Monday, November 25, 2013

PHS_3506- Instructor: Dr. Billack

November 25 :
Lecture Topic(s):

Chapter 2: Commensal and Pathogenic Microbial Flora in Humans, p. 6-15.
Chapter 14: Mechanisms of Bacterial Pathogenesis, p. 138-146


Reading Assignments from:

Medical Microbiology, 7th edition
Patrick R. Murray, Ken S. Rosenthal, Michael A. Pfaller
Elsevier Saunders, Philadelphia, PA


Homework Assignment: (based upon the lectures and the reading assignment)
To assist your understanding of the assigned readings, please answer the following questions in the space below:

(Chapter 2-related)
1. What is the role of commensal microbes, such as those that live in the microflora of the gut?

2. What are three outcomes of exposure of an individual to a microorganism? What is the difference between colonization and disease?

3. Define the term, “strict pathogens.” List 5 examples of strict pathogens.

4. Define the term, “opportunistic pathogens.” List 3 examples of opportunistic pathogens.

5. The upper respiratory tract (mouth, oropharynx and nasopharynx) is colonized by numerous bacteria. Which are the most common anaerobes? Aerobes? And potentially pathogenic organisms?

6. The ear is colonized by which strain of bacteria. Which are the most common bacterial pathogens of the ear?

7. The eye is usually colonized by which strains of bacteria? Bacterial pathogens of the eye are?

8. Which structures comprise the lower respiratory tract? Which strains normally colonize the lower respiratory tract? List some bacterial and fungal pathogens of the lower respiratory tract.

9. The esophagus is colonized by which strains of bacteria? Which species cause most cases of infective esophagitis?

10. Describe the microbial environment of the acidic stomach.

11. Describe the microbial environment of the small intestine. The large intestine?

12. Describe the microflora of the anterior urethra. Pathogens of this tissue?
13. Describe the microflora of the vagina. Pathogens of this tissue?

14. Describe the normal microflora of the cervix. Bacterial pathogens of this tissue?

15. Describe the normal microflora of the skin? Most common bacterial skin pathogens?

Chapter 14-Related

1. What are the processes involved in allowing a bacteria to “settle in” the host?

2. What are the processes by which bacteria “cause” disease?

3. Explain virulent bacteria vs. opportunistic bacteria

4. What are the main portals of entry into the body?

5. Explain adhesins. Can you name some?

6. What is a biofilm? What advantage does it provide to the organisms?

7. Name some enzymes that help bacteria gain entry to host cells/tissues.

8. What is a bacterial toxin? What’s the difference between an endotoxin and exotoxin? Describe the endotoxin response. What is an A-B exotoxin? Describe the mechanism of diphtheria toxin, cholera toxin, tetanus toxin, botulinum toxin (see Figure 14-2, p. 141).

9. What components of Gram+ organisms elicit an immune response in host cells? Same question for G- organisms.

10. What is a superantigen? List some examples of superantigens? What is the problem associated with superantigens?

11. How can bacteria evade host defenses?