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Bacteriology 🦠 > (1) Gram Negative Bacilli > Flashcards

(1) Gram Negative Bacilli Flashcards

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1
Q

What is the purpose of the Oxidase Test?

A

To identify bacteria that produce cytochrome oxidase, which turns indophenol blue.

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2
Q

What is the main reagent used in the Oxidase Test?

A

Tetramethyl-p-phenylenediamine dihydrochloride.

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3
Q

What is a positive result in the Oxidase Test?

A

A bluish-purple color, indicating the presence of cytochrome oxidase.

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4
Q

Which organisms are positive and negative in the Oxidase Test?

A

Positive: Pseudomonas; Negative: E. coli

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5
Q

What is the purpose of the Nitrate Reduction Test?

A

To determine if an organism can reduce nitrate (NO₃) to nitrite (NO₂).

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6
Q

What are the main reagents used in the Nitrate Reduction Test?

A

Sulfanilic acid and α-naphthylamine

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7
Q

What does a positive result look like in the Nitrate Reduction Test?

A

A red color, indicating nitrate reduction

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8
Q

What does a colorless result mean after adding zinc dust in the Nitrate Reduction Test?

A

True positive, indicating complete nitrate reduction beyond nitrite.

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9
Q

What does a red color after adding zinc dust in the Nitrate Reduction Test indicate?

A

True negative, meaning nitrate was not reduced.

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10
Q

What is the purpose of the ONPG Test?

A

To test for beta-galactosidase enzyme, which indicates lactose fermentation.

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11
Q

What is a positive result in the ONPG Test?

A

A yellow color, showing the presence of beta-galactosidase.

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12
Q

What is the purpose of the LOA Test?

A

To determine the presence of amino acid decarboxylase activity in organisms like Enterics, Aeromonas, Vibrio, and Plesiomonas.

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13
Q

What medium is used in the LOA Test?

A

Moeller’s Decarboxylase Medium.

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14
Q

What indicator is used in the LOA Test?

A

Bromcresol purple

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15
Q

What is a positive result in the LOA Test?

A

A purple color, indicating the production of amine products.

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16
Q

What does a yellow result mean in the LOA Test?

A

Negative result, indicating no production of amine products.

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17
Q

What is the purpose of the Triple Sugar Iron (TSI) Test?

A

To differentiate bacteria based on sugar fermentation, gas production, and hydrogen sulfide (H2S) production.

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18
Q

What indicator is used in the TSI Test?

A

Phenol red, which shows pH changes

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19
Q

What indicates H2S production in the TSI Test?

A

Black discoloration due to ferrous sulfate.

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20
Q

When is H2S seen in the TSI Test?

A

Only under acidic conditions.

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21
Q

How is gas production shown in the TSI Test?

A

By splits or cracks in the medium.

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22
Q

What are the conditions in the slant and butt of the TSI medium?

A

Slant: Aerobic; Butt: Anaerobic.

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23
Q

What does an A/A (yellow/yellow) result indicate in TSI?

A

2-3 sugars were fermented;
gas production may create space at the bottom (A/A + gas).

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24
Q

What does a K/A (red/yellow) result indicate in TSI?

A

Only glucose was fermented.

