Microbiology Exam 3 Homework Questions

Florence Nightingale is best known as a tireless and compassionate nurse, but she was also one of the first to use statistical data for analyzing causes of mortality. Her polar area pie chart, shown here, uses colored wedges to illustrate the number of soldiers who died from particular causes in the Crimean War. What was the number of months during the period from April, 1855-March, 1856 in which the majority of deaths could be attributed to infectious disease?

8

infection

A condition, when the pathogens enter and colonize the host tissue

Diseases in which symptoms develop rapidly and resolve quickly (within a few days or weeks) are called ____.

Acute Infections

In terms of the range of affected microbes, which of the following agents will likely affect vegetative bacterial cells, mycobacteria, spores, fungi, and viruses?

Aldehydes

Which of the following describes the first stage of surveillance?

An infection control practitioner reviews a patient's chart to check the signs and symptoms.

This figure indicates the number of hospitalizations and mortalities caused by H1N1 influenza between August 30, 2009, and April 3, 2010. An epidemiologist would use similar graphs to calculate a mortality rate [(number of mortalities/number of hospitalizations) multiplied by 100]. Which of the following statements accurately describes the information shown?

At the peak of hospitalizations, the mortality rate was approximately 4 percent.

AB subunit toxins are common among bacterial toxins. The ___ subunit always promotes penetration through host cell membranes, and the ___ subunit has toxic activity.

B, A

What is the function of the CDC and the WHO?

Both of these agencies are capable of tracking incidences of diseases within large populations.

disease

Disruption of the body structure or function, which can be characterized by a set of symptoms or harm to the host

____is an important virulence factor common to all Gram-negative bacteria.

Endotoxin

A theory is a truth.

False

In Koch's postulate step1, the disease need to be found in some of the infected host and not in the healthy host.

False

Koch's postulate can be applied to virus infections.

False

We can predict the evolutionary trend of sars-cov-2 based on the trade-off hypothesis with high confidence.

False

Who founded medical statistics?

Florence Nightingale

Chlorine gas, bleach, and iodine tinctures are classified in which disinfectant grouping?

Halogens

Which of the following conditions is/are used in the pasteurization of milk?

Heat only

What is the link between animal health infrastructures and human health?

Humans in close contact with animal reservoirs can contract zoonotic diseases.

Who showed that antiseptics could prevent the transmission of pathogens from doctor to patient?

Ignaz Semmelweis and Joseph Lister

Which of the following questions is considered important in identifying the source of a nosocomial infection?

Is each patient infected with an identical isolate of the pathogenic organism?

Consider the case of Lyme disease, caused by the bacterium Borrelia burgdorferi, and Koch's postulates. Regarding B. burgdorferi, what would have to occur in order to satisfy Koch's second postulate?

It would have to be isolated from a host suffering from Lyme disease and grown in pure culture.

Amphotericin B is used for long-term antimicrobial therapy for systemic fungal infections. Its use has been linked to damaging what part of the human body?

Kidneys

When a new emerging disease is reported to the CDC or the WHO, epidemiologists rush to determine the index case. Why is identification of the index case important?

Knowing the index case is useful in containing the spread of an epidemic.

Triclosan is a halogenated bisphenol. It is bactericidal at high concentration, but at low concentration, it is bacteriostatic because it inhibits biosynthesis of which of the following?

Lipids

These three graphs show the incidence of three vaccine-preventable diseases in the United States. Which of the following statements is true?

Measles and mumps have shown a general decline over time, while pertussis has recently increased.

What do we call the collection of bacteria, archaea, and eukaryotic microbes that normally inhabit the human body?

Microbiota

When humans live in close contact with wild and domestic animals, which of the following is likely to occur?

New diseases may erupt as bacteria and viruses in the animals evolve the ability to infect humans.

A patient with flue was detected Influenza A positive. You are a doctor. Should you prescribe some antibiotics to the patient to ease the symptoms?

No

In this figure, "P" represents pteridine, "G" represents glutamic acid, and "SFA" represents sulfanilamide. Sulfanilamide works by directly blocking folic acid synthesis. Sulfanilamide is an antibiotic that is similar in structure to

PABA

Pathogen A has an LD50 of 1,000, and pathogen B has an LD50 of 75. Which of the following is true?

Pathogen B is more virulent than pathogen A.

This diagram shows the spread of severe acute respiratory syndrome (SARS) through a population. The circles represent SARS patients within the population. Which of the following statements correctly matches a patient with his or her role in this outbreak?

Patient 35 is a "superspreader."

