STIs Flashcards
To be able to list common presentations, investigations and treatment options for common STIs in the UK
What causes bacterial vaginosis?
This is caused by an imbalance in the bacteria within the vagina (due to increased lactate production)
What signs can show bacterial vaginosis?
Positive KOH ‘whiff test’ - fishy odour on discharge Discharge may have bubbles, homogenous Increase in vaginal pH
What would a wet mount show?
Wet mount is when a sample of vaginal discharge is inspected under the microscope. There will likely be ‘CLUE CELLS’ - these are cells with a coccobaccilli coating (may make them look blurred) Lack of leucocytes - if there are some then think co-existent infection
Is bacterial vaginosis an STI?
no - so does not require treatment of partner
What can be complications of BV?
pelvic pain, upper reproductive organ inflammation, premature rupture of membranes, miscarriage, can increase risk of HIV
How is bacterial vaginosis treated?
Oral metronidazole for 7 days
What is the organism causing chlamydia? (give types)
chlamydia trachomatis (gram -ve)
A-C - affect eyes
D-K - affect genitals
L1-L3 = lymphgranuloma venereum (affects the lymph nodes)
What is the most common bacterial STI in the UK?
Chlamydia
How will chlamydia present?
70% of females and 50% of males are asymptomatic
Females: white mucopurulent cervicitis, intermenstrual/post-coital bleeding, dysparenuria (painful sex) and lower abdominal pain
Males: urethral discharge, urethritis, proctitis
What are complications of chlamydia?
PID - pelvic inflammatory disease
(if left untreated then a complication called Fitz-Hugh-Curtis syndrome can develop - this is when there is inflammation of the liver capsule and adhesions form)
Cervicitis, endometritis, saphlingitis Can cause tubal damage (leading to infertilify and ectopic pregnancy) Reactive arthritis Congenital (pass to baby during delivery - born with conjunctivitis)
How is chlamydia diagnosed?
HVS or VV swab (self-obtained) or first pass urine +/- rectal swab MUST BE DONE 14 DAYS AFTER POSSIBLE INOCULATION
How would lymphogranuloma venereum present?
PR bleeding, proctitis, abdominal pain, lymphadenopathy, rectal discharge
How is chlamydia treated?
Azithromycin (1g dose) OR Doxycycline for 7 days (100mg BD)
What is a fungal infection that can affect the genitals?
Candida infection (most commonly C.albicans)
How will C.albicans look on microscopy?
Will have budding fungal cells with hyphae extensions
How will candida infection present?
Present with increasing itch and change to discharge in females Males will have a spotty rash
How is candida diagnosed?
Mainly a clinical diagnosis but can also be swabbed if necessary
How is candida treated?
Clotrimazole cream or Fluconazole oral (look for AZOLE in the name and think fungal treatment)
What are some risk factors for developing candida infection?
Poorly controlled diabetes, immunocompromised patients, recent antibiotic therapy (allows for opportunistic infection) and high oestrogen levels (pill or pregnancy)
What organism causes gonorrhoea?
Neisseria gonorrhoea (gram negative diplococci)
How is gonorrhoea likely to be seen on gram film stain?
intracellularly as it is easily phagocytosed
What is the incubation period for Gonorrhoea?
2-5 days
How may someone present with gonorrhoea?
Females: pelvic pain, change to dicharge, dysuria
Males: purulent discharge and dysuria
What are coplications of gonorrhoea infection if untreated?
PID
tubal damage (infertility and ectopic)
miscarriage
passing to baby - conjunctivitis on delivery
proctitis
painful injection into testes
Where can both gonorrhoea and chlamydia infect?
Eyes, throat, rectum, urethra, endocervix
How do you treat gonorrhoea?
ceftriaxone (IM) and an antibiotic e.g. azithromicin (single dose no longer recommended)
(test of cure is recommended)
How is gonorrhoea diagnosed?
can be diagnosed via culture (endocervical swab or urethral swabs) - this will allow you to test against ABs to find appropriate treatment. Has 90% specificity for males but less for females (endocervical swab is also more invasive)
Can also be diagnosed via NAAT (urine or self-obtained vaginal swabs) - has higher sensitivity but cannot test against ABs
Describe the organism that causes syphilis
this is a spirochete shaped organism called Trepenoma Pallidum. It does not stain on gram stain so requires PCR, microscopy or serology for diagnosis.
