Morphology & Culture Characteristics of Neisseria gonorhoeae

MORPHOLOGY AND CULTURE CHARACTERISTICS OF NEISSERIA GONORRHOEAE (GONOCOCCUS OR GONOCOCCI)

MORPHOLOGY OF NEISSERIA GONORRHOEAE (GONOCOCCUS)

ShapeNeisseria gonorrhoeae is an oval or spherical (coccus) shape bacterium with the adjacent side Concave.

Size – The size of Neisseria gonorrhoeae is about 0.6 – 1.0 µm (micrometer) in diameter.

Arrangement Of CellsNeisseria gonorrhoeae is arranged in singly or in pairs (diplococci), with the adjacent side Concave and they are usually present intracellularly when direct microscopic examination of the specimen from the lesions is carried out.

Microscopic view of neisseria gonorrhoeae - morphology of neisseria gonorrhoeae
MICROSCOPIC VIEW OF THE SPECIMEN SHOWING INTRACELLULAR GONOCOCCI

MotilityNeisseria gonorrhoeae is a Non-motile bacterium.

FlagellaNeisseria gonorrhoeae is a Non-flagellated bacterium, fimbriae may present.

SporesNeisseria gonorrhoeae is a Non-sporing Bacterium

CapsuleN. gonorrhoeae is a capsulated bacterium and is present in such a way that a capsule encloses each pair of cocci. The capsule can easily be demonstrated using India ink preparation, appear as a clear halo in a dark background. Moreover, the presence of capsule depends on the origin of the specimen as the specimen taken from the carrier may or may not contains encapsulated N. gonorrhoeae whereas the sample isolated from Urethral or Vaginal discharge or from blood usually contains encapsulated N. gonorrhoeae.

Gram Staining Reaction – Neisseria gonorrhoeae is a Gram –ve (Negative) bacterium.

CULTURE REQUIREMENTS OF NEISSERIA GONORRHOEAE (GONOCOCCUS)

Special requirements – It is quite difficult to grow it in the laboratory as compared to N. meningitidis however, Gonococci or Neisseria gonorrhoeae have complex nutritional requirements and readily grow in a media containing Blood or Serum, commonly Blood Agar medium, Chocolate Agar medium & Mueller Hinton Agar medium is used for the cultivation of Neisseria gonorrhoeae in Laboratory.

 Optimum temperatureNeisseria gonorrhoeae grows best at 35 –36°C

⇒ Optimum pH – The pH requirement of N. gonorrhoeae ranges from 5.8 – 8.0 but the maximum growth in the laboratory is observed at 7.0 – 7.2.

⇒ Oxygen requirementsN. gonorrhoeae is an Aerobic bacterium i.e. can grow in the presence of oxygen as well as anaerobic organism i.e. can grow in the absence of oxygen.

⇒ It requires a moist environment with a 5 – 10% CO2 for the growth in the laboratory.

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MORPHOLOGY AND CULTURE CHARACTERISTICS OF NEISSERIA MENINGITIDIS (MENINGOCOCCUS)

⇒ There are various culture media used for the cultivation of N. gonorrhoeae (Gonococcus) in the laboratory and most commonly the Blood Agar and MHA medium is used, the other media are as follows –

  • Sheep Blood Agar medium
  • Columbia Horse Blood Agar medium
  • Chocolate agar medium
  • Thayer Martin medium with Antibiotics Vancomycin, Colistin, and Nystatin (selective medium)
  • Modified Thayer Martin medium with Antibiotics Vancomycin, Colistin, Nystatin & Trimethoprim (selective medium)
  • Martin – Lewis medium (selective medium)
  • New York city medium (selective medium)
  • The liquid medium (Glucose Broth medium, TSB medium, Peptone water etc.)

 The Thayer Martin medium which is a Selective medium for Neisseria gonorrhoeae can be prepared by incorporating Antibiotics and Nutrients in Thayer Martin Agar base or in GC Agar base medium for the growth of Neisseria gonorrhoeae (Gonococcus).

