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Enterobacteriacea Flashcards

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1
Q

Which genus typically has a fruity odor?

A

Pseudomonas

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2
Q

All fermenters in the Enterobacteriacea are oxidase ___?

A

Negative

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3
Q

What are the 3 non-motile genus that are fermenters?

A

Shigella, Klebsiella & Yersinia(all 3 spp. non-motile @ 37C, only Y. pestis @ 25 & 37 C)

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4
Q

On an HE plate shigella species appear as what color?

A

Green/Blue or colorless colonies with black dots in the center due to H2S production.

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5
Q

What are the 5 main characteristics of Enterobacteriacea?

A 
Gram negative bacilli
Ferment glucose with acid production
Reduce nitrates to nitrites
Oxidase negative
Facultative anaerobes
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6
Q

What are Yersinia’s motility characteristics?

A

Non-motile at 37C and motile at 22C

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7
Q

What are the most common bacteria to cause iatrogenic infections?

A

K. pneumoniae, E. coli, P. mirabilis

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8
Q

What is the sorbitol MAC plate used for?

A

Used as a screen for E. coli 0157:H7 which is sorbitol negative.

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9
Q

What is the significance of the SIM deep?

A

Tests for motility, indole, and H2S production

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10
Q

What are the only 3 organisms that are PAD positive?

A

Proteus, Providencia, and Morganella

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11
Q

What is the significance of the CIN agar?

A

Used in the isolation and detection of Yersinia spp which grow as clear colonies with red bullseye center is a presumptive ID.

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12
Q

What is in the CIN agar?

A

Peptone base with a yeast extract, manntiol as a source of carbohydrate, antibiotics, crystal violet, neutral red (indicator), and bile salts for inhibiting gram positive and gram negative bacteria other than Yersinia.

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13
Q

What is the SS agar and how is it used?

A

Salmonella-Shigella agar. Contains bile salts and sodium citrate and brilliant green for inhibiting gram positive and gram negative non-fermenters. Neutal red as the indicator and ferric acid and sodium thiosulfate to help visualize gas and H2S production.

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14
Q

What does it mean is the SS agar is pink or red?

A

A negative result

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15
Q

What is the O antigen?

A

Somatic, heat stable, lipopolysaccharide

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16
Q

What is the H antigen?

A

Flagellar, surface of the flagella, heat labile, protein

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17
Q

What is the K antigen?

A

Capsular, species specific, heat labile, polysaccharide, inhibits detection of underlying antigens (O Ag)

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18
Q

What is the Vi antigen?

A

Surface polysaccharide, heat labile, prevents phagocytosis, specific for Salmonella typhii.

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19
Q

How do you come into contact with Salmonella?

A

Ingestion of contaminated food/water, undercooked poultry, eggs, dairy products, contaminated cooking utensils. *It is susceptible to gastric acids.

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20
Q

What do you have to do if you have a positive Salmonella culture?

A

Must do a serotyping and then send a sample to the Ohio Department of Health for confirmation.

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21
Q

S. typhii has what type of antigen?

A

Vi antigen

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22
Q

S. typhii and S. paratyphii do what to the intestines?

A

Penetrates the intestinal mucosa and gains access to the lymph nodes, can travel to the liver and spleen and multiplies in the phagocytes.

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23
Q

How was Typhoid Mary a carrier?

A

Organisms are harbored in the gall bladder and are shed periodically in the stool without causing infection or illness in the carrier.

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24
Q

What are some important reaction characteristics of Salmonella?

A

H2S positive, citrate positive, ornithine positive, MR positive.

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25
Q

What is Shigella group A?

A

Shigella dysentariae

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26
Q

What is Shigella group B?

A

Shigella flexerni

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27
Q

What is Shigella group C?

A

Shigella boydii

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28
Q

What is Shigella group D?

A

Shigella sonnei

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29
Q

Which Shigella species is the most virulent?

A

Group A, S. dysentariae

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30
Q

Which Shigella species is the most common in the U.S.?

A

Group D, S. sonnei

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31
Q

What does the fecal sample of Salmonella contain?

A

Blood and mucous, NO WBC

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32
Q

What does the fecal sample of Shigella contain?

A

Blood, mucous and wbc’s

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33
Q

How do you do Shigella serotyping?

A

Prepare a suspension of the organism, add the Group A, B, C, or D antisera. A positive reaction is clumping. A negative reaction you must boil the suspension and retest with the antisera due to the capsule.

34
Q

What is a good way to differentiate Salmonella and Shigella?

A

H2S. Salmonella is positive, Shigella is negative.

35
Q

If you have urea negative, oxidase positive, indole negative, and catalase positive what is your presumptive ID?

A

Yersinia. *A sample must be sent to the health department.

36
Q

How is Yersinia pestis spread and what are the forms?

A

Rodents are the reservoir, transmitted through the rat of flea bite. Has 2 forms: Bubonic- develops 2-5 days after the infection, fever and pain in lymph nodes. Pneumonic- can be passed person to person and affects the repsiratory and blood stream.

37
Q

How do you treat Y. pestis?

A

Streptomycin or chloramphenicol

38
Q

What does Y. pestsis look like microscopically?

A

Short plump gram negative rods, when stained with methylene blue stain they show an intense bipolar staining which gives a safety pin appearance

39
Q

What does Y. enterocolitica cause?

A

Causes acute enteritis

40
Q

What are the reservoirs for Y. enterocolitica

A

Lakes, domesticated swine, dogs, and cats. Transmitted by handling inected animal or ingestion of contaminated food or water.

41
Q

What are the symptoms of Y. enterocolitica?

