Answer each question in essay form.
No reference page or in-text citations.
No minimum word or page count is required; however, a comprehensive and thorough answer is expected.
1. Probiotics are defined as live microbial cultures (usually bacterial or yeast-based) that are intended to
provide beneficial effects upon consumption.
Provide a review of how probiotics are supposed to work, and include in your response a discussion
of the functionality of the normal microflora, the types of symbiosis, and the concept of microbial
antagonism. In addition, discuss any potential negative consequences to the consumption of
probiotics.
Would probiotics work better, worse, or equally well on healthy or sick individuals? Explain.
2. The rise of so-called ‘superbugs,’ microbes that are resistant to the latest and best antibiotics and
medications, have been attributed to the improper use, misuse, and overuse of antibiotics.
A microbe that carries a gene that allows the microbe to survive a particular antibiotic will either
(situation #1) constantly express the gene (and produce the protein that provides antibiotic
resistance), or (situation #2) express the gene if exposed to an amount of the antibiotic that does not
immediately kill the microbe.
a) Explain why in the first situation, microbes that carry antibiotic resistance genes are at an
evolutionary disadvantage compared to normal microbes in an environment without
antibiotics.
b) When given a prescription for antibiotics, doctors always tell patients to finish the entire
prescription, even if they feel better after just a few doses. How does situation two relate
to this piece of advice?
A patient was diagnosed with a fungal infection on their skin. However, the doctor mistakenly
prescribes a regular antibiotic cream (think prescription-strength Neosporin), which is designed to
work against bacteria.
c) Explain why the antibiotic cream will likely be ineffective against the fungal infection,
referencing specific methods of antibiotic resistance from chapter 20 as needed.
d) Describe a negative effect of using the antibiotic cream and its consequences; do not use
the cream’s lack of effectiveness on the fungal infection (and the consequences of the
worsening fungal infection).
Farmers use the concept of crop rotation (planting different crops on the same field in successive
years) to replenish the soil. Crop A may remove mineral A from the field, but crop B may replace
mineral A while consuming mineral B, and crop A may return the favor by replacing mineral B
while consuming the newly-replenished mineral A.
e) Physicians and epidemiologists have been rotating antibiotics in their prescriptions for
some time. Explain how the concept discussed above and the principles behind crop
rotation contribute to antibiotic rotation being a good policy to reduce antibiotic resistance.
3. In chapter 15, a list of the common portals of entry is provided (Respiratory tract, gastrointestinal tract, genitourinary tract, skin/parenteral route).For each of the four portals of entry, explain how a microbe likely to be pathogenic when introduced through that portal of entry is less likely to be pathogenic when attempting to enter via another portal. (There are lists of organisms that
prefer each portal listed in chapter 15, but you do not need to reference a specific microbial species in your answer).
