50. Yersinia, Campylobacter, Helicobacter Flashcards
1
Q
Yersinia microbiology?
A
- GN
- enterobacteriaciae
- flagella
- motility at colder than body temp – refrigerated foods susceptible
2
Q
yersinia pathogenesis?
A
- 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
Q
yersinia virulence?
A
- cross epithelial barrier via adhesins
- inject efectors (Yops) via T3SS (resists phagocytosis, down regulates inflamm, cytokine suppression, apoptosis of macrophages)
4
Q
yersinia disease?
A
- abdominal pain
- fever, vomiting
- sepsis is rare (immunocompromised or iron-overloaded individuals)
Y.entercolitica: - inflammatory diarrhea +/- watery diarrhea
5
Q
yersinia dx?
A
- often mistaken for appendicitis – thanks to acute terminal ileitis and mesenteric lymphadinitis Stool culture - slow lactose fermenter (McConkey) - selective agar
6
Q
yersinia tx?
A
- Abx likely not beneficial
7
Q
yersinia common orgs?
A
Y. entercolitica:
- multiple serotypes
- common flora of farm animals
- foodborne gastroenteritis (pork, beef)
Y. pseudotuberculosis:
- zoonotic
- least common
8
Q
campylobacter microbiology?
A
- 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
Q
campylobacter Epi?
A
- 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
Q
campylobacter pathogenesis?
A
- 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
Q
campylobacter disease?
A
- 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
Q
campylobacter dx and tx?
A
- 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
Q
H.pylori microbiology?
A
- GN
- microaerophilic
- requires specialized growth media
- flagella
- genetic heterogeneity
14
Q
H pylori epi?
A
- huge problem worldwide
- we don’t know transmission
- most common infection in man (90% of pop in some areas)
15
Q
H.pylori pathogenesis?
A
- 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
