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CLS > Micro Quiz 2 (GNR, GPC) > Flashcards

Micro Quiz 2 (GNR, GPC) Flashcards

1
Q

Phenotypic features of Enterobacteriaceae

A

Gram neg bacilli or coocobacilli

Facultative anaerobes

No spores

Glucose fermenter, Catalase pos, Oxidase neg

Can reduce nitrates to nitrite, can grow on Mac Conkey

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2
Q

Why do stool cultures?

A

To rule out enteric pathogens (salmonella, shigella, campylobacter, E. coli O157:H7, yersinia, aeromonas, and vibrio)

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3
Q

Stool collection/transport

A

Plated immediately, or add preservatives and hold on ice for 2 hrs, or in transport medium for up to 4 days (usually Cary-Blair, Amies, or Staurt)

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4
Q

Enterobacteriaceae culture media

A

Main set up: Blood, Chocolate, Mac Conkey, PEA

Secondary: HE or XLD (use secondary to rule out salmonella)

Enrichment broth to enhance pathogen recovery

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5
Q

E. coli identification

A

Gram neg bacillus/coocobacillus Lactose-fermenter (pink on MAC)

A/A on TSI and KIA w/ or w/out gas

IMViC = + + - -

Oxidase neg, PYR neg, Nitrate pos, MUG pos

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6
Q

EHEC

A

Enterohemorrhagic E. coli, “shiga-toxin producing E. coli”

Causes hemorrhagic colitis and hemolytic-uremic syndrome

Nonmotile, MUG neg

Use SMAC media, produces colorless colonies (cannot ferment sorbitol)

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7
Q

What are O and H antigens?

A

O = somatic/cell wall antigens (seen in all)

H = flagellar antigens (not seen in non-motile strains)

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8
Q

Klebsiella spp. identification

A

Non-motile* Gram neg bacillus

Lactose-fermenter (pink on MAC)

Encapsulated (mucoid colonies)

A/A on TSI and KIA w/ gas

IMViC = - - + + (opposite E. coli)*

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9
Q

Serratia spp. identification

A

Motile Gram-neg bacillus (found in soil, water, etc)

Produces red pigment*

Late lactose-fermenter (may take 48 hrs)

A/A on TSI and KIA

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10
Q

Proteus spp. identification

A

Motile Gram neg bacillus/coccobacillus (“swarmers”)*

Non-lactose fermenter

K/A on TSI and KIA w/ H2S pos

PAD pos (rules out salmonella, shigella, etc)

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11
Q

Morganella morganii identification

A

Motile Gram neg bacillus/coccobacillus

Similar to Proteus but not “swarmers” and no H2S*

K/A on TSI and HIA

PAD pos

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12
Q

Providencia spp. identification

A

Motile Gram neg bacillus/coccobacillus

Similar to Moganella, slight difference in IMViC

No H2S, no swarming, PAD pos, K/A on TSI and KIA

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13
Q

Salmonella enterica - serotype Typhi

A

Passed person to person, can have asymptomatic carriers

High prolonged fever, involvement of RE system of liver, spleen, and intestines

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14
Q

Salmonella spp. identification

A

Motile Gram neg bacillus

Non-lactose fermenter, colorless on MAC, green/black on HE, red w/ black centers on XLD

K/A on TSI and KIA w/ H2S

IMViC = - + - V

Test with group and type specific antisera (O, H, and Vi)

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15
Q

Shigella spp.

A

No animal resevoir, 4 serogroups

Nonmotile, Gram neg bacilli

Non lactose fermenter, colorless on MAC, green on HE, colorless on XLD

K/A on TSI and KIA

IMViC = V + - -

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16
Q

Yersinia spp.

