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

1. flavored herb oil.

In oil, bacteria can grow that's why inhibitors are added.

2. Hops are known for their antibacterial activity. Hops are added in the beer to prevent growth of microorganisms in yeast.

the compound which will not inhibit growth of bacteria will be yeast.

Ethanol Inhibits cell membrane functionality

Low pH Affects enzyme activity

Enhances inhibitory effects of hops

Hops      Inhibits cell membrane functions

Affects Gram?positive bacteria only

3. She was an incubatory carrier.

This statement is not correct.

She was an asymptomatic carrier as she didn't have any symtpoms.

she was the index case.

she was a convalescent carrier.

Human reservoirs may or may not show the effects of illness. a carrier is a person with inapparent infection who is capable of transmitting the pathogen to others.

Asymptomatic or passive or healthy carriers are those who never experience symptoms despite being infected.

Incubatory carriers are those who can transmit the agent during the incubation period before clinical illness begins.

Convalescent carriers are those who have recovered from their illness but remain capable of transmitting to others.

4. All the above are components of components of gram-negative cell wall.

In the Gram-negative Bacteria the cell wall is composed of a single layer of peptidoglycan surrounded by a membranous structure called the outer membrane. The gram-negative bacteria do not retain crystal violet but are able to retain a counterstain, commonly safranin, which is added after the crystal violet. The safranin is responsible for the red or pink color seen with a gram-negative bacteria. The Gram-negative’s cell wall is thinner (10 nanometers thick) and less compact than that of Gram-positive bacteria, but remains strong, tough, and elastic to give them shape and protect them against extreme environmental conditions. The outer membrane of Gram-negative bacteria invariably contains a unique component, lipopolysaccharide (LPS) in addition to proteins and phospholipids. The LPS molecule is toxic and is classified as an endotoxin that elicits a strong immune response when the bacteria infect animals.