It is transmitted through sexual contact, blood transfusion, trans-placental or can be contracted in health work
What are the stages of syphilis infection?
- Primary (chancre) - there will be a primary lesion at the site of infection called the chancre, may be asymptomatic
- Secondary - this occurs a few weeks after initial infection and may have symptoms of generalised flu, lymphadenopathy, snail trail ulcers, patchy alopecia, condylomata lata (genital warts)
- Latent - infection lays dormant and can reactivate - may self-cure at this point
- Late - coplications in the nervous system e.g. meningitis, stroke or dementia
Which is the most infective stage of syphilis infection?
Secondary - lesions will be oozing with t.pallidum
How is diagnosis of syphilis made?
Dark ground microscopy - look for spirochetes
PCR
Specific and non-specific serological testing
Describe indications for specific and non-specific serological tests?
Specific - to confirm diagnosis (include TPPA and TPHA)
Non-specific - to assess response to treatment (RPR)
ELISA IgM and IgG for screening tests
How is Syphilis treated?
penicillin (need this for a long time so can get long acting injectable preparations but need to be cautious of resistance)
How do you measure response to penicillin treatment in syphilis?
Measure the RPR (serological test)
should decrease 4 fold in 3-6 months
if reactivation of infection then will increase by 4 fold
What is genital herpes caused by?
Caused by the HSV1 (also causes cold sores) or HSV2 virus.
What are the symptoms of genital herpes? why?
Small very painful vesicles in the epithelium of genitals - this is because the virus will extend down autonomic sensory nerves to the surface, cause irritation and inflammation (why they are very painful)
Why can genital herpes reactivate?
As it will lay dormant in the sacral root ganglion - more likely in HSV2 than HSV1
What is key information about HSV2?
It will cause a more mild form of the disease (shorter duration - 5-7 days rather than 14-21 days) with less painful vesicles but it is more likely to reactivate
How do you treat genital herpes?
Aciclovir +/- lidocaine for pain relief
What is trichomonas vaginalis?
this is a single-celled protozoan parasite that will devide by binary fission
How is trichomonas vaginalis diagnosed and treated?
HVS for microscopy (will have symptoms of irritation and change to vaginal discharge/urethritis)
oral metronidazole
What is the presentation of pubic lice?
Will have increased itch in the pubic area - lice will bite and drink blood (causing irritation) and will lay eggs at the base of hair follicles
How do you treat pubic lice?
malathion lotion
What is the most common viral infection in the UK?
HPV
Give examples of the main low and high risk forms of HPV?
low = 6, 11
high = 16, 18
What can HPV infection cause?
anogenital warts, palmar/plantar warts, cellular dysplasia, endothelial neoplasm
What is the incubation period for HPV infection?
anywhere between 3 weeks and 9 months
>90% of anogenital warts are caused by….
HPV 6,11
What are the clearance rates of HPV?
34% will clear spontaneously
60% will clear with treatment
20% will have persistent infection
How do you treat HPV related warts?
podophyllotoxin (wartcon) or imiquimod or cryotherapy
If a male <35 presents with prostitis what should you inspect for?
STI screen - prostitis is a rare complication of untreated STIs
What causes HIV and what is targetted?
Human immunodeficiency virus targets CD4 protein which is primarily expressed on CD4+ helper T cells (although will also be present on macrophages, dendritic cells and microglia)
What caused the global HIV pandemic?
HIV2
If CD4 proteins are targetted by HIV what is the downstream effect?
CD4 proteins become inactive/dysfunctional so there is decreased activation of the helper T-cells. These are required in the activation of CD8 cytotoxic T-cells and will lead to impaired cytokine release and lack of adaptive immune response.
What is the immune system like in HIV?
it is in a constant state of activation but will have impaired adaptive response. It will also be more susceptible to viral infections due to the reduction in activation of cytotoxic t-cells
What are normal levels of CD4 t-cells and what is an abnormal level?
500-1600 cells/mm3
<200 will leave a person open to opportunistic infection
When are viral replications of HIV at their highest?
in very early and very late stages of the disease
Initial infection occurs and viral load is high, then there will be a period of clinical latency where the CD4 t-cell count will grandually decrease. When the CD4 levels become <200 this allows for opportunistic infection and the HIV viral load to rocket.
What is the first destination of HIV virus and where will it go?
HIV will enter the body through mucosal lymphoid tissue (attached to langerhans and dendritic cells). it will then be carried to the lymph nodes and within 3 days there will be widespread disseminated disease.
