STD Flashcards
Definition of STI
STI is an infection caused by bacteria, viruses, fungi and protozoa, which can be transmitted through sexual intercourse or close body contact with another person that is infected with STI
aka STI or VD (venereal disease)
STI caused by bacteria
- Gonorrhoeae (Neisseria gonorrhoeae)
- Chlamydia (Chlamydia trachomatis) (non-gonorrhoeae urethritis)
- Syphillis (Treponema pallidum)
STI caused by viruses
- Ano-genital warts (HPV)
- Ano-genital herpes (HSV)
- AIDS/HIV
- Molluscum contagiosum
- Viral hepatitis (hep A/B/C)
STI caused by fungi
- Vagina candidiasis
STI caused by protozoa (parasites)
- Scabies
2. Pediculosis pubis
Legally notifiable STI
- notify within 72h of diagnosis
- for monitoring and evaluation of national control
- all STI EXCEPT HIV are not for contact tracing purposes
- only req demographic data (age, gender, nationality, ethnicity)
- partner notification in HIV/AIDS is mandatory
Mode of transmission of HIV
- sexual contact mainly
- direct contact of broken skin with open sores, blood or genital discharges
- contaminated blood
- infected mother to child (through placenta during pregnancy, child birth and breastfeeding)
Risk factors of STI
- unprotected sex
- number of sexual partner
- MSM
- CSW
- illicit drug use
Individual prevention methods
- barrier contraceptive methods
- abstinence and reduce sexual partners (long-term, mutually monogamous relationship)
- avoid drug abuse and sharing needles
- pre-exposure to vaccines (HPV, hepA and hepB)
- pre and post prophylaxis (HIV)
Importance of managing and prevention of STD
- protect the babies
- reduce related morbidities and progression to complicated diseases
- prevent HIV infection
- prevent serious complications in women (eg infertility)
Gonorrhoeae pathogen
- bacteria
- Neisseria gonorrhoeae
- intercellular gram-ve, diplococci
Transmission of Gonorrhoeae
Sexual contact and mother-child during child birth
Diagnosis of Gonorrhoeae
- gram staining of genital discharge
- bacterial culture
- NAAT (PCR)
Infection site of Gonorrhoeae
- urethritis
- proctitis (rectal)
- cervititis
- pharyngitis
- conjunctivitis
- disseminated (throughout systemic circulation)
Symptoms of Gonorrhoeae
- urinary frequency
- dysuria
- purulent genital discharge
can be asymptomatic
Complications of Gonorrhoeae
Males : - prostatitis - epididymitis - urethral stricture - disseminated disease Females : - pelvic inflammatory disease - ectopic pregnancy - infertility - disseminated disease Both (disseminated) : - skin lesions - tenosynovitis - monoarticular arthritis
Treatment for Gonorrhoeae
1st line :
IM Ceftriaxone 500mg single dose (if <150kg), PO Doxycycline 100mg BD x 7 days (unless Chlamydia infection is excluded)
Alternatives :
- IM Gentamicin 240mg single dose + PO Azithromycin 2g single dose
- PO Cefixime 800mg single dose, PO Doxycycline 100mg BD x 7 days (unless Chlamydia infection is excluded)
Management of sex partners (Gonorrhoeae)
- evaluation and treatment for sex partners in the last 60 days or the last sex partner if more than 60 days
- abstain from sexual activity for 7 days after treatment and resolution of symptoms
- abstain from sexual intercourse until all sex partners have been treated to minimise risk of re-infection
Chlamydia pathogen
- bacteria
- Chlamydia trachomatis
Transmission of Chlamydia
Sexual contact and mother-child during child birth
Diagnosis of Chlamydia
- antigen detection
- NAAT
Symptoms of Chlamydia
- urinary frequency
- dysuria
- purulent genital discharge
can be asymptomatic
Treatment for Chlamydia
1st line : PO Doxycycline 100mg BD x 7 days Alternatives : PO Azithromycin 1g single dose PO Levofloxacin 500mg OD x 7 days
Management of sex partners (Chlamydia)
- evaluation and treatment for sex partners in the last 60 days or the last sex partner if more than 60 days
- abstain from sexual activity for 7 days after single dose treatment or until end of 7 day dosing regimen and resolution of symptoms
- abstain from sexual intercourse until all sex partners have been treated to minimise risk of re-infection
Syphilis pathogen
- bacteria
- Treponema pallidum
- spirochete
Diagnosis of Syphillis
- darkfield microscopy
- 2 serological test for antibodies (treponemal & non-treponemal)
Stages of Syphillis (5)
- Primary (external genitalia, perianal region, mouth and throat)
- Secondary (multisystem - lymphadenopathy, and hematogenous spread)
- Latent (asymptomatic)
- Tertiary (multisystem - heart, eyes, bones, joints)
- Neusyphillis (any stage also can)
2 serological tests for Syphillis
- Treponemal test
- TPHA, TPPA
- use treponema antigen to detect treponema antibodies
- confirmatory tests
