STD Flashcards
definition of STD
infection causewd by bacteria, virus, fungi or protozoa, which can be transmitted through sexual intercourse or close body contact with another infected person
bacterial causes of STI
- syphilis - treponema pallidum
- gonorrhoea - neisseria gonorrhoeae
- non-gonococcal urethritis- chalmydia trachomatis, ureaplasma urealyticum; mycoplasma genitalium
- chancroid- haemophilus ducreyi
- lymphogranuloma venereum (LGV) - chlamydia trachomatis
- granuloma inguinale - calymmatobacteria granulomatis
viral causes of STI
- ano-genital herpes - herpes simplex virus (HSV) type 1&2
- ano-genital warts- HPV
- viral hepatitis- Hep ABC
- AIDS/HIV- human immunodeficiency virus type 1&2
- Molluscum contagiosum- molluscum contagiosum virus
fungi causing STI
- vaginal candidiasis- candida albicans
note: not all due to sex
STI caused by parasites
- scabies- sarcoptes scabiei
2. pediculosis pubis- phthirus pubis
mode of transmission
- sex w infected person
- direct contact of broken skin with open sores, blood or genital discharge
- receiving contaminated blood
- mother to child transmission pregnancy (eg. syphilis, HIV) or childbirth (eg. chlamydia, gonorrhea, HSV) or breastfeeding (eg. HIV)
types of mother to child transmission
- placenta (syphilis, HIV)
- childbirth (chlamydia, gonorrhea, HSV)
- breast milk (HIV)
risk factors of STD
- unprotected sex
- number of sexual partner
- MSM
- prostitution (CSW)
- Illicit drug use
individual prevention methods
- abstinence and reduce sex partners
- barrier contraceptives (condoms lol)
- avoid drug abus and sharing needle (sheEEEesh)
- pre-exposure vaccinationas (HPV, Hep B or A)
- pre & post- exposure prophylaxis (HIV)
why management and prevent of STD is important
- reduce related morbidity, progression to complicated disease
- prevent HIV infection
- prevent serious complications in women
- STI are main preventable cause of infertility
- prevention of HPV reduced cervical cancer - protect babies (untreated STI associated with congenital and perinatal infections in neonates, premature deliveries and neonatal death or stillbirth)
what is gonorrhoea caused by
bacteria- Neisseria gonorrhoea (intracellular gram-neg diplococci)
how is gonorrhoea transmitted by
sexual contact, mother to child (childbirth)
diagnosis of gonorrhoea
gram stain of genital discharge, culture, NAAT, culture or urine PCR test
where can gonorrhoea infect
- urethritis
- cervicitis
- proctitis (rectum)
- pharyngitis
- conjunctivitis
- disseminated
symptoms presented in gonorrhoea
Males: purulent urethral discharge, dysuria, urinary frequency
Females: mucopurulent vaginal discharge, dysuria, urinary frequency
complication in untreated gonorrhoea
Males: epididymitis, prostatitis, urethral stricture, disseminated disease
Females: pelvic inflammatory disease, ectopic pregnancy, infertility, disseminated disease
Both: disseminated, skin lesion, tenosynovitis, monoarticular arthritis
first line management of uncomplicated gonococcal infections
- ceftriaxone 500 mg IM single dose (if >150kg, give 1g)
2. if chlamydial infection not excluded, treat for chlamydia with Doxycycline 100mg PO BD x 7d
alternative regimens for uncomplicated gonococcal
if ceftriaxone cmi
- gentamicin 240mg IM single dose + Azithromycin 2g PO single dose
- cefixime 800mg single dose (+ doxy 100mg BD x 7d if chlamydia not excluded)
management of sex partners in uncomplicated gonococcal infection
- sex partners in last 60d should be evaluated and treated
- if last sexual exposure >60d, most recent partner should be treated
- to minimise disease transmission, abstain for 7d after tx and resolution of symptoms if any
- abstain until all sex partners treated
what causes chlamydial infections
bacteria- Chlamydia trachomatis
diagnosis of chlamydia
NAAT or antigen detection
infection sites of chlamydia
similar to gonorrhea
- urethritis
- cervicitis
- proctitis (rectum)
- pharyngitis
- conjunctivitis
- disseminated
transmission of chlamydia
sex, childbirth
management of chlamydia
doxycycline 100mg PO BD x 7d
alternative chlamydia tx
- azithromycin 1g PO single dose
2. levofloxacin 500mg PO OD x 7d
why is erythromycin no longer recommended for chlamydial infection
GI side effect reduces adherence
management of sex partner for chlamydia
- partners in last 60d should be evaluated and treated, if last sex >60d, most recent partner should be treated
- abstain for 7d single dose/ completion of 7d therapy and resolution of symptoms if present
- abstain until all sex partners treated
