Neisseria
Buga Rudolf
HTC LECTURE SERIES

Introduction
•Family- Neisseriaceae.
•Genus- Neisseria
•Species- N.gonorrhoeae, N.meningitidis,
N.pharyngis, N.lactamica, N.catarrhalis (Moraxella
catarrhalis).
•Two species of medical importance:N. gonorrhoeae
and N. meningitidis.
•Inhabit mucosal surfaces.
•Gram negative diplococci with opposing surfaces
flattened or with concavity.

Neisseria gonorrhoeae
Microscopy:
•Gram negative diplococci.
•Occurs in pairs with adjacent surfaces
flattened or concave.
•Intra/extracellular occurrence in
polymorpho nuclear neutrophils
(PMNs)

Diagnosis……..
Direct: Gram stained smears.
Culture:
•Specimens: U/swabs, cervical swabs,
eye/swab, ear/swabs, joint aspirate, etc.
•Media: Choc, MTM, MNYC agar.
•Incubation: 24-48 hrs, ambient air + 5-
10% CO2.

Diagnosis……..
Identification:
• Oxidase test +ve, Glucose +ve.
• Immunofluoresnce or COA
• Sero-grouping: A, B or C
• DNA probe test (not as sensitive as culture).
• Sensitivity test.

Pathogenesis
• Gonorrhoea is an STD, the sites are urethra (men) and
cervix (women)
• Transmission through sexual contact
• GC adheres to columnar epithelial cells, penetrate and
multiply on the basement membrane
• Adherence is facilitated by pili and Opa proteins
• GC LPS stimulates the production of tumour necrosis
factor (TNF), which causes cell damage

Pathogenesis…..
• GC may disseminate via blood stream.
• GC produces extracellular protease that cleaves a
proline-threonine bond in Ig A. This causes loss of
antibody activity.
• Approximately 9-15% affected women with PID have
polymicrobic infections.

Virulence factors
•LPS
•Extracellular IgA protease
•Pili/fimbriae
• Opa proteins

Host defenses
•Gonorrhoea infection stimulates local
immunity (secretory Igs may enhance
association with PMNs)
•Uncomplicated infection activates
complement via classical pathway,
while disseminated infections activate
complement via alternate pathway

Diseases caused
• Gonorrhoea
• Ophthalmia neonatorum
• Conjunctivitis
• Skin lesions
• Tenosynovitis
• Septic arthritis
• Endocarditis
• Meningitis (very rarely).

Epidemiology
•Sexually transmitted worldwide
•Highest attack rate men and women
occurs between 15 and 29 years of age
•The number of sexual partners, sexual
preference and population mobility
contribute to incidence of gonorrhoea

Antibiotics/Control
•Antibiotics
• 3rd Generation Cephalosporins
•Fluoroquinolones
•Doxycyline
•Spectinomycin
• Azithromycin

Control
• Treatment of sex partner
• No effective vaccine
• Abstinence
• Use condoms