Enterobacteriaceae

Question 1

What is the predominant reservoir for enterobacteriaceae?

Answer 1

Lower GI tract and environment

Question 2

Which sites are frequently colonized by enterobacterial species?

Answer 2

Human genitourinary tract and oropharynx

Question 3

Which individuals are particularly prone to colonization by enterobacteriacheae?

Answer 3

Hospitalized or immunosuppressed individuals

Question 4

What is a major global health threat related to enterobacteriaceae?

Answer 4

Antimicrobial resistance

Question 5

What are the main resistance mechanisms found in Enterobacteriaceae?

Answer 5

• Extended-spectrum β-lactamase (ESBL)–producing strains
• Metallo-β-lactamase (MBL)–producing strains
• Carbapenem-resistant Enterobacteriaceae (CRE)

Question 6

What gram type are enterobacteraceae?

Answer 6

Gramnegative

Question 7

What are the key functions of the inner membrane in Enterobacteriaceae?

Answer 7

• Maintaining the proton motive force for energy storage.
• Regulating the passage of molecules to and from the cytoplasm.

Question 8

What are some functions of the proteins in the inner membrane of Enterobacteriaceae?

Answer 8

• Electron transfer and oxidative phosphorylation
• Efflux pumps, solute transporters, protein translocation systems, and polysaccharide export systems
• Histidine kinase signaling proteins

Question 9

This is an aqueous, oxidizing environment between the inner and outer membranes.

Answer 9

Periplasmic space

Question 10

What types of proteins are found in the periplasmic space of Enterobacteriaceae?

Answer 10

• Oxidoreductases, isomerases, chaperones, proteases for protein folding and degradation.
• Lipoprotein-sorting proteins.
• Detoxifying enzymes.
• Solute-binding proteins that ferry molecules across the periplasmic space.

Question 11

What biosynthetic processes occur in the periplasmic space of Enterobacteriaceae?

Answer 11

Biogenesis of:
* Peptidoglycan
* Lipopolysaccharide
* Capsule

Question 12

Alternative name for the thin layer of peptidoglycan in enterobacteriaceae?

Answer 12

Murein

Question 13

What are the primary functions of the peptidoglycan layer in Enterobacteriaceae?

Answer 13

• Mantaining shape
• Providing osmotic stability

Question 14

Membrane proteins with a β-barrel fold that regulate the passage of hydrophilic molecules.

Answer 14

Porins

Question 15

How does the polarity of LPS affect molecule penetration?

Answer 15

Prevents the penetration of lipophilic molecules, including:
* Detergents
* Dyes
* Hydrophobic antimicrobials

Question 16

What antigen does LPS has?

Answer 16

O antigen

Question 17

What are the main surface polysaccharides found in Enterobacteriaceae?

Answer 17

• Enterobacterial common antigen
• Colonic acid
• Capsule

Question 18

How are true capsules linked in Enterobacteriaceae?

Answer 18

They are linked to either LPS or α-glycerol phosphate.

Question 19

What antigen do capsules have?

Answer 19

K antigen

Question 20

Flexible, rotating appendages that allow bacteria to propel through liquid environments.

Answer 20

Flagella

Question 21

This is the protein component of flagella and is recognized by the host innate immune system, triggering neutrophil recruitment and an inflammatory response.

Answer 21

Flagellin

Question 22

What antigen does flagella has?

Answer 22

H antigen

Question 23

This are are thin nanofilaments extending from the bacterial surface, mediating autoaggregation, adhesion to host cells, and bacterial conjugation/genetic exchange.

Answer 23

Pili

Question 24

What are the key functions of type IV pili?

Answer 24

Aid in:
* Aggregation
* Disaggregation
* Twiching motility

Question 25

What are the main types of adhesins in Enterobacteriaceae?

Answer 25

* Pili * Outer membrane proteins * Surface carbohydrates

Question 26

How do Enterobacteriaceae export toxins across their inner and outer membranes?

Answer 26

They require specific secretion machinery

Question 27

Toxins capable of lysing host cells, leading to zones of clearing on blood agar plates.

Answer 27

Hemolysins

Question 28

E. coli hemolysin is secreted in a single step across both the inner and outer membranes by a...

Answer 28

Type I secretion system (T1SS)

Question 29

Multiprotein complex spanning the periplasmic compartment. It is involved in the extracellular secretion of toxins and hydrolytic enzymes.

Answer 29

Type II secretion system (T2SS)

Question 30

This not only exports proteins through the bacterial membrane but also injects them into the host cell membrane forming a pore.

Answer 30

Type III secretion system (T3SS)

Question 31

Enterobacteriaceae have developed efficient systems to compete with host iron-binding proteins. These systems are called...

Answer 31

Iron scavenger systems

Question 32

These are low-molecular-weight compounds that have high affinity for iron.

Answer 32

Siderophores

Question 33

This protein is present in the cytoplasmic membrane, is involved in all iron uptake systems.

Answer 33

TonB