Sexually Transmitted Diseases (STDs)

a) Inflammatory STIs

  • Chlamydia

This is the commonest STD in the UK. The disease is caused by the bacteria Chlamydia trachomatis.

– It is spread during all types of sex and can be passed from mother to baby during birth


SymptomsMany times the infection is asymptomatic

– Female –> Inflammation of the cervix, increasing bleeding and vaginal discharge

                     – Deep dyspareunia

– Male –> Urethritis (dysuria and discharge)

– Eye disease –> spread from eye to eye by fingers and causes blindness

– Joints –> often a cause of reactive arthritis, urethritis, conjunctivitis and arthritis

– Untreated chlamydia infection is a major risk factor for Pelvic Inflammatory disease in women, which can result in subsequent infertility.


DiagnosisInvestigation of choice is nuclear acid amplification tests (NAAT)

– Women –> 1st line is vulvovaginal swab (not urine or cervical swab)                       

– Men –> 1st line is urine test


Management – 1st line is one dose azithromycin or 7 days doxycycline

– If pregnant –> azithromycin, erythromycin or amoxicillin


  • Gonorrhoea

This is an STI due to the bacteria Neisseria gonorrhoeae, a gram-negative diplococcus

– It gives similar symptoms to Chlamydia with additional complications

– You cannot immunise against it and reinfection is common due to antigenic variation



– Female –> Inflammation of the cervix, increasing bleeding and vaginal discharge

– Male –> Urethritis (dysuria and discharge) which can lead to urethral strictures

– Can also cause infections of the rectum and the pharynx



– Disseminated gonococcal infection –> due to the spread of bacteria in blood stream from the genitals

– Initially gives tenosynovitis, migratory polyarthritis and dermatitis

– Fitz-Hugh-Curtis syndrome –> combination of septic arthritis, endocarditis and perihepatitis


Diagnosis – Investigation of choice is nuclear acid amplification tests (NAAT) from swabs or urine


Management – 1st line is single dose IM ceftriaxone 1g

– If the bacteria is sensitive to oral ciprofloxacin, give this instead


  • Syphilis

This is a condition due to Treponema Pallidum, a spirochete bacteria.

– It is transmitted by sexual contact or during pregnancy from the mother to her baby

– The infection consists of 3 stages, increasing in severity



i) Primary –> gives a chancre (painless ulcer at site of sexual contact) + local painless lymphadenopathy


ii) Secondary (6-10 weeks) –> Rashes: particularly affecting the trunk, palms and soles of feet

-Erosions that occur in linear streaks in the mouth – “snail track” ulcers

– Systemic signs of infections (fatigue, lethargy, pyrexia)

– Condylomata lata (non-tender, lesions resembling verrucas on the genitalia)


iii) Tertiary –> CNS involvement –> dorsal column syndrome (loss of proprioception + vibration)

– Argyll Robertson pupil –> a pupil which can accommodate but not constrict

– Aortic aneurysms                                – Gummas (granuloma lesions of skin)


Diagnosis – This uses a mix of serological tests mainly as you cannot culture the bacteria artificially

i) Treponemal antibody tests –> tests for antibody against the bacteria and remains positive after treatment

ii) Cardiolipin –> Non-specific antibodies that react to cardiolipin are made and can be tested for

                             – It is a non-specific test which becomes negative after treatment is complete

                             – False positives are seen in: HIV, malaria, TB, SLE and pregnancy


Management – 1st line IM benzathine penicillin –> 2nd line is doxycycline

– After treatment can get Jarisch-Herzheimer reaction due to release of endotoxins after bacterial death

– Gives fever, rash, tachycardia but no treatment is required             


  • Congenital Syphilis

This is a form of syphilis which occurs in babies in utero and at birth causing a range of malformations

– Some infants have symptoms at birth, but many develop up the age of 5 years.



– Inflammation with hardening of the umbilical cord

– Low birth weight

– Facial deformities –> rhagades (scars at the edge of the mouth)

– Teeth deformities –> Mulberry molars

– Hutchinson’s triad –> peg-shaped upper incisors and interstitial keratitis.

– Developments delays, premature birth and seizures with enlarged liver and spleen


Management – Treat the mother during pregnancy, greatest risk when mother is in early stage of infection.


b) Ulcerating Conditions

  • Genital Herpes

This is an ulcerating STI which is caused by the Herpes Simplex virus (usually HSV-2)

– Most people have no or mild symptoms and do not know that they are infected

– Onset of symptoms occurs 4 days after exposure, giving primary infection which can be severe and then further outbreaks which are usually milder. 


