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Microbiology > Lab-test microbiology > Flashcards

Lab-test microbiology Flashcards

1
Q

Bouillon (broth)

A

For bacterial growth

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2
Q

Agar plate

A

Bacteria:

Lipofil pigments: staph epidermidis, S-aureus and serrata rubidea

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3
Q

Enrichment media: cooked meat bouillon

A

Promote bacterial growth

Holman (cooked meat) buillon

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4
Q

Blood agar

A

Hemolysis
Beta, alpha and gamma

Beta: i.e. S. aureus, S. agalacticae
alpha:
gamma:

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5
Q

Chocolate agar

A

Warming up blood agar
Good for isolation of N. meningitidis and Hemophilia spp.

Both factor V and X are present, which supplies the special growth of Hemophilius influenza, and when incubated in Co2 Neisseria spp.

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6
Q

Clauberg

A

C. diphteria

C. mitis
C. gravis
C. intermedium

Weak B-hemolysis

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7
Q

Löeffler

A

Isolation of C.diphteria

Contains clotted serum

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8
Q

Löwenstein-Jensen

A

Mycobacterium tuberculosis

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9
Q

Sula

A

Alternate liquid for L-J

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10
Q

EMB

A

pH-indicator dyes
Used to isolate fecal isoforms
Inhibit growth of most G+ organisms
Sucrose and lactose:fermenting CH

Black/purple colonies if they ferment the CH (i.e. Klebsiella)
E.coli form metallic-green pigment

Non-fermenting: clear colonies: i.e. Proteus and Salmonella

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11
Q

Bismuth-sulfite

A

Contain bismuth-green, bismuth and sodium sulphite.
Detect H2S-production
Colonies of Salmonella appear BLACK in the presence of heavy metals

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12
Q

Brilliant-green

A

Contain brilliant green, brilliant sugar and andrade-indicator

Salmonella: colorless colonies (lactose negative)
E.coli: red if grown (lactose +)

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13
Q

deoxycholate-citrate

A

Contain: deoxycholine acid, Na-citrate, lead acetate, iron-ammoniac sulphate, lactose and neutral red indicator

Shigella: colorless
E.coli: red if grown

inhibitory to most gut-bacteria

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14
Q

TCBS

A

Thiosulphate-citrate-bile salt-sucrose-agar
Selective agar to isolate Vibrio spp.
Vibrio will produce large yellow colonies, while non-vibrio colonies produces black colonies

Contains bromithol-blue indicator

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15
Q

Standard

Selective and differentiating media

A
  • Blood agar
  • Chocolate agar
  • Bouillon
  • slant agar
  • tube agar
  • agar plate
  • cooked meat bouillon
  • Clauberg (tellurite)
  • Löeffler
  • Löewenstein-Jensen
  • Sula
  • TCBS
  • Brilliant green
  • Deoxycholate-citrate (DC)
  • EMB
  • Bismuth-sulphate
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16
Q

Transport media

A
  • Stuart swabs
    for 48h, 0,2% agar, room T, anaerobe also survive
  • Growth media (Uricult)
    bacteria have multiplied by the time they reach the lab
    saves time
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17
Q

Blood culture

A

Important, as many hospitalized die of septicaemia
Collection:
- desinfect in order to reduce change of contamination
- either by needle or syringe

Timing:

  • before the use of AB
  • 1/2 before T-spike is ideal (or in T-spike)
  • in continous bacteremia: 3 cultures/day - 30 minutes apart

Volume:

  • 10mL and 30mL (adult)
  • 1-5mL (children)

Culture medium:
- bottles are multipurpose and nutritionally enriched

Cultivate further if + test provided, to specify species.
Gram-staining is added to blood culture to make a differentiation

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18
Q

Viral transport medium

A

prevent specimen for drying, maintains viral viability and retards the growth of microbial contaminants

Swab inside - to collect wanted sample

Speciment should be stored at 4*C

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19
Q

Staphylococcus aureus and S. epidermidis

blå

A

Simple agar
- Stap. au: golden pigment. Large, round and yellow pigments.
Skin infections

  • S.epidermidis: 2-3mm regular, round-shaped, glittering, chalk white
    UTI
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20
Q

S. Aureus (rød)

A

BLOOD AGAR

  • B-hemolysis
  • Other stronly staphylococci: S. hemolyticus and S. lugdunensis
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21
Q

S. epidermidis (rød)

A

BLOOD AGAR

  • regular, round-shaped, glittering colonies, chalk-white pigment. Do not penetrate into the medium
  • no hemolysis around the colonies
22
Q

S. saphrophyticus and S.epidermidis (BLUE) with novobiocin disc

A
  • 2nd most frequent UTIs after E.coli
  • Important to differentiate it from S.epidermidis - done by NOVOBIOSIN resistant test.

