Sexually transmitted infections Flashcards
List 6 common STI presentations in men
Asymptomatic Urethral discharge Dysuria Scrotal pain/swelling Rash/sores Systemic symptoms
List 8 common STI presentations in women
Asymptomatic Vaginal discharge (+/- urethral, rectal) Ulceration (painful/painless) Itching/ soreness "Lumps" Abnormal bleeding, IMB/PCB Pain - abdo/dyspareunia/dysuria Systemic symptoms
What are the 5 most common causes of abnormal discharge?
Gonorrhoea Chlamydia Trichomonas Candida Bacterial vaginosis
What are the 5 most common causes of genital ulceration?
Syphilis HSV Lymphogranuloma venereum (LGV) Chancroid Donovanosis
What are the 4 most common causes of genital rashes, lumps and growths?
Genital warts (HPV)
Molluscum contagiosum
Scabies
Pubic lice
What’s the difference between painful and painless genital ulcers?
Painful: more likely to be herpes or chancroid (soft chancre)
Painless: more likely to be syphilis (hard chancre) or LGV or donovanosis (granuloma inguinale)
Which pathogen causes gonorrhoea?
Neisseria gonorrhoeae
Describe the microscopic features of Neisseria gonorrhoeae
Fastidious, facultatively intracellular gram negative diplococci. Coffee bean shaped. Grow on chocolate agar.
What is opthalmia neonatorum and how is it caused?
= neonatal conjunctivitis
Develops if mother’s gonorrhoea untreated and transfers to child from birth canal
How does gonorrhoea affect patients with complement deficiency?
Disseminated gonococcal infection - septicaemia, rash and/or arthritis
What is the gold standard to test to diagnose gonorrhoea?
Culture from urethral (sensitivity 95%) or rectal (sensitivity 20%) smears
How is gonorrhoea treated?
Ceftriaxone - 250mg single dose IM or Cefixime - 400mg single dose PO
How is resistant gonorrhoea treated?
Spectinomycin - 2g single dose IM
Name 3 ways in which an uncomplicated gonorrhoea infection can present in men
Non-gonococcal urethritis (NGU)
- Most common STI in Europe
- Mucoid/mucopurulent discharge
Post-gonococcal urethritis (PGU)
- Follows gonorrhoea treatment
- Can be prevented by concomittant treatment with a tetracycline
Rectal proctitis
- Mainly in MSMHow does an uncomplicated gonorrhoea infection present in women?
Mucopurulent cervicitis
- Erythema and oedema of the endocervix - Abnormal vaginal discharge and bleeding
Name a complication of gonorrhoea in men
Prostatitis
Name a complication of gonorrhoea in women
PID (salpingitis)
- Ascending infection - Most common cause of female infertility in Europe
Describe the microscopic features of Chlamydia trachomatis
Gram negative, obligate intracellular non-motile ovoid bacterium. Cannot be cultured on agar
In the UK, what percentage of under 25s have chlamydia?
10%
What proportion of chlamydia infections are asymptomatic?
50% in men
80% in women
Name the two forms Chlamydia trachomatis can take at different stages of its growth cycle
- Elementary bodies (stable, extracellular)
- Reticulate particles (intracellular, metabolically active)
What is trachoma and which chlamydia serovars is it caused by?
Trachoma = eye infection which can lead to blindness. Caused by chlamydia serovars A, B and C
Which chlamydia serovars cause genital infection and opthalmia neonatorum?
Serovars D - K
List 3 complications of chlamydia in men
Epididymitis
Reiters syndrome (arthritis, conjunctivitis, urethritis)
Increased risk of infertility
What is Reiter’s syndrome?
A combination of reactive arthritis, conjunctivitis and urethritis. Often caused by chlamydia infection. More common in men.
List 6 complications of chlamydia in women
PID Tubal factor infertility Increased risk of ectopic pregnancy Increased risk of endometriosis Chronic pelvic pain Opthalmia neonatorum
What is the gold standard test for diagnosing chlamydia?
Nucleic acid amplification tests (NAATs)
High specificity and sensitivity
What is the treatment for uncomplicated chlamydia?
