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1-Scientific & lab basis of microbiology > Basic identification of bacteria > Flashcards

Basic identification of bacteria Flashcards

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1
Q

List genera of aerobic Gram-negative bacilli that are oxidase-negative.

(8)

A

OX- GNB:

  • Acinetobacter (2xCB)
  • Morganella
  • Proteus
  • Providencia
  • Salmonella
  • Shigella
  • Stenotrophomonas (lab grown green, ox “yellow”)
  • Yersinia
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2
Q

List genera of aerobic Gram-negative bacilli that are oxidase-positive.

(5)

A

OX+ GNB:

  • Aeromonas
  • Pasteurella (safety pin)
  • Plesiomonas
  • Pseudomonas
  • Vibrio (vibroid)
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3
Q

What are two types of alpha-hemolytic streptococci,
and what biochemical can you use to differentiate them?

A

S.pneumo

  • capsule -> optichin-R

Viridans Group streptococci (VGS) (S.mitis/S.mutans)

  • no capsule = opt-S
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4
Q

What are two types of beta-hemolytic streptococci,
and what biochemicals can you use to differentiate them?

A

GAS (bacitracin-s, PYR+)

GBS (bacitrcin-R, PYR-, CAMP+)

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5
Q

What are two types of gamma-hemolytic streptococci,
and what biochemical can you use to differentiate them?

A

GDS (e.g. S.bovis)

Enterococcus (g. in 6.5% NaCl)

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6
Q

When is bacitracin used in the lab?

A

a.k.a. TaxoA

Differentiates GAS vs GBS

  • GAS = bac-S
  • GBS = bac-R
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7
Q

Catalase positive organisms

A
  • Nocardia
  • Pseudomonas
  • Listeria
  • Aspergillus
  • Candida
  • E. coli
  • Staphylococci
  • Serratia
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8
Q

What test can you use to detect DNase activity?

A

Toluidine Blue O

E.g. for Elizabethkingea meningoseptica

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9
Q

What test can you use to detect DNase activity?

A

Toluidine Blue O

E.g. for Elizabethkingea meningoseptica

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10
Q

Genera of lactose-fermenting gut microbiota

A
  • Citrobacter
  • Escherichia
  • Enterobacter
  • Klebsiella
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11
Q

When is optichin used in the lab?

A

a.k.a. TaxoP

Differentiates S.pneumo vs. VGS

  • S.pneumo = opti-s
  • VGS = opti-R
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12
Q

Bacteria that are oxidase-positive:

(Genera)

A
  • Neisseria
  • Pseudomonas
  • Burkholderia
  • Brucella
  • Legionella
  • Vibrio
  • Campylobacter
  • Helicobacter
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13
Q

What are the general traits of Pseudomonas spp.?

  • Gram stain
  • Motility
  • Oxygen requirements
  • Oxidase
  • Catalase
  • Indole
  • Sugar fermentation & TSI reaction
  • Nitrate reduction
  • Citrate
  • Lipase
A
  • GS: GNB thin
  • motile by polar flagellum (<=1)
  • Facultative anaerobe
  • OX +
  • CAT +
  • Indole -
  • Non-lactose fermenter (TSI K/K)
  • Nitrate reduction +
  • Citrate +
  • Lipase +
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14
Q

What are three biochemical tests you can use to distinguish S.pneumoniae from VGS?

A
  • Optichin/TxP (S.pneumo = S)
  • Bile solubility (S.pneumo = +)
  • Inulin fermentation (S.pneumo = +)
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15
Q

Urease Positive Organisms

A
  • Cryptococcus
  • H. pylori
  • Proteus
  • Ureaplasma
  • Nocardia
  • Klebsiella
  • S. epidermidis
  • S. Saprophyticus
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16
Q

Bacillus

A

O2: O2 (obl/facan)

CAT+

Gram: GP bacilli. Oval endospores, central to subterminal.

ANTHRACIS:

  • GV, Long chains.
  • BAP colonies ground glass, beaten egg.

CEREUS:

  • Pallisades (not long chains)
  • BAP colonies ~green, larger than anthracis.
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17
Q

Corynebacterium

A

O2: O2 (obl/facan) CAT+ GS: GP bacilli Club/diphtheroid shape Form V’s, palisades, or Chinese letters

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18
Q

Erysipelothrix

A

O2: O2 (obl/facan) CAT- GS: Weak GP bacilli

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19
Q

Gardnerella

A

O2: FACAN CAT- GS: GV coccobacilli.

