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Microbiology 2 > Module 1: Niesseria and Moraxella > Flashcards

Module 1: Niesseria and Moraxella Flashcards

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Biology 101 flashcards
1
Q

What 4 genera are in the Nisseriaceae family?

A

Acinitobacter
Kingella
Neisseria
Moraxella

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2
Q

What are the 2 main Neisseria pathogens

A

N. meningitidis and N. gonorrhoeae

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3
Q

What basic media is used to isolate Neisseria?

A

Chocolate agar (enriched)

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4
Q

How is chocolate agar prepared?

A

Same as blood then slowly heat to 75-85 degrees for 10-15 minutes to lyse the blood and release nutrients
Cool to 50 degrees and add supplements (supplement B and Iso-Vitale X)

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5
Q

What typically used plate does N. gonorrhoeae not grow well on?

A

Blood agar

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6
Q

What selective media is used to isolate N. gonorrhoeae? Why?

A

Modified Thayer Martin (MTM)
New York City (NYC)

Because genital, rectal, and oropharyngeal swabs typically have many normal flora which will overgrow the N. gonorrhoeae

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7
Q

How is MTM media made?

A

GC agar base and hemoglobin rehydrated and autoclaved separately
Cooled to 50 degrees, IsoVitaleX and antibiotics added

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8
Q

What antibiotics are present in MTM? What do each of them do?

A

Vancomycin - inhibit gram positive (concentration is important, too much slows growth)
Colistin - inhibit gram negative and “non-pathogenic” Neisseria
Nystatin - inhibits yeast
Trimethoprim lactate - prevents Proteus swarming

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9
Q

How is NYC media made?

A

Lysed horse RBC, horse plasma, yeast dialysate, and glucose added to agar
Antimicrobials added

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10
Q

What antimicrobials are in NYC media? What do each of them do?

A

Vancomycin - inhibit gram positive
Colistin - inhibit gram negative
Amphotericin B - inhibit yeast
Trimethoprim lactate - inhibit Proteus swarming

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11
Q

What two types of transport media can be used for N. gonorrhoeae swabs if they cannot be immediately planted?

A

Non-nutrient holding media (Amie’s charcoal) and nutrient growing media

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12
Q

What is a recommended non-nutrient holding media for N. gonorrhoeae? How does it work?

A

Amie’s charcoal transport media
Maintains viability without growth in a buffered semi-solid media
Charcoal absorbs any fatty acids (vagina, cotton swabs) that may kill N. gonorrhoeae

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13
Q

What swabs are recommended for transporting N. gonorrhoeae on?

A

Synthetic ones such as calcium alginate

Cotton swabs should be soaked in charcoal or placed in Amie’s charcoal media

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14
Q

What is a growing transport media?

A

A selective plate is planted and placed in container with CO2 generating system, usually bicarbonate and citric acid, incubated 18-24 hours before transport and sent

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15
Q

What is the genus test for Neisseria and moraxella?

A

Oxidase positive

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16
Q

How does the oxidse test work?

A

Detects cytochrome oxidase enzyme
Uses aromatic amine (dimethyl or tetramethyl-para-phenylenediamine dihydrochloride) that is colorless in a reduced state and purple in an oxidized state

17
Q

What are the precautions about the oxidase reagent?

A

1% solution (Kovac’s oxidase) is unstable and is oxidized by oxygen and turns dark purple

18
Q

How is the oxidase reagent stabilized? What is a downside of doing this?

A

Stabilized with ascorbic acid

  1. 2% will be stable for a week
  2. 02% will be stable for a day

More ascorbic acid = less sensitive

19
Q

What are some oxidase test methods that can be used?

A

Filter paper
Swab
Drop on colonies

20
Q

What are the filter paper and swab oxidase methods?

A

Oxidase on filter paper, colonies rubbed on
Swab put in oxidase, touched to colony
Positive = purple

21
Q

What is the drop on colonies oxidase method?

A

Drop oxidase reagent on isolated colonies

Colonies turning purple = positive

22
Q

What are some precautions with the oxidase test?

A

Iron/nicrome loops cannot be used, causes false positives
Neisseria loses reactivity with age
Inhibitory/selective media may cause false negatives
Carbohydrate utilization media may cause acid production and cause false negatives
MAC may cause false positive (already pink/purple)

23
Q

What is the gram stain for Neisseria species?

A

Gram negative diplococci
“Jellybean” shaped
May be seen intracellularly in PMNs

24
Q

What unique gram stain feature may N. meningitidis have that N. gonorrhoeae will not?

A

Capsules

Seen as a “halo” around cells

25
Q

What are the growth requirements for N. gonorrhoeae?

A

Capnophillic obligate aerobes
Requires 3-7% CO2
35 degrees, moist environment for best growth
Requires nutrients (hemoglobin, yeast extract, serum)

26
Q

What are the cultural characteristics of N. gonorrhoeae

A

Small at 24 hours, may be missed

Gray, translucent

Microbiology 2 (14 decks)

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