Azithromycin 1g (4 capsules) single stat dose
OR
Doxycycline 100mg BD for 7 days
OR
Erythromycin 500mg QDS for 7 days or BD for 2 weeks
When should doxycycline not be given?
In pregnancy - can disturb bone growth and cause tooth discolouration
In the world of STIs not lorry driving, what does LGV stand for?
Lympho-granuloma venereum
What is LGV?
Lymphatic infection with Chlamydia serovars L1, L2 and L3
Who is more likely to get LGV in the developed world? (recent outbreaks)
MSM
Describe the primary stage of early LGV
3-12 days Genital ulcer: painless, non-indurated Balanitis (inflammation of the head of the penis/foreskin) Proctitis Cervicitis
Describe the secondary stage of early LGV
2-25 weeks
Inguinal buboes: painful, 2/3 unilateral, may rupture
Fever
Malaise
Proctocolitis
Hyperplasia of lymphoid tissue
Rarely: hepatitis, meningo-encephalitis, pneumonitis
Describe late LGV
Inguinal lymphadenopathy Abscess formation Genital elephantiasis Genital ulcers Frozen pelvis Rectal strictures Perirectal abscesses and fistulae Lymphorroids (peri-anal outgrowths of the upper rectum)
Describe the rectal symptoms presenting in the current LGV outbreak
Pain Tenesmus Bleeding Mucous discharge Proctitis
How is LGV diagnosed?
- NAAT (currently unlicensed) - if positive, sent to lab at central health protection agency.
- Confirmation of Chlamydia trachomatis by real time PCR on 2 platforms
- Genotypic identification of L1, L2 or L3 serovar
What is the treatment for LGV?
Doxycycline 100mg BD for 3 weeks
OR
Erythromycin QDS for 3 weeks
OR
Azithromycin 1g weekly for 3 weeksWhich bacterium causes syphilis?
Treponema pallidum
Describe the microscopic features of Treponema pallidum
Obligate gram negative spirochaete (spiral shaped). Can be seen in primary lesions by “dark-ground/dark-field” microscopy
Who tends to get syphilis?
Majority of cases in HIV positive pts. Often co-infected with hepC or another STI. Rising in UK
What is the diagnostic method of choice for Treponema pallidum?
Antibody detection
How can Treponema bacteria be directly detected? (NB these methods are much less commonly performed than antibody detection)
Darkfield microscopy
Multiplex real-time PCR
Describe the non-Treponemal antibody tests used in syphilis
This slide needs cutting up
- Detect non-specific antigens
- VDRL (venereal disease research laboratory) slide test: detects lipoidal antibody on both host and treponemal cells
- Reagents contain cardiolipin, lecithin and cholesterol (can get biological false positives)
- RPR (rapid plasma reagin) is a modified VDRL test
- Positive RPR is indicative of treponemal infection
- Useful in primary syphilis
- Titre falls in response to treatment therefore can be used to monitor response.
Which sort of syphilis tests are more sensitive, treponemal or non-treponemal?
Non-treponemal
Which sort of syphilis tests are more specific, treponemal or non-treponemal?
Treponemal
Describe the Treponemal antibody tests used in syphilis
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- Detect antibodies against specific antigens from T. pallidum
- Examples: Enzyme immunoassay (EIA), Fluorescent treponemal antibody (FTA), T. pallidum haemagglutination test (TPHA), T. pallidum particle agglutination test (TP-PA)
- More specific than non-Treponemal test
- Remains positive for years despite effective treatment
Why are biological false positives common in the non-treponemal tests?
Because the reagents contain cardiolipin, lecithin and cholesterol
Give four examples of treponemal tests for syphilis
Enzyme immunoassay (EIA)
Fluorescent treponemal antibody (FTA)
T. pallidum haemagglutination test (TPHA)
T. pallidum particle agglutination test (TP-PA)
Does a positive treponemal test always indicate a syphilis infection?
No, although the test is specific for syphilis it remains positive for years despite effective treatment (test is for antibodies, so not dependent on presence of pathogen)
Describe primary syphilis
Macule turns to papule turns to indurated painless genital ulcer
Ulcer appears 1-12 weeks after transmission
Often solitary
May persist 4-6 weeks as a chancre
Clean base with serous exudate
Regional adenopathy
How long after transmission of syphilis does the primary stage of the disease appear?
