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Microbiology > bacterial infect, GI tract, Lect 5 > Flashcards

bacterial infect, GI tract, Lect 5 Flashcards

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Biology 101 flashcards
1
Q

cholera is due to what organism

A

vibrio cholerae infection

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2
Q

where do cholera colonize?

A
  • Bacteria colonize the small intestine mucosa with the colonized mucosa showing NO change in physical integrity
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3
Q

what is the main clinical feature of cholera

A
  • Acute and massive watery diarrhea (1 liter/hour) is the main feature of this disease.
  • “rice water” stools
  • Rapid depletion of fluids and electrolytes leading to hypo-volemic shock, metabolic acidosis, death
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4
Q

cholera has abrupt onset of what symptoms

A
  • watery diarrhea
  • Muscle cramps, poor skin turgor, wrinkle skin over fingers, (“washerwoman hands”), sunken eyes, missing pulse in extremities.
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5
Q

the watery diarrhea in cholera is created by

A

cholera toxin

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6
Q

cholera toxin has identical toxin in what organism that causes traveler’s diarrhea

A

enterotoxigenic E-coli

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7
Q

describe the cholera agent: gram status

A
  • gram negative
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8
Q

describe the cholera agent: shape, does it form spores

A
  • bent rod shape
  • nonspore-former
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9
Q

can the cholera agent live in aerobic environement? is it motile?

A
  • facultative anaerobe
  • motile, polar flagellum
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10
Q

identify V. Cholerae serogroups

A
  • serogroup O-1: classic epidemic cholera
  • serogroup O-139
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11
Q

cholera treatment

A
  • For the majority of patients, successful therapy usually only requires replacement of fluids and electrolytes.
    • Provide by IV route if patient cannot take oral fluids
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12
Q

causative cholera microbes are found naturally in what environments

A

The causative microbes are found naturally in marine coastal areas and estuaries, including the United States Gulf Coast region.

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13
Q

how is cholera spread

A
  • This disease is spread through contaminated drinking water and food.
  • Not easily spread by person-to-person route
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14
Q

who are important reservoirs for cholera

A
  • Asymptomatic human carriers important as reservoirs
    • carrier rate 1-20% in endemic regions
    • a carrier may have initiated the current cholera epidemic in Haiti
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15
Q

are vaccines available for cholera

A
  • two killed organism vaccines
    • Shanchol: O-1 killed whole cells plus toxoid
    • Dukoral: bivalent O-1 and O-139 killed whole cells
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16
Q

primary prevention for cholera

A

proper control of sewer

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17
Q

travelers to cholera endemic regions can take

A

Prophylactic tetracycline treatment

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18
Q

what is the most common cause of food-borne illness in Japan.

A

Vibrio. parahaemolyticus

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19
Q

Vibrio. parahaemolyticus causes

A

gastroenteritis to a mild cholera-like illness

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20
Q

V. parahaemolyticus normal habitat

A

This organism is normal inhabitant of coastal ocean and estuary waters

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21
Q

US cases with V. parahaemolyticus is most frequently associated with

A

mishandling infected seafood

  • improper refrigeration
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22
Q

vibrio vulnificus normal habitat

A

Also a normal inhabitant of coastal marine and estuary waters.

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23
Q

vibrio vulnificus infection is associated with

A

Infection is frequently associated with oysters

  • Wound infections
    • Through direct contact of open wound with seawater or oysters.
  • sepsis
    • Due to consumption of raw oysters
  • Acute self-limiting diarrhea associated with raw oyster consumption
24
Q

clinical presentation

  • Eruption of bullous skin lesions, shock.
  • History of oyster consumption with suspicion of liver dysfunction (alcoholism commonly)
A

sepsis from V. vulnificus

25
Q

treatment of sepsis caused by V. vulnificus

A

tetracycline

26
Q

E-coli have two means by which to cause disease

A
  • O antigen (LPS) = serogroup
    • At least 160 serogroups exist
  • H antigen (flagella) = serotype
27
Q

MOA of Enterotoxigenic E. coli (ETEC)

A
  • adheres to mucosa of small intestine and produces symptoms by elaboration of toxinds that induce diarrhea
28
Q

Enterotoxigenic E. coli (ETEC) causes what condition

A

traveler’s diarrhea

  • afebrile, watery
29
Q

Enterotoxigenic E. coli (ETEC) can be fatal in what patient population

A

ETEC disease is like cholera, but far less severe. May be fatal in infants

30
Q

clinical presentation

  • primarily in developed world
  • diarrhea that becomes bloody after 1-3 days with cramps, vomiting
  • fever in 50% patients
A

