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Microbiology > Enterobacteriaceae Part 1 & 2 > Flashcards

Enterobacteriaceae Part 1 & 2 Flashcards

1
Q

What are some general characteristics of Enterobacteriaceae ?

A
  • commonly found in GI and water and dirt samples (all over our environment)
  • gram (-) rods
  • facultative anaerobes (prefer O2 resp but will do fermentation too)
  • some are motile
  • are fermenters (all can ferment glucose)
  • oxidase (-)
  • non spore forming
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2
Q

What are the uses of a MacConkey Agar ?

A

to differentiate lactose fermenting from nonlactose fermenting gram (-) bacteria (no growth of gram + cocci)
- isolates gram (-) enteric bacteria
- pink= lactose fermenting (mixed acids are produced which lowers pH which turns it pink)
- colorless= nonlactose fermenting

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3
Q

What is the use of the Indole test ?

A

determine if the bacteria produce the enzyme tryptophanase
- Kovac’s reagent will detect indole
- says tryptophan is present and the bacteria could use it to produce indole, pyruvic acid, and ammonia
- +: red ring at broth surface
- (-): no formation of red ring

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4
Q

What is the purpose of a methyl red (MR) test ?

A

determines whether the microbe performs mixed acids fermentation when supplied glucose
- creates acidic products which lowers pH
- breaking down or fermenting the glucose
- +: red color (low pH, acidic)
- (-): no methyl red color

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5
Q

What is the purpose of Voges-Proskauer (VP) ?

A

indicates a form of glucose fermentation called butanediol fermentation
- makes neutral products and acetyl methyl carbinol
- done in same broth as methyl red test

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6
Q

What is IMViC ?

A

Indole test, Methyl red test, Voges-Proskauer test, and citrate utilization test
- 4 tests that are usually run together to identify/differentiate the members of the Enterobacteriaceae family

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7
Q

What is the purpose of a Kligler’s Iron Agar (KIA) ?

A
  • detects the fermentation of glucose and lactose
  • detects the production of hydrogen sulfide and carbon dioxide
  • the butt is for reading glucose
  • the slant is for reading lactose
  • has to be read within a certain amount of time since the colors can reverse
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8
Q

What is the advantage of doing a Phenol Red Broths test over KIA ?

A

the color does not reverse after a period of time unlike the KIA test

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9
Q

What is the most common enterobacterial infection in the U.S ?

A

E. Coli infections

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10
Q

What is gastroenteritis ?

A

inflammation of the lining of the stomach and intestine
- mild to severe diarrhea, low grade fever, varying degrees of nausea and vomiting

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11
Q

What is toxigenic diarrhea ?

A

bacteria release enterotoxins onto the surface of the small intestine
- bacteria doesn’t invade the tissue but toxin does damage to tissue
- large volume of stool with little blood
- seen with cholera, some E.coli and shigella

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12
Q

What is invasive diarrhea ?

A

organism invade the wall of the intestines
- disrupts the structure leading to gross injury
- smaller fecal volume, rectum pain, blood in stool, and ulceration of inner mucosal lining
-seen with salmonella, some E.Coli, and Campylobacter

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13
Q

What is the greatest single cause of mortality among babies ?

A

infantile diarrhea
- in some areas of the world it’s 15-20% in kids < 5 yrs die
- usually results from feeding baby contaminated food and water
- common in crowded tropical regions
- encourage moms in 3rd world countries to breastfeed

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14
Q

What are some conditions for higher rates of infantile diarrhea ?

A

crowded tropical regions with poor sanitary facilities, contaminated water supplies, and adults carry pathogenic strains to which they have immunity

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15
Q

What are some characteristics of Enterotoxigenic E.Coli (ETEC) ?

A

produces an enterotoxin that causes a secretory diarrhea
- Traveler’s diarrhea /Montezuma’s revenge/Delhi belly
- travelers encounter the bacteria that the local population have developed immunity
- symptoms last 5 to 15 days
- bacteria must attack to surface of the intestinal epithelial cells for toxin production to occur

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16
Q

What are some characteristics of Enteropathogenic E.Coli (EPEC) ?

A

inflammatory reaction to breakdown of intestinal epithelium
- pathogenesis is unclear
- causes diarrheal symptoms mostly in children

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17
Q

Which E. Coli is ETEC ?

