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Neisseria gonorrhoeae (Gonococcus)

Neisseria gonorrhoeae (Gonococcus) N. gonorrhoeae causes the sexually transmitted disease gonorrhoea . The gonococcus was first described by Neisser in 1879 in gonorrheal pus. Gonococci resemble meningococci very closely in many properties. MORPHOLOGY:

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Neisseria gonorrhoeae (Gonococcus)

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  1. Neisseria gonorrhoeae (Gonococcus) • N. gonorrhoeae causes the sexually transmitted disease gonorrhoea. • The gonococcus was first described by Neisser in 1879 in gonorrheal pus. • Gonococci resemble meningococci very closely in many properties.

  2. MORPHOLOGY: • Gram negative diplococci with adjacent sides concave, being typically kidney shaped. • They are usually found with in the polymorphs. • They possess pili on their surface.

  3. CULTURE & CULTURAL CHARACTERISTICS: • Gonococci are fastidious organisms do not grow on ordinary culture media. • They are 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.

  4. Media used: a) Non selective media: Chocolate agar, Mueller-Hinton agar. b) Selective media: Thayer Martin medium with antibiotics (Vancomycin, Colistin & Nystatin.

  5. Colony morphology: Colonies are small, round, translucent, convex or slightly umbonate with finely granular surface & lobate margins.

  6. Biochemical reactions: • Oxidase test: Positive • Ferments only glucose but not maltose.

  7. PATHOGENICITY: Source of infection: 1. Asymptomatic carriers 2. Patients Mode of infection: 1. Venereal infection (sexual contact) 2. Nonvenereal infection

  8. Antigenic structure & virulence factors: 1. Pili: They help in adherence of bacteria to host epithelial cells & they are antiphagocytic. 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.

  9. Antigenic structure & virulence factors

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

  11. Disease: A) In men: The disease starts as an acute urethritis with a mucopurulent discharge The infection extends to the prostate, seminal vesicles & epididymis In some it may become chronic urethritis leading to stricture formation The infection may spread to the periurethral tissues, causing abscesses & multiple discharging sinuses (Watercan perineum)

  12. B) 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 PelvicInflammatoryDisease (PID) Rarely peritonitis may develop with perihepatic inflammation (Fitz-Hugh-Curtis syndrome)

  13. C) In both the sexes: Proctitis, pharyngitis, conjunctivitis, bacteraemia which may lead to metastatic infection such as arthritis, endocarditis, meningitis, pyemia & skin rashes. D) In neonates: Opthalmia neonatorum (a nonvenereal gonococcal conjunctivitis in the newborn) results from direct infection during passage through birth canal.

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

  15. C) In both the sexes: Blood, CSF, synovial fluid, throat swab, rectal swab & material from skin rashes. Transport:If there is delay in processing than the specimens should be sent in “ Stuart’s medium”.

  16. A) Direct microscopy: 1. Gram staining: Smear provides a presumptive evidence of gonorrhea in men. Gram negative diplococci are found. But it is unreliable in women. Methods of examination:

  17. 2. Immunofluorescence:

  18. B) Culture: Media used: Colony morphology: Gram’s smear: Reveals Gram negative cocci in pairs with adjacent sides concave. Biochemical reactions:

  19. C) Serology: • Complement fixation test, • Precipitation, • Passive agglutination, • Immunofluorescence, • Radioimmunoassay.

  20. 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.

  21. 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).

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

  23. NONGONOCOCCAL (NONSPECIFIC) URETHRITIS • Urethritis due to causative agents other than gonococcus. • Etiology: a) Bacteria- Chlamydia trachomatis Mycoplasma urealyticum Ureaplasma urealyticum b) Parasites- Trichomonas vaginalis c) Viruses- Herpes simplex Cytomegalovirus d) Fungi- Candida • NGU can be a part of Reiter’s syndrome- a clinical condition characterized by urethritis, arthritis & conjunctivitis.

  24. THANK YOU

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