A

Diarrhea, fever, headache, nausea, and abdominal cramps that mimic appendicitis. *lower right quadrant pain

42
Q

Y. enterocolitica is urea ___, ornithine ___, and sucrose___?

A

Urea positive, ornithine positive, and sucrose positive

43
Q

Y. pestsis is urea ___, ornithine ___, and sucrose ___?

A

Urea negative, ornithine negative, and sucrose negative.

44
Q

EPEC is what kind of E.coli?

A

causes infantile diarrhea and occurs in hospitalss or daycares. Stool has large amounts of mucous but no blood or wbcs

45
Q

ETEC is what kind of E. coli?

A

Traveler’s diarrhea that releass enterotoxins LT (heat labile) and ST (heat stable). Stool has no blood, no mucous and no wbcs.

46
Q

EIEC is what kind of E. coli?

A

Dysentery, with similar symptoms to Shigella. Directly penetrates and destroys the intestinal mucosa. Stool contains blood, wbcs, and mucous. Definitive ID with DNA probes. *Lactose and lysine negative

47
Q

What kind of E. coli is EaggEC?

A

Adheres to the intestinal mucosa, recovered primarily in children with chronic diarrhea.

48
Q

What kind of E. coli is EHEC?

A

Produces Shiga toxin, and associated with HUS, colitis, and hemorrhagic diarrhea. Acquired form undercooked hamburger or unpasteritzed milk. *Low infectious dose. E. coli 0157:H7 Stool has blood, mucous with no wbc’s

49
Q

How do you isolate EHEC?

A

Sorbitol MAC plate.

50
Q

What is the IMVC for E. coli?

A

IMVC ++–

51
Q

Klebsiella, Enterobacter, Serratia, and Hafnia all have what in common?

A

VP positive, normal flora of the animal/human intestines

52
Q

Klebsiella spp. have what characteristics?

A

Non-motile, Lactose positive, Ornithine negative, and restistant to ampicillin, tricarcillin, and carbenicillin.

53
Q

What is the IMVC reaction for K. pneumoniae?

A

IMVC –++

54
Q

K. oxytoca is different from all the other Klebsiella spp. by what reaction?

A

K. oxytoca is indole positive, while all the others are indole negative.

55
Q

Enterobacter is lactose ___, ornithine ___, and IMVC ___?

A

Lactose positive, ornithine positive, and IMVC –++

56
Q

How do you differentitate between Enterobacter and Klebsiella?

A

Ornithine, Enterobacter is ODH + and Klebsiella is ODH -

57
Q

What is unique about Serratia marcescens?

A

DNase positve *the only one

58
Q

How do you differentiate between all the Shigella spp. and Shigella sonnei?

A

All the Shigella spp. are ornithine negative while S. sonnei is ornithine positive.

59
Q

True of False?

Y. pestsis is non-motile at all temperatures

A

TRUE

60
Q

How do you differentiate between E. cloacae and E. aerogenes?

A

E. cloacoae = Lysine - and Arginine +

E. aerogenes = Lysine + and Arginine -

61
Q

What are the key characteristics of P. agglomerans?

A

LDH, ADH, ODH negative, has a yellow pigment on the BAP (which all other Enterobacteriacea have no pigment)

62
Q

True of False?

S. marcescens is a slow lactose fermenter

A

TRUE

63
Q

True of False?

S. marcescens can liquefy gelatin

A

TRUE

64
Q

What are the key characteristics of Proteus spp.?

A

H2S positive, urea positive, and resistant to polymixins, nitrofuratoin, and tetracycline

65
Q

How do you differentiate between P. mirabilis and P. vulgaris?

A

Ornithine.
P. mirabilis = ODH +
P. vulgaris = ODH -
*Lactose is another way of diff. and the reactions are opposite of ODH

66
Q

How do you differentiate between P. rettgeri and P. stuartii?

A

Adonitol
P. rettgeri = Adonitol +
P. stuartii = Adonitol -

67
Q

What is the differentiating characteristic between Proteus spp. and Morganella?

A

H2S production. Proteus is H2S pos. and Morganella is H2S neg

68
Q

What is the differentiating characteristic between Morganella and Providencia spp?

A

Citrate. Morganella is negative and Providencia is positive

69
Q

What is Edwardsiella associated with?

A

Reptiles and fresh water fish, common with wound infections

70
Q

Which enteric organisms are lactose positive?

A

E. coli, Klebsiella pneumoniae, E. aerogenes, and E. cloacae

71
Q

Vibrio is known by what kind of stool?

A

Rice water stool

72
Q

Vibrio has what kind of motility under a dark field microscope?

A

Shooting star motility

73
Q

Vibrio are gram ___, and what shape?

A

Gram negative rods that can be pleomorphic and comma shaped

74
Q

What does TCBS tell you?

A

Agar for vibrio and it differentiates between the sucrose fermenting (yellow colonies) and the non-sucrose fermenting (blue colonies). *Quick screen for cholera which is a sucrose fermenter.

75
Q

What does Campylobacter look like on a gram stain?

A

Gram negative rods that are curved and have a seagull appearance.

76
Q

Campylobacter likes what kind of environment?

A

Microaerophilic, and capnophilic at 42C

77
Q

What do you do if you suspect you have H. pylori?

A

Do not culture due to lack of growth. Test for serum antibodies using an ELISA or immunochromatography

78
Q

What is H. pylori associated with?

A

Gastric ulcers and gastric cancer

79
Q

How can you do a rapid screen for H. pylori?

A

Christensens medium 37C for 2 hours (CLO test) which is a rapid urease test or a urea breath test

80
Q

What is the main difference between diarrhea and dysentery?

A

Diarrhea has no histological changes in the intestinal wall and usually due to an enterotoxin.
Dysentery causes epithelial necrosis, ulceration, and inflammation due to bacterial invasion.

Microbiology (2 decks)

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