B15. Sexually transmitted diseases (STD)

Page created on June 8, 2021. Last updated on January 13, 2022 at 09:28


Definition and epidemiology

Gonorrhoea is caused by Neisseria gonorrhoeae. It mostly affects young adults. It may progress to pelvic inflammatory disease.

Clinical features

Women are often asymptomatic (30 – 60%). The incubation time can be days or weeks.

Symptoms in women can be:

  • Dysuria
  • Yellow, purulent, malodourous discharge
  • Cervical tenderness and bleeding on physical examination

Diagnosis and evaluation

PCR of a vaginal and endocervical swab is the first choice. Should also be performed of the pharynx if oral sex occurred.

Alternatives include gram staining and culture.


The ideal treatment for gonorrhoea:

  • Treats the gonorrhoea
  • Treats any coexisting syphilis and chlamydia
  • Is single dose
  • Covers resistant strains of gonorrhoea (many are resistant to cephalosporins)

There are two treatment options which fulfil these criteria. Either

  • Single-dose ceftriaxone IM + single-dose azithromycin PO
  • Single-dose cefixime PO + single-dose ciprofloxacin PO

Postgonococcal urethritis can occur due to secondary colonization with mycoplasma and chlamydia. Treatment of this is tetracycline.


Disseminated gonococcal infection (arthritis-dermatitis syndrome) is a rare complication of gonorrhoea. It occurs in 2% of cases, mostly in women.

  • Intermittent fever
  • Migratory arthritis
    • Pain spreads from one joint to another
  • Skin lesions
    • Flea bite-like papules
    • Haemorrhagic pustules on palms, soles

Gonococcal conjunctivitis can occur in neonates who are born to mothers with gonorrhoea. It occurs due to direct contact from genitalia to hand to eye. It’s treated by silver nitrate eye drops.



Chlamydia is most common STD, if you don’t count HPV. It’s caused by Chlamydia trachomatis serotypes D-K. It may progress to pelvic inflammatory disease.

Clinical features

90% of affected people are asymptomatic. Possible symptoms include:

  • Urethritis with dysuria
  • Mucopurulent discharge
  • Postcoital bleeding

Diagnosis and evaluation

PCR of vaginal swab.


Single dose 1 g PO azithromycin or doxycyclin for 7 days.


Reiter syndrome/reactive arthritis is a complication of many bacterial infections, most commonly after chlamydia. It’s associated with HLA-B27 and mostly affects young males. It’s characterised by a clinical triad of:

  • Arthritis
  • Conjunctivitis
  • Urethritis


Definition and epidemiology

Trichomoniasis is a sexually transmitted infection caused by trichomonas vaginalis.

Clinical features

It’s asymptomatic in 70%. Foul-smelling, yellow-green coloured vaginal discharge is highly suspicious for trichomoniasis. Other symptoms include:

  • Itching
  • Burning
  • Dyspareunia
  • Itchiness
  • Redness
  • Strawberry cervix – typical appearance of cervix like a strawberry

Diagnosis and evaluation

Physical examination may reveal characteristic appearance or odour.

pH measurement is also important. The pH of the vagina is normally 4 – 4,5, but in case of bacterial vaginosis or trichomoniasis, the pH is > 4,5. The Amine test (for bacterial vaginosis) is positive here as well.

Vaginal smear, the examination of vaginal fluid under the microscope, may also be performed. For trichomoniasis, motile organisms with multiple flagella are visible.


Metronidazole is the first line treatment for both the patient and the partner.



Syphilis is an STD which is sometimes called lues. It’s caused by infection of the spirochete Treponema pallidum. It’s a very rare disease nowadays. Mostly only the primary stage is seen nowadays.

