Neisseria gonorrhoeae is the causative agent of gonorrhea, first identified in 1879, characterized as gram-negative cocci that require specific culture media for growth. The bacteria infects mucosal surfaces, leading to conditions like urethritis and pelvic inflammatory disease, with different manifestations in men and women. Treatment has evolved due to antibiotic resistance, with ceftriaxone or ciprofloxacin being current options, while prevention focuses on early detection and education.

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