Question 1

Endotoxin is released when

Accepted Answer

Endotoxin is a component of the outer membrane of Gram-negative bacteria. It is released when the bacteria are lysed or divide, leading to its release into the surrounding environment.

Question 2

Virulence may be measured experimentally at the host level by the __________ __________ __________,which measures the number of pathogens that kills 50% of an experimental group of hosts within a specified amount of time.

Accepted Answer

The answer of Virulence may be measured experimentally at the...

Question 3

Pathogenicity islands are typically associated with

Accepted Answer

Pathogenicity islands often contain gene clusters encoding virulence factors, such as toxins and adhesins, which are often flanked by tRNA genes. These tRNA genes are thought to facilitate the integration of the pathogenicity island into the bacterial genome by promoting recombination events.

Question 4

A ________________ infection is a disease caused by a parasitic organism that is normally found in animals other than humans.

Accepted Answer

The answer of A ________________ infection is a disease caused...

Question 5

A patient develops a high fever due to a Gram-negative pathogen.Which of the following is a certain mediator of illness in this case?

Accepted Answer

Gram-negative pathogens contain endotoxins (lipopolysaccharides) in their cellular membrane, which are released upon bacterial death or lysis and can lead to fever, sepsis, and other symptoms of illness. Exotoxins are secreted by the bacteria and can also cause illness, but their presence cannot be assumed in all cases of Gram-negative infection. Therefore, the certain mediator of illness in this case is endotoxin (choice A).

Question 6

The capacity of an organism to produce a toxin is called __________.

Accepted Answer

The answer of The capacity of an organism to produce...

Question 7

Endotoxins include which of the following?

Accepted Answer

Endotoxins are lipopolysaccharides present in the outer membrane of Gram-negative bacteria. Diphtheria toxin, tetanus toxin, and botulinum toxin are exotoxins produced by Gram-positive bacteria.

Question 8

The toxic component of lipopolysaccharide is called _________.

Accepted Answer

Lipid A is the toxic component of lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria. It is responsible for inducing septic shock and inflammation in the host. Exotoxins and hemolysins are secreted by some bacteria and can cause damage to host tissues, but they are not part of LPS. O antigen polysaccharide is the variable component of LPS and is used for serotyping bacterial species.

Question 9

Inanimate materials involved in pathogen transmission are called reservoirs.

Accepted Answer

Inanimate materials involved in pathogen transmission are called fomites, not reservoirs. Reservoirs refer to the primary habitat in the natural world from which a pathogen originates.

Question 10

The characteristics of a pathogen that determine its virulence include which of the following?

Accepted Answer

All of the choices (pathogenicity, invasiveness, infectivity) contribute to a pathogen's virulence. Pathogenicity refers to the ability of a microbe to cause disease, invasiveness refers to the ability of the microbe to invade host tissues, and infectivity refers to the ability of the microbe to establish an infection. A pathogen with high levels of all three characteristics is likely to be more virulent than one with lower levels of one or more characteristics.

Question 11

Place the events associated with each stage of infectious disease in the correct order with regard to time.
Prodromal stage
Incubation period
Convalescence
Illness period

Accepted Answer

The answer of Place the events associated with each stage...

Question 12

Your brother mentions that several days ago he began to feel as if he was coming down with a cold,but now is no longer experiencing any signs or symptoms and feels fine.Having just studied the infectious disease process in your microbiology course,you immediately recognize that he is describing the phase of illness.

Accepted Answer

The answer of Your brother mentions that several days ago...

Question 13

Which of the following is not a characteristic of lipid A?

Accepted Answer

Lipid A is not neurotoxic. It is a component of the lipopolysaccharide (LPS) molecule found in the outer membrane of Gram-negative bacteria. Lipid A is heat-stable, toxic in nanogram amounts, and weakly immunogenic. Its toxicity is responsible for the fever, chills, and shock associated with Gram-negative bacterial infections.

Question 14

The only organisms to produce endotoxins are Gram-negative bacteria.

Accepted Answer

Endotoxins are toxic substances that are part of the cell wall of Gram-negative bacteria. Therefore, only Gram-negative bacteria are capable of producing endotoxins.

Question 15

Generally,exotoxins tend to be more heat stable than endotoxins.

Accepted Answer

Endotoxins, which are part of the outer membrane of the cell wall of Gram-negative bacteria, tend to be more heat stable than exotoxins, which are usually proteins secreted by bacteria and can be denatured by heat.

Question 16

Listeria monocytogenes propels itself through mammalian host cells using

Accepted Answer

Listeria monocytogenes propels itself through mammalian host cells by using host cell actin and other cytoskeletal proteins, a process known as actin-based motility.

Question 17

The term __________ refers to the degree or intensity of pathogenicity.

Accepted Answer

The answer of The term __________ refers to the degree...

Question 18

Bacteria within biofilms exchange

Accepted Answer

Bacteria within biofilms exchange plasmids, quorum-sensing molecules, and nutrients. Plasmids are small DNA molecules that can be passed between bacterial cells, allowing for the exchange of genetic material. Quorum-sensing molecules are signaling molecules that bacteria use to communicate with one another, coordinating behavior such as the formation of biofilms. Nutrient exchange can occur within the biofilm matrix, allowing bacterial cells to share resources and increase their overall survival. Therefore, all of the choices listed are correct.

Question 19

Transfer of pathogens from host to environment and then to another host are said to be transmitted _________.

Accepted Answer

The answer of Transfer of pathogens from host to environment...

Question 20

Which of the following is not a biological effect associated with endotoxin?

Accepted Answer

Endotoxin is an LPS (Lipopolysaccharide) found in the cell wall of gram-negative bacteria. Coagulation, fever, and fibrinolysis are all biological effects associated with endotoxin. However, paralysis is not associated with endotoxin.

Quiz 35: Pathogenicity and Infection