs in antiseptics/disinfectants.
Why is the overuse of antibiotics a concern?
Overuse of antibiotics can lead to antibiotic resistance, making infections harder to treat.
What is the significance of a bacterium with better defense mechanisms?
It is more likely to survive antibiotic treatment.
Why is Mueller-Hinton agar used instead of Nutrient Agar (NA)?
Because it is more permeable than NA.
How can bacteria pass along defenses?
Through gene transfer, specifically plasmid transfer.
How does natural selection contribute to antibiotic resistance?
Bacteria with mutations that confer resistance are more likely to survive and reproduce, passing on the resistant traits to future generations.
What are healthcare-associated infections (HAIs) and their relation to antibiotic resistance?
HAIs are infections patients acquire while receiving treatment for other conditions in a healthcare setting, often involving antibiotic-resistant bacteria.
What is done after creating the lawn on the agar plate?
Antibiotics are dispensed.
Give examples of common antiseptics.
Hydrogen peroxide, iodine, alcohol.
Can disinfectants be used on the skin?
No, they are only for use on surfaces and objects.
At what temperature and for how long is the plate incubated?
At 37°C for 24 hours.
What is antibiotic resistance?
Antibiotic resistance occurs when bacteria evolve to survive exposure to antibiotics that would normally kill them or stop their growth.
Give examples of common disinfectants.
Bleach, formaldehyde, phenol.
From which plate is a colony being chosen?
From an S. epidermidis plate.
What happens to individuals with stronger defenses against antibiotics?
They may not die.
What is the primary action of antibiotics?
Antibiotics kill bacteria.
How is the lawn created on the agar plate?
By streaking the plate in 3 directions using 1 cotton swab.
What type of agar plate is being labeled today?
A Mueller-Hinton agar plate.