A

More growth at RT

Non motile Gram neg bacillus, bipolar staining (“safety pin”)

Slow grower, pinpoint colonies at 24 hrs, colonies have raised “fried egg” appearance

Non lactose fermenter

K/A on TSI and KIA

IMViC = - + - -

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17
Q

Microaerophile

A

Low O2 concentration and increased CO2

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18
Q

Capnophiles

A

Increased CO2

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19
Q

Differential media vs selective media

A

Differential = still grows several organisms but differentiates between them

Selective = only grows specific organisms

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20
Q

Gram stain procedure

A

Crystal violet (rinse)

Iodine (rinse)

Decolorizer (rinse)

Safranin (rinse)

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21
Q

GNR characteristics of whole group

A

1) Glucose utitilization
- fermenters, oxidizers, asaccharolytic (no sugar utilization)
2) Oxidase reaction
- pos and neg
3) Growth on MAC
- pos and neg

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22
Q

Group 1 Bioterrorism species

A

Brucella spp., Francisella tularensis, Yersinia pestis

23
Q

Brucella spp.

A

“Udulant fever”/”Mediterranean fever”

Infects humans and animals, transmission via wound/mucous membrane contact with contaminated food/dairy/birthing or inhalation

Granulomas of liver, bone marrow, spleen, lungs, lymph nodes, testes, kidneys, brain

Slow growers (72 hrs, better on choc, blood cultures kept for 4 wks*)

Look Gram pos, tough to decolorize

Oxidase pos, nitrate pos, urease pos, catalase pos

24
Q

Francisella tularensis

A

“Tick fever”, spread by water/soil, handling ill/dead animals, tick/flea bites

Lives in macrophages, require cysteine for growth (grow on choc, Thayer-Martin, BCYE, not blood), poor grower

Catalase pos, oxidase neg, urease neg

25
Q

Group II: Glucose ferment, MAC pos, Oxidase pos

A

Aeromonas hydrophila

Pleisiomonas shigelloides

Vibrio spp.

26
Q

Aeromonas hydrophila

A

Gastroenteritis, HUS, wound infections, septicemia

Selective media = CIN

Beta hemolytic on blood, oxidase pos, indole pos, not halophilic

27
Q

Pleisiomonas shigelloides

A

Same as Aeromonas

Oxidase pos, pos for decarboxylase of lysine, ornithine, and arginine

Not halophilic

28
Q

Vibrio spp.

A

Cholera, gastroenteritis, some sucrose fermenters, some not, oysters

Halophilic (grow on TCBS)

String test differentiates V. cholerae from others (draw string from slide when mixed with bile salts)

29
Q

Group III: GNR Non-fermenters (oxidizers), MAC pos, Oxidase var.

A

Pseudomonas spp.

Acinetobacter spp.

Burkholderia spp.

30
Q

P. aeruginosa

A

Thin GNR, pigmented on blood (blueish-green), fluorescent, pleasent smell, metallic sheen, serated edges, beta hemolytic on blood

Ubiquitious, serious for CF patients

Oxidase pos, TSI = K/No change, grow at 42C, do AST

31
Q

P. fluorescens/putida

A

Can’t grow at 42C

Fluorescent, no distinctive odor or morphology

32
Q

Acinetobacter spp.

A

Can survive in dry or moist

Non hemolytic, gray colonies, may be lightly pink on MAC (oxidation of lactose)

Oxidase neg, catalase pos

33
Q

Burkholderia cepacia

A

Found in animals, water, soil

Transmitted aerosols, skin contact, ingestion

Can be drug resistant, infects CF patients

Selective media = BCSA

Yellow on iron containing media (TSI), earthy dirt odor

34
Q

Burkholderia pseudomallei

A

Pneumonia, UTI, genital infections, may be dormant and reactivate

SE Asia and Australia

Oxidase pos, Gram neg bipolar staining

35
Q

Group IV: GNR Fastidious (“difficult”)

A

Bartonella spp.

Pasturella spp.

C. jejuni

H. pylori

Bordetella spp.

Legionella spp.

Haemophilus spp.

HACEK

36
Q

Bartonella spp.

A

B. henselae = “cat scratch”

Skin has red, berry lesions, collar of scaling

Nomal flora in cat mouth, passed by scratch

Culture on fresh choc agar, 5-10% CO2 (capnophilic)

Oxidase neg, urease neg, catalase neg

37
Q

Pasteurella spp.