causes of Syphilis
bacteria- treponema pallidum
transmission of syphillis
sex, placenta
diagnosis of syphillis
- darkfield microscopy of exudates from lesions
- 2 serological test (treponemal and non-treponemal)
primary syphilis
- heals spontaneously in 1-8w
- site of infection: external genitalia, perianal region, mouth, throat
- signs and symptoms: single painless ulcer or chancre at site of infection but can also present with multiple, atypical, or painful lesion
secondary syphilis
- develops 2-8w after initial infection (if untreated/ not properly)
- disappears in 4-10w untreated
- site of infection: multisystem involvement due to hematogenous and lymphatic spread
- signs and symptoms: can include skin rash, mucocutaneous lesions, and lymphadenopathy
latent syphilis
- develops4-10w after secondary stage infection (if untreated/ not properly)
- site of infection: possible multisystem involvement
- signs and symptoms: asymptomatic but picked up by serology testing; internal organs continue to be afected by infection
tertiary syphilis
- develops approx 30% of untreated or inadequately treated individuals (10-30yrs after intial infection)
- disappears in 4-10w untreated
- site of infection: possible multisystem - heart, eyes, bones, joints
- signs and symptoms: can present with gummatous lesions in joints leading impaired movement; cardiac involvement leading to heart-aortic insufficiency
neurosyphilis `
- CNS involvement can occur at any stage of syphilis
- eg cognitive dysfunction, motor or sensory deficits, ophthalmic or auditory symptoms, signs and symptoms of meningitis, stroke
treponemal test
- uses treponemal antigen to detect treponemal antibody
- eg T. pallidum haemagglutination test (TPHA), T. pallidum passive particle agglutination assay
(TPPA) - more sensitive and specific than nontreponemal tests, used as confirmatory test
- may remain reactive for life (hence not for monitoring response of tx)
non-trepnonemal test
- use nontreponemal antigen (cardiolipin) to detect treponemal antibodies
- venereal disease research laboratory (VDRL) slide test and Rapid plasma reagin (RPR) card test
- positive test can indicate presence of any stage of syphilis
- correlates with disease activity hence used as a monitor tool
- usually declines after tx and become non-reactive with time
- less specific hence more a screening tool (eg. when test is positive need to be confirmed with treponemal test)
what does the quantitative VDRL/RPR test suggest
1:16 - positive
1:32- no reaction seen
higher the proportion, the higher the load of treponemal antibody, higher antigen present
treatment of primary syphilis
Normal:
IM benzathine penicillin G 2.4 MU x 1dose
Pen allergy:
PO doxycycline 100mg BD x 14d
(take w food to reduce GI SE; water and upright to precent heartburn, avoid milk for 2h)
treatment of late latent syphilis (>1y/ unknown duration)
Normal:
IM benzathine penicillin G 2.4 MU once a week x 3 dose
Pen allergy:
PO doxycycline 100 BD x28d
treatment of neurosyphilis
Normal:
- IV crystalline pen G 3-4 MU q4h
- IV crystalline pen G 18-24 MU/d as continuous infusion x 10-14d
- IM procaine pen G 2.4 MU OD + PO probenecid 500mg QID x 10-14d
Pen allergy:
IV/IM ceftriaxone 2g OD x 10-14d
(if concern for cross sensi. do skin test to confirm, desensitize if need)
purpose of probenecid
reduce/ prevent excretion of pen G
monitoring syphilis
- Jarisch-Herxheimer reaction: acute febrile rxn accompanied by HA, myalgia and other symptoms that usually occur within first 24h after any tx for syphilis
- successful tx: decrease of VDRL/RPR titree by 4 fold (eg. 1:64 to 1:16)
how often to check on latent and neurosyphilis
latent: 6,12,24mth
neuro: CSF examination every 6mth until CSF normal
what happens when tx fail at 6mth
- show sign and symptoms of disease
- failure to decrease VDRL/RPR titre by four folds
- increase in VDRL/RPR titre
- retreat and re-evaluate for unrecognize neurosyphilis
management of sex partners in syphilis
- partners should be evaluated and treated
- abstain until all completed tx
general description of HSV type 1
- usually infect young children
- transmission: contact, often saliva
- common form of disease: herpes gingivostomatitis, herpes labialis (cold sore)
general description of HSV type 2
- usually infect young adults
- transmission: secual
- common form of disease: genital herpes
reactivation / relapse/ recurrence/ flares of HSV 1 or 2
- stimuli such as fever, menstruation, sunlight, stress can reactivate virus
