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Neisseria

MSc. Sarah Ahmed

• Many commensals

• Two important human pathogens:
• Neisseria gonorrhoeae (gonococci)
• Neisseria meningitidis ( meningococci)

General Characters of the Genus

1. Gram-negative diplococci

CULTURE & CULTURAL CHARACTERISTICS:

fastidious organisms do not grow on ordinary culture media.

aerobic but may grow anaerobically also
It is essential to provide 5-10% CO2.

The optimum temperature for growth is 35-36°C & optimum pH is 7.2-7.6.

2- Oxidase positive (the key test of the genus)

D. Identification:

1- Identification at the genus level


Gram –ve diplococci Oxidase +ve

2)Culture-

Non- specific-
Chocolate agar- Heat lysed sheep blood+ Agar
Specific culture media-
A) Modified New York City media (MNYCM)
Heat lysed sheep blood+ Agar+ Antibiotic (Lincomycin, Colistin, Nystatin, Trimethoprim)
B) Thayer Martin Media (TMM)
Heat lysed sheep blood+ Agar+ Antibiotic (Vancomycin, Colistin, Nystatin, Trimethoprim)







Neisseria meningitidis
Colonies growth on New_York_City_Medium Agar

Incubate at 37C for 18-24 hrs in microaerophilic environment by candle jar.

Observation- 0.5-1 mm, circular, convex, graiysh white translucent colony.

) Biochemical test-

Oxidase test- Positive test
carbohydrate utilization test (CUT)-
N. Gonorrhoeae ferment glucose but not maltose.
N. meningitidis ferment both.

• Biochemical reactions:

Ferments only glucose
• but not maltose.
•







Glucose
Maltose

Identification to the species level

Sugar utilization Ferments glucose and maltose.( N.meningitidis)