Question 1

Vibrio cholerae is a highly virulent pathogen compared with the influenza virus.

Accepted Answer

Vibrio cholerae, while capable of causing severe cholera outbreaks, is not inherently more virulent than the influenza virus. Virulence varies widely among strains of both pathogens, and the impact of each disease depends on a range of factors including the strain, environmental conditions, and host immunity. Influenza can be highly virulent, causing global pandemics with significant mortality rates.

Question 2

Diphtheria toxin inactivates elongation factor 2 by catalyzing the attachment of adenosine diphosphate ribose from NAD⁺.

Accepted Answer

Diphtheria toxin inhibits protein synthesis by transferring ADP-ribose from NAD⁺ to the amino acid histidine in the eukaryotic translation elongation factor 2 (eEF2), leading to the inactivation of eEF2 and blocking protein synthesis.

Question 3

Gram-positive bacteria produce endotoxins.

Accepted Answer

Gram-positive bacteria do not produce endotoxins. Endotoxins are found in the outer membrane of Gram-negative bacteria, while Gram-positive bacteria have a thick peptidoglycan layer that does not contain endotoxins. Gram-positive bacteria can produce exotoxins, which are soluble and released by the bacteria into the surrounding environment.

Question 4

Endotoxins are released in large amounts only when cells lyse.

Accepted Answer

Endotoxins are released from the cell wall of gram-negative bacteria when they die or lyse. The release of endotoxins is not dependent on the amount of bacteria but rather on the death or lysis of the bacteria.

Question 5

It used to be thought that streptococci were the primary bacteria in dental plaque. What do we now know about the composition of dental plaque and how do we know it?

Accepted Answer

The answer of It used to be thought that streptococci...

Question 6

Hyaluronidase worsens infection by causing damage to red blood cells.

Accepted Answer

Hyaluronidase is an enzyme that helps bacteria break down hyaluronic acid, a substance that helps hold cells together in tissues. While hyaluronidase can help bacteria spread and infect tissues, it does not directly damage red blood cells.

Question 7

When does an infection become a disease?

Accepted Answer

The answer of When does an infection become a disease?...

Question 8

Why does Neisseria gonorrhea adhere only to mucosal epithelial cells in the genitourinary tract, eye, rectum, and throat?

Accepted Answer

The answer of Why does Neisseria gonorrhea adhere only to...

Question 9

The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

Accepted Answer

The Limulus amebocyte lysate assay is a test used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

Question 10

R plasmids help prevent the spread of virulence factors.

Accepted Answer

R plasmids are primarily known for carrying antibiotic resistance genes, which can contribute to the spread of resistance among bacterial populations, rather than preventing the spread of virulence factors.

Question 11

Clostridium botulinum are endospore-forming bacteria normally found in the soil.

Accepted Answer

Clostridium botulinum are indeed endospore-forming bacteria that are commonly found in soil, sediments of marine and freshwater environments, and the gastrointestinal tracts of animals.

Question 12

Because malnutrition can make the immune system weaker, the number of Vibrio cholera cells necessary to produce cholera in an exposed individual is drastically reduced in individuals with substantial malnutrition.

Accepted Answer

Malnutrition weakens the immune system and makes an individual more susceptible to infections like cholera. As such, it takes a much smaller number of Vibrio cholera cells to cause the disease in malnourished individuals compared to those who are well-nourished.

Question 13

Clostridium botulinum cannot produce toxins in improperly preserved foods.

Accepted Answer

Clostridium botulinum can produce toxins in improperly preserved foods, which can cause botulism. It is important to practice safe food handling and preservation techniques to prevent this.

Question 14

HIV infection causes immunosuppression because it causes the destruction of CD4 lymphocytes.

Accepted Answer

HIV specifically targets and infects CD4 lymphocytes, which play a critical role in the immune response. As the virus replicates, it destroys CD4 cells, leading to a weakened immune system and increased susceptibility to infections and certain types of cancers.

Question 15

Invasion is the ability of a pathogen to enter into host cells or tissues, spread, and cause disease.

Accepted Answer

Invasion refers to the ability of a pathogen to enter into host cells or tissues, spread, and cause disease.

Question 16

Explain how diet plays a role in the development of dental caries.

Accepted Answer

The answer of Explain how diet plays a role in...

Question 17

Hormones that are produced under stress boost normal immune responses and play a role in stress-mediated disease resistance.

Accepted Answer

The answer of Hormones that are produced under stress boost...

Question 18

The toxic lipopolysaccharides produced by most gram-negative bacteria are called exotoxins.

Accepted Answer

The toxic lipopolysaccharides produced by most gram-negative bacteria are called endotoxins, not exotoxins. Exotoxins are secreted proteins that are released by bacteria into the surrounding environment.

Question 19

Virulence genes may be located on mobile genetic elements.

Accepted Answer

Virulence genes can be located on mobile genetic elements such as plasmids, transposons or bacteriophages that can transfer from one bacterial cell to another, facilitating the spread of virulence factors among different bacterial species.

Question 20

Design an experiment to determine whether a potential pathogen produces hemolysins.

Accepted Answer

The answer of Design an experiment to determine whether a...

Quiz 25: Microbial Infection and Pathogenesis