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This article provides an overview of sexually transmitted infections (STIs) including the organisms involved, symptoms, signs, investigations and management options. Due to changes in sexual behaviours, diagnostic investigations and demographics, the epidemiology of STIs continue to change, with chlamydia now being the most common STI in the UK.


Risk factors for STIs

  • Unprotected sexual intercourse
  • Multiple sexual partners
  • 15-24 year-olds
  • Illicit drug use and alcohol use
  • Men who have sex with men (MSM)
  • Sex workers
  • Urban areas

Just remember that if one STI is present the chances are there will be another one due to co-infection, so ALWAYS test for others!


Chlamydia

Causative organism

Chlamydia trachomatis

 

Transmission

These obligate intracellular bacteria are predominantly transmitted via sexual contact. However, perinatal transmission from an infected mother to her baby during vaginal delivery is possible which can lead to neonatal conjunctivitis (ophthalmia neonatorum) and pneumonia.

 

Presentation

Asymptomatic in more than 80% of cases.

Males: Mucopurulent urethral discharge, dysuria, scrotal pain, proctitis.

Females: Mucopurulent vaginal discharge, cervicitis, cervical bleeding upon contact, proctitis, post-coital bleeding, intermenstrual bleeding.

 

Diagnostic investigations

Nucleic Acid Amplification Test (NAAT)- First pass urine in males and vulvovaginal swabs in females are used for testing.

Oropharyngeal and rectal sites can also be swabbed for NAAT testing.

 

Management

Azithromycin 1g oral as a single dose

or

Doxycycline 100mg oral twice daily for 7 days (favoured if proctitis is present)

or

Erythromycin 500mg oral twice daily for 14 days

Contact tracing and partner notification need to be offered. Advise that all forms of sexual intercourse need to be avoided until both parties are tested and treated.

 

Complications

  • Pelvic inflammatory disease (PID)- increases the risk of ectopic pregnancy and infertility
  • Epididymitis
  • Prostatitis
  • Reactive arthritis

 

Lymphogranuloma venereum is caused by a more invasive serotype of chlamydia trachomatis which causes a triad of inguinal lymphadenopathy, proctocolitis and fever.


Gonorrhoea

Causative organism 

Neisseria gonorrhoeae

 

Transmission

This gram-negative diplococcus bacteria is predominantly transmitted via sexual contact. Mucosal epithelium lining the genital tract, oropharynx and the rectum are most commonly infected. Similar to chlamydia, vertical transmission of gonorrhoea during childbirth can cause ophthalmia neonatorum however the onset of gonococcal conjunctivitis is earlier then chlamydial conjunctivitis.

 

Presentation

Males: Mucopurulent urethral discharge, dysuria, orchitis.

Females: Mucopurulent cervical discharge with cervicitis, cervical bleeding upon contact, dyspareunia, pelvic pain.

Rectal infection can cause: rectal bleeding, rectal discharge, tenesmus, proctitis.

Oropharyngeal infection can cause: Pharyngitis, anterior cervical lymphadenopathy.

 

Diagnostic investigations

Nucleic Acid Amplification Test (NAAT)- First pass urine in males and vulvovaginal swabs in females are used for testing.

If oropharyngeal or rectal symptoms are present these sites can also be swabbed for NAAT.

In addition, cultures (urethral, cervical, anal or oropharyngeal) are taken prior to administering antibiotics to assess antibiotic susceptibility.

 

Management

Ceftriaxone 500mg intramuscular injection as a single dose

plus

Azithromycin 1g oral as a single dose

Contact tracing and partner notification need to be offered. Advise that all forms of sexual intercourse need to be avoided until both parties are tested and treated.

Test of cure following two weeks after treatment using NAAT is recommended to ensure adequate treatment.

 

Complications

  • Pelvic inflammatory disease (PID)- increases the risk of ectopic pregnancy and infertility
  • Fitz-Hugh-Curtis syndrome- secondary to PID there is inflammation of the hepatic capsule leading to perihepatic adhesions
  • Chronic pelvic pain in females
  • Infertility in males secondary to epididymitis
  • Prostatitis
  • Bartholinitis

Syphilis

Causative organism

Treponema pallidum

 

Transmission

This spirochete bacterium can be transmitted via direct sexual contact with an infected individual who has a lesion on the skin or mucosa. Congenital syphilis in infants occurs as a result of trans-placental transmission which increases the risk of stillbirth and miscarriage.

 

Presentation

There are 5 stages of syphilis each with its characteristic features. An individual is most infectious during the primary and secondary stages.

  1. Primary: Development of an indurated painless ulcer called a chancre forms most often on the genitals. This can form from 9-90 days.
  2. Secondary: 6 weeks to 6 months following the primary infection a widespread non-pruritic maculopapular rash involving the palms and soles develops accompanied by alopecia, condylomata lata, generalised lymphadenopathy, oral snail-track lesions and constitutional symptoms (pyrexia, fatigue, malaise).
  3. Early latent: Asymptomatic infection plus positive diagnostic serology obtained within two years of infection.
  4. Late latent: Asymptomatic infection plus positive diagnostic serology obtained after two years of infection.
  5. Tertiary: Untreated syphilis over many years can develop into:
  • Neurosyphilis Tabes dorsalis, general paresis, strokes
  • Cardiovascular syphilis Aortitis, aortic aneurysms
  • Gummatous syphilis Formation of granulomas on bone, skin and mucosa

 

Diagnostic investigations

Dark ground microscopy of the chancre fluid – shows motile spring-shaped bacteria in primary syphilis.

