#Yersinia, Campylobacter + Helicobacter

Question 1

Three important pathogenic Yersinia spp are __

Answer 1

Y pestis – causes bubonic plague

Y enterolitica – causes bloody, inflammatory diarrhea (this one’s the one you’ll likely see in the US)

Y pseudotuberculosis – similar to Y enterolitica

Question 2

Yersinia morphology, gram staining, enzymes etc

Answer 2

Gram negative motile (flagella) oxidase +ve curved rod

Question 3

Y enterocolitica is part of the normal flora of ___. Causes foodborne gastroenteritis, primarily from ingestion of contaminated __

Answer 3

Y enterocolitica is part of the normal flora of farm animals (sketchy says pets also). Causes foodborne gastroenteritis, primarily from ingestion of pork

Question 4

Y enterocolitica likes to grow in __ temperatures (hence why you can also find it in contaminated milk)

Answer 4

Cold temps

Question 5

Dx for Y enterocolitica

Answer 5

stool culture (slow lactose fermentation on McConkey agar)

Question 6

Rx for Y enterocolitica

Answer 6

Rx: antibiotics not usually helpful but if sensitive isolate, use cephalosporins

Question 7

Yersinia generally colonizes the ___ in the distal small intestine/proximal colon following entry thru M cells

The bug avaoids killing by macrophages via __ released by a Type 3 secretion system

The hallmark of Yersnia infection = ___

Answer 7

Colonizes Payer’s patches and lymphoid tissue following invasion into M cells

Avoids killing by macrophages via YOP proteins (yersinia outer membrane proteins) that are released by a type 3 secretion system

Hallmark of Yersinia infection = neutrophil influx (again Yersinia likes to hang out in lymphoid tissue)

**replicates extracellulary so can cause abscesses or lesions**

Question 8

Yersinia can sometimes be mis Dx’d as ___

Answer 8

Appendicitis (yersinia mimics appendicitis)

Question 9

Presentation of Yersinia infection

Rx of Yersinia infection

Answer 9

Fever, vomiting, inflammatory and/or watery diarrhea

Rx for Yersinia: cephalosporins + aminoglycosides with severe/complicated disease (ceftriaxone w/ gentamicin or ciprofloxacin)

Question 10

The virulence factors that Yersinia pestis has that the others don’t are ___

Answer 10

f1 capsule

Plasminogen activator

(all Yersinia have a Type III Secretion system)

Question 11

___ is the main Campylobacter pathogen and causes traveler’s diarrhea

Answer 11

C jejuni

Question 12

C jejuni infection is ass’d with ___(type of meat) and transmission is via __

Answer 12

Campy – often associated with poultry; lives in the guts of animals so transmission = fecal/oral

**remember the camp fire with the chicken roasting**

**can also be transmitted by ingestion of raw milk**

Question 13

Campylobacter morphological/enzyme/gram stain characteristics

Answer 13

Gram negative CURVED microaerophilic rod (oxidase +ve)

Motile

Question 14

Campy causes an __ diarrhea (like Salmonella and Shigella) and requires a __ infectious dose

Answer 14

Causes bloody inflammatory diarrhea like Salmonella and Shigella

Low infectious dose

Question 15

Rx for campylobacter infection includes __ if given only within frst 72 hrs

Answer 15

Rx: azithromycin (only effective within 72 hrs)

Question 16

Campy infection can lead to ___ (ascending paralysis) via cross-reacting surface antigens

Answer 16

Guillain-Barre syndrome (ascending paralysis, contrast with botulism which causes descending paralysis) – antibodies made against a specific call wall structure of Campy can attack host neurons (which have a similar looking structure on their surfaces #molecularmimicry)

**about 1-3 weeks post infection**

Question 17

Virulence factors of Campylobacter

Answer 17

Flagella (invasion)

CDT (cytolethal distending toxin) - host cell cycle arrest

Altered flagellin (avoid TLR5) and high AT content (avoid TLR9)

Question 18

A 26-yr old medical student presents with diarrhea and abdominal pain after eating chicken and pork in the previous 5 days. A typical Gram-negative rod, that is lactose-negative on MacConkey agar is cultured from the stool. What is the most likely pathogen?

A.Campylobacter

B.Yersinia

C.Shigella

D.Salmonella (NTS)

E.S. Typhi

Answer 18

B, C or D (what the actual heck bruh)

Question 19

Helicobacter pylori characteristics (morphology, gram staining etc)

Answer 19

Gram negative, microaeropholic, motile, helical, oxidase +ve rod

Question 20

H pylori mostly affects the __ and __

Answer 20

Stomach and duodenum

Question 21

Transmission of H pylori:

Answer 21

Person-to-person

Fomites

Food/water

Question 22

Chronic H. pylori infection is the most important

etiological factor for ___

Answer 22

Chronic H. pylori infection is the most important

etiological factor for gastric cancer

Question 23

The most important virulence factor in H pylori is ___

Answer 23

The most important virulence factor in H pylori is urease

**The conversion of urea to NH3 and CO2 allow for the neutralization of stomach acid, making an environment for the bug to #thrive**

Question 24

Outcomes of H pylori infection (3)

Gastritis in the pyloric region of the stomach results in __

Answer 24

Gastric ulcer or gastric cancer

Chronic gastritis

Duodenal ulcer

Pyloric region gastritis >> hypersecretion of acid

Question 25

H pylori virulence factors:

Flagella

__ (creates alkaline environment)

Modified LPS

Toxins (__ and ___)

Answer 25

Flagella - move thru mucous

Urease (creates alkaline environment)

Modified LPS (evade TLR4)

Toxins (VacA - forms holes in epithelial cell membrane and cagA – higher risk of severe disease and cancer)

Question 26

Role of H pylori Type IV secretion system and CagA

Answer 26

H pylori has a Type IV secretion system and release of CagA causes the following:

IL8 mediated inflammation

Actin polymerization >> change cell shape to Hummingbird phenotype

Question 27

What is one thing about the H pylori infectious process that is unique to it?

Answer 27

Unique to helicobacter: H pylori triggers host immune response but the infection itself isn’t cleared

Question 28

H pylori Dx

Answer 28

Endoscopic: urease test/tissue biopsy/histology

Non-endoscopic: serology/urease breath test

**Urease breath test: patient ingests labeled solution of urea which makes its way to the gut. If the pt has H pylori, the urea will be broken down to ammonia and CO2, then the CO2 (radiolabeled) amount is measured**

Question 29

H pylori Rx

Answer 29

Triple therapy:

PPI, amoxicillin/metronidazole, clarithromycin

Question 30

Antibiotic treatment is indicated for infections due to which of the following pathogens:

A.Salmonella (NTS) and Yersinia

B.Helicobacter, S. Typhi, and Shigella

C.Campylobacter and Shigella

D.Campylobacter and Salmonella (NTS)

Answer 30

B