1-12 weeks
In primary syphilis are the genital ulcers painful or painless?
Painless
Describe secondary syphilis
bollocks slide, someone fix please
Most important part: - 1-6 months after primary infection Systemic bacteraemia Low grade fever and malaise Symmetrical, non-pruritic, maculo-papular rash on back, trunk, arms, legs, palms, soles, face
Also good to know: - Mucosal lesions Uveitis Choroidoretinitis (inflammation of the choroid and retina) Alopecia "Snail trail" oral ulcers Condyloma acuminate (genital warts) Can have neurological involvement: aseptic meningitis, cranial nerve palsies, optic neuritis, acute nerve deafness
What are “snail trail” oral ulcers a sign of?
Secondary syphilis
Without treatment, what proportion of people with syphilis go on to develop a tertiary infection?
Approx 1/3
Name the three possible types of tertiary syphilis
Gummatous syphilis (15% of primary infections) Late neurosyphilis (6.5%) Cardiovascular syphilis (10%)
Describe gummatous tertiary syphilis
Rare
Occurs 2-40 years later
Formation of chronic “gummas” - soft, tumor-like balls of inflammation
Particularly affects skin, bone, liver and mucosa but can occur anywhere
Spirochaetes (the bacteria) scanty - this is why there is a strong DTH response
What is a DTH reaction and how does it predict the course of a syphilis infection?
DTH = delayed type hypersensitivity
A strong DTH response is associated with clearance of the infecting organisms in a well-developed chancre, whereas a cytotoxic T-cell response or strong humoral antibody response is associated with prolonged infection and progression to tertiary disease.
Is tertiary syphilis infectious?
No
Describe neurosyphilis
Most common in people with HIV
Occurs 2-30 years later
Four different forms: asymptomatic, meningovascular, tabes dorsalis, and general paresis ("of the insane")
Can present with gumma
Spirochaetes in CSF
Small vessel vasculitis
Argyll-Robertson pupilWhat are the four forms of neurosyphilis?
Asymptomatic
Meningovascular
Tabes dorsalis
General paresis of the insane
What is tabes dorsalis?
AKA syphilitic myelopathy
Slow demyelination of the nerves primarily in the dorsal columns (posterior columns) of the spinal cord.
Therefore affects proprioception, vibration sensation and discriminative touch.
What is Argyll-Robertson pupil also known as?
Prostitute’s pupil
What is Argyll-Robertson pupil/prostitute’s pupil?
Bilateral small pupils that constrict when the patient focuses on a near object, but do not constrict when exposed to bright light.
“Accommodates but does not react”
What is the treatment for syphilis, at any stage?
Single dose IM benzathine penicillin (doxycycline if allergic)
When is treatment considered successful?
Depends on a four fold reduction in RPR (rapid plasma reagin)
Describe cardiovascular tertiary syphilis
10-30 years later
Un-/complicated aortitis
+++spirochaetes
+++inflammation
Which reaction commonly occurs following treatment for syphilis?
Jarisch-Herxheimer reaction
- Fever, headache, myalgia
- Develops in hours and clears within 24 hours
Due to reaction to endotoxin-like products released by the death of spirochaetes.
Occurs in 50% primary and 90% secondary
What is latent syphilis?
Occurs between secondary and tertiary stages. No obvious signs/symptoms but serological infection present
Describe congenital syphilis
Can be passed from mother to child druing either pregnancy (via placenta) or birth
Features in first couple of years: hepatosplenomegaly, rash, fever, neurosyphilis, pnemonitis
Late congenital syphilis (presenting after 2 years old) occurs in 40%
Which bacteria causes chancroid?
Haemophilus ducreyi
Describe the microscopic features of Haemophilus ducreyi
Gram -ve coccobacillus (like Hib)
Describe chancroid
Tropical ulcer disease causing multiple painful ulcers. More common in Africa, rare in UK
How is chancroid (Haemophilus ducreyi) diagnosed?
Culture on chocolate agar
PCR
What is Donovanosis also known as?