Syphilis PCR from a swab taken from an ulcerated lesion.

Treponemal-specific serology remains positive throughout life:

  • Treponemal enzyme immunoassay (EIA)
  • T.pallidum haemagglutination test (TPHA)
  • T. pallidum particle agglutination test (TPPA)

Cardiolipin serology tests are used as an indicator to measure disease activity, disease staging and treatment efficacy. These include:

  • Rapid Plasma Reagin (RPR)
  • Venereal Disease Research Laboratory (VDRL)

 

Management

Benzathine benzylpenicillin 1.8g intramuscular injection as a single dose

plus

Prednisolone 60 mg oral once daily for 3 days (commence 24 hours prior to penicillin administration)

Contact tracing and partner notification need to be offered.

  

Complications

  • Jarisch-Herxheimer reaction- antibiotic treatment of syphilis causes a sepsis-like picture due to the release of toxins from treponemal bacterium breakdown, therefore steroids are administered beforehand to prevent this.
  • HIV co-infection

Herpes simplex virus (HSV)

Causative organism

HSV-1 and HSV-2

 

Transmission

HSV are double-stranded DNA viruses which are transmitted through mucosal surfaces or broken skin. HSV-1 (oral herpes) is predominantly spread via the oral-oral route but due to oral sex HSV-1 can also affect the genitals. HSV-2 (genital herpes) is sexually transmitted and affects the genital or anal area. Infection with HSV is lifelong as it lies dormant within the sensory ganglia causing intermittent reactivation. The virus is transmitted even in the absence of symptoms and this is known as asymptomatic shedding.

 

Presentation

Primary infection

Multiple painful blisters erupt around the genitals or mouth which burst to leave ulcers and fissures. This is accompanied by dysuria, pyrexia, painful inguinal lymphadenopathy and neuropathic pain around the external genitalia.

This first episode can last up to 3 weeks.

Recurrent infections only last around 3 days and present with milder symptoms.

 

Diagnostic investigations

HSV PCR or culture from swabs taken from lesions- when taking the sample remember to burst the lesion and swab the base of the ulcer.

 

Management

Primary episode: Aciclovir 400mg oral three times a day for 7–10 days (treatment must be commenced within three days of symptom onset)

Recurrent episodes: Aciclovir 800mg oral three times a day for 2 days

Salt water baths, oral analgesia and topical lidocaine can be used for pain control.

 

Complications

  • Urinary retention
  • HSV keratitis- dendritic lesion on the cornea
  • Aseptic meningitis
  • Neonatal HSV- an increased risk if the mother becomes infected in the third trimester
  • Herpetic whitlow

Genital warts

Causative organism

Human papillomavirus (HPV) 6 and 11

 

Transmission

This double-stranded DNA virus is transmitted via direct skin to skin contact. Many sexually active individuals carry the virus however not all of them will develop genital warts.

 

Presentation

Warts can vary in size, colour and texture but mostly appear around the vaginal opening and penis as these areas are exposed to more friction. The anus, cervix and urethral meatus can also be affected. Predominantly genital warts are asymptomatic however itching, bleeding and pain can occur.

 

Diagnostic investigations

Diagnosis is clinical however biopsies should be obtained if the lesion bleeds, is ulcerated or indurated.

 

Management

First line:

  • Topical podophyllotoxin
  • Topical imiquimod

 

Second line:

  • Cryotherapy
  • Surgical excision

 

Complications:

  • Ano-genital cancer
  • Scarring following treatment

Trichomoniasis

Causative organism

Trichomonas vaginalis

 

Transmission

This flagellated protozoan is transmitted via sexual intercourse.

 

Presentation

Asymptomatic in more than 50% of cases.

Females: Vaginal discharge (thin, frothy yellow coloured with a ‘fishy’ smell), vulval pruritus, vulvovaginitis, dysuria, dyspareunia

Males: urethral discharge, dysuria, balanitis

 

Diagnostic investigations

Vaginal pH- is alkaline >5 in trichomoniasis (normal 3.5-4.5)

High vaginal swab for wet mount microscopy

Culture of vaginal discharge

In men, a culture of urethral swab or first pass urine can be used.

 

Management

Metronidazole 2g oral as a single dose

Contact tracing and partner notification need to be offered.

Advise that all forms of sexual intercourse need to be avoided until both parties are tested and treated.

 

Complications

  • Pelvic inflammatory disease – increases the risk of ectopic pregnancy and infertility
  • Altered vaginal flora
  • Prostatitis
  • In pregnancy, there is an increased risk of premature rupture of membranes and preterm birth.

References


 

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