STI

Question 1

Trichomonas vaginalis

Answer 1

highly motile, flagellated protozoan parasite. Trichomoniasis is a STI Features: vaginal discharge: offensive, yellow/green, frothy, vulvovaginitis, strawberry cervix pH > 4.5 in men is usually asymptomatic but may cause urethritis Investigation: microscopy of a wet mount shows motile trophozoites Management: oral metronidazole for 5-7 days OR a one-off dose of 2g metronidazole

Question 2

Bacterial vaginosis vs Trichomonas vaginalis

Answer 2

• COMMON:‘offensive’ vaginal discharge.
  
  • Vaginal pH >4.5.
  • Treat with metronidazole
• BV: thin, white discharge, clue cells on microscopy
• TV: frothy, yellow-green discharge, vulvoginitis, strawberry cervix. Wet mount: motile trophozites

Question 3

Chlamydia - Chlamydia trachomatis

Answer 3

• Obligate intracellular parasite - gram negative non-motile.
• Features: asymptomatic in around 70% of women and 50% of men women: cervicitis (discharge, bleeding), dysuria men: urethral discharge, dysuria.
• Potential complications: epididymitis, PID, endometritis, increased incidence of ectopic pregnancies, infertility, reactive arthritis, perihepatitis (Fitz-Hugh-Curtis syndrome)
• Ix: urine (first void urine sample), vulvovaginal swab or cervical swab may be tested using the NAAT technique
  
  • for women: the vulvovaginal swab is first-line
  • for men: the urine test is first-line
• Chlamydia testing should be carried out two weeks after a possible exposure

Question 4

Chlamydia treatment

Answer 4

• doxycycline 7/7 or azithromycin (single dose) If pregnant then azithromycin, erythromycin or amoxicillin may be used.

Question 5

Human papilloma virus

Answer 5

• HPV infects the keratinocytes of the skin and mucous membranes is carcinogenic.
• There are dozens of strains of HPV.
  
  • 6 & 11: causes genital warts
  • 16 &18: linked to a variety of cancers, most notably cervical cancer
• HPV infection is linked to: over 99.7% of cervical cancers around 85% of anal cancers around 50% of vulval and vaginal cancers around 20-30% of mouth and throat cancers

Question 6

Syphilis - primary features

Answer 6

chancre - painless ulcer at the site of sexual contact local non-tender lymphadenopathy often not seen in women (the lesion may be on the cervix)

Question 7

Syphilis - secondary features

Answer 7

systemic symptoms:

• fevers, lymphadenopathy
• rash on trunk, palms and soles
• buccal ‘snail track’ ulcers (30%)
• condylomata lata (painless, warty lesions on the genitalia )

Question 8

Syphilis - tertiary features

Answer 8

• gummas (granulomatous lesions of the skin and bones)
• ascending aortic aneurysms
• general paralysis of the insane, tabes dorsalis
• Argyll-Robertson pupil

Question 9

Genital ulcers painless

Answer 9

• Chancre - syphilis (Treponema pallidum) -> ulcer with well define borders
• Condyloma acuminata (HPV) -> skin colored papules, warts
• Granuloma inguinale - donocanosis (klebsiella) -> sharply demarcated ulcer with beefy red granulation tissue

Question 10

Genital ulcers painful

Answer 10

• Genital herpes
• Chancroid - haemophilus ducreyi
• Lymphogranuloma venereum - chlamydia trachomatis

Question 11

Enteric fever (typhoid/paratyhoid)

Answer 11

• Spread via F-O route.
• Aerobic, Gram-negative rods which are not normally present as commensals in the gut,
• Presentation: initially systemic upset as above relative bradycardia abdominal pain, distension
• constipation: although Salmonella is a recognised cause of diarrhoea, constipation is more common in typhoid
• rose spots: present on the trunk in 40% of patients, and are more common in paratyphoid
• Complications: OM (especially in sickle cell disease where Salmonella is one of the most common pathogens)
• GI bleed/perforation meningitis cholecystitis chronic carriage

Question 12

Lymphogranuloma venereum - Chlamydia trachomatis

Answer 12

• Tropical sti can be caused by multiple serovars of Chlamydia Trachomatis.
• The bacterium gains entry through breaches in the epithelial/mucous membranes, travelling through the lymphatics via macrophages to local nodes.
• It is endemic to Africa, India, Caribbean, central America and southeast Asia.
• Primary stage: Self-limiting painless genital ulcer at the site of inoculation 3-12 days later.
• Secondary stage: Presents 1-6 months later with unilateral painful lymphadenitis/lymphangitis. The site of inoculation dictates symptomatology, if rectally, then tenesmus, proctocolitis, strictures and fistulas can ensue.
• Cervicitis and urethritis are also common features.
• Enlarged lymph nodes are known as buboes, they are often painful and can lead to thinning of the overlying skin causing abscesses.
• Groove sign is separation inguinal nodes by the inguinal ligament and is characteristic of the disease.
• Diagnosis is achieved by enzyme linked immunoassays or polymerase chain reaction of infected sample areas/pus.
• Acute and convalescent sera can be used, but requires two samples 2 weeks apart.
• Treatment involves Abx, either doxycycline or macrolides (azithromycin or erythromycin) and potential surgical drainage/aspiration of the buboes or abscesses.
• Complications of the disease include: genital elephantiasis, hepatitis, infertility, pelvic inflammatory disease, arthritis and fitz hugh curtis syndrome.

Question 13

Stages of Syphilis Infection

Answer 13