Salmonella spp.

Question 1

How many species are currently recognized in the genus Salmonella?

Answer 1

Two species:
* Salmonella enterica
* Salmonella bongori

Question 2

How many subspecies does Salmonella enterica have?

Answer 2

Six subspecies:
* I
* II
* IIIa
* IIIb
* IV
* VI

Question 3

What was Salmonella bongori previously classified as?

Answer 3

Subespecies V of Salmonella enterica

Question 4

What are the general characteristics of Salmonella?

Answer 4

• Gram-negative bacilli
• Non-spore-forming
• Facultative anaerobe

Question 5

What type of flagella do motile Salmonella possess?

Answer 5

Peritrichous flagella

Question 6

T/F. Salmonella species ferment lactose.

Answer 6

False, most don´t

Question 7

Which Salmonella serotype does not produce gas on sugar fermentation?

Answer 7

Salmonella typhi

Question 8

What type of sample is preferred for Salmonella isolation?

Answer 8

Freshly passed stool

Question 9

What are examples of low-selective media used for Salmonella isolation?

Answer 9

MacConkey agar and deoxycholate agar

Question 10

What are examples of intermediate-selective media for Salmonella?

Answer 10

• Salmonella-shigella agar
• Xylose-lysine-deoxycholate agar
• Hektoen enteric agar

Question 11

What selective chromogenic medium is used for Salmonella?

Answer 11

CHROMagar Salmonella

Question 12

What are examples of highly selective media for Salmonella?

Answer 12

• Selenite with brilliant green
• Bismuth sulfite agar

Question 13

What special medium is preferred for Salmonella Typhi?

Answer 13

Bismuth sulfite agar

Question 14

What is the purpose of DNA-based syndrome panels in Salmonella detection?

Answer 14

Rapid identification of gastroenteritis causes

Question 15

What methods can be used after primary isolation to confirm Salmonella?

Answer 15

• Commercial identification systems
• Screening media like TSI agar and lysine-iron agar

Question 16

How do S. Typhi and S. Paratyphi differ from NTS (Non-Typhoidal Salmonella) in terms of reservoirs?

Answer 16

• S. Typhi and Paratyphi have human-only reservoirs
• NTS can be acquired from multiple animal reservoirs

Question 17

What are the main transmission routes of NTS?

Answer 17

• Food: Eggs, poultry, undercooked ground meat, dairy
• Direct contact: with animals or their environment
• Contaminated water

Question 18

Where does Salmonella commonly reside in food animals?

Answer 18

In the intestines

Question 19

What are common sources of cross-contamination leading to sporadic salmonellosis?

Answer 19

• Raw poultry during food handling
• Poor hand hygiene

Question 20

What fresh produce has been linked to recent Salmonella outbreaks?

Answer 20

• Papayas
• Cantaloupe
• Pistachios
• Cucumbers
• Alfalfa sprouts
• Bean sprouts
• Tomatoes

Question 21

What manufactured food products have been linked to Salmonella infections?

Answer 21

• Milk and milk products
• Icea cream
• Powdered infant formula

Question 22

How does Salmonella infection begin?

Answer 22

Through ingestion of contaminated food or water

Question 23

What is the initial barrier to Salmonella colonization?

Answer 23

Gastric acidity

Question 24

How do conditions that increase gastric pH affect Salmonella susceptibility?

Answer 24

They increase susceptibility

Question 25

What adaptive response allows Salmonella to survive gastric acidity?

Answer 25

Acid tolerance response

Question 26

What host antimicrobial factors does Salmonella need to evade in the intestinal lumen?

Answer 26

* Antimicrobial peptides * Bile salts * IgA

Question 27

What physical barrier must Salmonella cross before reaching intestinal epithelial cells?

Answer 27

The protective mucous barrier

Question 28

How does Salmonella adhere to intestinal epithelial cells?

Answer 28

By expressing distinct fimbriae that enable tight adherence

Question 29

How does Salmonella invade intestinal epithelial cells?

Answer 29

Bacteria-mediated endocytosis

Question 30

After salmonella adheres to the apical epithelial surface there's a cytoskeletal rearrangement that leads to:

Answer 30

* Disrtuption of the epithelial brush border * Induction of membrane ruffles that encoles bacteria in vesicles

Question 31

What happens to Salmonella-containing vesicles after internalization?

Answer 31

Some vesicles transcytose to the basolateral membrane

Question 32

What happens to the apical epithelial brush border after Salmonella invasion?

Answer 32

It is reconstitued

Question 33

Whats the function of T3SS in salmonella?

Answer 33

* Bacteria-mediated endocytosis * Intestinal epithelial invasion

Question 34

This proteins promote membrane ruffling and Salmonella invasion by interacting with the actin cytoskeleton.

Answer 34

SipC and Sip A

Question 35

This protein: * Inserts into the host cell plasma membrane to facilitate translocation of additional virulence proteins. * Nucleates actin polymerization. * Stimulates actin filament bundling.

Answer 35

SipC

Question 36

This protein: * Enhances actin polymerization. * Stabilizes actin filaments. * Lowers the critical concentration required for polymerization.