 Similarly, the New York City medium which is also a selective medium for Neisseria gonorrhoeae can be prepared by incorporating Antibiotics and Supplementary nutrients in the NYC Agar Base medium for the Growth of Neisseria gonorrhoeae (Meningococcus)



CULTURE CHARACTERISTICS OF NEISSERIA GONORRHOEAE (GONOCOCCUS)

Culture CharactersBlood Agar Medium (BAM)Thayer Martin MediumNew York City MediumChocolate Agar Medium (CAM)
Hemolysis γ – Hemolysis (No hemolysis) γ – Hemolysis (No hemolysis) γ – Hemolysis (No hemolysis) γ – Hemolysis (No hemolysis)
ShapeCircular or RoundCircular or RoundCircular or RoundCircular or Round
Size1-2 mm1-3 mm1 -2 mm1 -2 mm
ElevationConvex or slightly UmbonateConvex or slightly UmbonateConvex or slightly UmbonateConvex or slightly Umbonate
SurfaceFinely granular or smooth (s per the strain)Finely granular or smooth (s per the strain)Finely granular or smooth (s per the strain)Finely granular or smooth (s per the strain)
ColorGreyColorless to GreyColorless to GreyColorless to Grey
StructureOpaqueTransparent  or OpaqueTransparent  or OpaqueOpaque

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MORPHOLOGY AND CULTURE CHARACTERISTICS OF PROTEUS VULGARIS (PR. VULGARIS)

There is much variation in the colony morphology of Neisseria gonorrhoeae which are divided into 4 types as T1 to T4 which are described as follows:

CharacteristicsT1T2T3T4
SizeSmall (1-2 mm)Small (1-2 mm)Large (2-4 mm)Large (2-4 mm)
ColorBrownBrownUsually ColorlessUsually Colorless
Auto agglutinationAuto agglutinableAuto agglutinableNon- Auto agglutinableNon- Auto agglutinable
VirulenceHighly virulentHighly virulentAvirulentAvirulent
PigmentationPresentPresentNon – PigmentedNon – Pigmented
PiliPresentPresentAbsentAbsent
Commonly known asP+P++P-P-



In liquid culture media like peptone water and TS broth, the growth of the bacterium occurs as a Granular turbidity in the broth medium which is further analyzed for the morphology (under the microscope), gram reaction, biochemical tests, and Neisseria gonorrhoeae specific tests.

In Blood Agar medium, the colonies of the Neisseria gonorrhoeae are small, grayish in color and show γ – Hemolysis i.e. N. gonorrhoeae produce Non-Hemolytic colonies.

Neisseria gonorrhoeae on blood agar medium
CULTURE OF NEISSERIA GONORRHOEAE ON BLOOD AGAR MEDIUM

Similarly, on chocolate agar medium, N. gonorrhoeae grows well, producing small translucent colonies.

neissria gonorrhoeae on chocolate agar medium
CULTURE OF NEISSERIA GONORRHOEAE ON CHOCOLATE AGAR MEDIUM

In Modified Thayer Martin medium, the colonies of Neisseria gonorrhoeae are small, grayish and Granular with slight umbonation.

Neisseria gonorrhoeae on thayer martin medium
CULTURE OF NEISSERIA GONORRHOEAE ON THAYER MARTIN MEDIUM

In New York City medium, Neisseria gonorrhoeae grow well and produce circular, convex, grayish or colorless colonies usually.

Neisseria gonorrhoeae on Ney york city medium
CULTURE OF NEISSERIA GONORRHOEAE ON NEW YORK CITY MEDIUM

That’s all about the Morphology & Culture characteristics of Neisseria gonorrhoeae



Further Reading:

Characteristics of Neisseria gonorrhoeae – CDC

Neisseria species – Hardydiagnostics

N. gonorrhoeae on Blood & Chocolate agar – Openi

N. gonorrhoeae – wiki.ubc

Neisseria gonorrhoeae – Wikipedia

Neisseria gonorrhoeae – Antimicrobe

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