PART A

Nearly all the antibiotics used to stop bacterial infections are natural compounds that come from microbes themselves. For example, penicillin is derived from a fungus, while vancomycin, the antibiotic used when bacteria are resistant to many other drugs, comes from a bacterium. Furthermore, although many antibiotics are chemically synthesized to resemble natural antibiotics, the “models” for them are natural products of microbes themselves.

As more bacteria become resistant to traditional antibiotics, alternative drugs must be found. Recently, scientists discovered a completely new type of antibiotic that comes from Hydra, pictured above, a small freshwater creature famous for regenerating itself when its tissues are severed. While investigating defensive mechanisms on the skin of hydras in 2008, scientists at the University of Keil in Germany came across a protein that is active against both gram-negative and gram-positive bacteria. Most importantly, it works against some drug-resistant strains of bacteria. They named this protein hydramacin.

– Can you imagine why microbes produce chemicals that are inhibitory to other microbes?

– What enables a new drug to be effective against bacteria that are able to resist old drugs?

–  How do you suppose the scientists figured out that the compound in Hydra acts against both gram-negative and gram-positive bacteria?

Ref.: Cowan, M. K. (2014) (4th Ed.). Microbiology: A Systems Approach, McGraw Hill

PART B

Directions for the students: There are 4 essay questions. Please be sure to complete all of them with thorough substantive responses. Citations are required for all responses. There is no time limit.

1. Individuals who smoke have much higher rates of lung infection. Explain which first-line defenses mechanisms may be impaired by smoking, allowing pathogens to more readily enter the lower respiratory tract.

2. The diagnosis of tuberculosis involves the observation of lung structures called tubercles on an X ray. What immunologic process leads to the formation of tubercles, and what type of immune cells may comprise these lesions?

3. Provide an explanation in support of or refuting the following statement: “Humans would never develop natural immunity to a novel biological agent created in a laboratory.”

4. Explain how super-antigens, such as toxic shock syndrome toxin produced by Staphylococcus aureus, often lead to the development of life-threatening symptoms in an infected individual.