Answer 36

SipA

Question 37

What SPI-1 translocated proteins activate Rac1 and Cdc42 during Salmonella invasion?

Answer 37

SopE and SopE2

Question 38

Proteins activated by SopE and SopE2.

Answer 38

Rac1 and Cdc42

Question 39

What cellular effects result from SopE and SopE2 activation of Rho GTPases?

Answer 39

* Membrane ruffling * Macropynocitosis

Question 40

This protein: * Acts as an inositol polyphosphatase. * Stimulates Rho GTPases. * Promotes membrane ruffling.

Question 41

By inducing a secretory response in the intestinal epithelium salmonella triggers...

Answer 41

Neutrophil recruitment

Question 42

This induces synthesis and polarized secretion of inflammatory mediators and neutrophil chemokines (e.g., IL-8).

Answer 42

Translocation of SPI-1 proteins

Question 43

What effect does SopB accumulation have on the intestine?

Answer 43

Causes basal chloride secretion and increases fluid flux (diarrhea)

Question 44

Which SPI-1 translocated proteins contribute to intestinal secretory and inflammatory responses?

Answer 44

SopA and SopD

Question 45

Intestinal inflammation may also be induced by activation of which innate immune receptors?

Answer 45

* TLR4 by LPS * TLR5 by flagellin

Question 46

How does inflammation contribute to diarrhea in Salmonella infection?

Answer 46

Disrupts the epithelial barrier, leading to fluid secretion

Question 47

This protein inactivates Rho GTPase signaling, reducing membrane ruffling and proinflammatory signaling.

Answer 47

SptP

Question 48

This proteins help mantain host cell integrity and evade the immune response. They inhibit NF-κB activation.

Answer 48

SspH1 and AvrA

Question 49

How does Salmonella generate energy in a microaerobic environment?

Answer 49

By using tetrathionate reductase complex

Question 50

What converts thiosulfate into tetrathionate?

Answer 50

Neutrophil-derived reactive oxygen radicals

Question 51

Why does tetrathionate respiration give Salmonella an advantage?

Answer 51

Allows Salmonella to outcompete commensal bacteria in the gut

Question 52

Why are typhoidal salmonellae poor intestinal colonizers?

Answer 52

They lack tetrathionate respiration

Question 53

How does Salmonella enter macrophages?

Answer 53

Through bacteria-mediated macropinocytosis or phagocytosis.

Question 54

Why is Salmonella survival in macrophages important?

Answer 54

Enables dissemination and systemic disease

Question 55

T/F. Salmonella can survive inside the phagolysosome.

Answer 55

True

Question 56

Two-component regulatory system that helps Salmonella adapt to the intracellular environment (acidity).

Answer 56

PhoP/PhoQ

Question 57

What bacterial modifications occur after PhoP/PhoQ activation?

Answer 57

* Changes in LPS structure * Membrane modifications * Repression of flagellin synthesis

Question 58

What structure does S. Typhi synthesize for immune evasion?

Answer 58

Vi capsule

Question 59

How does the Vi capsule protect S. Typhi?

Answer 59

Resists phagocytosis, complement killin, and LPS recognition

Question 60

What advantage does the Vi capsule provide inside macrophages?

Answer 60

Promotes survivial within macrophages

Question 61

What is the role of SPI-2 translocated proteins in Salmonella?

Answer 61

They alter phagosome trafficking to promote bacterial growth

Question 62

Common manifestations of salmonella infection.

Answer 62

* Gastroenteritis * Enteric fever * Bacteremia and vascular infection * Localized infections * Chronic carrier state

Question 63

What type of Salmonella causes acute gastroenteritis?

Answer 63

Nontyphoidal salmonella

Question 64

What are the common symptoms of NTS gastroenteritis?

Answer 64

* Nausea * Vomiting * Diarrhea

Question 65

What systemic symptoms can occur with NTS gastroenteritis?

Answer 65

* Fever * Abdominal cramping * Chills * Headache * Myalgias

Question 66

What conditions can NTS gastroenteritis mimic?

Answer 66

* Pseudoapendicitis * Inflammatory bowerl disease * Toxic megacolon

Question 67

Who is at high risk for severe NTS disease?

Answer 67

* Elderly * Immunocompromised individuals

Question 68

What long-term condition is linked to NTS gastroenteritis?

Answer 68

Irritable bowel syndrome

Question 69

What bacteria cause enteric fever?

Answer 69

S.Typhi and S. Paratyphi

Question 70

What is required for a definitive diagnosis of enteric fever?

Answer 70

Isolation of the bacteria from: * Blood, bone marrow, or a sterile site * Intestinal secretions * Punch bipsy of rose spots

Question 71

Faint salmon-colored lesions on the trunk, seen in week 1 of enteric fever.

Answer 71

Rose spots

Question 72

What are the hallmark symptoms of enteric fever?

Answer 72

Fever and abdominal pain

Question 73

T/F. Gastroenteritis caused by salmonella just needs fluid and electrolyte treatment. Antimicrobial treatment is not recommended.

Answer 73

True

Question 74

Which organ is colonized by salmonella in the chronic carrier state?

Answer 74

Gallbladder