STIs Flashcards
What does Molluscum contagiosum cause?
Viral skin infection (DNA pox virus) —> causes firm, smooth, umbilicated papules (central depression on small swelling of skin) ~2-5mm in diameter
?sexually transmitted (occurs in children therefore is primarily non-sexually transmitted)
Children = trunk/extremities Adults = lower abdomen, inner thighs, genitals
What are the groups at risk of STIs?
- young people
- certain ethnicities (affects type of STI): white & Asian = genital warts and Black & Mixed = genital warts & gonorrhoea
- low socio-economic status groups
- age at 1st intercourse, no. of partners, sexual orientation (particularly MSM - syphilis & gonorrhoea), unsafe sexual activity
- females aged 15-25yrs have high incidence of chlamydia
Give some reasons for the increased incidence of STIs.
- increased transmission due to changes in sexual/social behaviour e.g. post-war, 60s & oral contraceptive pill, HIV epidemic and increased density/mobility of populations
- increased GUM attendance (reduced stigma)
- greater public/medical/national awareness e.g. chlamydia screening campaign
- improved diagnostic methods of screening programmes
What are some factors contributing to the medical burden of STIs?
- acute & chronic/relapsing infections
- stigma: impacts on diagnosis & tracing sexual contacts
- consequences: PID, infertility, reproductive tract cancers, disseminated infections, transmission to foetus/neonate
Outline the general management of STIs.
Treatment preferably single dose (reduces resistance)
Co-infections are common therefore screen for other STIs & consider empiric treatment
Contact tracing
Sexual health education, advice on contraception, detailed instruction on practice & need for safer sex
Contrast sexually transmitted infections and sexually transmitted diseases.
Sexually transmitted infection (STI) = any infection transmitted through sexual activity
- sexual activity is the principal mode of transmission but does not have to be exclusive e.g. blood-borne viruses
- includes asymptomatic & symptomatic cases
Sexually transmitted disease = infectious disease transmitted via sexual activity
- only includes symptomatic cases
note: it is possible for intestinal pathogens to be sexually transmitted, particularly in MSM e.g. Salmonella, Shigella, Giardia, Entamoeba
(gastrointestinal opportunistic infections)
note: non-specific genital infections include: HIV new diagnoses, scabies, trichomoniasis, chancroid, pediculosis pubis, Molluscum contagiosum
Outline the types of HPV. How is it diagnosed, treated, and screened for?
DNA virus, 100+ types
Most common viral STI (~4% of young adults)
HPV 6 & 11:
- cause cutaneous, mucosal, & anogenital warts
- benign and painless (verrucous epithelial/mucosal outgrowths)
- warts can present on penis, vulva, vagina, urethra, cervix, perianal skin
HPV 16 & 18 = oncogenic types associated with cervical cancer (70%+ - most common cancer in women aged 15-34yrs) & anogenital cancer
Diagnosis = biopsy + genome analysis, hybrid capture
Treatment:
- none; sponataneously resolves (70% in 1yr, 90% in 2yrs)
- persistent = topical podophyllin, cryotherapy, intralesional interferon, imiquimocl, surgery
Screening: cervical pap smear cytology & cervical swab for HPV hybrid capture
—> abnormal result —> colposcopy (look at cervix using microscope with bright light) with acetowhite test (stains abnormal areas white - acetowhite lesions)
Vaccine: offered to girls aged 12-13yrs (ideally before sexual activity has started); 2 doses, 99% effective in preventing HPV 16 & 18 - related cervical abnormalities (in those not already affected)
- Cervarix (HPV 16 & 18 - oncogenic types only) = used initially in the UK
- Gordasil (HPV 6, 11, 16, 18 - oncogenic & non-oncogenic types) = used from 2011 onwards
Outline the presentation of chlamydia infection. How is it diagnosed, treated, and screened for?
Chlamydia trachomatis (differentiate from chlamydia-related respiratory infections) = non-specific genital chlamydial infections (serotypes D-K)
note: often asymptomatic
Males: urethritis, epididymitis, prostatitis, proctitis +/- discharge
Females: urethritis, cervicitis, salpingitis, perihepatitis (causes RUQ pain referred to shoulder tip due to inflammation of liver capsule/diaphragm —> Fitz-Hugh-Curtis syndrome) +/- discharge
+ ocular inoculation-conjunctivitis
+ neonatal infections = inclusion conjunctivitis, pneumonia, opthalmia neonatorum (any conjunctivitis in the first 28 days after birth)
Diagnosis: nucleic acid amplification test (NAAT) - does not have to be symptomatic & can test for N. gonorrhoeae at same time
- endocervical & urethral swabs (female)
- 1st void urine (male & female)
- (conjunctival swabs)
Treatment: doxycycline or azithromycin
(erythromycin in children)
Screening: 50% of all cases detected via screening programme (targets sexually active under 25yrs)
- necessary due to causing PID, ectopic pregnancy, fertility problems
Outline the types of herpes virus. How is it diagnosed and treated?
