Microbial Interactions with humans:Symbiosis and Infections and pathogenesis (Lec 18)

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Which of the following is NOT a characteristic of virulence in Salmonella?

Presence of surface adhesion proteins

Inhibition of phagocyte killing

Ability to promote invasion (correct)

Resistance to host defenses

What is the main function of exotoxins?

To cause secretion of fluid into the intestinal lumen

To kill host cells

To inhibit host cell function (correct)

To damage host cell membranes

Which of the following is NOT an example of an AB toxin?

Diphtheria toxin

Staphylococcal α-toxin (correct)

Cholera toxin

Botulinum toxin

What is the function of the B subunit in AB toxins?

To bind to host cell receptor and transfer a damaging agent across the cell membrane Signup and view all the answers

Which of the following is a characteristic of Diphtheria and Cholera toxin?

ADP-Ribosyltransferase activity Signup and view all the answers

Where is Clostridium botulinum which produces botulinum toxin commonly found?

In soil Signup and view all the answers

What is the main effect of botulinum toxin on the body?

Blockage of Acetylcholine release Signup and view all the answers

Which of the following statements about normal microflora is correct?

Normal microflora allows for growth of dangerous microorganisms Signup and view all the answers

What is the role of the host in the symbiotic relationship with normal microflora?

The host provides a microenvironment that supports microbial growth Signup and view all the answers

Which of the following is NOT a mode of transmission for pathogens?

Comsumption Signup and view all the answers

Which of the following is NOT an example of an opportunistic microbe?

E. coli (normal levels) Signup and view all the answers

What is the definition of pathogenicity?

The ability of a pathogen to cause disease Signup and view all the answers

What can Pneumocystis carinii can cause within individuals with AIDS's?

Lethal pneumonia Signup and view all the answers

How is virulence measured?

By the number of cells required to kill 50% of the test animals Signup and view all the answers

Which of the following can cause heart disease if they enter the bloodstream?

Oral streptococci Signup and view all the answers

What are virulence factors?

Genes that encode factors allowing a pathogen to invade the host Signup and view all the answers

Where does Pneumocystis carinii normally occur?

Upper respiratory tract Signup and view all the answers

What are pathogenicity islands?

Sections of the genome that contain multiple virulence genes Signup and view all the answers

In which group of individuals can Pneumocystis carinii cause lethal pneumonia?

AIDS patients Signup and view all the answers

What is the function of capsules and slime layers in pathogenic bacteria?

To protect the bacteria from host defense mechanisms Signup and view all the answers

Where does colonization by pathogens typically begin?

In mucous membranes Signup and view all the answers

Which of the following toxins stimulates significantly more immune cells than normal, resulting in an inappropriately strong inflammatory immune response?

Superantigen toxins Signup and view all the answers

Which of the following toxins can cause systemic shock and death?

S. aureus toxic shock syndrome toxin Signup and view all the answers

Which component of the cell envelope of certain gram-negative bacteria is responsible for toxicity?

Lipid A Signup and view all the answers

Which of the following is NOT true about endotoxins?

They cause scarlet fever Signup and view all the answers

What can reduce host resistance and increase the probability of infection?

All of the above Signup and view all the answers

Which of the following is NOT a factor that can reduce host resistance?

Acute or chronic infection with another agent Signup and view all the answers

Which of the following is responsible for the extensive inflammation and tissue damage caused by botulinum toxin?

Lack of well-developed microflora in infants Signup and view all the answers

Salmonella species have three major sites of virulence factors, which is NOT one?

F prime plasmid Signup and view all the answers

The process of infection is the start of a pathogens process and results in disease most often. Thus, infection is the growth and disease if the tissue damage/ injury that results from infection.

True Signup and view all the answers