A

Enterotoxigenic E.Coli
- toxigenic

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18
Q

Which E.Coli is EPEC ?

A

Enteropathogenic E.Coli
- invasive

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19
Q

Which E.Coli is EIEC ?

A

Enteroinvasive E.Coli
- invasive

20
Q

What are some characteristics of Enteroinvasive E.Coli (EIEC) ?

A

bacteria penetrate the intestinal epithelial cells causing a inflammatory diarrhea
- feces contain blood, mucous, and WBC

21
Q

Which E.Coli is EHEC/VTEC ?

A

Enterohemorrhagic E.Coli
- toxigenic

22
Q

What are some characteristics of Enterohemorrhagic E.Coli (EHEC) ?

A

associated with hemorrhagic colitis and hemolytic uremic syndrome
- produces bloody diarrhea due to toxin damage of epithelial cells

23
Q

What is hemorrhagic colitis ?

A

present with abdominal cramps and watery diarrhea followed by blood diarrhea
- no significant fever or WBC in stool

24
Q

What is hemolytic uremic syndrome ?

A

leading cause of acute renal failure in children
- only type of E.Coli that is sorbitol (-)
- distinguished by using MAC with sorbitol instead of lactose

25
Q

Which E.Coli is the only one that can’t ferment sorbitol ?

A

EHEC (enterohemorrhagic e.coli)

26
Q

What is the most communicable of bacterial diarrheas ?

A

shigella

27
Q

What are some characteristics of Shigella ?

A
  • do not ferment lactose (glucose +)
  • typically biochemical inert (most all test -)
  • fecal to oral route, takes only a few organisms
  • toxigenic only
28
Q

What are some characteristics of Yersinia Pestis ?

A
  • found in various rodents (rats & ground squirrels)
  • from rodent to rodent or from rodent to human by the rat flea
29
Q

What are the 3 different clinical forms of the Yersinia Pestis disease ?

A

bubonic, septicemic, or pneumonic plague

30
Q

What are some characteristics of the bubonic plague ?

A

(bubo=swollen lymph node)
- bacteria multiple from a flea bite then enter lymph system
- inflammation of lymph nodes called a bubo (located typically in groin, less often on axilla or neck)
- 2-8 days, ends abruptly with onset of fever, chills, headache, nausea, malaise, weakness and extreme tenderness of bubo

31
Q

What are some characteristics of the septicemic plague ?

A

bubonic plague progresses to massive bacterial growth in the blood
- initiates clotting mechanism
- palpations, chest pain and stiffness caused by circulatory stagnation
- subcutaneous hemorrhage
- purpura that may degenerate into necrosis and gangrene
- high fatality rate when untreated

32
Q

What are some characteristics of the pneumonic plague ?

A
  • dreaded complication
  • infection is lodged in lungs
  • highly contagious
  • high fatality rate when untreated
33
Q

What are the 4 internationally quarantinable diseases ?

A
  • plague
  • smallpox
  • cholera
  • yellow fever
34
Q

What are the products of butanediol fermentation ?

A

neutral products and acetylmethyl carbinol

35
Q

What are the products of mixed acid fermentation ?

A

lactic, acetic and formic acids
- acidic products

36
Q

What does a glucose fermenting only KIA result look like ?

A

K/A
- Red(top)/Yellow (bottom)

37
Q

What does a glucose and lactose fermenting KIA result look like ?

A

A/A
- yellow/yellow

38
Q

What does a nonfermenting KIA result look like ?

A

K/K
- red/red

39
Q

What does a lactose fermenting KIA result look like ?

A

A/K
- yellow/red

40
Q

What would the citrate test result of a bacteria that has the citrate transport enzyme look like ?

A

blue color (basic pH)

41
Q

What would the citrate test result of a bacteria that doesn’t have the citrate transport enzyme look like ?

A

green color (neutral pH)

42
Q

What is the pH indicator in a Citrate test ?

A

bromthymol blue

43
Q

What is the purpose of the citrate test ?

A

indicates what bacteria possess citrate transport enzyme

44
Q

What is the purpose of a Urea test ?

A

if bacteria has enzyme urease
- breaks down into ammonia and CO2

45
Q

What is the indicator in a urea test ?

A

phenol red

Microbiology (18 decks)

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