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25
What does a K/K (red/red) result indicate in TSI?
No sugars were fermented; typical of non-fermenters like Pseudomonas.
26
What is the purpose of the Lysine Iron Agar (LIA) Test?
To determine an organism's ability to decarboxylate or deaminate lysine and produce H2S.
27
What medium and indicator are used in the LIA Test?
Moeller's Medium with bromcresol purple as the pH indicator.
28
What indicates H2S production in the LIA Test?
Ferric ammonium citrate.
29
What does a positive lysine decarboxylation (LDC) result look like in LIA?
Purple color in the butt, indicating decarboxylation under anaerobic conditions.
30
What does a negative lysine decarboxylation (LDC) result look like in LIA?
Yellow in the butt, indicating no decarboxylation.
31
What does a positive lysine deamination result look like in LIA?
Red color on the slant, indicating deamination under aerobic conditions.
32
What does a K/K (purple/purple) result indicate in LIA?
Positive for decarboxylation
33
What does a K/A (purple/yellow) result indicate in LIA?
Negative for decarboxylation (no reaction/neutral).
34
What does an R/A (red/yellow) result indicate in LIA?
Positive for deamination
35
What reagent is used in the Indole Test?
Kovac's reagent and Ehrlich's reagent (PDAB)
36
What is a positive result in the Indole Test?
A red ring, commonly seen in E. coli
37
What is the purpose of the Rapid Spot Indole Test?
To quickly screen for indole production under anaerobic conditions.
38
What material is used in the Rapid Spot Indole Test?
Filter paper impregnated with p-DAC
39
What does a positive result look like in the Rapid Spot Indole Test?
A blue spot indicates the presence of indole.
40
What pathway does the Methyl Red Test detect in bacteria?
The mixed acid pathway of glucose fermentation.
41
What indicator is used in the Methyl Red Test?
Methyl red
42
What medium is used in the Methyl Red Test?
MRVP medium
43
How long is the Methyl Red Test incubated?
3-5 days to achieve turbidity.
44
What does a yellow result mean in the Methyl Red Test?
Negative result, indicating a pH above 4.4.
45
What is a positive result in the Methyl Red Test?
A red color at pH 4.4
46
What metabolic pathway is detected by the Voges-Proskauer Test?
The butylene glycol pathway of glucose fermentation.
47
What medium is used in the Voges-Proskauer Test?
MRVP medium
48
What are the end products detected in the Voges-Proskauer Test?
Acetoin or acetylmethylcarbinol
49
What reagents are used in Barritt’s Method for the VP Test?
α-naphthol and KOH.
50
What color indicates a positive result in the VP Test (Coblentz Method)?
Cherry red or port wine red
51
What color indicates a negative result in the VP Test?
Chocolate brown
52
What medium is used in the Citrate Utilization Test?
Simmons' citrate medium.
53
What indicator is used in the Citrate Utilization Test?
Bromthymol blue
54
What is the end product in the Citrate Utilization Test?
Ammonia
55
What color indicates a positive result in the Citrate Utilization Test?
Blue
56
What color indicates a negative result in the Citrate Utilization Test?
Green
57
What mediums are used in the Urea Hydrolysis Test?
Christensen's agar or Stuart urea broth
58
What indicator is used in the Urea Hydrolysis Test?
Phenol red
59
What color indicates a positive result in the Urea Hydrolysis Test?
Fuchsia pink or deep pink
60
What color indicates a negative result in the Urea Hydrolysis Test?
Yellow
61
How long can the Urea Hydrolysis Test be incubated?
Up to 7 days at 35°C
62
What does a positive result look like in the KCN Broth Test?
Turbidity in the broth
63
What does a negative result look like in the KCN Broth Test?
Clear broth
64
What genera are positive in the KCN Broth Test?
KEPC: Klebsiella, Enterobacter, Proteus, Providencia, Citrobacter
65
What reagent is used in the String Test?
0.5% sodium deoxycholate (bile salt)
66
What indicates a positive result in the String Test?
String-like colony formation
67
What organism is identified by a positive String Test?
Vibrio cholerae
68
What does a positive result look like in the Esculin Hydrolysis Test?
Black color, seen in Klebsiella pneumoniae.
69
What does a negative result look like in the Esculin Hydrolysis Test?
Yellow color, seen in Shigella flexneri
70
What substrate is used in the MUG Test?
4-methylumbelliferyl-D-glucuronide
71
What does a positive colorimetric result look like in the MUG Test?
Yellow fluorescence
72
What does a positive fluorogenic result look like in the MUG Test?
Electric blue fluorescence, indicating Escherichia coli.
73
Which organism gives a negative result in the MUG Test?
Pseudomonas aeruginosa.