Herpes simplex virus:
- cold sores (HSV1)
- genital herpes (HSV2)
- herpetic Whitlow = on terminal phalanx of fingers (very painful; 60% HSV1)
PRIMARY:
- extensive painful genital ulceration
- dysuria
- inguinal lymphadenopathy
- fever
RECURRENT: latent infection in dorsal root ganglia
- asymptomatic —> moderate
- risk of transmission during pregnancy (affects decision of delivery method)
Diagnosis: PCR of vesicle fluid/ulcer base
Treatment:
- aciclovir
- prophylaxis might be required for freq. recurrences
- barrier contraception to reduce risk of transmission
Outline the features of gonorrhoea infection. How is it diagnosed and treated?
Neisseria gonorrhoeae = Gram-ve intracellular diplococcus
Males: urethritis, epididymitis, prostatitis, proctitis, pharyngitis +/- discharge (depends on sexual practices)
Females: asymptomatic, endocervicitis, urethritis, PID (may lead to infertility)
+ disseminated gonococcal infection (particularly in young females) —–> bacteraemia, skin lesions, joint lesions
Diagnosis:
- swab from urethra, cervix, (+ throat, rectum)
- urine (NAAT)
note: Gram stain can be done on pus (fairly reliable) or on a normally sterile site (more specific identification needed & special media required)
Treatment: IM ceftriaxone + azithromycin (test/treat for chlamydia, prevents emergence of cephalosporin-resistant strains)
Outline the features of syphilis infection. How is it diagnosed and treated?
Treponema pallidum = spirochete
Most cases MSM and commercial sex workers
PRIMARY: indurated, painless ulcer (chancre)
SECONDARY (6-8wks later): chancre disappears, fever, rash, lymphadenopathy, mucosal lesions
LATENT: asymptomatic (years)
TERTIARY:
- neurosyphilis (tabes dorsalis/syphilitic myelopathy = slow demyelination of nerves in dorsal columns of spinal cord, chronic meningoencephalitis —> cerebral atrophy —> general paresis/paralytic dementia)
- cardiovascular syphilis (myocarditis, coronary stenosis, aortic aneurysm, aortitis, aortic insufficiency)
- gummas (soft, non-cancerous growth which causes local destruction)
CONGENITAL
Diagnosis: cannot be grown!
- dark-field microscopy
- serology: initial screening with EIA antibody test, positive result leads to rapid plasma reagin titre (non-specific; cross-reaching antigen) & TP particle agglutination (specific)
Treatment: penicillin + refer to GUM/infectious diseases
Give some examples of less common tropical STIs which can cause inguinal lymphadenopathy.
Lymphogranuloma venereum =
- C. trachomatis L1, L2, L3
- usually MSM
- rapidly healing papule —> inguinal bubo
Chancroid =
- Haemophilus ducreyi
- painful genital ulcer (differentiates from chancre)
Granuloma inguinale =
- Klebsiella granulomatis
- genital nodules —> ulcers
What is trichomonas vaginalis? How is it diagnosed and treated?
Trichomonas vaginalis = flagellated protozoan —> trichomonas vaginitis
Predominantly sexually transmitted
S&S:
- thin, frothy, offensive discharge
- irritation
- dysuria
- vaginal inflammation
Diagnosis = vaginal wet preparation +/- culture enhancement
Treatment = metronidazole (anaerobes & some protozoa)
What is vulvovaginal candidiasis? How is it diagnosed and treated?
Thrush = Candida albicans + other Candida spp.
- sexually transmitted, nappy rash, opportunistic
- risk factors: antibiotics, oral contraceptive pill, pregnancy, obesity, steroids, diabetes
S&S: profuse, white, itchy, curd-like discharge
Diagnosis: high vaginal smear +/- culture
Treatment:
- topical azoles
- nystatin
- oral fluconazole
What are the most common causes of vaginal discharge?
Trichomonas vaginalis
Vulvovaginal candidiasis
Bacterial vaginosis
note: as treatment is the same, often little point in specific investigations
