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Enterobacteriaceae > Enterobacteriaceae > Flashcards

Enterobacteriaceae Flashcards

2
Q

What are the characteristics of enterobacteriaceae?

A

Gram negative, non spore forming, rod shaped bacteria.
oxidase (-) negative
Ferment glucose and may or may not produce gas in the process
Reduce nitrate to nitrite
Are facultative anaerobes
Normal inhabitants of intestinal tract
Some are enteric pathogens and others are urinary or respiratory tract pathogens

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3
Q

How is differentiation based on in regards to enterobacteriaceae?

A

Its based on biochemical reactions and differences in antigenic structure

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4
Q

What do most enterobacteriaceae grow well on?

A

Lab media developed for the selective isolation of enteric pathogens
Addition of dyes and bile salts inhibit the growth of gram positive organisms

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5
Q

Many enterobacteriaceae are differentiated based on whether or not they ferment _________ and/or produce _______

A

Lactose

H2S

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6
Q

What are the three most useful media for screening stool cultures for potential pathogens are?

A

TSI (KIA)
LIA
urea
phenylalanine agar

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7
Q

The antigenic structure of enterobacteriaceae may be used to differentiate organisms within a genus or species. What are the three major classes of antigens found?

A

O antigens - heat stable
Flagellar H antigens - heat labile
Envelope or capsule K antigens - boiling destroys this and unmasks the O antigens

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8
Q

The K antigen is called what in salmonella?

A

It is called the Vi (virulence) antigen in salmonella

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9
Q

What bacteria is a major cause of urinary tract infection?

A

E. coli

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10
Q

E. coli?

A

Is a normal inhabitant of the GI Tract
Some strains cause various forms of Gastroenteritis
Is a major cause of urinary tract infection and neonatal meningitis and septicemia

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11
Q

E. coli biochemistry?

A 
TSI = A/A + gas
LIA = K/K
Urea (-)
Indole (+)
Citrate (-)
Motility (+)
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12
Q

K/K on KIA means?

A

No carbohydrate fermentation

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13
Q

K/A reaction on KIA means?

Examples of these species are?

A

Glucose is fermented but not lactose

Or in order: lactose not fermented
Glucose fermented

Example is the shigella species

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14
Q

A/A reaction on KIA means?

Examples of these species are?

A

Lactose and glucose fermented.

Examples: E. coli; klebsiella- enterobacter species

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15
Q

K/A / H2S reaction on KIA means?

Examples of these species are?

A

Lactose not fermented; glucose fermented and hydrogen sulfide produced.

Examples: salmonella; citrobacter; proteus species

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16
Q

What are the virulence factors of E. coli?

Hint: (it is a toxin)

A

Toxins: enterotoxins: which are produced by enterotoxigenic strains of E.coli. These cause a movement of water and ions from the tissues to the bowel resulting in watery diarrhea.

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17
Q

What are the two types of enterotoxins (ETEC) in E. coli?

A

LT and ST

LT: heat labile causes amplification of cAMP to increase movement of ions and water to bowel

ST: heat STABLE and causes amplification of cGMP to increase movement of ions and water to bowel

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18
Q

E. coli is the leading cause of what clinically?

A

Urinary tract infection!

Which can lead to acute cystitis (bladder infection) and pyelonephritis (kidney infection)

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19
Q

E. coli also causes what?

A

Neonatal meningitis and gastroenteritis

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20
Q

What are the several types of E. coli that lead to gastroenteritis?

A

ETEC

EIEC

EPEC

EAEC

EHEC (hemmoraging) caused by serotype O157:H7!! Also produces shiga like toxins!!!

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21
Q

Shigella species

Contains what four types?

A

S. dysenteriae
S. flexneri
S. boydii
S. sonnei

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22
Q

What is the biochemistry of Shigella species?

A

TSI: K/A with NO gas!
LIA: K/A
Urea (-)
Motility (-)!

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23
Q

Salmonella species have two species?

A

s. enterica which causes most human infections

s. bongori

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24
Q

Biochemistry of salmonella species?

A 
TSI: K/A + gas and H2S 
Urea (-)
Motility (+)
Citrate +/-
Indole -
25
Q

How do salmonella species move?

A

They have flagella that allows them to move through intestinal mucous

26
Q

Salmonella causes two difference kinds of disease ?

A

Enteric fevers: bacteria spread (paratyphoid and typhoid) typhoid being more severe due to s. typhi

Gastroenteritis: bacteria restricted to intestine where it produces a strong inflammatory response allowing bacteria to be constricted to only this area of body

Transmission is via the fecal oral route through contaminated water or food

27
Q

What is the difference between shigella and salmonella species?

A

Salmonella species is more severe

Shigella species are nonmotile as are klebsiella species

Shigella species produce NO GAS

28
Q

Biochemistry of citrobacter species

A

TSI : K/A or A/A both gas and h2s
Urea is usually +
Motility +
They are opportunistic pathogens causing urinary tract or respiratory tract infections and occasionally wound infections, osteomyelitis, endocarditis, and meningitis

29
Q

Biochemistry of edwardsiella species

A 
TSI: K/A + gas + h2s
LIA: K/K + H2s
Urea (-)
Citrate (-)
Indole (+)
30
Q

Biochemistry of klebsiella species?

