Neiserria gonorrhoeae, gram Negative, Cocci, Diplococci, Classification, Structure, Shape, Morphology, Growth characteristics, Culture Characteristics, Biochemical reaction, Growth Media, Infections caused by Neiserria gonorrhoeae, diagnosis , treatments

1. Neisseria gonorrhoeae
Lecture 03 (B)

2. Neisseria gonorrhoeae (Gonococcus)
• N. gonorrhoeae causes the sexually transmitted disease gonorrhoea.
• first described by Neisser in 1879 in gonorrheal pus.
• resembles meningococci very closely in many properties.

3. MORPHOLOGY:
• Gram negative
• oval/spherical cocci
• usually found with in the
polymorphs
• Arranged in pairs (adjacent
sides concave)
• Kidney shaped
• possess pili on their surface

4. CULTURE & CULTURAL CHARACTERISTICS:
• fastidious organisms do not
grow on ordinary culture media.
• aerobic but may grow
anaerobically also
• The optimum temperature for
growth is 35-36°C &
• optimum pH is 7.2-7.6.
• It is essential to provide 5-10%
CO2.

5. Media used:
a) Non selective media:
• Chocolate agar,
• Mueller-Hinton agar
• Modified New York City medium
b) Selective media:
• Thayer Martin medium
• with antibiotics (Vancomycin, Colistin &
Nystatin)

6. Colony morphology
Colonies are
• small
• round
• translucent
• convex or slightly umbonate
• finely granular surface
• lobate margins.

7. Biochemical reactions:
• 1) Oxidase test: Positive
• 2) Ferments only glucose but
not maltose.

8. PATHOGENICITY:
•Asymptomatic carriers
•Patients
Source of infection:
•Venereal infection (sexual
contact)
•Nonvenereal infection
Mode of infection:

9. Antigenic structure & virulence factors:
1. Pili
2. Lipooligosaccharide: Endotoxic.
3. Outer membrane proteins: 3 types
• a) Protein I (por)- it is a porin & helps in adherence.
• b) Protein II (opa)- helps in adherence.
• c) Protein III (rmp)- it is associated with protein I.
4. IgA1 protease: Splits & inactivates IgA

11. Antigenic structure & virulence factors

12. Mechanism of pathogenesis:
1. Gonococci adhere to epithelial cells of urethra or other mucosal
surface through pili
2. penetrate through the intercellular space
3. reach the sub epithelial connective tissue &
4. causes inflammation
5. Leads to clinical manifestations
6. Incubation period: 2-8 days.

13. Disease In men:
• The disease starts as an acute urethritis with a muco-purulent
discharge
• extends to the prostate, seminal vesicles & epididymis
• In some it may become chronic urethritis
• The infection may spread to the peri-urethral tissues,
• causing abscesses & multiple discharging sinuses

14. Diseases In women:
• The initial infection is urethritis & cervicitis
• but vaginitis does not occur in adult female
• (vulvovaginitis can occur in prepubertal girls)
• The infection may extend to Bartholin’s glands,
• endometrium & fallopian tubes causing
• Pelvic Inflammatory Disease (PID)
• Rarely peritonitis may develop with perihepatic

15. In both the sexes:
• Proctitis,
• pharyngitis,
• conjunctivitis,
• bacteraemia which may lead to metastatic infection such as
• arthritis,
• endocarditis,
• meningitis,
• pyemia &
• skin rashes.

16. LABORATORY DIAGNOSIS:
• In men:
• a) Acute infection- Urethral discharge
• b) Chronic infection) Morning drop
• ii) Discharge collected after prostatic massage
• iii) Centrifuged deposit of urine
• B) In women:
• i) Urethral discharge
• ii) Cervical swabs

17. In both the
sexes:
Blood,
CSF, s
ynovial fluid,
throat swab,
rectal swab &
material from skin rashes

18. A) Direct microscopy:
• Gram staining:
Smear provides a
presumptive
evidence
of gonorrhea in men.
Gram negative
diplococci are found.
But it is unreliable
in women.

19. Immunofluorescence:

20. Serology:
Complement fixation test,
Precipitation,
Passive agglutination,
Immunofluorescence,
Radioimmunoassay.(uses whole-cell lysate,pilus
protein and lipopolysaccharide antigen)

21. TREATMENT:
• Previously Penicillin was drug of choice but
resistance developed rapidly.
• Penicillin resistant is due to production of
penicillinase enzyme & the strains are called
as penicillinase producing Neisseria
gonorrhoeae (PPNG).
• Now Ceftriaxone or Ciprofloxacin plus
Doxycycline or Erythromycin is useful.

22. EPIDEMIOLOGY:
• Gonorrhoea is an exclusively human disease.
• The only source of infection is a human
carrier or less often a patient.
• Asymptomatic carriage in women makes them
a reservoir to spread infection among their
male contact.
• Gonorrhoea is an venereal disease (STD)

23. PROPHYLAXIS:
Early detection of cases,
Tracing of contacts,
Health education,
General measures,
Vaccination has no role in prophylaxis.

24. COMMENSAL NEISSERIAE
• N. lactamica
• N.pharyngis
• N. polysaccreae
• N. cinerea
• N. flavescens
• N. mucosa