Enterohemorrhagic E. coli (EHEC)

31
Q

Enterohemorrhagic E. coli (EHEC) express what toxin (key virulence factor)

A

Shiga-like toxin (SLT)

32
Q

Enterohemorrhagic E. coli (EHEC) complications

A
  1. develop hemolytic uremic syndrome (HUS): can be fatal.
  2. acute renal failure
    1. 8-10% of O157:H7
33
Q

Enterohemorrhagic E. coli (EHEC): which One form predominates

A

O157:H7

34
Q

STEC also induces hemolytic uremic syndrome. what does STEC stand for

A

Shiga toxin producing E. coli

  • other forms of E-coli that may produce same disease syndrome
35
Q

Enterohemorrhagic E. coli (EHEC) is more common in what patient populations

A

elderly and young

36
Q

how is EHEC (O157:H7) Diagnosed

A
  • MacConkeys’s sorbitol agar can differentiate this pathogen from normal flora E. coli
    • This pathogenic strain cannot ferment sorbitol and appears white on MAC sorbitol plates while other nonpathogenic E. coli strains are a bright red/pink color.
37
Q

EHEC (O157:H7) treatment

A
  • oral rehydration
  • avoid Abx
    • Risk of HUS induction
  • do NOT use antimotility agents in children and infants
38
Q

EHEC O157:H7 is associated with what food source

A
  • reservoir is CATTLE
  • beef
  • raw milk
39
Q

route of transmission of EHEC O157:H7

A
  • This is an extreme low-dose pathogen
    • Person-to-person transmission documented
40
Q

what is E. coli O104:H4

A

a new form of enterogaggregative E. coli O104:H4 emerged in Europe

41
Q

E. coli O104:H4 traced to what food source

A

alfalfa sprouts

42
Q

E. coli O104:H4 expresses what toxin

A

shiga toxin

  • ability to produce HUS, high case fatality rate
43
Q

Campylobacter jejuni is widely distributed in what food products

A

undercooked chicken

44
Q

Give the characteristics of Campylobacter jejuni

  • gram status
  • aerobic?
  • what temp it grows best at
A
  • Gram negative
  • curved rod (sea gull shaped)
  • Motile
  • Microaerophilic
  • Grows well at 42º C
45
Q

clinical presentation

  • Very commonly patient has prodrome with fever, headache, malaise, myalgia 12-24 hours before diarrhea onset.
  • Enteritis with diarrhea
    • Loose stools to dysentery (bloody diarrhea)
    • Fever
    • abdominal pain (cramping)
  • Self-limiting (improvement after several days).
  • Severe acute abdominal pain in lower right quadrant (mimics appendicitis).
A

Campylobacter jejuni

46
Q

reservoir of Campylobacter jejuni

A
  • intestinal tract of animals
    • birds especially
47
Q

Campylobacter has the highest infection rate in what patient population

A

This GI pathogen is unusual in that the highest infection rate is in young adults (college age)

48
Q

complications of Campylobacter infection

A
  • Reiters syndrome
    • HLA-B27 individuals
  • Guillain-Barre syndrome
    • C. jejuni is the chieg precipitant of Guillain-Barre syndrome
49
Q

which bacteria has these characteristics

  • copious production of urease
A

Helicobacter pylori

  • Urease - Produces CO2 and NH4 + that raises pH and protects H. pylori
50
Q

which bacteria has these characteristics

  • gram negative
  • curved rods
  • highly motile
  • stain best in tissue biopsy with Giemsa
  • copious production of urease
A

Helicobacter pylori

51
Q

What is H. Pylori’s primary target in the host

A

Epithelial cells of pylorus

52
Q

clinical presentation

  • gastritis
    • cramps
    • halitosis: bad breath
    • N/V
  • eradication of bacteria is not correlated with relief of symptoms
A

H. Pylori

53
Q

reservoir of H. pylori

A

humans

  • gastritis has been produced by ingestion of large inoculum
54
Q

which bacteria associated with stomach adenocarcinoma

A

H. Pylori

55
Q

how is H. Pylori diagnosed

A

CLO test – detection of urease activity in biopsy tissue by pH change

56
Q

treatment for H. Pylori

A
  • The optimal antibiotic therapy has not yet been evolved.
  • Combination of antibiotics (tetracycline) plus bismuth-containing drugs are used
  • Patient may be re-infected after antibiotic eradication (by family/contacts)

Microbiology (8 decks)

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