- remains reactive for life, hence not useful for monitoring - Non-treponemal test
- VDRL (venereal disease research laboratory) , RPR (rapid plasma region)
- use non-treponema antigen (cardiolipin) to detect treponema antibodies
- reports most diluted serum concentration with a positive reaction
- antibodies titres correlates with disease activity
- VDRL and RPR are not inter-changeable, if use VDRL, use VDRL throughout monitoring
- less specific hence used as a screening tool
Treatment for Syphillis
Primary, secondary and latent stage :
- IM Benzathine Pen G 2.4 MU single dose
- PO Doxycycline 100mg BD x 14 days
Late latent and tertiary stage :
- IM Benzathine Pen G 2.4 MU once weekly x 3 doses
- PO Doxycycline 100mg BD x 28 days
Neurosyphillis :
- IV Crystalline Pen G 3-4 MU q4h x 10-14 days
- IV Crystalline Pen G 18-24/day MU infusion x 10-14 days
- IM Procaine Pen G 2.4 MU OD + PO Probenecid 500mg QDS/QID x 10-14 days
- IV/IM Ceftriaxone 2g OD x 10-14 days
Monitoring of Syphillis treatment
- Jarisch-Herxheimer reaction (fever, myalgia) within 24h of treatment
- Treatment success if at least 4 fold decrease in VDRL/RPR tire at 6 months w/o signs or symptoms
primary and secondary : 6 and 12 month
latent and tertiary : 6, 12 and 24 months
neurosyphillis : every 6 months until CSF normal
Management of sex partners (syphillis)
- evaluation and treatment for sex partners
- abstain from sexual activity for 7 days after single dose treatment or until end of 7 day dosing regimen and resolution of symptoms
Human Herpes Virus
- double stranded DNA
- enveloped
- latent stage present
Types of Human Herpes Viruses
- HSV 1 (cold sores)
- HSV 2 (genital herpes)
- VZV (chicken pox and shingles)
Treatment for varicella / shingles
Within 24-48h
1. PO Acyclovir 800mg 5 times a day x 7 days
2 PO Valacyclovir 1g TDS x 7 days
Prevention of varicella and shingles
Vaccination
Are varicella and shingles STI?
No
Genital herpes pathogens
HSV 2 > HSV 1
Symptoms of varicella
- fever starts 1-2 days before rash appears and lasts 4-5 days, abates once all rash have appeared
- new lesions appear over 4-7 days
Symptoms of shingles
- new lesions appear over 3-5 days
- dries with crusting in 7-10 days
- rash is preceded by tingling/itching/pain for 2-3 days
- post-herpetic neuralgia in 10-50% of patients, may persists for many months or years
Symptoms of genital herpes
- vesicles develop over 7-10 days and heal in 2-4 weeks
- asymptomatic viral shedding possible
Stages of genital herpes
- Mucocutaneous infection
- Nerve ganglia infection
- Latency
- Reactivation
- Recurrent flares
Transmission of genital herpes
- Transfer of body fluids
- Intimate skin-skin contact
- Asymptomatic transmission via viral shedding
Natural history of genital herpes
It is a chronic and life-long disease
Symptoms of genital herpes
- classical painful multiple vesicular or ulcerative lesions
- local itching, pain, tender inguinal lymphadenopathy
- flu-like symptoms first few days of lesion appearance (fever, headache, malaise)
- prodromal symptoms in 50% of patients before appearance of lesions (mild burning, itching or tingling)
- symptoms are less severe in recurrent disease
Diagnosis of genital herpes
- Virologic tests (viral cell culture and NAAT/PCR)
2. Type specific serologic tests (takes 6-8 weeks for serological detection)
Supportive care for genital herpes
- warm saline bath relieves discomfort
- good genital hygiene to prevent superinfection
- counselling regarding natural history of genital herpes (cannot be cured)
Treatment for genital herpes (Initial episode)
maximum benefit if within 72h
1. PO Acyclovir 400mg TDS x 7-10 days
2. IV Acyclovir 5-10mg/kg q8h x 7-10 days (severe disease or complications req hospitalisation)
3. PO Valacyclovir 1g BD x 7-10 days
treatment can be extended if healing is incomplete after 10 days
Counselling for Acyclovir / Valacyclovir
- headache
- hydration to prevent crystallisation in renal tubules
Treatment for recurrent genital herpes (chronic suppressive therapy)
- PO Acyclovir 400mg BD
- PO Valacyclovir 1g OD
- PO Valacyclovir 500mg OD (if <10 flares/year)
Treatment for recurrent genital herpes (episodic treatment)
- PO Acyclovir 800mg TDS x 2 days
- PO Acyclovir 800mg BD x 5 days
- PO Valacyclovir 1g OD x 5 days
- PO Valacyclovir 500mg BD x 3 days
Counselling for genital herpes
- reduce risk of HSV transmission by chronic suppressive therapy and correct use of latex condoms
- increased risk of HIV infection
Management of sex partner (genital herpes)
- symptomatic sex partner should be evaluated and treated in the same manner
- asymptomatic sex partners should be questioned concerning histories of genital herpes and type-specific serological testing for HSV2
