STIs Flashcards
Chlamydia- features
Most common STI in UK. C. trachomatis is a gram neg obligate intracellular bacteria with incubation 7-21 days. Often asymptomatic.
F- discharge, bleeding, dysuria.
M- urethral discharge, dysuria.
Partner tracing- men with symptoms, partners since 4 weeks prior to onset. Men without symptoms and all women- from last 6 months.
Chlamydia- treatment
1st line- doxycycline for 7 days (also covers mycoplasma genitalium).
2nd line- Azithromycin 1g once then 500mg for 2d. Used if pregnancy, or doxycycline contraindicated.
Gonorrhoea- features
Neisseria gonorrhoea, gram neg diplococcus, incubation 2-5 days. Often asymptomatic,
F- discharge, bleeding, dysuria, abdominal pain
M- urethral discharge, dysuria.
Gonorrhoea- treatment
Ceftriaxone 1g IM.
If needle phobic - oral cefixime and oral azithromycin.
Gonorrhoea- complications
Disseminated gonococcal infection and gonococcal arthritis. Most common cause of septic arthritis in young people.
As with any STI: epididymo-orchitis, PID, pregnancy complications etc
Trichomoniasis- features
Most common worldwide. Motile flagellated protozoan.
F- yellow/green offensive discharge. Itching. Strawberry cervix due to multiple small haemorrhages. Vaginal pH > 4.5.
Trichomoniasis- treatment
1st line- Metronidazole for 5-7 days
HPV types 6 + 11
Cause genital warts. Painless, benign, epithelial tumours. 1/3 resolve but can reoccur.
Treat with topical podophyllum, 2nd line imiquimod.
Herpes (HSV)
HSV1 causes oral cold sores. HSV2 causes genital herpes. Primary infection ascends peripheral sensory nerves and establishes latency in dorsal root ganglion.
Symptoms- painful shallow ulcers on genitals. Cold sores and gingivostomatitis in the mouth.
Treatment- Aciclovir.
Syphilis- features
Treponema pallidum. Mobile spiral bacteria.
Primary- painless ulcer/chancre. Local non tender lymphadenopathy.
Secondary- widespread maculopapular rash, buccal snail trail ulcers, lymphadenopathy, fever, fatigue.
Tertiary- complications such as neurosyphilis, CV syphilis (aortitis, AAA), gummatous syphilis (lesions on the skin and bones).
Syphilis- investigations and treatment
Treponemal specific serology- remains positive for life.
Cardiolipin serology- positive in active disease, insensitive in late stage.
Treatment: Benzylpenicillin IM (2.4 million units)
Jarisch-Herxheimer Reaction- fever, rash, tachycardia, no wheeze or hypotension. Due to release of endotoxins from bacterial death. Occurs within a few hours. No treatment required.
HIV- features
RNA retrovirus. Contains 2 RNA strands, protein capsid p24, viral enzymes, reverse transcriptase, integrase and HIV protease. Allows replication after host cell entry and integration. Infects CD4 T cells, macrophages, dendritic cells. gp120 binds to CD4.
Immunological changes: declining CD4 count, decline in natural killer cell function, decreased IL2 production and polyclonal B cell activation.
HIV-symptoms, tests and treatment
3-12 weeks post infection: sore throat, lymphadenopathy, myalgia, malaise, arthralgia, diarrhoea, rash, mouth ulcers.
Antibodies may not yet be present. Do HIV PCR and p24 antigen tests 4 weeks post exposure. Then again at 12 weeks.
HIV antibody test- 99% accurate by 3 months.
Antiviral therapy. 2 nucleoside reverse transcriptase inhibitors + protease inhibitor/non-nucleoside RTI. Start on diagnosis.
HIV infections at CD4 500-200.
Oral thrush, candida.
Shingles.
Hairy leucoplakia 2nd to EBV infection
Kaposi sarcoma 2nd to HHV-8
HIV infections at CD4 200-100
Pneumocystis pneumonia Multifocal leukoencephalopathy Cerebral toxoplasmosis Cryptosporidiosis HIV dementia
