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MLS503 > Week Two > Flashcards

Week Two Flashcards

1
Q

Explain why the Gram stain is the most important stain in the clinical microbiology lab.

A

Determine if its Gram + or Gram -
Cell shape and arrangment

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2
Q

Explain when direct Gram stains are used and why this information is useful to the physician.

A

Direct speciemn Gram stain- 24hrs
Colony- 24-48hrs

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3
Q

Explain in detail the Gram stain procedure and components (inside and out, backwards and forwards). Include the role and action of the different reagents and reagent designations (i.e. primary stain, mordant, decolorizing agent, and counterstain).

A

photo in phone

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4
Q

List the Gram stain “Rules of Thumb,” and explain each

A

photo in phone

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5
Q

Define the rating of oil immersion fields (numerical, i.e. 1+ to 4+ and also few to many). Given a gram stain photo, use the proper description to report the results. List the bacteria that are commonly used for Gram stain controls.

A
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6
Q

Name and recognize the different bacterial cell morphologies. Briefly explain what makes a bacteria form chains, clusters, or pairs. Define cocci, coccus, diplococcus, bacillus, bacilli, fusobacterium, and spirochete.

A
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7
Q

Recognize and define the different types of cell arrangements.

A
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7
Q

Describe the characteristics of agar. List the percentages of agar used in plating and tubed media.

A
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8
Q

Define enriched, selective, and differential culture media.

A
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8
Q

For the following types of plating media, state what each letter stands for (example: SBA = Sheep Blood Agar), explain in detail their application, list the ingredients, and the function of each ingredient:
a) SBA
b) Choc (also state what NAD stands for)
c) MAC
d) MSA
e) MTM
f) PEA
g) CNA
h) HEA

A
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9
Q

Explain the use of thioglycolate broth and name the reducing agent used in the media. List and explain two main purposes for using the broth.

A
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10
Q

which would be in CO2 air incubator?
SBA CHOC MAC MSA MTM PEA CNA HEA

A
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11
Q

List what plates should be read at 24 and 48 hours, and explain why.

A
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12
Q

List the percentages of oxygen and carbon dioxide in atmospheric air and in the CO2incubators. List the percentage of oxygen for microaerophiles. List the percentage of carbon dioxide for capnophiles.

A
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13
Q

Define the following terms:
a) obligate aerobes
b) obligate anaerobes
c) facultative anaerobes
d) microaerophiles
e) capnophiles

A
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14
Q

List the terms used to describe colony morphology and characteristics.
List the generalized steps involved in clinical pathogen identification. Define direct Gram stain, somatic cells, primary plating media.
List and explain the four critical questions when evaluating a clinical specimen for the presence of a pathogen.
List and explain the generalized procedure for solving for clinical unknowns.
Define normal flora. List two other terms used to refer to normal flora. Define the term opportunistic pathogen. List conditions that may change the normal flora.
Diagram and describe the correct method for sub-culturing a colony onto plating media to obtain isolated colonies, including when it is appropriate to flame the loop.
Based on a given scenario, be able to make conclusions about plate growth information.

A
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15
Q

During the Gram stain procedure, after the Crystal Violet staining step, all cells are

A

Violet

16
Q

This slide is a direct Gram stain of a leg wound culture. Using the correct reporting guidelines, give a description that would be sent to the physician

A

4+ Gram pos cocci/chain pic hearted on phone

17
Q

The macromolecule that is only found in bacteria is called:

A

peptidoglycan

18
Q

The cell membrane of bacteria is composed mainly of:

A

a phospholipid bilayer

19
Q

Which plating media is used to isolate only Gram negative rods:

A

MAC

20
Q

This is a direct Gram stain from a blood culture. On which of the following plating media would you expect to see growth of this non-fastidious organism?

A

CNA and CHOC pic Gram pos diplococcus pic on phone hearted

21
Q

A) Give the name of this plating media and B) Is this organism Lactose positive or negative?

A

Lac pos and MAC red plate on phone

22
Q

On HEA plates, non pathogens (i.e. intestinal flora) ferment (i.e. utilize) the sugars and produce what color of colonies?

A

yellow or salmon

23
Q

On HEA plates, if hydrogen sulfide is produced by the organism, what color would it turn the colony? (Note: Salmonella species usually produce hydrogen sulfide).

A

black

24
Q

SBA

A

Sheep blood agar, general primary plating media. Grows most non-fastidious organisms. 5% defibrillated sheep RBC’s. Cool 50c add blood, CO2 INC

25
Q

CHOC

A

Chocolatized blood. Same components as SBA add RBC’s at 80c which releases hemoglobin NAD. Grows both fastidious and non fastidious organisms eg. Haemophilis and Neisseria, CO2 INC

26
Q

MAC MacConkey

A

Selective for enteric Gram neg rods. Has lactose(sole carb) changes PH reddish, Bile salts(inhibit most Gram pos cocci, crystal violet(inhibit Gram pos cocci), peptones(PH change for proteins), AIR INC
Lac pos=red, lac neg=yellow

27
Q

Primary stain is? How long? Outcome?

A

Crystal violet, 30s, all violet

28
Q

Mordant stain? Time? Outcome?

A

Iodine, 1min, intensifies crystal violet to form CV-I complex- both will looks purple

29
Q

Decolonized? Time? Outcome?

A

Ethanol/ Acetone, 2-3s, G + will stay purple, G- will loose color

30
Q

Counterstain? Time? Outcome?

A

Safranin, 30s, G+ will stay purple, G- will be reddish

31
Q

MTM modified Thayer Martin

A

Selective for pathogenic gonorrhea. CHOC + 4 antimicrobials.(inhibit Gram pos bact, Gram neg bact, yeast, proteus spp.) CO2 INC

32
Q

MSA mannitol salt agar

A

Selective for staph spp, like S. aureus. Mannitol(sole carb) 7.5% salt, peptones(used if can’t use mannitol) phenol red(ph indicator). AIR INC. Man pos=yellow, man neg=red

33
Q

PEA Phenyl Ethyl alcohol agar

A

SBA w/ PEA, selective for Gram pos cocci, slows G neg rods. CO2 INC

34
Q

CNA Colistin Nalidixic Agar

A

SBA+ colistin and nalidixic acid, selective of Gram pos cocci, prevents growth of Gram neg rods, CO2 INC

35
Q

HEA Hektoen Enteric Agar

A

Bile salts inhibits Gram pos, also some Gram neg rods, orange or yellow lac/sun pos, black or green lac/suc neg(pathogen) ,AIR INC

36
Q

Beta hemolysis

A

Complete clearing around colony

37
Q

Alpha hemolysis

A

Color change around colony

38
Q

Gamma hemolysis

A

Non hemolytic

39
Q

What go into the CO2 incubator?

A

SBA
MTM
PEA
CNA

40
Q

What goes into the air incubator?

A

MAC
MSA
HEA

MLS503 (6 decks)

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