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May 12 and 14, 2015 homework 參考答案
1. What is the virulence factor responsible for the typical symptoms of diphtheria?
Slide 7 : lysogenized strains produce an exotoxin that inhibits protein synthesis and is
responsible for pathogenesis
Why not all Corynebacterium diphtheria strains possess this factor?
同上，非 lysogenized strains 不致病
How are individuals protected against this infection?
Slide 9 :
treatment, prevention, and control
–antitoxin given to neutralized unabsorbed exotoxin in patient’s tissues
–antibiotic therapy
–active immunization with DPT (diphtheria-pertussis-tetanus) or acellular DTap vaccine
2. Different from Corynebacterium diphtheria, Legionella spp. does not produce potent toxins, and
yet Legionella spp. could cause severe infections in high risk group. What is the major
virulence factor of Legionella spp.?
Facultative intracellular parasites 絕對細胞內寄生
或 capable of replication in alveolar macrophages & monocytes; inhibit phagolysosome fusion
What is the reservoir of this bacterium?
Slide 10 :
spread by airborne transmission from environmental reservoir to human host
–soil, aquatic ecosystems, air-conditioning systems, and shower stalls
Why microscopic examination and cultivationt are not efficient for diagnosis of this bacterium?
Facultative intracellular parasites 絕對細胞內寄生
Then, what is the suitable way for diagnosis?
Textbook P935 : 偵測血液中抗體或尿液中抗原
3. How is tuberculosis diagnosed and what is the key virulence factor of Mycobacterium tuberculosis?
Slide 23 diagnosis & Slide 18 virulence factors
Describe the various types of tuberculosis lesions and how they are formed.
Slide 20 :
Why a complex antibiotic therapy is used for treatment?
How does multidrug-resistant strains of tuberculosis develop? How to increase the ‘herd
immunity’ against tuberculosis?
Slide 23 & Textbook P940
4. How is the infection of Orientia tsutsugamushi (恙蟲立克次體) (the old name, Rickettsia
tsutsugamushi) transmitted? How does trasnovarian passage occur?
Slide 43, transmitted by ticks
–transovarian passage (經卵傳播)–transmission of bacteria from generation to generation of
ticks through their eggs
–passage by tick feeding or by defecation of tick and rubbed into skin
This bacterium is very different from most other bacteria in physiology and metabolism.
Briefly describe its physiology and metabolism (see textbook p.518).
Textbook P518
Textbook P948
5.
How do humans acquire gas gangrene?
Slide 47 & 48
6.
How does Helicobacter pylori establish infections in humans? Studies have shown that H.
pylori is also a causative agent for gastric cancer. Explain why.
Slide 56 & 57
7.
Why a vaccine for Neisseria gonorrhea is not available?
(1) N. gonorrhoeae has surface proteins, which bind to receptors on immune cells. In so
doing, N. gonorrhoeae is able to prevent an immune response.
(2) N. gonorrhoeae can also evade the immune system through a process called antigenic
variation, in which the N. gonorrhoeae bacterium is able to alter the antigenic determinants (sites
where antibodies bind). The many permutations of surface proteins make it more difficult for
immune cells to recognize N. gonorrhoeae and mount a defense.
What is the best way to prevent infections caused by Neisseria gonorrhea?
Slide 64
8.
What is the major virulence factor of Staphylococcus aureus responsible for the clinical
symptoms of Staphylococcal toxic shock syndrome? How does this virulence factor work?
Slide 81 & Textbook P959
9.
How is trachoma transmitted? Why blindness may occur?
Slide 90
10. Define infection and intoxication. Which one does the food poisoning caused by
Staphylococcus aureus and Vibrio parahaemolyticus belong to?
Slide 94 & Glossary G-14 & G-15
11. Why botulinum toxin could be used to reduce wrinkles? How does this toxin work?
Slide 95 & 96
12. What is the toxin produced by enterohemorrhagic E. coli? What is the origin of this toxin?
Slide 105 & Textbook P970
releases shiga-like toxins, 參考 Slide 113 shiga toxin & Slide 40 Type III secretion
What is the major virulence determinant of enteropathogenic E. coli?
Slide 103 & 104 Type III secretion & Textbook P969-970
參考 Slide 40 Type III secretion
13. What is zoonotic infections?
Slide 117, diseases transmitted from animals to humans
Why the zoonotic infection Anthrax could be used as bioterrorism?
Slide 118
14. In both Clostridium difficle-associated disease and bacterial vaginosis, the diseases begins when
the normal microbiota of the site is altered. Why?
Slide 133
為 normal flora, 若體內其他正常菌叢失去平衡 (如濫用抗生素), 伺機而起