– Primary infection –> multiple blisters that form painful ulcers

                  – Males –> seen of glans, shaft of penis, thigh or anus

                  – Females –> on vulva, buttocks, clitoris or anus

                  – Fever and headache with general malaise

                  – Can cause urine retention

– Relapses –> 80% get recurrence with milder symptoms


Diagnosis – Nucleic acid amplification testing of swab


Management – No cure possible, but managed with oral acyclovir

– If pregnant >28 weeks gestation –> opt for elective caesarean section


  • Lymphogranuloma Venereum (LGV)

This is invasion of the inguinal lymph system, causing granulomatous inflammation.

– It is a complication of the STI Chlamydia trachomatis

– It leads to ulceration and a tender inguinal canal with swollen inguinal lymph         nodes

– It heals with fibrosis, but can involve perianal structures giving rectal stricture


Symptoms – These are seen in 2 main stages

i) Primary –> begins as painless genital ulcer at contact site 3-12 days after infection, healing in a few days

 ii) Secondary –> Gives bilateral or unilateral swollen, painful inguinal lymph nodes 10-30 days later

– If route was anal, can develop proctocolitis, inflammation of colon 12cm above anus

– Gives proctitis symptoms (anal pain, tenesmus) + diarrhoea and abdominal cramps


Diagnosis – Serological testing                                            Treatment – Doxycycline

  • Chancroid

This is a STD which is caused by the bacteria Haemophilus ducreyi

– Rare in UK, but it is the commonest cause of genital ulceration in the world

– It only gives local symptoms and there are usually no systemic signs


Symptoms – Painful ulcers with sharply defined irregular (saucer-shaped)                                                           borders

                  – Painful inguinal lymphadenopathy unilaterally

                  – Males –> 50% usually only have single ulcer

                  – Females –> Dysuria and dyspareunia


Management – 1st line is macrolide antibiotics (Azithromycin, erythromycin)

c) Conditions affecting women

  • Bacterial Vaginosis

This condition is due to an overgrowth of bacteria in the vaginal canal

– Vagina is normally dominated by Lactobacillus, but overgrowth of the anaerobic bacteria Gardnerella vaginalis creates a biofilm which allows other opportunistic bacteria to thrive.

– Colonisation of anaerobic bacteria means aerobic Lactobacilli stop making lactic acid raising pH


Symptoms – It is asymptomatic in about half of women and usually not painful

– “Fishy” odour which smells bad and is white or grey in colour


Diagnosis – This is done using a vaginal swab. Looking for at least 3 features:

i) pH > 4.5

ii) Thin, white discharge

iii) Clue cells seen on microscopy

iv) Positive whiff test –> this is when adding potassium hydroxide gives a fishy odour


Management – 1st line is oral metronidazole for 5-7 days

  • Trichomonas Vaginalis

This is a protozoan parasite which causes the STI trichomoniasis, spread via skin-to-skin contact.



– Women –> Offensive smelling vaginal discharge yellow/green in colour

– Vulvovaginitis (itching, burning, pain) with a strawberry cervix)

– Men –> usually asymptomatic but can cause urethritis

Diagnosis – Vaginal smear and wet mount microscopy shows the trophozoites

– pH of vaginal discharge > 4.5


Management – 1st line is oral metronidazole for 5-7 days

  • Candidiasis

This is called vaginal thrush and it is usually self-diagnosed and managed.

– It is due to excessive growth of the yeast Candida which colonises the vagina causing irritation

– Not entirely regarded as a STI as there is no infectious risk to the partner


Risk factors – Age, immunosuppression, pregnancy, diabetes

Symptoms – Itchy vagina with dyspareunia (painful intercourse)

– “Cottage-cheese” discharge which does not smell offensive

– Symptoms can worsen just before a woman’s period


Tests – Usually diagnosed clinically, but if doubt take vaginal swab


Management – If moderate or pregnant –> Intravaginal antifungal

– If more severe –> Oral fluconazole single dose

1. Grook Da Oger / CC BY-SA (
2. Wellcome Images / CC BY (
3. CDC/Alexander J. da Silva, PhD/Melanie Moser (PHIL #3426), 2002. / Public Domain

Sign up to our mailing list to get an exclusive 10% discount on In2Med courses!