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20
Q

GI commensals (MGIF)

A

OX- L(N)F GNB Enterococcus ANA’s

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21
Q

GP branching filaments

A

AEROBIC: Nocardia (weakly acid-fast) ANO2: Actinomyces (not AF)

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22
Q

You see Gram-negative bacilli on your slide from a culture grown aerobically.

What genera could they be?

A

Coliforms:

  • Escherichia
  • Klebsiella (encapsulated)
  • Enterobacter
  • Serratia
  • Citrobacter
  • Shigella
  • Salmonella
  • & other Enterobacterales

Non-fermenters:

  • Pseudomonas
  • Acinetobacter

Pasteurella

HACEK organisms:

  • Haemophilus (can be coccobacilli)
  • Aggregatibacter
  • Cardiobacter
  • Eikenella
  • Kingella

Bacillus*

*Bacillus & related genera can easily over-decolourize on Gram stains.

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23
Q

You see Gram-negative cocci on your slide from a culture grown aerobically.

What genera could they be?

A
  • Neisseria (coffee-bean shape)
  • Moraxella (coffee-bean shape)
  • Haemophilus/HACEK (coccobacilli)
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24
Q

You see Gram-positive bacilli on your slide from a culture grown aerobically.

What genera could they be?

A
  • Corynebacterium
  • Bacillus
  • Listeria
  • Erysipelothrix
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25
You see **Gram-positive cocci** on your slide from a culture grown **aerobically**. What genera could they be?
* *Staphylococcus* * *Streptococcus* * *Enterococcus* * "Nutritionally variant streptococci" (*Granulicatella, Abiotrophia*)
26
You see **Gram-negative bacilli** on your slide from a culture grown **ANaerobically**. What genera could they be?
* *Bacteroides* * *Fusobacterium* * *Prevotella* * *Prophyromonas* * *Leptotrichia*
27
You see **Gram-negative cocci** on your slide from a culture grown **ANaerobically**. What genera could they be?
* *Veillonella*\* \* *Veillonella* is phylogenetically Gram-positive, within the *Negativicute**s* group, so stains Gram-negative.
28
You see **Gram-positive bacilli** on your slide from a culture grown **ANaerobically**. What genera could they be?
* *Clostridium* * *Actinomyces* * *Cutibacterium* & *Propionibacterium* * *Eggerthella* * *Eubacterium*
29
You see **Gram-positive cocci** on your slide from a culture grown **ANaerobically**. What genera could they be?
* *Peptostreptococcus* * *Parvimonas* * *Finegoldia* * *Staphylococcus saccharolyticus*
30
You see **Gram-negative bacilli** on your slide. They appear **curved**. What genera could they be?
* *Vibrio* (comma-shaped) * *Campylobacter* (gull-winged) * *Helicobacter* * *Anaerobiospirillum* * *Arcobacter*
31
You see **Gram-negative bacilli** on your slide. They appear **fusiform**. What genera could they be?
* *Fusobacterium* * *Leptotrichia* * *Capnocytophaga*
32
You see **Gram-negative coccobacilli** on your slide. What genera could they be?
* Haemophilus* * Acinetobacter* * Aggregatibacter* * Moraxella* * Pasteurella* * Bacteroides* * Brucella* **(RG3!)** * Francisella* **(RG3!)**
33
You see **Gram-variable bacilli** on your slide. What genera could they be?
* *Bacillus* (*Paenibacillus, Lysinibacillus*) * *Clostridium* * *Gardnerella* * *Leptotrichia*
34
What bacterial are **obligate intracellular bacteria**? (genera)
* *Chlamydia/Chlamydophila* * *Coxiella* * *Rickettsia* * *Orientia* * *Ehrlichia* * *Anaplasma*
35
What bacterial are **spirochetes**? (genera)
* *Borrelia/Borreliella* * *Leptospira* * *Treponema*
36
You see **TINY Gram-negative bacilli** on your slide. What genera could they be?
* *Brucella* **(RG3!)** * *Francisella* **(RG3!)**
37
How can we determine the serotype of an ***H.influenzae*** isolate?
**Latex agglutination** (unless non-mucoid strain, a.k.a. non-typeable)
38
How can we determine the serotype of an ***H.influenzae*** isolate?
**Latex agglutination** (unless non-mucoid strain, a.k.a. non-typeable)
39
Lactobacillus
O2: FACAN. (Grows better ANO2) CAT- GS: GP bacilli Colonies: Look like VGS (but different GS) ID with growth on LBS
