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:
 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.
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.
Media used:
a) Non selective media: Chocolate agar,
Mueller-Hinton agar.
b) Selective media: Thayer Martin medium
with antibiotics (Vancomycin, Colistin &
Nystatin.
Colony morphology: Colonies are small,
round, translucent, convex or slightly
umbonate with finely granular surface &
lobate margins.
Biochemical reactions:
1)
Oxidase test: Positive
2)
Ferments only glucose
but not maltose.
PATHOGENICITY:
Source of infection:
1. Asymptomatic carriers
2. Patients
Mode of infection:
1. Venereal infection (sexual contact)
2. Nonvenereal infection
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.
Antigenic structure & virulence factors
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.
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)
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
Pelvic Inflammatory Disease (PID)
Rarely peritonitis may develop with perihepatic
inflammation (Fitz-Hugh-Curtis syndrome)
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.
LABORATORY DIAGNOSIS:
Specimens collected:
A) In men:
a) Acute infection- Urethral discharge
b) Chronic infectioni)
Morning drop
ii)
Discharge collected after prostatic massage
iii) Centrifuged deposit of urine
B) In women:
i)
ii)
Urethral discharge
Cervical swabs
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”.
Methods of examination:
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.
2. Immunofluorescence:
B) Culture:
Media used:
Colony morphology:
Gram’s smear:
Reveals Gram negative
cocci in pairs with
adjacent sides concave.
Biochemical reactions:
C) Serology:

Complement fixation test,

Precipitation,

Passive agglutination,

Immunofluorescence,

Radioimmunoassay.
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.
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).
PROPHYLAXIS:
 Early
detection of cases,
 Tracing
 Health
of contacts,
education,
 General
measures,
 Vaccination
has no role in prophylaxis.
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.
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