Neisseria spp: Neisseria gonorrhoeae

Neisseria spp: Neisseria gonorrhoeae

• Gram-negative diplococci
° kidney or bean shaped
• Capsulated
• Possess pili
Medically important species
• N. meningitidis (cause meningitis)
• N. gonorrhoeae (cause gonorrhoea)

Cultural characteristics
• Aerobic; require 5-7% CO2 and moisture
• Only grow on enriched media –
° blood and chocolate agar:
• Oxidase positive
• N. gonorrhoeae : ferment glucose
• N. meningitidis : ferment glucose and maltose

Antigenic structure
• Pili – antigenically different among various types of gonococci
• Lipo-oligosacchardie – an endotoxin
• Outer membrane protein (OMP)
• Capsule
Antigenic variation
• In vitro and in vivo changes in structure of pili and OMP II
Pathogenesis
Attachment by pili to epithelial cells of :
• Urethera and endocervix
• Fallopian tubes
• Sperms - help spread to fallopian tubes
• Neutrophils - lead to delayed phagocytosis
IgA protease– hydrolyses secretory IgA – help in attachment
• Capsule (adherence & antiphagocytic).

Invasion & Damage
• Organisms enter epithelial cells, multiply and
pass to submucosa ? acute inflammatory response
• Lipo-oligosaccharide (endotoxin)

Gonorrhoea
• An old sexually transmitted disease
• Has a short incubation period (2-7 days)
• Only a human disease

Source of infection
• Infected male and female
• Usually asymptomatic female
• 50% of infection in female is asymptomatic

Clinical features & complications in male

1. Acute anterior urethritis
• Purulent discharge & dysuria (5% asymptomatic)
2. Posterior urethritis - stricture formation
3. Chronic prostatitis
• Low backache and urethral discharge (morning drop)
4. Acute epididymo-orchitis
5. Bacteremia ? skin and joint infections

Clinical features & complications in female
• Primarily is disease of endocervix
• 50% of females asymptomatic
• Vaginal discharge and dysuria in minor percent
• Pelvic inflammatory disease - leads to sterility
• Bacteremia ? skin & joint infections
Ophthalmia neonatorum
° Neonate gets infected from mother.
° A severe purulent eye discharge within few days of birth.

Lab diagnosis of gonorrhoea
Specimens
• Male : Urethral discharge or urethral swab
• Female : Cervical swab (HVS is less specific)
Transport of specimen – without delay
Direct Gram Smear
• Intra & extracellular Gram-negative diplococci
• 95% sensitive in men (less sensitive in women)
Culture on:
• Chocolate agar
• Require 5-7% CO2

Treatment of gonorrhoea
1. Penicillin still drug of choice for sensitive gonococci
• Resistance to penicillin by two ways:
° Altered PBP
° Beta-lactamase production
Penicillin– resistant strains are treated with:
2. Tetracycline for 7-10 days
• Also effective against co-existing chlamydial infection
3. Ceftriaxone

Prevention of gonorrhoea
• Tracing and treatment of infected persons
• Ophthalmia neonatorum– use of erythromycin eye ointment at birth (compulsory in USA).
• Development of vaccine under trial