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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

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
What strain of brucella causes Brucellosis in humans
Brucella melitensis
26
How does a human get brucellosis via brucella melitensis?
Its associated with the consumption of unpasteurised milk and soft cheeses made from the milk of infected animals
27
How do you carry out an X/V test for Haemophilus (6)
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
What controls could you use for the X/V factor test?
Use a H.influenzae control -> needs X and V
29
How should you incubate the V/X test
Incubate in 5% CO2 at 35-37 degrees
30
List the four lactose fermenting enterobacterales
Escherichia Citrobacter Klebsiella Enterobacter
31
Why are lactose fermenters so called?
They produce acid or acid and gas rapidly from lactose
32
What are lactose fermenters also called?
coliform bacilli
33
What infections does E.Coli cause
UTIs Infantile gastroenteritis Bloodstream infection
34
What infections can Klebsiella pneumoniae cause
Bacterial pneumonia HCA UTI and wound infections particularly in immunocompromised
35
Where is citrobacter found and what infection does it cause
Found in soil Incriminated in UTI and wound sepsis
36
Where is enterobacter found and what infection does it cause
Found in soil and water Associated with systemic infection
37
List the non lactose fermenters (5)
Salmonella Yersinia Shigella Proteus Serratia
38
What infections does salmonella cause
Foodborne infection and enteric infection
39
What infection does shigella cause
Bacillary dysentery
40
What species of proteus are clinically significant
Proteus mirabilis Proteus vulgaris
41
How can you identify proteus on an agar plate
Swarming colonies
42
What infections do proteus cause
UTIs and in suppurating wounds
43
What are the clinically significant strains of pseudomonas
P. aeruginosa P. fluorescence
44
How can you identify P. aeruginosa from the case study
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
What two tests do you need to carry out for Pseudomonas
Growth at different temperatures -> 4 and 42 degrees King's A Media
46
How do you carry out a growth at different temperatures test for pseudomonas? (5)
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
At what temperature does P. aeruginosa grow at
42 degrees
48
At what temperature does P. fluorescence grow at
4 degrees
49
How do you carry out a King's A Medium test (5)
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
What is a positive result for King's A Medium
P. aeruginosa grows at 37 degrees with green fluorescence
51
What is a negative result for King's A Medium
P. fluorescence will grow but won't be fluorescent green E.Coli will not grow at all
52
What is the principle behind King's A Medium (3)
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
What is the principle behind Brilliance Agar used to grow enterobacterales
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
What testing is carried out for Enterobacterales
Biochemical testing
55
List the 8 biochemical tests
Citrate utilisation Indole production Methyl Red Voges Proskauer Test Hydrolysis of Urea Peptone water sugars Amino acid decarboxylase Amino acid deaminase
56
List the ten components of the biochemical test
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
What must you make sure to do when inoculating your biochemical tests
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
NEED TO DO THEORY OF BIOCHEMICAL TESTS FOUND IN PRACTICAL 7
NEED TO DO THEORY OF BIOCHEMICAL TESTS FOUND IN PRACTICAL 7

2.2 Microbiology (60 decks)

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