Risk factors

  • Men who have sex with men
  • Promiscuity
  • Unprotected sex

Clinical features

Incubation period can last from 10 – 90 days (average 21). Syphilis has 4 characteristic stages

  • Primary syphilis
    • Characterised by a special lesion called a chancre
    • Chancres occur at the site where the bacterium enters the body
    • It’s a painless, firm ulcer with indurated borders and a smooth base
    • Chancres resolve spontaneously without scarring after 3 – 6 weeks
  • Secondary syphilis
    • Known as the “great imitator” as its skin symptoms resemble those of many other skin diseases
    • Begins 8 – 12 weeks after primary infection
    • Lasts 2 – 6 weeks
    • Condyloma lata
      • Broad-based, wart-like papular erosions
      • In anogenital region, intertriginous folds, oral mucosa
    • Disseminated, polymorphic, symmetric rash
    • Mucous patches (White patches on mucous membranes)
    • Patchy alopecia
    • Necklace of Venus = hypopigmentation around the neck
  • Latent syphilis
    • The patient is seropositive but there are no symptoms
    • Can last months, years or the rest of the patient’s life
    • There are four outcomes:
      • The disease resolves and the patient becomes healthy
      • The disease reactivates as secondary syphilis
      • The disease progresses into tertiary syphilis
      • The patient dies before any of these outcomes occur
  • Tertiary syphilis
    • Occur in approx. 30% of untreated patients in the latent stage
    • Gummas (Destructive and ulcerative granulomatous lesions with necrotic centre)
      • Can occur anywhere on or in the body, even on organs and bones
    • Nodules
    • Psoriasiform granulomatous lesions
    • Cardiovascular syphilis
      • Aortitis with resulting aneurysm of the aorta
      • Dilated aortic root
    • Neurosyphilis
      • Meningitis
      • Stroke
      • Tabes dorsalis (broad-based sensory ataxia)
      • Dysesthesia
      • General paresis
      • Widespread cerebellar atrophy
      • Dementia
      • Argyll Robertson pupil (Bilateral miosis, pupils don’t react to light)

Diagnosis and evaluation

A specimen is taken from a lesion. Nontreponemal tests like RPR and VDRL are used for screening. These are sensitive but not specific tests. Treponemal tests are used for confirming the diagnosis. These are highly specific.

Direct visualization of treponema is also possible, and may be useful in the primary stage, when the serological tests below can be negative. The bacteria are visible by darkfield microscopy.


  • For prevention, primary, secondary, and early latent syphilis: 2,4 million units of benzathine penicillin G intramuscularly – single dose
  • For tertiary (except neurosyphilis) and late latent syphilis: 2,4 million units of benzathine penicillin G IM – once weekly for three weeks
  • For neurosyphilis: IV penicillin G for 10 to 14 days

Jarisch-Herxheimer reaction may occur, a systemic reaction to bacterial endotoxins. It is usually self-limiting.

Lymphogranuloma venereum

Lymphogranuloma venereum is an STD caused by Chlamydia trachomatis serotypes L1-L3. It’s most common in tropical and subtropical countries.

In the primary stage, the patient has small, painless genital ulcers that heal within a few days. In the secondary stage, painful swelling of inguinal lymph nodes with abscess formation occurs.

Diagnosis is by PCR, and treatment is with doxycycline.

Genital herpes

Genital herpes is an STD caused by HSV-2 in most cases, but rarely HSV-1.

It’s often asymptomatic, but it can cause painful ulcerative vesicles to form on the genitals. Painful inguinal lymphadenopathy may also occur.

The virus may then return to be latent in lumbar or sacral ganglia, from which it can reactivate later. Reactivation is most common during stress or immunosuppression.

It can be diagnosed based on either of the following:

  • Light microscopy with a Tzanck smear
  • Viral culture
  • PCR

Treatment involves topical or oral valacyclovir, famciclovir, or acyclovir.

Genital warts

Genital warts (condyloma acuminata) are caused by infection by HPV 6 or 11. These warts are painless, like condyloma lata.

It can be treated by topical podophyllotoxin solution or surgical excision.

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