40
Listeria
O2: FACAN CAT- GS: GPB (can be coccobacilli). Single or short chains. - GS of CSF or old cultures look GV coccoid, very similar to S.pneumo!
41
What organisms can grow on ***B.cepacia* selective agar**?
* *B.cepacia* complex * *Ralstonia* spp.
42
What organisms can grow on ***B.cepacia* selective agar**?
* *B.cepacia* complex * *Ralstonia* spp.
43
What's in **Chocolate agar** that allows it to support *Haemophilus influenzae* growth?
* NAD (Factor V) * Hemin (Factor X)
44
What genus is **Lowenstein-Jensen** agar used to culture?
*Mycobacterium* spp., including *M.tuberculosis*
45
What organisms grow on **MacConkey agar**?
**Enteric Gram-negative** organisms. Fermentation of lactose in the medium turns colonies pink.
46
What organisms grow on **Sabouraud** agar?
Fungi
47
What is in **Thayer-Martin** agar that allows it to select for *Neisseria gonorrhoeae* and *N. meningitidis*?
* Vancomycin * Trimethoprim * Colistin * Nystatin
48
How can we determine the **serogroup** of an ***N.meningitidis*** isolate?
PCR assay with two targets: * ***ctrA*** = *N.meningitidis* **capsular transport gene** (confirms spp. ID & encapsulated). * ***said*** = serogroup-specific **poly-sialyltransferase** gene. NB: Serotyping done @NML for surveillance.
49
How can we determine the **serogroup** of an ***N.meningitidis*** isolate?
PCR assay with two targets: * ***ctrA*** = *N.meningitidis* **capsular transport gene** (confirms spp. ID & encapsulated). * ***said*** = serogroup-specific **poly-sialyltransferase** gene. NB: Serotyping done @NML for surveillance.
50
Nocardia
O2: STRICT aerobe CAT+ GS: GP bacilli, weakGPB - Long, thin, delicate,branching chains/filaments. - Filaments can break apart from culture
51
Obligate intracellular bacteria
* *Chlamydia* * *Coxiella* * *Ehrlichia* * *Rickettsia*
52
Oral cavity commensals (MOF)
CoNS Dips NP Neisseria VGS ANA GPC + Lactobacillus
53
How do we determine ***S.pneumoniae*** serotypes?
Done by **Quellung** reaction
54
How do we determine ***S.pneumoniae*** serotypes?
Done by **Quellung** reaction
55
Skin commensals (MSF)
CoNS Dips NP Neisseria VGS ANA GPC + Propioni
56
What is the **Trichrome** stain used for?
To detect **intestinal protozoa**/spx
57
What is the **Trichrome** stain used for?
To detect **intestinal protozoa**/spx
58
Which bacteria stain acid-fast: (genera)
* *Mycobacterium* spp. * Actinomycetes (e.g. *Nocardia, Rhodococcus*). * *Legionella micdadei*
59
What organisms would you want to use a **Fite** stain to see?
* *Mycobacterium leprae* * Often decolourizes with ZN/Kinyoun stains NB: *Nocardia* will also stain Fite+, so non-specific.
60
What organisms would only stain weakly with Gram stain, so a **Giemsa** stain would be preferred? (genera)
* *Borrelia/Borreliella* * *Ehrlichia* * *Anaplasma* * *Rickettsia* * *Helicobacter*
61
What organisms would you want to use a **GMS** stain to see? (GMS = Gomori methenamine silver)
**Fungi** * Used broadly as a fungal screen in histology * Including *Pneumocystis jiroveci* (*Histoplasma* granuloma shown with question)
62
What organisms would you want to use an **India ink** stain to see?
*Cryptococcus spp.*
63
What organisms would you want to use a **Mucicarmine** stain to see?
* *Cryptococcus* spp.
64
What organisms would you want to use **PAS** (Period acid-Schiff) stain to see?
*Tropheryma whipplei* in tissue (PAS+ macrophages in the lamina propria are pathognomonic for Whipple's disease)
65
What organisms would you want to use a **Warthin-Starry** stain to see?
* Spirochetes: * *Treponema* (*e.g*. syphilis) * *Borrelia/Borreliella* * *Leptospira* * *Helicobacter pylori* * *Bartonella henselae* (bacillary angiomatosis)
66
What organisms would you want to use a **Ziehl-Neelsen** stain to see?
* Acid fast bacteria: * *Mycobacterium* spp. * Actinomycetes (*e.g. Nocardia*, *Tsukamurella, Gordonia*) * *Legionella micdadei* * Coccidian parasites, *e.g. Cryptosporidium*
67
Strictly aerobic GN bacilli
Pseudomonas

1-Scientific & lab basis of microbiology (9 decks)

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