Module 9 quiz questions

What is the best definition of virulence factors in bacterial infections?

Molecules produced or strategies employed by disease-causing bacteria to infect and survive in the host

Which phase of the bacterial growth curve is characterized by the upregulation of genes encoding toxins and degradative enzymes?

Stationary phase

What is the purpose of adhesins in bacterial infection?

To mediate the attachment of the bacterium to the host and promote a close association with host cells

What is the role of siderophores in bacterial survival?

To transfer lactoferrin and other iron-binding proteins

What is the primary component of the matrix in biofilms?

Polysaccharides

What stain or dye is commonly used to visualize biofilm formation?

Crystal violet

What is the role of defensins in antimicrobial activity?

Depolarization of bacterial cell membranes

How do capsules contribute to bacterial resistance against antimicrobial peptides (AMPs)?

They limit the diffusion of AMPs

What are siderophores?

Low molecular weight proteins that have a high affinity for iron

Which type of pili in Salmonella Typhimurium is involved in the formation of aggregates and biofilms?

Type 5 pili (curli pili)

When a host cell ingests bacteria, the bacteria become enclosed in a membrane-bound compartment called a:

Phagosome

One method pathogens use to evade the complement system and phagocytosis is by producing:

Capsules

Why are encapsulated bacteria not necessarily serum-resistant?

Proteins can diffuse through the loose network of the capsules

How do bacteria mimic host polysaccharides?

By producing capsules

What is the function of glycosylation in bacterial pili?

It masks the antigenic sites of pili

What advantage do encapsulated bacteria gain by preventing C3bBb formation on their surfaces?

Reduced formation of the membrane attack complex (MAC)

What is the role of modified LPS in immune mimicry?

It allows the pathogen to evade detection by the host immune system

What are the two categories of bacterial invasion pathways?

“Zipper” and “trigger”

What are invasins?

Bacterial surface proteins

What is the purpose of escaping the phagosome?

To avoid the hostile environment of the lysosome

What is the effective host defense against bacteria that escape from the phagosome?

Cytotoxic T cell response or natural killer (NK) cell response

What is the function of ActA in Listeria monocytogenes?

To recruit actin and form comet tails

Which bacterial species exhibit actin-based motility similar to Listeria?

Shigella flexneri and Rickettsia spp.

What are the two distinct developmental forms of Chlamydia bacteria?

Elementary body (EB) and reticulate body (RB)

What are the two developmental forms of Coxiella burnetii?

Small-cell variant (SCV) and large-cell variant (LCV)

How does Legionella pneumophila evade fusion with the lysosome within host cells?

By inhibiting lysosomal fusion

How does Salmonella Typhimurium evade the host immune response and replicate inside host cells?

By preventing phagolysosomal maturation; by forming unique Salmonella-containing vacuoles; By triggering actin rearrangements in host cells; By delivering effectors that establish a growth-conducive environment

How does Brucella evade acidic conditions within the phagolysosome?

By residing within membrane-bound vacuoles that do not fuse with lysosomes

What are two enzymes produced by bacteria to neutralize reactive oxygen species?

Catalase and superoxide dismutase (SoD)

What are the two main species of Salmonella?

Salmonella enterica and Salmonella bongori

What are the two major types of Salmonella infections?

Nontyphoidal salmonellosis and enteric fever

What does the "O" antigen of Salmonella refer to?

oligosaccharides found on the lipopolysaccharides

Which antigen is associated with flagellar proteins in Salmonella?

H antigen

Why is the Vi capsular polysaccharide vaccine not effective against non-typhoidal strains of Salmonella?

Non-typhoidal strains lack the Vi antigen

When are antibiotics typically prescribed for salmonellosis?

In high-risk individuals or specific Salmonella strains

What is the relationship between the genomic repertoire of Salmonella and the severity of the disease it causes?

The more diverse the genomic repertoire, the milder the disease

What is a potential complication of gastroenteritis cause by Salmonella?

Reiter’s syndrome

What is the incubation period of enteric fever caused by Salmonella?

10 to 14 days

Which component of Salmonella's lipopolysaccharide (LPS) is responsible for anchoring LPS to the outer membrane?

Lipid A

Flagella in Salmonella are responsible for:

Facilitating motility and chemotaxis

What is the unique feature possessed by S. Typhi, the causative agent of typhoid fever?

Vi antigen

What is the main function of the SPI-1 TTSS during the early stages of infection?

Facilitating reorganization of the host cell structure

What is the purpose of the acid tolerance response in Salmonella?

Overcome acidic pH levels in the stomach