16.E: Microbial Mechanisms of Pathogenicity (Exercises)
- Page ID
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)16.1: Characteristics of Infectious Diseases
In an infection, a microorganism enters a host and begins to multiply. Some infections cause disease, which is any deviation from the normal function or structure of the host. Signs of a disease are objective and are measured. Symptoms of a disease are subjective and are reported by the patient. Diseases can either be noninfectious (due to genetics and environment) or infectious (due to pathogens).
Multiple Choice
Which of the following would be a sign of an infection?
- muscle aches
- headache
- fever
- nausea
- Answer
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C
Which of the following is an example of a noncommunicable infectious disease?
- infection with a respiratory virus
- food poisoning due to a preformed bacterial toxin in food
- skin infection acquired from a dog bite
- infection acquired from the stick of a contaminated needle
- Answer
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B
During an oral surgery, the surgeon nicked the patient’s gum with a sharp instrument. This allowed Streptococcus, a bacterium normally present in the mouth, to gain access to the blood. As a result, the patient developed bacterial endocarditis (an infection of the heart). Which type of disease is this?
- iatrogenic
- nosocomial
- vectors
- zoonotic
- Answer
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A
Which period is the stage of disease during which the patient begins to present general signs and symptoms?
- convalescence
- incubation
- illness
- prodromal
- Answer
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D
A communicable disease that can be easily transmitted from person to person is which type of disease?
- contagious
- iatrogenic
- acute
- nosocomial
- Answer
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A
Fill in the Blank
A difference between an acute disease and chronic disease is that chronic diseases have an extended period of __________.
- Answer
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illness
A person steps on a rusty nail and develops tetanus. In this case, the person has acquired a(n) __________ disease.
- Answer
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noncommunicable
Short Answer
Brian goes to the hospital after not feeling well for a week. He has a fever of 38 °C (100.4 °F) and complains of nausea and a constant migraine. Distinguish between the signs and symptoms of disease in Brian’s case.
Critical Thinking
Two periods of acute disease are the periods of illness and period of decline. (a) In what way are both of these periods similar? (b) In terms of quantity of pathogen, in what way are these periods different? (c) What initiates the period of decline?
In July 2015, a report1 was released indicating the gram-negative bacterium Pseudomonas aeruginosa was found on hospital sinks 10 years after the initial outbreak in a neonatal intensive care unit. P. aeruginosa usually causes localized ear and eye infections but can cause pneumonia or septicemia in vulnerable individuals like newborn babies. Explain how the current discovery of the presence of this reported P. aeruginosa could lead to a recurrence of nosocomial disease.
16.2: How Pathogens Cause Disease
Koch’s postulates are used to determine whether a particular microorganism is a pathogen. Molecular Koch’s postulates are used to determine what genes contribute to a pathogen’s ability to cause disease. Virulence, the degree to which a pathogen can cause disease, can be quantified by calculating either the ID50 or LD50 of a pathogen on a given population. Primary pathogens are capable of causing pathological changes associated with disease in a healthy individual.
Multiple Choice
Which of the following is a pathogen that could not be identified by the original Koch’s postulates?
- Staphylococcus aureus
- Pseudomonas aeruginosa
- Human immunodeficiency virus
- Salmonella enterica serovar Typhimurium
- Answer
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C
Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50of 1 × 106 particles. Which pathogen is most virulent?
- pathogen A
- pathogen B
- pathogen C
- Answer
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A
Fill in the Blank
A(n) __________ pathogen causes disease only when conditions are favorable for the microorganism because of transfer to an inappropriate body site or weakened immunity in an individual.
- Answer
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opportunistic
The concentration of pathogen needed to kill 50% of an infected group of test animals is the __________.
- Answer
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LD50
A(n) __________ infection is a small region of infection from which a pathogen may move to another part of the body to establish a second infection.
- Answer
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focal
Cilia, fimbriae, and pili are all examples of structures used by microbes for __________.
- Answer
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adhesion
Critical Thinking
Diseases that involve biofilm-producing bacteria are of serious concern. They are not as easily treated compared with those involving free-floating (or planktonic) bacteria. Explain three reasons why biofilm formers are more pathogenic.
A microbiologist has identified a new gram-negative pathogen that causes liver disease in rats. She suspects that the bacterium’s fimbriae are a virulence factor. Describe how molecular Koch’s postulates could be used to test this hypothesis.
Acupuncture is a form of alternative medicine that is used for pain relief. Explain how acupuncture could facilitate exposure to pathogens.
