PSAT Reading Practice Question 591
Question: 591
A nurse practitioner shares information about treatments for antimicrobials. Written in 2016.
Antimicrobials, commonly known as
antibiotics, have been around in different
forms for thousands of years. It is believed
that the ancient Egyptians and Greeks were
05some of the first societies to use garlic and
other spices for medicinal purposes to help
boost the strength and endurance of their
workers and soldiers. While the use of spices
as antimicrobials is still a practice within
10Traditional Chinese Medicine, the utilization
of pharmaceutical antimicrobials is more
widespread in Western culture.
The past few decades have seen an
explosion in antibiotic use as scientists
15continue to develop and release new
medicines for bacterial, viral, and fungal
infections. Antibiotics prescribed by doctors
today are so advanced that they are able
to target the action mechanisms of certain
20microorganisms. For example, one class
of antibiotics targets cell wall synthesis of
the microorganism, while another class
inhibits protein synthesis. Targeting different
mechanisms of action will either completely
25kill the microorganism or slow its growth.
If the antibiotic kills the microorganism,
it is classified as a bactericidal drug, while
if it only slows the growth, it is considered
bacteriostatic. Both categories of drugs have
30their advantages and disadvantages.
Bacteriostatic antibiotics are often
prescribed to patients who have an intact
immune system that can assist in killing
the microorganism causing the infection.
35Allowing the innate immune system to
do some of the work decreases the length
of time the patient needs to be on the
antibiotic, which can help eliminate some
of the unwanted side effects. Bactericidal
40drugs are prescribed when the patient
may be immunocompromised (i.e., the
natural immune system is not functioning
properly) and cannot fight off the infection.
Depending on the severity and type of
45infection, a doctor may select a narrow or
broad-spectrum bactericidal drug. Narrow
spectrum drugs are better for the patient
as they only kill the microorganism causing
the infection via a specific mechanism of
50action. This differs from broad-spectrum
drugs as they kill the microorganism and any
other cell with the same type of mechanism
of action. This often causes serious and
unpleasant side effects for the patient, such
55as superinfections and a wipeout of the
body's natural flora barrier.
Both doctors and patients want to avoid
complications from antibiotics, which is
why doctors will often collect a sample
60of the microorganism from the patient in
order to perform a culture and sensitivity
test. This test helps to identify the specific
microorganism causing the infection as
well as the best antibiotic for treatment.
65Lab technicians are able to pinpoint the
best antibiotic by measuring the "zone of
inhibition" on the microorganism growth
plate. The zone with the largest diameter
typically signifies that it will be the best
70at fighting the infection. Prescribing an
antibiotic that tests positive for the
inhibition of growth or completely stops the
growth of the microorganism will hopefully
help the patient heal faster and experience
75fewer side effects.
As the use of antibiotics continues
to increase, there is growing concern
within the healthcare community about
the development of antibiotic resistant
80microorganisms. Microorganisms that
cause infections are able to gain resistance
when their DNA spontaneously mutates,
or when they receive DNA from another
microorganism via conjugation. Once the
85microorganism has secured the needed
DNA sequence, many common antibiotics
become ineffective in fighting the infection.
The most common example of this is
MRSA (methicillin-resistant staphylococcus
90aureus), which has become a frequent
hospital-acquired infection for many sick
patients. MRSA is very difficult to fight and
requires the use of very potent antibiotic
treatments, such as IV vancomycin, for full
95body infections. To help prevent these types
of infections, the healthcare community is
trying to better educate patients on proper
use of antibiotics.
When patients receive a prescription
100for an antibiotic from their pharmacy, they
also receive instructions on how to properly
complete the antibiotic regimen. Instructions
include taking the entire prescription,
even if the patient feels better half-way
105through the regimen, as well as taking the
correct dosage of the medication (e.g., do
not double a dose). These instructions are
important to follow because patients do not
want to provide an optimal environment for
110microorganisms to thrive. By following these
simple instructions, patients will help to
decrease antibiotic-resistant infections.
| Antibiotic Tested | E. coli Zone of Inhibition | S. aureus Zone of Inhibition |
| Vancomycin | 0 mm | 20 mm |
| Ciprofloxacin | 17 mm | 16 mm |
| Amoxicillin | 10 mm | 15 mm |
Zone of Inhibition measurements to determine
the effectiveness of certain antibiotics against the microorganisms E. coli and S. aureus.
Which option gives the best evidence for the answer to the previous question?
Correct Answer: B
Explanation:
(B) Lines 76–80 speak of "growing concern" about the "development of antibiotic resistant organisms," which would be organisms not susceptible to current medical treatments. This matches the question's requirements. Lines 8–12 speak of the use of spices, and the author makes no mention of an opinion on these. Lines 88–92 describe MRSA, which is a large problem in the medical community. However, the mention of MRSA, alone, does not constitute sufficient evidence for the question. Lines 102–107 merely mention instructions for taking antibiotics, which also doesn't entirely satisfy the question's requirement of "a major concern" for the author.