A 
TSI : A/A + gas
LIA : K/K 
Urea (+) 
Citrate (+)
MR (-) 
VP (+) !!!!!!!!!!
Motility (-)!!!!!!!!
31
Q

Biochemistry of Enterobacter species

A

TSI LIA and urea vary with species
Citrate (+)
Motility (+)

32
Q

Biochemistry of serratia species

A

TSI A/A or K/A +- gas
Citrate (+)
Motility (+)
Urea -/+

33
Q

Biochemistry or proteus, providencia and morganella species

A 
All motile with proteus swarming!!
PA +!!!!
Lysine deamination 
Urea (+)
TSI varies for each!
Indole + except for p. mirabilis
34
Q

The urease produced by the proteus providencia and morganella species may damage what?

A

The ammonia produced by urease may damage the epithelial cells of the UT

35
Q

Yersinia species have what three important species that important pathogens in man?

A

Yersenia Pestis - causes plague

Yersenis enterocolitica - entercolitis, septicemia

Yersinia pseudotuberculosis - mesenteric lymphadenitis

36
Q

Which yersinia species is non motile

A

Y. Pestis

37
Q

Biochemistry of yersinia Pestis

A

TSI : K/A no gas!
Urea (-)

Endotoxin is responsible for many of the symptoms

Murine toxin effects only rodents

38
Q

What does y. Pestis cause in humans?

A

Bubonic plague - transmitted by fleas from infected rodent

Lymph nodes get very enlarged.

Bacteria in lymph nodes leak into bloodstream leading to septic shock

39
Q

Bubonic plague from y. Pestis leads to what greater complication?

A

It leads to pneumonic plague when the bacteria reach the lungs from the bloodstream.

This is can be transmitted easily via aerosol

Mortality rate is very high!!!

40
Q

Yersinia enterocolitica and yersinia pseudotuberculosis biochemistry?

A

Both are motile at 22-25 degrees but non motile at 37 degrees

Both exhibit bipolar staining

TSI A/A but with sucrose fermentation not lactose

Urea (+) for both!

ODC (+) for Y. Enterocolitica only!

41
Q

Yersinia Pestis exhibits what appearance after staining?

A

A safety pin appearance

42
Q

Yersinia are the only enterobacteriaceae that grow on what media?

A

CIN agar!!!!
Because it contains mannitol and phenol red for isolation

They will look like pink (due to mannitol fermentation) colonies with a BULLS EYE APPEARANCE

43
Q

What is indole production? And why is it used as a detection method?

A

Indole is one of the degradation products of the amino acid tryptophan.
Bacteria that possess the enzyme tryptophanase are capable of cleaving tryptophan thereby producing indole, pyruvic acid and ammonia!

Shows RED only after adding a solution containing
p-dimethylaminobenzaldehyde called kovach’s reagent!

44
Q

The methyl red test provides what?

A

A valuable characteristic for identifying bacterial species that produce strong acids from glucose

45
Q

Vogues proskauer test?

A

A test who has positive members that consists of the species

Klebsielleae

46
Q

Citrate utilization?

A

To determine the ability of an organism to use sodium citrate as the source of carbon for metabolism and growth

Shows blue!

47
Q

Urease production test

A

Microorganisms that possess the enzyme urease hydrolyze urea, releasing ammonia and producing a pink-red color change in the medium

48
Q

Phenylalanine deaminase production test

A

This test is useful in the differentiation of proteus, morganella, and providencia species from other enterobacteriaceae

Only members of these genera possess the enzyme responsible for the oxidative deamination of phenylalanine

Green color after ferric chloride is reagent is added.

49
Q

Hydrogen sulfide production test

A

Shows as a black precipitate in the medium

50
Q

Motility test

A

Important as well in making a final determination of a species

Shows as a diffuse of growth from the point of inoculation

51
Q

Which two species are non motile?

A

Klebsiella and shigella!!!

52
Q

Which species are hydrogen sulfide positive?

A 
Edwardsiella tarda
Salmonella
Citrobacter freundii
Proteus vulgaris
Proteus mirabilis
53
Q

Vogues proskauer positive species are?

A

Klebsiella
Enterobacter
And serratia species

54
Q

Phenylalanine deaminase positive species are ?

A

Proteus

Morganella and providencia species

55
Q

Which species are nonmotile at 36 degrees

A

Shigella

Yersenia and klebsiella species!

56
Q

Cytochrome oxidase activity?

A

Any organism showing oxidase activity is EXCLUDED from the enterobacteriaceae group

57
Q

Nitrate reduction in enterobacteriaceae?

A

All enterobacteriaceae reduce nitrate to nitrite. Zinc dust needs to be added and organisms will reduce within 24 hrs. Readings must be done as soon as possible.

57
Q

Entero means what in regards to enterobacteriaceae?

A

It means intestinal

will be learning about most bacteria that occur in the gut

Enterobacteriaceae (1 decks)

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