1. ‫بسم ا الرحمن الرحيم‬
FAMILY:
NEISSERIACEAE
Prof. Khalifa Sifaw Ghenghesh

2. Genus: Neisseria
• G-ve, diplococci, kidney shaped
• Oxidase: +ve

3. Neisseria gonorrhoeae

4. 1. N. gonorrhoeae
• Gonorrhoea
• Virulence Factors
-----------------------------------------------------------------------------------Factor
Responsible for:
-----------------------------------------------------------------------------------Pili
Attachment to epithelial cell
OMP II (PrII)
OMP I (PrI)
Invasion of epithelial cells
LPS
Damage to epithelial cells
IgA protease
Destruction of secretory Ab
------------------------------------------------------------------------------------

5. Clinical Significance
• Transmitted by direct, close, usually sexual
contact between individuals.
• Uncomplicated gonorrhoea:
– In men: acute urethritis >purulent discharge
– in women (endocervix): vaginal discharge
• asymptomatic:
• ii. Conjunctivitis (ophthalmia neonatorum):
• iii. Pelvic inflamatory disease (PID):
• iv. Disseminated gonococcal infection

6. Laboratory Diagnosis
• Specimens:
Transport media!!!!
– Men: Urethral samples.
– Women: Uretheral, cervical and rectal specimens.
• Endocervical swab >>
• In DGI:
– Blood, swabs from skin lesions, or pus aspirated from a
joint.
• In neonatal ophthalmia: Conjunctival material.
• Urine specimen:

7. • Gram stain
• Thayer-Martin Media:
–Oxidase test
–Carbohydrate utilization

8. Gram-stain of urethral discharge from an infected
individual, showing Gram-negative diplococci.

9. Neisseria gonorrhoeae
Urethral smear with gram negative
intracellular diplococci

10. Treatment
• N. gonorrhoeae > β-lactamase
• 3rd generation cephalosporins
– Ceftriaxone
• Ciprofloxacin:
– resistance?

11. 2. N. meningitidis
• Virulence Factors: > Capsule.
• Serological Classification:
– Serogroups A, B, and C.
– Others: X, Y, Z, Z' (29E), and W-135

12. Gram-stain of Neisseria meningitidis
Gram-negative diplococci

13. Clinical Significance
• Habitat: Oro- or naso-pharynges of
asymptomatic carriers
• Transmission:
• Meningococcemia and/or meningitis >
- rash
- "Waterhouse-Friderchsen syndrome"
• Pneumonia >

14. Laboratory Diagnosis
Specimens: >> Transport media !!!!!
• CSF, blood, aspirate from skin lesions or
pus from an infected joint.
• Carriers:
• Gram stain & Blood agar/ TM medium
• Grouping: Specific antisera.
• CSF: can be examined for meningococcal
polysaccharide antigen by latex
agglutination, coagglutination, etc...

15. Control
• Chemoprophylaxis.
• Vaccination.
Treatment
– Penicillin
– Rifampicin
– Ciprofloxacin

16. • Other Neisseria species:
– Moraxella (Branhamella) catarrhalis

17. Moraxella catarrhalis