Question

1. The The Food and Drug Administration (FDA) requires which ONE of the following products to contain specific levels of microbial inhibitors or acidifying agents such as phosphoric or citric acid to prevent production of Clostridium botulinum toxin in the product? (NOTE: An anaerobic environment is present in both bottled and canned products. )

Hint: Look at the lecture slides that discuss how some of these products are made. You can also look up specific information for these items on the Internet. (Microbial inhibitors are added to prevent growth of microbial contamination of the product AFTER it has been processed.)

a. bottled herb-flavored vinegar

b. bottled herb-flavored oil

c. canned oranges

d. canned sauerkraut

2. People have long known that drinking beer might be safer than drinking water because pathogens can't survive in beer. Which, if any, of the following does NOT prevent the growth of pathogens in beer?

a. ethanol

b. hops

c. yeast

d. a low pH

e. All of the above prevent growth of pathogens in beer.

3. Although Typhoid Mary did not recall ever having typhoid fever, she apparently was infected (possibly sub-clinically) at some point in her life, because she was the source of two epidemics. (It is impossible to transmit the disease if you are never infected!) Which of the following statements regarding Typhoid Mary is NOT correct?

a. She was an incubatory carrier.

b. She was a convalescent carrier.

c. She was an asymptomatic carrier.

d. She was a reservoir host for the bacteria.

e. She was the index case for these outbreaks.

4. All of the following are components of the Gram-negative cell wall EXCEPT:

a. cytoplasmic (plasma) membrane

b. lipid A

c. outer membrane

d. LPS

e. O-antigen

f. All of the above are components of the Gram-negative cell wall

Answer 1

Answer 1- Correct answer is (B) Bottle Herb-Flavored oil

Explanation:-

In Herb-flavoured Oil, Garlic and herbs are placed in oil at oxygen free environment that favours the growth of bacteria (Clostridium botulinium). So a specific level of acidification by microbial inhibitors is required to inhibit the growth of these bacteria.

Answer 2- Correct answer is (C) Yeast

Explanation:-

Pathogens cannot survive in beer, due to the presence of antimicrobial agent’s like hop (hop bitter acid), ethanol, low pH.

Ethanol inhibits cell membrane functions and inactivates bacterial activity. Low pH (3.4-4.8) is another hurdle that prevents the pathogenic activity, in addition low pH displays a synergistic effect with antimicrobial properties of Hop. It was also reported by Simpson and Hammond (1991) that a slight reduction of 0.2 in pH can increase antibacterial activity by 50 %.

Answer 3- Correct answer is (B) She was a convalescent carrier

Explanation:-

Typhoid Mary was not a convalescent carrier, because convalescent carrier are those who are clinically recovered from the infectious disease, but in the case of Typhoid Mary, she was the index case of disease outbreak that remained undisclosed for a longer period of time. During that period, she remained as asymptomatic chronic carrier as well as incubatory carrier and reservoir host of Salmonella Typhi , that unintentionally infected dozens of people.

Answer 4- Correct answer is (F) All of the above are component of the Gram-negative cell wall

Explanation:-

Cell wall of a Gram-negative bacteria is consists of plasma membrane, a gel like matrix in the periplasmic space. Lipid A, as an endotoxin accountable for toxicity of gram negative bacteria. Outer membrane is also present as an single layer of peptidoglycan surrounded by membranous structure. Lipopolysaccharides (LPS) are molecules consists of lipid and polysaccharide composed of O-antigen, present in the outer membrane of Gram-negative bacteria.