Granuloma inguinale
Which bacterium causes Donovanosis/granuloma inguinale?
Klebsiella granulomatis
Describe the microscopic features of Klebsiella granulomatis
Gram -ve bacillus
Where does Donovanosis commonly occur?
Africa, India, Papau New Guinea, Australian aboriginal communities
Describe Donovanosis
“Beefy” red appearance
Large, expanding ulcers. Start as papule or nodule that breaks down
How is Donovanosis diagnosed?
Giemsa stain of biopsy/tissue crush shows Donovan bodies
What kind of stain is used in the diagnosis of Donovanosis?
Giemsa stain
What is the treatment for Donovanosis?
Azithromycin
Name 3 non-viral enteric pathogens that can be sexually transmitted (through oro-anal contact)
Shigella
Salmonella
Giardia (protozoan)
Occasionally also strongyloides
Which flagellated protozoan causes trichomoniasis?
Trichomonas vaginalis
How is trichomoniasis diagnosed?
Wet prep microscopy
PCR
How does trichomoniasis present?
Asymptomatic/urethritis in men
Discharge in women
What risks is trichomoniasis associated with?
Increased risk of HIV acquisition and of pre-term labour
What is the treatment for trichomoniasis?
Metronidazole
Which polymicrobial disorder is associated with abnormal vaginal flora and a decrease in vaginal lactobacilli?
Bacterial vaginosis (BV)
How does BV present?
Abnormal discharge and very strong odour.
Often recurrent
Is BV an STI?
No but it may be “sexually associated”.
Also associated with overzealous hygiene practices (douching)
How is BV diagnosed?
Microscopy of Gram stain
Raised pH
“Whiff test” :(
“Clue cells” on wet mount - epithelial cells coated in bacteria can be seen on microscopy of vaginal discharge with a drop of sodium chloride solution
What is the main risk associated with BV in pregnancy?
Pre-term labour
What causes candidiasis (thrush)?
Usually Candida albicans (yeast)
How does thrush present?
Can be asymptomatic
White thick discharge, itching, soreness, redness
Vulvovaginitis in women; balanitis in men
Is thrush sexually transmitted?
No, candida albicans can be part of normal flora
Recurrence may be associated with immunodeficiency or overzealous hygiene practices
Give two examples of “hormonal disturbances” associated with increased risk of thrush?
Pregnancy
OCP
How is thrush treated?
Topical/oral antifungals eg clotrimazole, fluconazole
What sort of pathogen causes molluscum contagiosum?
Pox virus
What kind of genetic material does the pox virus have?
dsDNA
How is molluscum spread in children and which areas does it affect?
Spread by skin to skin contact, affects hands and faces. (should worry if genital involvement)
How is molluscum spread in adults and which areas does it affect?
Sexual contact - genital lesions
What does facial molluscum in adults indicate?
Immunocompromise - should assume HIV until proven otherwise. Can also cause giant lesions.
How is molluscum treatment?
Cryotherapy, but treatment only required if destructive, otherwise self-limiting
Which virus causes genital warts?
dsDNA human papillomavirus
Which HPV strains cause visible genital warts?
HPV 6 and HPV 11
Are HPV 6 and 11 associated with increased risk of cervical dysplasia?
No
What is the incubation time for genital warts?
3 weeks - 8 months
Genital warts are diagnosed by examination. What are their key dermatological features?
Papular Planar Pedunculated Carpet Keratinised Pigmented
What is the treatment for genital warts?
At home: podophyllotoxin solution/cream (not suitable for pregnant women)
In clinic: 1st line cryotherapy; 2nd line imiquimod
However, can often recur after treatment
Which strains of HPV are oncogenic?
16 and 18
Name 6 types of cancer associated with HPV
Cervical Anal Penile Vulval Head Neck
What change was made to the HPV vaccine in 2012?
Became quadrivalent - now includes 6 and 11 as well as 16 and 18
Name 5 sexually transmitted viruses other than HPV
HAV HBV HCV Herpes HIV
How is Hep A sexually transmitted?
Oro-anal sex
Who is most likely to contract hep C?
HIV +ve MSM
rarely hetero-sexually transmitted
