IC18 STI Flashcards
mode of transmission for STI
- spread by sexual contact with an infected person
- by direct contact of broken skin with open sores, blood or genital discharge
- receiving contaminated blood
- from infected mother to child during
- pregnancy (syphilis, HIV)
- childbirth (chlamydia, gonorrhea, HSV)
- breastfeeding (HIV)
RF for STI
- unprotected sex
- multiple sex partners
- sexual contact with people who have multiple sexual partners
- men sex with men
- prostitution (commercial sex worker)
- illicit drug use (sharing needles, unsafe act when drunk)
List pharmacological and non-pharmacological (lifestyle modification) advice for prevention of STIs
- abstinence and reduce no. of sexual partners
- barrier contraceptive methods
- avoid drug abuse and sharing needles
- pre-exposire vaccination (HPV, Hep B)
- Pre and post exposure propylaxis
why is prevention of STI important?
- reduce morbidity, progression to complicated disease
- prevent HIV infection (pt with STD should check for HIV)
- prevent serious complications in women (infertility, cervical cancer)
- protect the babies
gonorrhoea (pathogen, transmission)
Neisseria gonorrhoea (gram -‘ve diplococci)
transmission via
- sexual contact
- mother to child during birth
gonorrhoea (diagnosis, site of infection)
dx:
1. gram stain of genital discharge
2. culture
3. NAAT (nucleic acid amplification test)
sites if infection: urethritis, cervicitis, proctitis (rectal area), pharyngitis, conjunctivitis, disseminated
gonorrhoea: presentation
- can be asymptomatic
(males) - purulent urethral discharge, dysuria, urinary frequency
(females) - mucopurulent vaginal discharge, dysuria, urinary frequency
Management of uncomplicated gonococcal infections
(which abx cannot be used?)
- resistant to ciprofloxacin (fluroquinlones not recommended)
- treat tgt for chlamydia therapy (ie doxycycline) unless chlamydia infection excluded
Ceftriaxone 500mg IM single dose (<150kg)
+ doxycyline 100mg BD x7days (chlamydia)
Alternatives:
Gentamicin 240mg IM single dose
+ Azithromycin 2g PO single dose
+ doxycyline 100mg BD x7days
Gonorrhoea: management of sex partners
- sex partners in last 60 days: evaluated and treated
- sex partners >60 days (most recent partner to be treated)
- minimised disease transmission (pt to abstain from sex for 7 days after treatment & resolution of sx)
- abstain from sex until all sex partners have been treated
Chlamydia: pathogens, presentation, diagnosis, sites of infection, transmission
Bacteria: Chlamydia trachomatis
Presentation: similar to gonorrhoea (milder)
Diagnosis: NAAT
Sites of infection: same as gonorrhoea
Transmission: same as gonorrhoea (sexual contact, mother to child during childbirth)
Management of chlamydia (abx used)
PO doxycyline 100mg BD x7 days
alternatives:
PO azithromycin 1g single dose OR
PO levofloxacin 500mg OD x7d
- use azithromycin if adherence issue
- no test of cure needed tx highly effective)
Chlamydia: management of sexual partners
- sex partners in last 60 days: evaluated and treated
- sex partners >60 days (most recent partner to be treated)
- minimised disease transmission (pt to abstain from sex for 7 days after single dose tx or completion of 7 day regimen & resolution of sx)
- abstain from sex until all sex partners have been treated
Syphilis: pathogen, transmission
pathogen: Treponema pallidum (bacteria)
transmission: sexual contact, mother to child (transplacental during pregnancy)
Syphilis: clinical presentation
painless sore on the genital, anus, or mouth
sore heals by itself without treatment but rashes will appear on face, palms, and soles
Syphilis: diagnosis
darkfield microscopy of exudates from lesions
requires 2 serological tests - treponemal and non-treponemal tests
How does treponemal tests work? What is it useful for?
Using treponemal antigen to detect treponemal antibody
Used as confirmatory tests, not for monitoring of response to treatment (as positive antibody does not necessarily indicate active infection)
How does non-treponemal test works? What is it useful for?
