Pathogenesis of
Gonococcal Infection: Click on the image.
Gonorrhea is a sexually transmitted disease caused by
various strains of the gram-negative diplococcus Neisseria gonorrhoea.
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The infection is usually localized to the urogenital tract, most
commonly the urethra of men and the endocervix of women. About one
half of infected women have no symptoms. In men, however, infection is
usually symptomatic.
Gonorrhea is a serious public health problem in most
parts of the world, and is epidemic in many countries. It is
especially common in the tropics, where the prevalence is high in
prostitutes, who transmit it to migrant male workers.
Gonococci are readily seen in smears (urethral,
endocervical, or conjunctival exudates) and cultures, and appear as
bean-shaped pairs, with the flat sides apposed.
The organisms are
cultured from tampons, urethral swabs, urine, specimens from endocervix, vagina, anus, and pharynx.
Gonorrhea begins as a surface infection of the
mucous membranes, that is, a catarrh.
The bacteria attach to and
spread along the cells of the surface mucous membranes, after which
they invade superficially and provoke acute inflammation.
The mucous
membranes of the urethra, endocervix, and salpinx are characteristic
sites.
The cell wall of N. gonorrhoea contains lipopolysaccharide,
protein, and phospholipid. It lacks a true polysaccharide capsule, but
projecting from the cell wall are hairlike extensions called pili.
Within these pili is a protease that digest IgA on the surface of the
mucus membrane, thus facilitating the attachment of gonococci to the
columnar and transitional epithelium of the urogenital tract. "Smooth" strains with few pili are less virulent and less prone to cause
urethritis or cervicitis.
After an incubation period of 3 to 5 days, men
usually have purulent urethral discharge and dysuria.
With prompt
antibiotic treatment the infection is arrested and gonococci are
confined to the mucosa of the anterior urethra.
However, if treatment
is not instituted promptly the organisms extend to the prostate, epididymis, accessory glands, where they cause urethral stricture,
epididymitis, orchitis, and sometimes male infertility.
Urethral stricture may be associated
with fistulas between the urethra and perineum (“watering can”
perineum).
Male homosexuals develop pharyngitis and proctitis.
The first manifestation of infection in women is
usually endocervicitis, with vaginal discharge or bleeding.
There may
be urethritis, manifestated by dysuria rather than by urethral
discharge.
In some women (usually during the first menses after
exposure), the infection extends to the fallopian tubes, where it
produces acute and chronic salpingitis and pelvic inflammatory
disease.
The fallopian tubes swell with pus,
causing acute abdominal pain.
Infertility occurs when inflammatory
adhesions close the tubes at both ends, blocking the ascent of sperm
and the descent of ova.
Infected fallopian tubes ('pus tubes')
have the shape of a retort flask.
From the fallopian tubes the infection may spread to
the peritoneum, healing as fine adhesions (“violin string” adhesions)
between the capsule of the liver and the parietal peritoneum.
The
vaginal discharge may infect the anal crypts, leading to mucopurulent
anal discharge, rectal pruritus, and tenesmus.
Chronic endometritis is
a persistent complication of gonococcal infection and is usually a
consequence of chronic gonococcal salpingitis.
In such cases the endometrium contains many lymphocytes and plasma cells.
Women (and to
a lesser extent men) may also develop bacteremia, producing
disseminated gonococcal infection, which in turn leads to monoarthritis
or polyarthritis.
Neonatal infections from infected
amniotic fluid or an infected birth canal result in symptoms within a
few days after birth.
These infections involve the
conjunctiva and constitute a major cause of blindness in much of
Africa and Asia.
Other sites of neonatal
infection are the pharynx, respiratory tract, vagina, anus,
leptomeninges, joints, and blood.
Uncomplicated gonococcal infections of the urethra and
endocervix are treated with penicillin and other antibiotics.N. gonorrhoea is displaying increasing resistance to penicillin. Penicillinase-producing strains are especially common in Africa and
Asia.
Visit:
Syphilis
;
Syphilitic Gumma
;
Granuloma Inguinale (Donovanosis)
;
Chancroid
;
Lymphogranuloma Venereum
;
Herpes Simplex Virus Infection
.
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