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2.2 Microbiology > Practical 5: Investigation of Gram negative Aerobic bacilli/coccobacilli (NOT FINISHED) > Flashcards

Practical 5: Investigation of Gram negative Aerobic bacilli/coccobacilli (NOT FINISHED) Flashcards

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Biology 101 flashcards
1
Q

List the four genus of gram negative bacilli

A

Haemophilus

Psuedomonas

Enterobacterales
- Escherichia
- Enterobacter
- Salmonella
- Proteus

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2
Q

List the four enterobacterales

A

Escherichia

Enterobacter

Salmonella

Proteus

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3
Q

What are the 2 genus of lactose fermenting enterobacterales

A

Escheruchua

Enterobacter

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4
Q

What are the 2 genus of non lactose fermenting enterobacterales

A

Salmonella

Proteus

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5
Q

How can you tell a bacteria is a gram negative bacilli from the plate?

A

GNBs don’t grow well on blood agar

They may not grow at all on MacConkey

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6
Q

List the five gram negative aerobic bacilli

A

Haemophilus

Bordetella

Brucella

Pseudomonas

Enterobacterales

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7
Q

How do you differentiate pseudomonas from enterobacterales

A

Pseudomonas is oxidase positive

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8
Q

List the five clinically significant species of Haemophilus

A

H. influenzae

H. parainfluenzae

H. ducreyi

H. aegyptius

H. aphrophilus

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9
Q

How can you identify capsular H. influenzae from the case study

A

Isolated from nasopharynx

Bloodstream infections

Pneumoniae

Acute bacterial meningitis

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10
Q

How do you identify non capsulated H. influenzae (2)

A

Ear infections

Sinusitis in children

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11
Q

How do you identify H. ducreyi

A

Causes chancroid STD

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12
Q

What test do you carry out to confirm ID of Haemophilus species

A

X and V factors

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13
Q

What is the principle behind the X and V factor test for Haemophilus
(3)

A

Haemophilus species are all dependant on one or both of the growth factors, X and V

X = haemin

V = nicotinamide adenine dinucleotide (NAD)

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14
Q

Explain why Haemophilus species can grow on chocolate agar
(3)

A

Horse blood agar contains X factor normally

Horse blood agar contains a NADase enzyme which inactivates factor V(NAD)

However when the blood is heated to 80 degrees (chocolate agar) the NADase activity is destroyed and thus makes the V factor available

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15
Q

What growth factors does H. influenzae need?

A

X factor and V factor

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16
Q

What growth factors does H. parainfluenzae need?

A

V factor only

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17
Q

What growth factors does H.ducreyi need?

A

X factor only

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18
Q

What growth factors does H. aegyptius need?

A

X factor and V factor

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19
Q

What growth factors does H. aphrophilus need?

A

Variable growth with X only

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20
Q

What is the main clinically significant species of Bordetella

A

B. pertussis

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21
Q

What infection does Bordetella pertussis cause?

A

Whooping cough

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22
Q

How would you identify Bordetella pertussis?
(3)

A

WONT GROW ON BLOOD AGAR

Its not dependent on X or V growth factors -> it will grow all over the plate

It needs a highly nutritious medium (without peptone) for primary isolation e.g. chocolate agar or Boredt-Gengou medium (won’t grow on normal blood agar)

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23
Q

What are the clinically significant strains of brucella
(2)

A

Brucella abortus

Brucella melitensis

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24
Q

What infection does Brucella abortus cause

A

Causes brucellosis in cattle

25
Q

What strain of brucella causes Brucellosis in humans

A

Brucella melitensis

26
Q

How does a human get brucellosis via brucella melitensis?

A

Its associated with the consumption of unpasteurised milk and soft cheeses made from the milk of infected animals

27
Q

How do you carry out an X/V test for Haemophilus
(6)

A

Ask for X, V, X/V discs, a bijou jar and a Diagnostic Sensitivity Agar (DST) plate

Make a light suspension of the test organism by touching one or more colonies and emulsifying in a reduced volume (avoid picking up chocolate agar)

Lawn the bacterial suspension evenly

Position the three discs on the inoculum

Do the same for your controls

Incubate in 5% CO2 at 35-37 degrees

28
Q

What controls could you use for the X/V factor test?

A

Use a H.influenzae control -> needs X and V

29
Q

How should you incubate the V/X test

A

Incubate in 5% CO2 at 35-37 degrees

30
Q

List the four lactose fermenting enterobacterales

A

Escherichia

Citrobacter

Klebsiella

Enterobacter

31
Q

Why are lactose fermenters so called?

A

They produce acid or acid and gas rapidly from lactose

32
Q

What are lactose fermenters also called?