____ causes a life-threatening, chronic lung infection in individuals with cystic fibrosis (CF).

Pseudomonas aeruginosa

Who were the first to record observations of microbes through simple microscopes.

Robert Hooke and Antonie van Leeuwenhoek

The figure shown illustrates one criterion in Koch's postulates. What is the outcome of this step if the microbe suspected of causing the disease is the true agent?

Signs and symptoms of the disease under investigation will develop.

Which of the following is a potential problem with satisfying Koch's third postulate in practice?

Some disease-causing microorganisms only cause infection in humans, so no animal models are available.

Consider the image and then answer the question. Assume microbial growth medium is contained inside the Erlenmeyer flask. Which of the following best describes the process that is taking place and the instrument being used?

Sterilization in an autoclave

Why are pandemics more likely now than they were 100 years ago?

Technology has made it possible for people to travel around the globe more rapidly.

While monitoring the presence of an infectious agent in a population, a clinical microbiologist notices the appearance of a new mutant strain that is associated with increased virulence. Therefore, the researcher decides to measure the LD50 of the mutant strain. Based on the initial observation of increased virulence, what would the researcher expect to see?

The LD50 is decreased.

pathogenicity

The ability of an organism to cause a disease to a host

virulence

The level of harm caused by a pathogen to the host

Mia is excited to be starting her junior year of high school after months of quarantine, but for the last few weeks she has been coughing all the time, has been tired, and has lost at least 10 pounds. When she started coughing up blood, her parents took her to the emergency room. An X-ray revealed the signs of infection in her lungs, including a large hole eaten away by bacteria. Her sputum sample revealed a gram-variable rod-shaped microbe with a waxy cell wall. Mia's rapid COVID-19 test was negative. Awaiting further test results, doctors prescribed isoniazid and rifampin, which do not seem to be helping. Unfortunately, additional students and teachers are also presenting with similar symptoms and the very same test results. Healthy students have not had the same sputum sample results. Which of Koch's postulates describes why multiple students have similar symptoms and the same test results, while others have had no symptoms and are probably not infected?

The microbe is found in all cases of the disease but is absent from healthy individuals.

Koch's postulates include ___ (choose all that apply)

The microbe is isolated from the diseased host and grown in pure culture, when the microbe is introduced into a healthy, susceptible host (or animal model), the same disease occurs, and the same strain of microbe is obtained from the newly diseased host. When cultured, the strain shows the same characteristics as before.

Following the previous question, Mycobacterium leprae is an obligate intracellular pathogen. As such, which of Koch's postulates cannot be applied in this case to establish disease causation?

The microbe is isolated from the diseased host and grown in pure culture.

A new species of bacteria is discovered and DNA sequencing reveals the presence of a β-lactamase gene. What can be deduced from the information given?

The new species of bacteria will be resistant to antibiotics with a ß-lactam ring.

An epidemiologist studying diphtheria in Eastern Europe gathers information about the total number of active cases in a given area and the number of new cases in that area over a given time. If an epidemic occurs, which of the following would the epidemiologist notice?

The prevalence and incidence would both increase.

Pathogens can evolve from nonpathogens via horizontal gene transfers.

True

R plasmid can be transmitted among different populations of bacteria in nature.

True

True or False: Antibiotic resistance can arise spontaneously.

True

What is clavulanic acid?

a beta-lactam compound that competitively binds beta-lactamases

An endemic disease will exhibit

a low prevalence and incidence.

An 11-year-old girl undergoing a routine surgery at a local hospital develops a surgical-wound infection. Even with aggressive treatment, the girl dies. The infection she developed is best known as

a nosocomical infection.

If an avian influenza virus evolves and spreads easily from person to person, the concern is that the virus may spread across continents as

a pandemic.

Which of the following is NOT a mechanism of antibiotic resistance?

addition of modifying groups to activate the antibiotic

One way to measure virulence is to calculate the lethal dose 50% (LD50): the number of pathogens required to kill 50% of an experimental group of animal hosts. Which agent in the figure below is more virulent?

agent 1

Which statement is FALSE?

antibiotic resistance started from lab strains instead of present in nature

Which antibiotic inhibits cell wall synthesis by binding to the bactoprenol lipid carrier molecule?

bacitracin

Why is acyclovir selectively toxic to viral replication?

because the host DNA polymerase has effective proofreading activity not found in the viral polymerase

"Daisy chain" nosocomial infections

begin as patients with infections are transferred frequently between different hospital and nursing home facilities.