74
What does a positive result look like in the Gelatin Hydrolysis Test?
Gel liquefies, as seen in Proteus vulgaris.
75
What does a negative result look like in the Gelatin Hydrolysis Test?
Gel remains solid, as seen in Enterobacter aerogenes.
76
How long can the Gelatin Hydrolysis Test be incubated?
Up to 14 days at 4°C
77
Are all glucose fermenters motile (gram negative bacilli)?
Yes, all are motile with peritrichous flagella except Klebsiella spp. and Shigella spp.
78
Which genus is cytochrome oxidase positive among Enterobacteriaceae?
Plesiomonas spp.
79
Are Enterobacteriaceae catalase positive and nitrate reducers?
Yes, they are catalase positive and nitrate reducers.
80
What are the antigenic structures in Enterobacteriaceae?
Capsule (K), cell wall/somatic (O), and flagella (H/Vi)
81
What effect does boiling have on the Vi antigen?
Boiling removes the Vi antigen
82
Which organisms are Lactose Fermenters among Enterobacteriaceae?
Escherichia coli, Klebsiella spp., Enterobacter spp., Arizona, Citrobacter spp., and Hafnia.
83
Which organisms are Non-Lactose Fermenters among Enterobacteriaceae?
Proteus, Morganella spp., Providencia spp., Serratia spp., Salmonella spp., Shigella spp., Yersinia spp., and Plesiomonas spp.
84
What is the Gram stain result and shape of Enterobacteriaceae?
Gram-negative bacilli
85
What is another name for Escherichia coli?
Colon bacillus
86
Can Escherichia coli be part of normal flora?
Yes, it can be either normal flora or pathogenic.
87
What are common infections caused by Escherichia coli?
Watery diarrhea (due to enterotoxin), UTI, gram-negative sepsis, neonatal meningitis, nosocomial infections, wound infections, bacteremia, and pneumonia.
88
What is the most common cause of UTI?
Escherichia coli
89
What is the role of the K1 antigen in Escherichia coli?
It is associated with neonatal meningitis, often acquired during vaginal delivery.
90
What is the #1 cause of gram-negative sepsis?
Escherichia coli
91
What is Enterotoxigenic Escherichia coli (ETEC) commonly known to cause?
Traveler's diarrhea (Turista)
92
What type of toxin is produced by ETEC?
Cholera-like toxin that is heat-labile.
93
What are common serotypes of ETEC?
06, 08, and 025
94
What symptoms are typically caused by ETEC?
Watery diarrhea
95
What type of diarrhea does EPEC cause?
Infantile diarrhea
96
What is a key virulence structure in EPEC?
Pathogenicity island
97
What are common serotypes of EPEC?
0111 and 0114
98
What type of diarrhea does EIEC cause?
Dysentery-like diarrhea, similar to Shigella.
99
What is the major virulence factor in EIEC?
Invasin
100
What does EIEC-infected stool typically contain?
Blood and mucus
101
What test is used to detect EIEC virulence?
Sereny test (ocular test in animals) showing keratoconjunctivitis as a positive result.
102
What are common serotypes of EIEC?
0124, 0143, and 0164
103
What syndromes are caused by EHEC?
Hemolytic uremic syndrome (HUS) and hemorrhagic colitis
104
Which organs are primarily affected by EHEC?
Kidneys and gastrointestinal tract (GIT).
105
What is the major virulence factor in EHEC?
Verotoxin (Shigella-like toxin)
106
What is a notable strain of EHEC?
E. coli O157
107
What is the result for EHEC on Sorbitol MacConkey (SMAC) and MUG tests?
Sorbitol MacConkey negative and MUG negative
108
What type of diarrhea is associated with EAEC?
Both acute and chronic diarrhea
109
What is the major virulence factor in EAEC?
Aggregative adhesion fimbriae
110
What unique cell pattern is formed by EAEC?
Stacked brick pattern
111
What is another name for Klebsiella pneumoniae?
Friedlander's bacillus
112
Is Klebsiella pneumoniae motile or non-motile?
Non-motile
113
What colony characteristic does Klebsiella pneumoniae exhibit on MacConkey agar?
Mucoid colony
114
What is the result of the String Test for Klebsiella pneumoniae?
Positive
115
What are the TSI and LIA results for Klebsiella pneumoniae?
TSI: A/A + gas; LIA: K/K
116
What is the IMViC result for Klebsiella pneumoniae?
(-) (-) (+) (+)
117
What infections can Klebsiella pneumoniae cause?
Pneumonia, wound infection, meningitis, and UTI
118
What is a distinctive characteristic of Proteus spp. on Blood Agar Plate (BAP)?
Proteus spp. swarms on BAP
119
What are the TSI results for Proteus spp.?
TSI: K/A + gas + H2S.
120
What is the second leading cause of UTI?
Proteus spp.
121
What phenomenon is associated with Proteus spp.?
Dienes phenomenon (+)
122
What type of stones can Proteus spp. induce?
Renal stones, due to urease production (NH4 carbonate)
123
What is the medium used for Indole test?
SIM Medium (Sulfide Indole Motility

Bacteriology 🦠 (2 decks)

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