Epidermidis = sensitive, so novobiocin will therefore be able to clear bacteria from agar –> zone of inhibition

Other similar test: optochin (s. pneumonia and viridans) and bacitracin (S.pyogenes and S. agalacticae)

23
Q

Streptococcus pyogenes (RØD)

A
  • colorless, glittering, round-shaped and very small with a huge B-hemolytoc zone
  • main diseases: strep throat and scarlet fever
24
Q

S.mitis (RØD og BRUN)

A
  • a-hemolytic –> leave greenish colonies on the blood agar

- main disease: endocarditis

25
Q

S. pneumoniae RØD og BRUN

A
  • grayish, glittering, round shaped, 1-2mm with a-hemolytic zone
  • capsule-producing strain grow with large, mucoid apperance
  • NOT grow on simple agar
  • both strep. penumonia and viridans are a-hemolytic and OPTOCHIN test is used to differentiate them
  • pneumonia = SENSITIVE
  • —> create large zone of inhibition
  • viridans = RESISTANT

Main disease: pneumonia

26
Q

Haemophilus influenza (BROWN)

A
  • “Love heme”. Require a precursor of heme to grow
  • Prefer a complex medium, and require preformed GF that are present in blood (X and V) with 5-10% CO2 enriched
  • usually grow on chocolate agar -> heat releases X and V from RBC
  • Satellite phenomenom is when hemophilus influenza is grown on blood agar, but only grows around other bacteria.
  • i.e. stap. aureus create beta-hemolysis and then release X and V-factors
  • Blank/white/pale dots. Grow around other bacteria
27
Q

E. coli BLUE and PURPLE

A
  • EMB: colonies of fermenting bacteria (E.coli) are PURPLE-black while non-fermenting colonies are colorless. Due to metachromatic properties of dyes, E.coli will give a distinctive metallic green
  • Agar: Intermediate sized, glistering, irridescent, colorless
    Main disease: UTI and abdominal infections
28
Q

Proteus RØD and LILLA

A
  • Swarming on an agar plate, bacteria is spred throughout entire plate.
    Main disease: UTI
29
Q

Pseudomonas aergunosa on BLÅ og RØD

A
  • blood agar: beta hemolysis. Round colonies.
  • Agar: fluorescent greenish from pyoverdin, the fluorescent pigment pyoacin will diffuse into he agar.
    Dark red pigment = pyomelanin
    GRAPE-like ODOR (or TACO)

Main disease: pneumonia, sepsis, UTI

30
Q

Klebsiella on BLÅ og LILLA

A
  • Klebsiella has a PS-capsule which give a characteristic look on agar
  • Simple agar: mucoid like colonies (capsule)
  • Unpleasent urine smell
    Show purple colonies in EM. It is lactose +.

Main disease: UTI, cholecystitis and pneumonia

31
Q

Salmonella sp. on BISMUTH-SULPHITE medium

A
  • BLACK, because they can convert sulphus soruce into H2S –> produce black precipitate in presence of heavy metals (bismuth)

Main disease: Typhoid fever and gastroenteritis

32
Q

E.coli and Salmonella sp. BRILLIANT GREEN

A
  • E.coli is lactate fermenting –> turn medium red

- Salmonella is non-lactose fermenting and medium will remain colorless

33
Q

E.coli and Shigella sp. on deoxycholate medium

A
  • Appear yellow or colorless (Salmonella and shigella)
  • E.coli: red, big grown, inhibited by deoxycholate
    Main disease: Shigellosis
34
Q

Faeces of patient with dysentry on LILLA

A
  • DC: this agar will most likely show red colonies (E.coli) and yello/colorless (Shigella)

EM-media: E.coli cause dark colonies
Shigella/Salmonella = colorless

35
Q

RUSSEL medium (steril)

A

Double sugar agar. Used for differentiation of G- enteric bacilli on the basis of their ability to fermed dextrose and lactose.

Lactose fermentors: medium to deep red

Dextrose fermentors: butt-redd

Lactose non-fermenters: no color change

Gaseous fermentation: splitting of the agar or by bubble formation in the butt

Possibilities
- Lactose fermentors with gas production = slat and butt is red, and there are bubbles. KLEBSIELLA AND E.COLI

  • DEXTROSE fermentors only, with gas production = only butt-red + bubbles
    PRETEUS and SALMONELLA (not typhi)
  • Dextrose fermentation only, no gas: only butt red colored and no bubbles
    = Salmonella typhi and Shigella
36
Q

Fermentation of dextrose and lactose

A

E.coli: both

Klebsiella: both

Proteus, Salmonella and Shigella: only dextrose

37
Q

Christensen medium (sterile)

A

UREASE test

  • rapid for diagnosis of H.pylori
  • Bacteria secretes ureases, which catalyzes the conversion of urea to ammonium and CO2
  • test is performed at the time of gastroscopy where a biopsy at the antrum of the mucosa is taken and placed into a medium containing urea and an indicator (phenol red)
  • If urea is present: urea–>ammonia –> raises pH of the medoum, and color is changed from yello (-) to red (+)
38
Q

UREASE

A

Urease +: proteus, Klebsiella and H.pylori

Urease-: E.coli, salmonella and Shigella

39
Q

Cornyebacterium on Clauberg (tellurite) and Löffler

A

Clauberg: black colonies with garlic smell, might be weak beta-hemolysis

Löffler: ivory-colored, red-shaped pleomorphic bacteria can be seen
Main disease: Diphteria