The antiviral DNA synthesis inhibitors work on ___ (choose all that apply)

chickenpox virus, herpes simplex virus, and HIV

Which of the following is NOT a way that antibiotic resistance genes can first originate?

conjugation

The low level of disease noted in this figure by an asterisk illustrates a(n)

endemic disease

Which of the following compounds is present in fungi but not humans?

ergosterol

Which drug is bacteriostatic?

erythromycin

A young child is diagnosed with strep throat. The signs and symptoms of strep throat are caused by the virulence and invasiveness of the ________.

etiologic agent

In addition to her work as a famous nurse, Florence Nightingale also contributed to the field of microbiology by

founding the science of medical statistics.

Which of the following did Ignaz Semmelweis demonstrate to be an important means of preventing disease transmission?

handwashing

A particular flu strain spreads easily from person to person and also has high mortality. This flu strain has

high infectivity and high virulence.

The ____begins when typical symptoms and signs of the disease appear.

illness phase

Which of the following is a common antiviral target for HIV?

inhibiting reverse transcriptase

LD50 refers to ___

lethal dose 50%

Throughout history, more soldiers have died from ________ than anything else.

microbial infections

A mutualistic relationship exists between human hosts and

microbiota

In some cases of bacterial disease it is difficult to culture the etiologic agent. Which of the following techniques would be most useful in identifying whether the agent is a bacterium?

molecular techniques, such as PCR amplification and DNA sequence analysis

The lungs use a ____ to rid themselves of foreign bodies.

mucociliary escalator

"MDR" is short for____

multidrug resistance

Infection acquired during a hospital stay (hospital-acquired infection) is called ____

nosocomial infection

Quinolones are a class of antibiotics that inhibit DNA replication. What is the molecular target of quinolones?

nucleic acid function

The links in the chain of infection from left to right in this figure are

organism, reservoir, transmission, susceptible host.

During a cholera outbreak in London in 1854, John Snow created this map. The thick black lines represent cholera deaths. The circle near the middle represents the location of a well that Snow suspected was involved in the outbreak. This map would be considered

part of an observational study.

Cell-cell communication via ____ can also help pathogens evade the immune system.

quorum sensing

Which drug target the RNA synthesis process?

rifamycin

Pick the pair of words that will make the following sentence correct. (The first word will fill in the first blank, and the second word will fill in the second blank.) A _________ is a disease manifestation that can be observed and measured by clinicians, whereas a __________ is a disease manifestation that can only be felt or experienced by the patient.

sign; symptom

Which of the following was not used to develop the germ theory of disease?

spontaneous generation

Which drug is bacteriostatic?

sulfa drugs

Which drug can cause the off target effect of stained teeth?

tetracycline

T.I. is an important parameter to consider in prescription. What statement is correct?

the higher T.I. means the safer the drug is

Which of the following statement is NOT correct?

the virulence of a pathogen remain the constant on one host

Drugs that target RNA polymerase are direct inhibitors of

transcription

Ministering to OutcastsCatherine steps inside the dimly lit leprosarium on the outskirts of Siena. It is 1367, and both leprosy and the Black Death have had devastating effects on the populations of central Italy. Catherine is here to tend to an elderly woman named Tecca who has advanced leprosy. In modern times, leprosy can be cured with antibiotics, but in the fourteenth century, there was no known treatment for the disease, and patients like Tecca were typically sequestered in colonies or special hospitals. In addition to developing large skin lesions, patients with leprosy suffer numbness and disfigurement of the face and extremities. Perhaps because of her great suffering, Tecca is abusive to her nurse, but Catherine treats her with kindness and compassion. When Tecca eventually succumbs to the disease, Catherine is alone in her task to wash and prepare the body for burial. This young woman's selfless example of caring for victims of leprosy and plague led to her canonization as the patron saint of nurses. Leprosy is caused by Mycobacterium leprae, a close relative of the causative agent of _____

tuberculosis

Which of the following is NOT considered a standard (routine) infection control measure?

using gowns and masks to interact with all patients

What drug do you use to treat a beta-lactam highly resistant bacterial population?

vancomycin

Imagine you are working on an organic farm and notice one day that the cucumbers are yellowing and bumpy, and their leaves are wrinkled and withered. You contact the agricultural extension agent at the local university and she offers to help identify the cause. After collecting leaves from affected plants, she returns to her lab to process the samples. Several days later, she calls to explain that the infectious agent appears to be microbial, although she cannot visualize it with her light microscope. The organisms also do not grow on standard laboratory media, but preparations of nucleic acid yielded single-stranded RNA. Because you have taken microbiology, you are not surprised when she tells you that a _____ is the probable cause of cucumbers' condition.

virus