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Clinical Bacteriology > (M) Lab: Biochemical Identification of Bacteria (Part 1) > Flashcards

(M) Lab: Biochemical Identification of Bacteria (Part 1) Flashcards

Biochemical Identification/Properties of Bacteria

1
Q
  • One important request from doctors that we received in the laboratory
  • Done to specifically identify the genus and species of the pathogen that causes the infection or disease of the patient
A

Culture and Sensitivity

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2
Q
  • Growing a specific bacteria
  • Demonstrated by the presence of colonies on the culture medium
  • Where you will get a new sample for follow-up biochemical identification
A

Colony (Growth)

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3
Q

Serves as the artificial environment

A

Culture medium

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4
Q
  • Basis for the follow-up tests to be performed
  • The colonies are inoculated based on the biochemical test required to perform
A

Gram-Staining Reaction

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5
Q
  • These two groups are the most common pathogens we observe in the laboratory
  • Two groups of bacterium cover the majority of the isolates recovered in the laboratory
  • Also causative agents of infections
  • The common workflow for the different biochemical tests focuses on these two groups
A

Gram-positive cocci and gram-negative bacilli

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6
Q
  • Observe and check for the fermentation process in a sample or colony
  • Can the bacteria ferment a carbohydrate, specifically sugar
  • The end product is acid formation or production
  • Identifies genus and species of G(-) cocci
  • Only for screening or it is only presumptive
A

Carbohydrate Fermentation

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7
Q

T or F: When you have the fermentation process, sugar is involved.

A

T

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8
Q

Carbohydrate Fermentation

Most common indicator

A

Phenol red

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9
Q

Carbohydrate Fermentation

Indicated by a change in color reported as:

A
  • Positive: Yellow
  • Negative: Original color / Red
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10
Q

When done alone, it can still be confirmatory if G/S results is G(-) cocci.

A

Carbohydrate Fermentation

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11
Q

Study the procedures for carbohydrate fermentation.

A

Go bestie mwa

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12
Q

Results for Carbohydrate Fermentation

N. gonorrhea

A

Glucose (+)
Maltose, Sucrose, Lactose (-)

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13
Q

Results for Carbohydrate Fermentation

N. meningitidis

A

Glucose, Maltose (+)
Sucrose, Lactose (-)

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14
Q

Results for Carbohydrate Fermentation

N. lactamica

A

Glucose, Lactose (+)
Maltose, Sucrose (-)

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15
Q

Results for Carbohydrate Fermentation

N. secca

A

Glucose, Sucrose (+)
Maltose, Lactose (-)

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16
Q

Results for Carbohydrate Fermentation

Assacharolytic

A

Glucose, Maltose, Sucrose, Lactose (-)

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17
Q

Carbohydrate Fermentation

  • Labeled as dextrose
  • Very important in G(-) cocci
A

Glucose

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18
Q
  • A medically important G(-) cocci genus, is automatically a glucose fermenter
A

Neisseria

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19
Q
  • Also important as it identifies N. meningitidis which is a very important pathogen
A

Maltose

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20
Q
  • A non-fermenter; characteristic of Moraxella catarrhalis
  • Tests negative for all sugar panels, despite being a G(-) cocci
A

Assacharolytic

21
Q
  • Is also important for the screening/presumptive ID of the groups of different bacteria
  • Basis for specific follow-up tests
  • Because of the enzyme hemolysin that causes RBC lysis
A

Hemolysis of RBCs

22
Q

Hemolysis of RBCs

Means you are not sure, you just have an idea about the genus and species

A

Screening/presumptive

23
Q

Hemolysin production is best demonstrated in?

Clue: A differential medium for hemolysis

A

BAP

24
Q

Hemolysis of RBCs

T or F: The pattern should be enhanced especially for G(+) cocci.

A

T

25
Q

Hemolysis of RBCs

It is highly presumptive for G(+) cocci

A

Hemolysis pattern

26
Q

Study the procedure for hemolysis of RBCs.

A

Go on pls !!

27
Q

Identify the pattern.

  • Partial hemolysis (incomplete)
  • Greenish halo around the colony
  • S. pneumoniae, Viridans strep
A

Alpha-hemolytic pattern

28
Q

Identify the pattern.

  • Complete hemolysis
  • Yellowish halo around colony
  • (Bright → if enhanced)
  • S. aureus, S.pyogenes, S. agalactiae
A

Beta-hemolytic pattern

29
Q

Identify the pattern.

  • No hemolysis (no hemolysin)
  • White colony, plain growth w/o any halo
  • Group D Enterococci
A

Gamma-hemolytic pattern

30
Q
  • Based on this biochemical test, we look at whether the bacterium produces an amylase enzyme
  • Differentiates for G(+) bacilli, specifically the biotypes of Corynebacterium diphtheria
A

Starch Hydrolysis

31
Q

Starch Hydrolysis

Hydrolyses starch producing maltose, a monosaccharide

A

Amylases

32
Q

Starch Hydrolysis

Cell walls are highly permeable to this sugar, it can easily enter the cell wall

A

Maltose

33
Q

Starch Hydrolysis

Lyses the cell wall

A

Increased amounts of maltose

34
Q

Same genus and species that differ in biochemical properties

A

Biotypes

35
Q

Biotypes of Corynebacterium diphtheria?

A
  • Gravitis
  • Mitis
  • Intermedius
36
Q

Starch Hydrolysis

Positive results?

A

Colorless halo around bacterial growth

37
Q

Starch Hydrolysis

Negative results?

A

Original color: blue/purple with growth

38
Q
  • Detects whether bacteria produce gelatinase
  • Differentiates some members of the Enterobacteriaceae
A

Gelatin Liquefaction

39
Q

Liquefies the medium

A

Gelatinase

40
Q

Gelatin Liquefaction

Positive Results?

A

Liquid medium (change in the consistency)

41
Q

Gelatin Liquefaction

Negative results?

A

Solid gel (as is)

42
Q
  • Used to verify results that involve changes in consistency or physical properties
  • Done by titling the tube to check for changes
A

Tilt Tube Method

43
Q
  • Whether bacterium releases a specific pigment, therefore producing specific-colored colonies
  • Very helpful for the presumptive identification of genus and species
  • Confirmatory for Chromobacterium violaceum
A

Pigment Production

44
Q

Pigment Production

Produces purple colonies that can be demonstrated even on a MacConkey agar

A

Chromobacterium violaceum

45
Q

Study the procedure for pigment production.

A

GOOOOO

46
Q

Identify the organism based on pigment production.

  • Lipochrome → golden colonies
A

S. aureus

47
Q

Identify the organism based on pigment production.

  • Pyoverdin → green colonies; the most common pigment by aeruginosa; usually in MHA
  • Pyocyanin → blue or blue green colonies
  • Pyorubin → red colony (rare)
  • Pyomelanin → brown colonies (rare)
A

P. aeruginosa

48
Q

Identify the organism based on pigment production.

  • Prodigiosin → red colonies; by G(-) bacilli: S. marcenscens; enhanced if incubated at room temperature
A

S. marcenscens

49
Q

Identify the organism based on pigment production.

  • Violacein → violet pigment that can be demonstrated on a MAC
A

Chromobacterium violaceum

Clinical Bacteriology (33 decks)

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