40
Q

Myobacterium tuberculosis on Löwenstein medium

A
  • Appear brown, granular, “rough” and “tough”
  • large, irregular and fuzzy.
  • hard colonies
    .- incubation require 2-4w
    Main disease: tuberculosis
41
Q

Leptospira on KORTHOF medium

A
  • “smooth”-like growth of leptospira
  • Mild growth in the bottom, after shakin, mild opacity
  • contains 10% rabbit serum, pepton and salt
  • slow groth: 2-6w at low temperature

Disease: leptospirosis, Weil´s disease

42
Q

Bacillus cereus BLÅ og RØD

A

Agar: large, rhizoid, medusa-like colonies
Blood agar: B-hemolytic

Main disease: food poisoning

43
Q

Clostridium tetani in Holman and thioglycolate medium

Gasgangrene clostridia in Holman and thioglycolate medium

A
  • obligate anaerobes are posioned by O2 in the thioglycolate medium –> gather at the bottom of the tube where O2 is lowest
    • E.g. C.tetani
  • Facultative anaerobes can grow w/ or w/o O2 because they can metabolise energy aerobically or anaerobically

Gather mostly on the top because aerob respiration generates more ATP than either fermentation or anaerobic respiration

C.perfringens

44
Q

DIFFERENTIATION. Simple agar.

A

In total 6 normal agar plates:

  • S. eureus + S.epidermis
  • S.epidermis + S.sapro
  • E.coli
  • Pseudomonas aeruginosa
  • Bacillus sereus
  • Klebsiella

S.aureus + S.epidermis

  • Easy to recognize cause it is the only one with two cultures
  • S. aureus is more golden

S.epidermis + S.saphro
- only agar with susceptibility test (novobiocin)

Pseudomonas aeruginosa
- very bright neon green, easy to recognize

Klebsiella:
- mucoid colonies

Bacillus cereus and E.coli

  • Ecoli is intermediate sized colonies
  • Bacillus: large
45
Q

BLOOD agar

A

8 different

  • S. aureus
  • S. epidermis
  • pseudomonas aerguinosa
  • Str. pyogenes
  • str. mitis
  • proteus
  • str. pneumonia
  • bacillus cereus

Str. pyogenes, S. aureus and proteus:

  • Hard to differentiate
  • proteus is swarming
  • Str. pyogenes have MORE B-hemolytic zone

S.epidermis:
- only chalk white colonies

Bacillus cereus: big colonies, and B-hemolytic

Str. mitis and str. pneumonia: a-hemolytic

Pseudomonas aergunosa: B-hemolytic

46
Q

CHOCOLATE agars

A

there are 3

  • S.mitis: a-hemolytic
  • S. pneumonia (a-hemolytic)
  • Hameophil. influenza: NOT-a hemolytic
47
Q

EMB-agars

A

3 EM-agars

  • E.coli
  • Proteus
  • Faeces of patients with dysentery
48
Q

ELEK test

A
  • used to identify TOXIN production by C.diphteria
  • Filter paper is used by cutting it to 75% of the seize of the agar plate
  • Streak the test organism at right angles to the filter paper
  • streak positive and negative control
  • incubate: 24h, 37*C
  • antitoxin from the filter paper and toxin from the organism will diffuse into medium
  • where they meet: line of precipitation
  • if no line: C.diptheria has not yet ben attacked by a phage causing toxin production
49
Q

Widals type tube agglutination

A
  • to show presence and establish titre of specific Ab in sera
    Titre: smallest amount that gives + result
  • Gruber-Widal: abdominal thyfus (salmonella)
  • Wright: Brucella/Francisella
  • Weil-Felix: epidemic typhus (Rickettsia)
  • Paul-Bunnel: EBV
50
Q

Aspecific serological test for diagnosis of syphilis: WASSERMAN reaction, RPR, VDRL

A

Non-specific treponemal test, measure Ab directed against lipid Ag, principally cardiolipin

  • Ag: cardiolipin from beef-heart
  • Ab: developed against lipids released from damaged cells

WASSERMANN: complement fixation test

  • diluted serum
  • incubate with cardiolipin
  • sensitised RBC are pipetted into the tubes
  • Negative: RBC lysed, hemolysis = red tube
  • Positive: remain intact and sediment to the bottom

VDLR

  • a drop of cardiolipin suspension is placed on glass slide mixed with inactivated serum
  • Negative: cardiolipin suspension remain dispersed
  • positive: cardiolipin forms visible clumps when combining with regain

RPR-test (rapid-plasma)

  • Ag: cardiolipin suspension attatched to latex particles
  • A drop of cardiolipin-latex placed on glass slide, and mixed with serum

Negative: cardiolipin-latex remains intact
Positive: cardiolipin-latex is agglutinated and sediment as rough granula

51
Q

Hemagglutination

A

Rubella and influenza. Can also be use for other viruses and bactriae

52
Q

ELISA

A

HIV-1 and HIV-2

Hepatitis A and B, competitive

Hepatitis B and C, ELISA

Microbiology (1 decks)

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