A

In cat/dog mouth, passed by bite, abcess, septicemia, arthritis, peritonitis

P. multocida most common

Non-hemolytic, shiny colonies, capnophilic, don’t grow on MAC, earthy odor

Use selective media w/ vancomycin, clindamycin, and amikacin

Oxidase pos, catalase pos, indole pos, nitrate pos

38
Q

Campylobacter

A

Gastroenteritis, transmitted by contaminated food/poultry/milk/water, infected animals (cats/dogs)

Use Campy blood agar w/ 5 antibiotics, at 42C for 72 hrs, microaerophilic

Curved GNR, “gull wings” ,Oxidase pos, perform AST

39
Q

Helicobacter pylori

A

Lives in gastric mucosa of lumen, causes gastritis, ulcers, gastric cancer

Use urease to neutralize acid in stomach, small neutral area around them

Diagnose via biopsy, endoscopy, breath test, EIA

40
Q

Bordetella pertussis

A

Vaccine preventable

Nasopharyngeal swab, innoculate bedside

Selective media = Bordet Gengou, Regan-Lowe (charcol and horse blood)

Use DFA or PCR to confirm culture, slow grower

41
Q

Legionella pneumophila

A

“Legionnaire’s disease”, pneumoniae, can disseminate to other organs

Survives in moist environments

Selective media = BCYE

42
Q

HACEK

A

Haemphophilus aphrophilis

Actinobacillus actinomycetemcomitans

Cardiobacterium hominis

Eikenella corrodens

Kingella spp.

Usual flora of mouth, can cause endocarditis, capnophilic

Abnormal morphology on blood plates

43
Q

Gram positive cocci

A

Staphyloccocus

Streptococcus

Enterococcus

44
Q

Staphylococcus aureus

A

Causes food poisoning, toxic shock, boils, pneumonia, etc.

Has protein A in cell wall to prevent phagocytosis

Yellow/gold colonies, buttery, usually beta hemolytic, grape like clusters

Catalase pos, coagulase pos

Perform AST, can be highly resistant (MRSA - use oxacillin salt plate for screening)

45
Q

Coagulase neg Staphylococcus

A

S. epidermidis, S. saprophyticus, S. lugdeninsis

Normal flora, can be pathogens

S. saprophyticus = UTI, S. epidermidis/lugdeninsis = biofilm attach to plastic (catheter infections, heart valve endocarditis)

White, non-hemolytic

Test AST, S. saprophytics = Novobiocin resistant

46
Q

Micrococcus spp.

A

Considered contaminate, looks like staph but w/ tetrad

Coagulase neg, lemon yellow colonies

Differentiate from staph by Bacitracin susceptible, oxidase pos

47
Q

How to differentiate Streptococcus spp.?

A

1) Hemolysis pattern
2) Lancefield classification (based on cell wall antigens)
- groups A-H
3) Size ( < or > 0.5 mm)

48
Q

Beta hemolytic Streptococcus spp.

A

S. pyogenes

S. dysgalactiae

S. angiosus

S. agalactiae

49
Q

S. pyogenes

A

Group A, beta hemolysis, white colonies, large (>0.5mm), Catalase neg, PYR pos, Bacitracin sus., agglutinate in Lancefield type A serum

Pharyngitis, leads to rheumatic fever (autoimmune attacks on heart), and glomerulonephritis

Stab and streak on sheep blood agar w/ Trimeth/sulfa disk (makes media Strep selective), incubate w/ CO2

50
Q

S. agalactiae

A

Group B, weak beta hemolytic, white colonies, small

Catalase neg, CAMP pos, Hippurate pos, bile esculin neg, not hapnophilic

GBS issue in pregnant women, neonatal meningitis/pneumoniae

Can look like Listeria, catalase differentiates

51
Q

S. pneumoniae

A

Alpha hemolytic, gray colonies, tiny, doughnut shaped

Catalase neg, Optochin sensitive, bile soluble

Causes pnumonia, meningitis, sinusitis, otitis media

Gram pos dipplococci

52
Q

Streptococcus viridans group

A

Alpha hemolytic, slow grower, white colonies

Catalase neg, Esculin neg, Optochin resistant, not bile soluble (Makes it different from S. pneumoniae)

53
Q

Enterococcus spp. (E. faecalis/faecium)

A

White/gray, not usually hemolytic

Catalase neg (weak bubbles), hapnophilic, Bile esculin pos, PYR pos, Lancefield Group D

E.faecalis/faecium can be vancomycin resistant

CLS (15 decks)

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