15.4 Non-Gonococcal Urethritis, Mycoplasma genitalium, Trichomoniasis, Vaginal Infections & Balanitis

15.4 Non-Gonococcal Urethritis, Mycoplasma genitalium, Trichomoniasis, Vaginal Infections & Balanitis

The official venereology syllabus covers the "clinical diagnosis and management of STIs, including systemic manifestations, genito-anal dermatoses and the local and systemic complications", plus laboratory diagnosis. This section adds the infections not covered in the syphilis, gonorrhoea, chlamydia, and genital ulcer sections. European IUSTI guidelines are used first.

Urethritis in Men

Urethritis causes dysuria and urethral discharge, but it can be asymptomatic.

• Confirm urethral inflammation with a Gram- or methylene blue-stained urethral smear. European and UK guidance uses ≥ 5 polymorphonuclear leucocytes (PMNL) per high-power field; the US CDC uses ≥ 2. A first-void urine sediment can also be used.
• Gonococcal urethritis: Gram-negative intracellular diplococci on the smear; see the gonorrhoea section.
• Non-gonococcal urethritis (NGU): causes include Chlamydia trachomatis (the most common), Mycoplasma genitalium, Trichomonas vaginalis, adenovirus (with conjunctivitis), herpes simplex virus, and Neisseria meningitidis (after oral sex). The role of Ureaplasma urealyticum is uncertain. Many cases have no identified pathogen.
• Empirical treatment of NGU: doxycycline 100 mg twice daily for 7 days is preferred. Single-dose azithromycin 1 g is no longer favoured because it selects macrolide resistance in M. genitalium.
• Test for gonorrhoea, chlamydia, and M. genitalium with NAATs, and offer HIV and syphilis testing. Treat and test partners, and advise no sex until treatment is complete.

Mycoplasma genitalium

M. genitalium causes urethritis in men and cervicitis, pelvic inflammatory disease (PID), and possibly infertility in women. It lacks a cell wall (so beta-lactams do not work) and rapidly acquires resistance to macrolides and fluoroquinolones.

Testing (European guidance):

• Test symptomatic patients (urethritis, cervicitis, PID, epididymitis, proctitis) and current partners of infected patients.
• Do not screen asymptomatic people, because treatment drives resistance and the benefit is unclear.
• Use a NAAT followed by a macrolide resistance-associated mutation assay (23S rRNA gene).

Resistance-guided treatment:

Some guidelines, for example in the UK, give doxycycline first to lower the bacterial load before the targeted antibiotic. A test of cure is advised no earlier than 3 weeks after starting treatment.

Trichomoniasis

Trichomonas vaginalis is a flagellated protozoan.

• Women: frothy yellow-green offensive discharge, vulvovaginal soreness, and sometimes a "strawberry cervix" (colpitis macularis); vaginal pH is above 4.5. Many are asymptomatic.
• Men: usually asymptomatic, sometimes urethritis.
• Diagnosis: NAAT is the most sensitive test. Wet-mount microscopy of motile trichomonads is quick but misses many cases.
• Treatment: metronidazole 500 mg twice daily for 7 days (the preferred regimen, especially for women), or a single 2 g dose as an alternative. Treat partners at the same time, and test for other STIs. Metronidazole can be used in pregnancy. Patients are usually advised to avoid alcohol during treatment.

Bacterial Vaginosis (BV)

BV is a change in vaginal flora, with loss of Lactobacillus and overgrowth of anaerobes (Gardnerella, Fannyhessea (Atopobium) vaginae, and others). It is associated with sexual activity but is not classed as a classic STI.

• Amsel criteria (at least 3 of 4): thin, white-grey, homogeneous discharge; vaginal pH above 4.5; a positive "whiff" test (fishy amine smell when potassium hydroxide is added); and clue cells on microscopy.
• Nugent score (Gram stain): 7–10 indicates BV.
• Treatment of symptomatic BV: oral metronidazole for 5–7 days, metronidazole gel for 5 days, or clindamycin cream for 7 days. Recurrence is common. Routine treatment of male partners is not recommended.
• BV in pregnancy is linked to preterm birth and late miscarriage.

Vulvovaginal Candidiasis (VVC)

• Cause: Candida albicans in about 90% of cases; non-albicans species such as C. glabrata are harder to treat.
• Clinical: itch, soreness, and thick white "cottage cheese" discharge; vaginal pH is normal (4.5 or below).
• Treatment: a single clotrimazole 500 mg pessary or fluconazole 150 mg orally. In pregnancy, use topical azoles for 7 days only.
• Recurrent VVC (4 or more episodes a year): confirm with culture, check for diabetes and other factors, then give induction therapy followed by weekly fluconazole 150 mg for 6 months.

Balanitis and Balanoposthitis

Other Syndromes

• Epididymo-orchitis: in younger sexually active men it is usually caused by C. trachomatis or N. gonorrhoeae (treat with ceftriaxone plus doxycycline). In older men and after instrumentation, enteric organisms such as E. coli are more likely (treat with a fluoroquinolone). Always exclude testicular torsion, which is a surgical emergency.
• Pelvic inflammatory disease: lower abdominal pain, deep dyspareunia, cervical motion tenderness, and fever. Treat promptly on clinical suspicion with a single IM ceftriaxone dose plus doxycycline and metronidazole for 14 days, and treat partners. Complications are infertility, ectopic pregnancy, and chronic pelvic pain. Perihepatitis is Fitz-Hugh-Curtis syndrome.
• Proctitis: anal pain, discharge, tenesmus, and bleeding after receptive anal sex. Causes include gonorrhoea, chlamydia (especially LGV), herpes simplex virus, and syphilis. Take rectal NAAT swabs, and treat empirically for gonorrhoea and chlamydia (doxycycline for 3 weeks if LGV is suspected).

Sexually Transmitted Hepatitis