A

coliform bacilli

33
Q

What infections does E.Coli cause

A

UTIs

Infantile gastroenteritis

Bloodstream infection

34
Q

What infections can Klebsiella pneumoniae cause

A

Bacterial pneumonia

HCA UTI and wound infections particularly in immunocompromised

35
Q

Where is citrobacter found and what infection does it cause

A

Found in soil

Incriminated in UTI and wound sepsis

36
Q

Where is enterobacter found and what infection does it cause

A

Found in soil and water

Associated with systemic infection

37
Q

List the non lactose fermenters
(5)

A

Salmonella

Yersinia

Shigella

Proteus

Serratia

38
Q

What infections does salmonella cause

A

Foodborne infection and enteric infection

39
Q

What infection does shigella cause

A

Bacillary dysentery

40
Q

What species of proteus are clinically significant

A

Proteus mirabilis

Proteus vulgaris

41
Q

How can you identify proteus on an agar plate

A

Swarming colonies

42
Q

What infections do proteus cause

A

UTIs and in suppurating wounds

43
Q

What are the clinically significant strains of pseudomonas

A

P. aeruginosa

P. fluorescence

44
Q

How can you identify P. aeruginosa from the case study

A

Opportunistic UTI, respiratory tract infections, soft tissue infections, bloodstream infections particularly in cystic fibrosis and severe burns or immunosuppressed

Resistant to antibiotics and disinfectants

45
Q

What two tests do you need to carry out for Pseudomonas

A

Growth at different temperatures -> 4 and 42 degrees

King’s A Media

46
Q

How do you carry out a growth at different temperatures test for pseudomonas?
(5)

A

Ask for 2 blood/nutrient agar plates

Split plate into 3, test and controls

Zig-zag inoculum of test and controls (+ P. aeruginosa, - P. fluorescence)

Incubate at 42 degrees

Repeat this but reverse controls and incubate at 4 degrees

47
Q

At what temperature does P. aeruginosa grow at

A

42 degrees

48
Q

At what temperature does P. fluorescence grow at

A

4 degrees

49
Q

How do you carry out a King’s A Medium test
(5)

A

Ask for King’s A Medium, P. fluorescence and P. aeruginosa

Separate plate into 3 for test and controls

+ control = P. aeruginosa, - control = P. fluorescence

Streak inoculate the test onto the agar

Incubate at 37 degrees

50
Q

What is a positive result for King’s A Medium

A

P. aeruginosa grows at 37 degrees with green fluorescence

51
Q

What is a negative result for King’s A Medium

A

P. fluorescence will grow but won’t be fluorescent green

E.Coli will not grow at all

52
Q

What is the principle behind King’s A Medium
(3)

A

Contains magnesium chloride and potassium sulphate which enhances pigment profuction

Selective supplement = antimicrobial cocktail comprising centrimide (antiseptic) and nalidixic acid (antibiotic)

P. aeruginosa is resistant to both these selective agents

53
Q

What is the principle behind Brilliance Agar used to grow enterobacterales

A

Contains specific chromogenic substrates (Red Gal) which are cleaved by the B-galactosidase enzymes prouced by E. Coli and coliforms, resulting in pink colonies

Medium also contains phenylalanine and tryptophan, as an indication of tryptophan deaminase activity, indicating the presence of Proteus species, morganella and providencia species which appear brown

54
Q

What testing is carried out for Enterobacterales

A

Biochemical testing

55
Q

List the 8 biochemical tests

A

Citrate utilisation

Indole production

Methyl Red

Voges Proskauer Test

Hydrolysis of Urea

Peptone water sugars

Amino acid decarboxylase

Amino acid deaminase

56
Q

List the ten components of the biochemical test

A

Inoculate a sterile water

  • Peptone (water) indole
  • Buffered glucose Methyl Red
  • Buffered glucose Voges Proskauer Test
  • Peptone sugar dulcitol
  • Lysine decarb base control
  • Lysine decarb test
  • Phenylalanine agar
  • Urea agar
  • MacConkey purity plate
  • Citrate slope
57
Q

What must you make sure to do when inoculating your biochemical tests

A

Label each cap and loosen them

Use a single well isolated colony in about 5mls water

Don’t flame between each test

Inoculate by sliding loop along side of meniscus and shaking

Zig zag over agar slopes and stab

Leave cap loose on citrate -> stab citrate

Add mineral oil to two decarboxylase reactions

58
Q

NEED TO DO THEORY OF BIOCHEMICAL TESTS FOUND IN PRACTICAL 7

A

NEED TO DO THEORY OF BIOCHEMICAL TESTS FOUND IN PRACTICAL 7

2.2 Microbiology (60 decks)

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