50. Yersinia, Campylobacter, Helicobacter Flashcards Preview

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Flashcards in 50. Yersinia, Campylobacter, Helicobacter Deck (18):
1

Yersinia microbiology?

- GN
- enterobacteriaciae
- flagella
- motility at colder than body temp – refrigerated foods susceptible

2

yersinia pathogenesis?

- tropism for lymphoid tissue (invades and replicates within macrophages and travels to mesenteric lymph nodes where they form micro-colonies)
- virulence plasmid
- evade host immune response
- differences among species thanks to chromosomal islands and additional plasmids
- highly regulated by temperature
- colonization of distal small intestine, proximal colon
- penetrates M cells and epithelial cells
- replicate extracellularly in MLN in micro-abscesses and resist phagocytosis

3

yersinia virulence?

- cross epithelial barrier via adhesins
- inject efectors (Yops) via T3SS (resists phagocytosis, down regulates inflamm, cytokine suppression, apoptosis of macrophages)

4

yersinia disease?

- abdominal pain
- fever, vomiting
- sepsis is rare (immunocompromised or iron-overloaded individuals)

Y.entercolitica: - inflammatory diarrhea +/- watery diarrhea

5

yersinia dx?

- often mistaken for appendicitis – thanks to acute terminal ileitis and mesenteric lymphadinitis
Stool culture
- slow lactose fermenter
(McConkey)
- selective agar

6

yersinia tx?

- Abx likely not beneficial

7

yersinia common orgs?

Y. entercolitica:
- multiple serotypes
- common flora of farm animals
- foodborne gastroenteritis (pork, beef)

Y. pseudotuberculosis:
- zoonotic
- least common

8

campylobacter microbiology?

- curved GN rods
- microaerophilic
- flagella
- extensive genetic variation b/w strains esp in genes for LOS, capsule, and flagellin…also may play a role in immune evasion

9

campylobacter Epi?

- major cause of foodborne bacterial infection
- commensal flora of birds
- colonizes avian GI mucosa at high numbers
- pathogen in human GI tract
- consumption of contaminated foods
- esp concern for military personnel

10

campylobacter pathogenesis?

- infectious dose is low
- guillian-barre syndrome: infection induces production of cross reacting antibodies to gangliosides tha tare damaging to peripheral nerve tissue Specific types of campylobacter LOS from the antiens that mimic gangliosides and induce Abs = molecular mimicry (RARE)

- flagella
- cytolethal distending toxin (CDT) causes disruption of host cell cycle and IL-8 secretion
- avoids innate immune response: altered flagellin structure unrecognizable by TLR-5
- curved shape for penetration, uses MT (not actin)

11

campylobacter disease?

- bacterial gastroenteritis: stool w/blood and mucus, abd cramps/pain
- fever
- traveler’s diarrhea
- systemic infections in immunocompromised
- can cause Guillian Barre syndrome (ascending paralysis) 1-3 weeks post infec.

12

campylobacter dx and tx?

- culture organism on special agar from stool sample

- Abx only if given early: macrolides and FQ
- oral replacement of fluids and electrolytes
- protective immunity

13

H.pylori microbiology?

- GN
- microaerophilic
- requires specialized growth media
- flagella
- genetic heterogeneity

14

H pylori epi?

- huge problem worldwide
- we don’t know transmission
- most common infection in man (90% of pop in some areas)

15

H.pylori pathogenesis?

- flagella allows penetration of mucous layer
- urease
-inflammatory response
- pyloric region gastritis -> excessive acid -> duodenal ulcer
- pangastritis -> atrophic gastritis -> inflammation-> hypochlorhydria -> gastric ulcer ->cancer
- promote robust immune response without clearing infec

16

H.pylori virulence?

- flagella, urease
- modified LPS not recog by TLR4
- VacA gene – variation in activity b/w strains thnx to heterogeneity (form pores in epith cell membs)
- Cag island – chrom. Gene cluster in virulent strains – CagA transported by T4SS

17

H.pylori disease?

- chronic gastritis
- duodenal ulcer disease
- gastric carcinoma
- lymphoma
- mostly asymptomatic

18

H,pylori Dx and tx?

- serology
- urea breath test
- biopsy
- cx

- super prevalent – but treat anyone + re: risk of gastric carcinoma
- combo: amoxicillin, clarithromyin, metronidaxole