LAB 12 – NEISSERIA, MORAXELLA

Question 1

What are appropriate specimens for Neisseria meningitidis?

Answer 1

• CSF for STAT (2-5 mL)
• Blood (2 specimens at separate intervals during chills or fever)
• Skin lesions (from petechia)
• Throat/ nasopharynx (of asymptomatic carrier)

Question 2

What are appropriate specimens for Neisseria gonorrhoeae?

Answer 2

• Endocervical swabs
• Urethral swabs
• Anorectal swabs
• Pharyngeal swabs

Question 3

What are the basic differences between pathogenic and non-pathogenic Neisseria sp. ?
a. Organisms
b. Nutritional requirements
c. Atmospheric requirements
d. Temperature requirements
e. Colonial morphology

Answer 3

Pathogenic vs Non-pathogenic Neisseria sp. :

a. N. gonorrhoeae, N. Meningitidis vs N. lactamica
b. Enriched media (CAP, NYC) vs Simple media (BAP)
c. CO2 vs O2
d. Strict 35°C vs 37°C (and RT)
e. sm shy gy, sm gy +/- muc vs sm gy

Question 4

You look at a direct smear that has G-dc but there is no growth when cultured. What could be a few reasons for this?

Answer 4

• fastidious; requires CO2 and enriched media at 35°C
  Eg. Thayer-Martin Agar, New York City Agar

Question 5

List 5 environmental conditions that Neisseria sp. are susceptible to?

Answer 5

1. Dry environment conditions
2. Extreme temperature changes
3. Extreme pH
4. Toxic fatty acids
5. O2

Question 6

Name 2 types of transport media that are used for Neisseria gonorrhoeae?
a. Give examples of each

Answer 6

1. Non-nutritive Transport Media: Stuart’s, Amies
2. Nutritive Transport Media: Transgrow, JEMBEC, Gono-pack

Question 7

What swabs should be used for specimen collection of Neisseria sp? Why?

Answer 7

swabs should be made of DACRON or RAYON (cotton and calcium alginate swabs may be inhibitory)

Question 8

In what situations would you culture gonococci specimens?

Answer 8

When women have vaginal flora that resemble gonococci (g-dc), a culture is necessary for confirmation

Question 9

What is the tributyrin hydrolysis test? Which organism is it used for?

Answer 9

• key test for M. catarrhalis
• butyrate esterase produced by M. catarrhalis hydrolyzes tributyrin substrate
  Result: lowered pH causes color change (yellow)

Question 10

How is the superoxol test different from catalase?

Answer 10

30% hydrogen peroxide (contrast to 3% used in catalase test)
- immediate and vigorous bubbling from N. gonorrhoeae

Question 11

What order do you report the direct smear components?

Answer 11

WBC, RBC, EPI, Bacteria, Yeast

Question 12

For the isolation of Neisseria gonorrhoeae, what should the media be enriched with? Why?

Answer 12

• fastidious; requires CAP enriched with rich iron, serum/albumin/ starch to neutralize toxic fatty acids, amino acids, vitamins
• antimicrobics also added to inhibit mixed microflora from suppressing N. gonorrhoeae growth

Question 13

Explain the CTA sugar test.
a. What does the media contain?
b. What type of reaction is it? Under what atmospheric conditions?
c. What can cause a false color change?
d. CTA base – what is it? What is it used for?

Answer 13

a. 1% carbohydrate with phenol red (indicator); yellow when positive
b. oxidative sugar breakdown in O2
c. CO2 provides acidic pH in media = false positive
d. CTA base has no sugar; it is a negative (pink) control; ensures organism doesn’t grow without sugar

Question 14

When would you work up Moraxella catarrhalis?

Answer 14

• only worked up when plate of respiratory specimen has predominant growth of Moraxella catarrhalis
• otherwise, considered normal flora in upper respiratory tract

Question 15

When transporting a Neisseria meningitidis specimen, what must you protect the sample
from what?

Answer 15

• protect from drying and cold temperature