When will symptoms set in and what symptoms will present?
2-4 weeks after initial infection
Fever, myalgia, rash (maculopapular), pharyngitis
very high rate of transmission
What is an opportunistic infection?
An infection that would not normally illicit an infection
Give example of some opportunistic infections experienced in late-stage HIV.
Pneumocystic pneumonia caused by pneumocystis jiroveci
TB
CMV
cerebral toxoplasmosis
neurological impairment (more common in HIV1)
What is ‘slim’s disease’?
This is wasting associated with HIV and is due to a number of processes e.g. increased metabolism, malabsorption, anorexia (due to infection) and hypogonadism
Give example of 3 AIDs related cancers
Kaposi’s sarcoma
Non-hodgkin’s lymphoma
Cervical cancer
What is Kaposi’s sarcoma?
This is cancer of the skin and internal organs caused by human herpes virus 8 (HHV-8)
Only affects HIV, immunocompromised or those with genetic predisposition
Small painles lesions purple in colour on the skin or mucosal surfaces
Symptoms of internal organs (SOB, chest pain, lymphoedema, nausea etc)
What is non-hodgkin’s lymphoma?
this is a cancer of the lymphocytes that is caused mainly by EBV. There will be painless swelling of lymph nodes in the neck, groin and armpits. also night sweats, SOB, weight loss, itching of skin, bleeding problems
What is required for diagnosis of Non-hodgkin’s lymphoma?
Biopsy of lymph node, Blood, CT/MRI
PET and lumbar puncture may be indicated
How is non-hodkin’s lymphoma (associated with HIV treated?)
Chemo +/- biological (rituximab) and HAART
Why does cerival cancer increase in prevalence in HIV?
persistent HPV infection
What are the modes of transmission for HIV?
Sexual (96%) - anoreceptive, ulceration, trauma or concurrent STIs will increase chance of contraction
Parenternal - shared needles, blood products
Mother to child - in-utero or through delivery or breast milk, 1 in 4 will contract and 33% of these will die before first birthday
When is screening appropriate?
In high risk populations (MSM, TOP clinics, drug dependent)
Areas of high prevalence
Clinical symptoms suggest
Explain the life cycle of HIV virus
- attaches onto the CD4 receptor of host cell
- Release RNA into host cell which is then transcripted by reverse transcriptase into DNA
- integrates into host cell DNA by integrase
- Host cell now makes the viral proteins, these can be cleaved (into virians) and pass into other cells to infect further
Which step gives HIV a survival advantage?
Transcription by reverse transcriptase as there is no modulation of mistakes (proof reading) so these mistakes can sometimes give a survival advantage
What are some targets of HIV treatment?
Reverse transcriptase (NRTI or NNRTI)
Integrase (inhibitors)
Proteases (inhibitors)
Entry (CCr5 receptor on cell - prevents HIV from binding to the cell) (inhibitors)
What is HAART?
Highly active anti-retroviral treatment - this is a combination of 3 medications from at least 2 different drug classes. This is to try avoid resistance.
Which is the most potent class of HIV drug?
protease inhibitors - have more side effects (mainly GI)
What is imperitive to HIV treatment?
COMPLIANCE - as soon as there are missed pills then there is opportunity to build up resistance
If you know someone will not be compliant then put on a protease inhibitor as these are the least likely to cause resistance.
What can increase compliance?
formulations of drugs into one tablet
What can be used when had sex with an HIV positive person NOT being treated?
When would this be ineffective?
PEP - post-exposure prophylaxis
Ineffective after 72 hrs (like the morning after pill but for HIV)
What is the rate of transmission if on treatment?
If undetectable viral load then virtually zero
How is pregnancy and conception affected by HIV treatment?
Without treatment risk of transmission to child is 1 in 4, with treatment then risk of transmission is less than 1 in 100 . (<1%)
Some HIV drugs can be teratogenic so need to have medication review before conceiving
What is given to neonates of HIV positive mothers?
Post-exposure prophylaxis for 4 weeks after birth
if mum has detectable viral load then 3 drugs
if mum has undetectable viral load then 1 drug
What can be done to prevent infections in HIV positive patients apart from HAART?
STI screening
Smoking cessation
Vaccine (hep, hpv, flu etc)
Encourage smoking of drugs over injection (prevents sharing of needles)
How long can an HIV virus lay latent for?
around 8 years
