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ABBEY MSII U6 > Micro Enteric Bacteria 2 > Flashcards

Micro Enteric Bacteria 2 Flashcards

1
Q

salmonella bacteriology

A
  • gram - rods
  • motile
  • seldom lactose fermenting
  • oxidase negative
  • urease negative
  • H2S producing
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2
Q

salmonella pathogenesisxmk4o

A
  1. enterocolitis
  2. enteric fevers (typhoid)
  3. septicemia
  4. risk of reactive arthritis (Reiter’s syndrome)
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3
Q

salmonella enterocolitis

A
  • usually s. typhimurium, s enteritidis, s heidelberg
  • bacteria invade gut wall (M cells) by fimbriae - immune containment
  • bacteremia rare
  • MC in children and nursing homes in US
  • high infectious dose
  • cause inflammation and diarrhea, nausea, vomiting
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4
Q

salmonella enteric fever

A

high infectious dose, invasion of gut wall - specifically peyer’s patches of distal ileum = transport in macrophages (trojan horse) to lymphatics and major organs and causes macrophage apoptosis, bacteremia, toxemia
-protected from humoral immunity by Vi capsul

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5
Q

virulence factors salmonella

A
  1. ipf operon enhances adhesion to M cells in Peyer’s patches
  2. Type 3 secretion system injects M cell, enhances bacterial translocation
  3. SipB injected by Spi1 type 3 system causes macrophage apoptosis
  4. Vi antigen: s. typhi capsule for immune evasion
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6
Q

what is the difference between shigella and salmonella?

A

shigella lower infectious dose and risk of HUS

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7
Q

salmonella enteric and typhoid fevers symptoms

A
  • onset: fever, malaise, diffuse abdominal pain, constipation
  • 3-4 week progression: dry cough, stupor, delirium, intestinal hemorrhage, bowel perforation, myocarditis, death
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8
Q

what causes hemorrhage/perforation in salmonella enteric/typhoid fevers

A

necrosis of the infected peyer patches

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9
Q

what pathogens use macrophage as trojan horse?

A

salmonella, TB, cryptococcus, histoplasma

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10
Q

penetration of gut by salmonella resisted by what?

A

CFTR cystic fibrosis allele (heterozygotes)

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11
Q

host risk factors for salmonella

A

corticosteroids, other immunosuppressants, malignancy, diabetes, HIV

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12
Q

salmonella septicemia

A
  • very rare in previously healthy adults

- underlying chronic disease like sickle cell predisposes

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13
Q

what are the most common sequelae to salmonella septicemia?

A

osteomyelitis, pneumonia, meningitis

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14
Q

salmonella diagnosis

A
  1. enterocolitis: nonbloody diarrhea, fever, dehydration, culture from stool
  2. typhoid: travel abroad, high fever, headache, tender abdomen, anorexia, sometimes rose spots (pink, blanchable, slightly raised), lethargy
  3. septicemia: focal symptoms related to affected organ [bone (osteomyelitis), lung (pneumonia), meninges]
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15
Q

salmonella treatment

A

enterocolitis: self-limited

enteric fevers and septicemia: IV ceftriaxone or ciprofloxacin - drain focal abscesses

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16
Q

Yersinia enterocolitica and pseudotuberculosis bacteriology

A
  • gram - oval rods
  • lack yersinia pestis virulence factors (no plague)
  • not lactose fermenting
  • urease positive
  • grows in cold
  • motile at 25 C, non motile at 37
17
Q

what does Yersinia enterocolitica and pseudotuberculosis cause?

A

foodborne gastroenteritis

18
Q

Yersinia enterocolitica pathogenesis

A

high infectious dose
-penetration of mucosa occurs in ileum –> multiplication in Peyer patches (M cells) –> spread to local lymph nodes –> mesenteric lymphadenitis (false appendicitis)

19
Q

Yersinia enterocolitica virulence factors

A

carried on chromosome and plasmid

  1. pili and Inv adhesin enhance binding to M cells in Peyer’s patches
  2. CNF dermonecrotic toxin destroys tissue
  3. Yop Type 3 secretion system injects proteins in macrophages (no phagocytosis = reduced inflammatory response)
20
Q

what is there a risk for with Yersinia enterocolitica and pseudotuberculosis

A

reactive arthritis

21
Q

pseudotuberculosis

A

similar to yersinia enterocolitica but rarer and seen with immunocompromised or liver disease
-may be associated with izumi fever in children (fever, rash, conjunctival injection, cervical lymphadenitis, inflammation of the lips and oral cavity, edema of hands and feet

22
Q

Yersinia enterocolitica and pseudotuberculosis diagnosis

A

-exam: diarrhea, dehydration, false appendicitis
-lab: culture from stool or blood
grow well after cold-enrichment

23
Q

how is pseudotuberculosis differentiated from enterocolitica?

A

pseudotuberculosis has fermentation of sorbitol and ornithine decarboxylase activity

24
Q

listeria monocytogenes bacteriology

A
  • small gram +
  • facultative anerobe
  • blue-green sheen on non-blood agar
  • forms Ls and Vs
  • grows well in cold
  • tumbling motility by termperature-sensitive flagella
  • beta hemolytic
  • intracellular
25
Q

what foods is listeria monocytogenes associated with?

A

unpasteurized dairy products, undercooked meat, raw veggies (cold food)

26
Q

what does listeria cause?

A

gastroenteritis - usually in immunosuppressed and pregnant/fetus

27
Q

what does listeria infection cause in pregnant women?

A

3rd trimester - escape GI and proliferate in the placenta

-causes preterm labor, abortion, stillbirth, intrauterine infection

28
Q

what does listeria cause in the neonate?

A
  • early onset sepsis and premature birth with abscesses and/or granulomas
  • transmission from vagina during birth = late-onset meningitis with sepsis
29
Q

listeria diagnosis on exam

A

previously healthy: watery diarrhea, fever, headache, cramps

pregnancy: fever, arthralgia, back pain, headache
immunocompromised: (think transplant!) CNS: mental status changes, seizures, cranial nerve deficits, strokelike hemiplegia, tremor, myoclonus, ataxia, brain abscess

30
Q

listeria lab

A

gram stain: diphtheroids

culture: small, gray, beta-hemolytic colonies, motility (tumbling), sugar fermentation

31
Q

which bacteria have risk of HUS?

A

shigella and enterohemorrhagic E coli (O157:H7)

32
Q

which bacteria have a risk of reactive arthritis/Reiter’s syndrome?

A

shigella, salmonella, yersinia

ABBEY MSII U6 (18 decks)

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