Using nontreponemal antigen to detect treponemal antibodies
Used to monitor response to treatment
eg. VDLR/RPR where results are reported in quantitative antibody titres (lower titre = lower antibody = lower disease activity)
VDLR and RPR is NOT interchangeable
Syphilis treatment
Primary, secondary, early latent (< 1 yr):
IM Benzathine Pen G 2.4 MU ONCE (if pen allergy: doxycycline 100mg BD x 14 days)
Late latent (> 1yr), tertiary:
IM Benzathine Pen G 2.4 MU once per week x 3 doses (if pen allergy: doxycycline 100mg BD x 28 days)
Neurosyphilis:
IV Crystalline Pen G 3-4 MU Q4H or 18-24 MU daily as continuous infusion x 10-14 days
OR
[IM Procaine Pen G 2.4 MU once daily + PO Probenecid 500mg QDS] x 10-14 days
(if pen allergy: IM/IV ceftriaxone 2g once daily x 10-14 days)
What constitutes treatment failure in syphilis?
At 6 months:
- shows signs and symptoms of disease
OR
- failure to decrease VDRL or RPR titre by fourfold
Next step: Retreat and re-evaluate for unrecognised neurosyphilis
What do you need to monitor for syphilis treatment?
Safety:
- Jarisch-Herxheimer reaction: acute febrile reaction that occurs within the first 24 hours of any syphilis therapy
Efficacy:
- decrease of VDRL or RPR titre by at least 4-fold (at 3, 6, 12, 18, 24 months)
- For neurosyphilis, CSF examination every 6 months until normalization
Syphilis management of sexual partners
- All at risk sexual partners should be evaluated and treated if tested positive
- Abstain from sexual contact with new partners until lesions completely healed (check with Dr if fully treated)
Genital herpes: pathogen, transmission
HSV-1 and HSV-2 (most common)
Transmission by transfer of body fluids and skin-to-skin contact
Genital herpes: clinical presentation
- Painful small blisters which break down to form ulcers in the genital or anal region (develop over 7-10 days, heal in 2-4 weeks)
- Local itching, pain, swelling of groin lymph nodes
- Flu-like symptoms first few days after appearance of lesions
- Prodromal symptoms prior to appearance of recurrent lesions
- First infection usually more severe
- Chronic and life-long
- Can still be transmitted when asymptomatic (intermittent viral shedding)
Stages of HSV infection
mucocutaneous, nerve ganglia, latency, reactivation, outbreak
Diagnosis of genital herpes
- Patient history
- Presentation/symptoms
- Virologic tests: viral cell culture and NAAT/PCR for HSV DNA
- HSV-2 serologic tests: presence of antibodies to HSV, usually 6-8 weeks after first episode
Principles of antiviral treatment for genital herpes
- maximum benefit when initiated within 72 hours of disease
- topical antiviral is discouraged (minimal clinical benefit)
- to prevent latency or reduce frequency and severity of recurrent disease, drug needs to be taken continuously
Benefits of oral acyclovir and valacyclovir
- Reduce viral shedding by 7 days
- Reduce duration of symptoms by 2 days
- Reduce time to healing of 1st episode by 4 days
Genital herpes: treatment (first episode)
Acyclovir PO 400mg TDS x 7-10 days
OR in severely ill patients eg. immunocompromised,
IV acyclovir 5-10mg/kg Q8H x 2-7 days, then complete with PO for a total of 10 days
PO Valacyclovir 1g BD x 7-10 days
*If use IV, need to maintain hydration to prevent crystallization in renal tubules
*Treatment can be extended if healing is incomplete after 10 days
Genital herpes: treatment (subsequent episodes)
Chronic suppressive therapy:
PO Acyclovir 400mg BD
PO Valacyclovir 500mg OD (may not be effective in those with ≥ 10 outbreaks per year)
PO Valacyclovir 1g OD
Episodic therapy:
PO Acyclovir 800mg TDS x 2 days
PO Acyclovir 800mg BD x 5 days
PO Valacyclovir 500mg BD x 3 days
PO Valacyclovir 1g OD x 5 days
PO Acyclovir 400mg TDS x 5 days (may have adherence issues)
Pros and cons of chronic suppresive therapy for genital herpes
Pros:
Reduce frequency of recurrences
Improved symptoms
Decreased risk of transmission
Established long term safety and efficacy
Cons:
Cost
Adherence
Pros and cons of episodic therapy for genital herpes
Pros:
Better than not using any treatment
Cost
Adherence
Cons:
Does not reduce risk of transmission (due to intermittent viral shedding)
Need to take within 1 day of lesion appearance or prodomal symptoms
Management of sex partners for genital herpes
- Symptomatic sex partners should be evaluated and treated
- Asymptomatic sex partners should be questioned on history of genital lesions, encourage to examine themselves for lesions, and seek medical attention if needed. May be offered serologic test for HSV-2.