- reactivation may be clinically asymptomatic, or it may produce life-threatening disease
management of HSV 1
usually self limiting
PO Acyclovir / Valacyclovir TOP acyclovir (modest benefit, not much use)
management of HSV 2
usually self limiting
PO acyclovir or valacyclovir
what disease does Varicella zoster virus causes
VZV causes two clinically distinct form:
- varicella (chicken pox) - usually primary infection, diffuse vesicular rash
- herpes zoster (shingles) - reactivation of laten VZV typically result in localised skin infection
what is varicella
- benign self limiting, but can be severe in immuno
- fever 1-2d before rashes 4-5d
- usually abates once the rash has completely appeared
- group of new lesions 4-7d
types of pox/rash
- macules
- papules
- vesicles
- pustules
- scabs
what is herpes zoster
- major risk is increasing age and immuno
- rash begins as papules -> vesicles -> pustules
- new lesions appear over period of 3-5d, usually dries with crusting in 7-10d
- rash + tingling/itching/pain for 2-3d
- symptoms: continuous / episodic
- post herpetic neuralgia (10-50% of pt), pain persisting after rash resolve (nerve pain), may persist for mth/yr
tx of shingles/varicella
- Acyclovir PO 800mg 5x a day x 7d
- Valacyclovir PO 1g TDS x 7d
start within 24-48h of rash to reduce duration and severity of symptoms
what are genital herpes
- most recurrent cause by HSV 2
- transmission via transfer of body fluids and intimate skin-to-skin contact
- vesicles develop over 7-10d, heal in 24h
- chronic and life long viral infection
- intermittent viral shedding from epithelial cells
- may not be symptomatic while shedding
stages of HSV cycle
- primary mucocutaneous infection
- infection of nerve ganglia
- establishment of latency
- reactivation
- recurrent outbreaks/flairs
signs of genital herpes
- Hx: previous lesion. sexual contact w similar lesions
- classical painful multiple vesicular/ ulcerative lesions
- local itching, pain, tender inguinal lymphadenopathy
- flu-like symptoms ( fever, HA, malaise) during first few d of lesions
- prodromal symptoms(mild burning, itching, tingling ~50% pt)
- less severe symptoms in recurrent disease
Test to diagnose genital herpes
- virologic test: viral cell culture and NAAT/PCR for HSV DNA from general lesions
- type specific serologic test:
- antibodies to HSV develop during first several w after infection and persist indefinitely
- presence of HSV implies anogenital infection
why and when is serology not useful for Herpes
- during first episode infection
- takes between 6-8 w for serological detection following first episode
(mainly for genital herpes)
supportive care of genital herpes
- warm saline bath relieve discomfort
- good genital hygiene to prevent superinfection
- counseling regarding natural hx
tx for first episode of genital herpes
- PO Acyclovir 400 TDS x 7-10d
- IV acyclovir 5-10mg/kg q8h x 2-7d (complete total 10d including PO; IV for severe case ie. hospitalisation)
- Valacyclovir 1g BD x7-10d
MOA of valacyclovir
- L-valine ester of acyclovir (inhibit DNA polymerase)
- rapidly and almost completely converted in man to acyclovir and valine
MOA of cyclovir
- inhibitis viral DNA polymerase; inhibit DNA synthesis and replication
- lower F than valacyclovir
Counselling tips for acyclovir
- take w/o food, after if GI upset
- SE: malaise, HA, N&V, Diarrhoea
- care cystallisation
counselling tip for valacyclovir
- take w/o food, after if GI upset
- main SE: HA
benefits of chronic suppressive therapy
- reduced freq of recurrence by 70-80%
- many pt report no symptomatic outbreaks hence better QOL
- established long term safety and efficacy
- decrease risk of transmission (combi w consistent use of condoms/ abstinence)
cons of chronic suppressive theory
- expensive
2. compliance
chronic suppressive therapy regimens
- acyclovir 400mg PO BD
- valacyclovir 500mg PO OD (maybe less effective than other regimens for those who have frequent recurrences >=10/yr)
- valacyclovir 1g PO OD
- Famciclovir 250mg PO BD (not in SG)
benefits of episodic therapy
- shorten duration and severity of symptoms
- less $$
- pt more likely to be compliant
cons of episodic therapy
- require initiation of therapy within 1d of lesion onset/ during prodrome that precedes some outbreaks
- does not reduce risk of transmission
episodic therapy regimen
- acyclovir 800mg PO BD x 5d
- acyclovir 800mg PO TD x 2d
- valacyclovir 500mg PO BD x 3d
- valacyclovir 1g PO OD x 5d
- famciclovir 1g PO BD x 1d
- famciclovir 500mg PO once, then 250mg BD x 2d
- famciclovir 125mg PO BD x 5d
