STIs Flashcards
most common STI in the UK?
chlamydia
describe chlamydia bacteria
gram -ve obligate intracellular bacterium
vaginal, oral or anal transmission
chlamydia pathogenesis?
unclear
mucosal epithelial cells are primary target, bacteria replicates within vacuole in cytoplasm of host cell
risk of pelvic inflammatory disease in chlamydia?
9%
- risk of ectopic pregnancy
how does chlamydia present in females?
often asymptomatic post coital or intermenstrual bleeding lower abdominal pain dyspareunia mucopurulent cervicitis
how does chlamydia present in males?
urethral discharge dysuria urethritis epididymo-orchitis proctitis (LGV)
potential complications of chlamydia?
PID reactive arthritis (urethritis, uveitis, arthritis) conjuntivitis (more in babies) Fitz-hugh curtis syndrome (perihepatitis) transmission to neonate tubal damage ectopic pregnancy chronic pelvic pain
advice in chlamydia testing?
stop testing for chlamydia in women >25 with discharge (more likely to be candida)
do test women who have had chlamydia in the past year
- 1 in 5 become reinfected within 10 months
serovars L1-L3 of chlamydia?
lymphogranuloma verenum (LGV) type of chlamydia more common in MSM and tropical regions
features of serovars L1-L3?
rectal pain
discharge
bleeding
high risk of concurrent STIs
how is chlamydia diagnosed?
test 14 days after exposure
do NAAT
- vulvovaginal swab in females (self taken)
- first pass urine in males (self taken)
- ass rectal swab if receptive anal intercourse
how is chalmydia treated?
most commonly used doxycyline 100mg BD for 7 days
can still use single 1g dose of azithromycin followed by 500mg daily for next 2 days but not used as much (resistance)
what is mycoplasma genitalium?
emerging STI
associated with non-gonococcal urethritis and PID
- if treatment fails for either of these then test for mycoplasma genitalium
how is mycoplasma genitalium tested?
NAAT (same sites as chlamydia)
ghonoorhoea bacteria?
gram -ve intracellular diplococcus
primary sites of infection in gonorrhoea?
mucous membranes of urethra, endocervix, rectum and pharynx
incubation of gonorrhoea?
urehtral infection in men = 2-5 days
in which direction is gonorrhoea most likely to be transmitted?
more likely in male to female
how does gonorrhoea present in males?
only <10% are asymptomatic green/yellow purulent urethral discharge dysuria pharyngeal/rectal infections - mostly asymptomatic
how does gonorrhoea present in females?
up to 50% are asymptomatic
increased/altered vaginal discharge (in 40%)
dysuria
pelvic pain (<5%)
pharyngeal and rectal infection are usually asymptomatic
potential complications in gonorrhoea?
barthonlinitis tysonitis periurethral abscess rectal abscess epididymitis urethral stricture endometritis PID hydrosalpinx infertility ectopic pregnancy prostatitis
how is gonorrhoea diagnosed?
NAAT screening test microscopy (if symptomatic) - more sensitive in urethral vs endocervical culture (if micro +ve or contact of GC) - gives antibiotic sensitivity
how is gonorrhoea treated?
1st line = ceftriaxone 1g IM
2nd line = cefixime 400mg and azithromycin 2g oral (only if IM injection is contraindicated or refused by patient)
always test for cure after 2 weeks in patient
- check all sites where they had a positive swab
3 classifications of genital herpes presentations?
primary infection
non-primary first episode (have already been exposed but first symptomatic presentation)
recurrent infection
incubation period for primary infection genital herpes?
incubation = 3-6 days duration = 14-21 days
features of symptomatic genital herpes?
blistering and ulceration of external genitalia extreme pain external dysuria vaginal or urethral discharge local lymphadenopathy fever and myalgia (prodrome)
first episode vs recurrent episodes?
first usually worse
features of recurrent episodes?
more common with HSV2
usually unilateral, small blisters and ulcers
minimal systemic symptoms, resolve within 5-7 days
how is genital herpes investigated?
swab base of ulcer for HSV PCR
how is genital herpes managed?
oral aciclovir 400mg 3 times daily for 5 days
consider topical lidocaine 5% ointment if very painful
saline bathing
analgesia
HSV1 vs HSV2?
HSV2 has more attacks per year
viral shedding following HSV2 is consistently higher than HSV1
how does viral shedding occur in herpes?
more frequent in first year of infection
more in individuals with frequent recurrences
reduced by suppressive therapy (aciclovir)
special circumstances in herpes?
risk of neonatal transmission if first episode in 3rd trimester (within 6 weeks of EDD)
- recurrent episode not as bad as foetus will have developed antibodies from mother
- should inform O+G and review birth plan
most common viral STI in UK?
HPV
low risk vs high risk HPV?
low risk = 6, 11
high risk = 16, 18
different clinical sequele in different types of HPV?
latent infection
anogenital warts (6 and 11)
palmar and plantar warts (1 and 2)
cellular dysplasia/intraepithelial neoplasia
incubation period of HPV?
3 weeks to 9 months
- can have it for years asymptomatically then have symptoms in some cases
how do warts clear in HPV?
20-34% clear spontaneously
60% clear with treatment
20% persist despite treatment
how is HPV managed?
podophyllotoxin (warticon) - topical cytotoxic agent not licensed for extra genital warts but widely used imiquimod (aldara) - immune modifier - 2nd line or first line in anal warts cryotherapy - cytolytic can require repeat treatments electrocautery
syphilis bacteria?
treponema pallidum (spirochete bacteria)
how can syphilis be transmitted?
sexual contact
trans-placental/during birth
blood transfusions
non-sexual contact (healthcare workers)
classification of syphilis?
congenital
- early infectious stage = primary, secondary and early latent phase
acquired
- late non-infectious stage = late latent and tertiary phase
features of primary syphilis?
9-90 day incubation (mean 21) primary painless lesion (chancre) at site of inoculation 90% are genital 10% extra-genital non-tender lympahdenopathy
features of secondary syphilis?
6 weeks - 6 month incubation
skin features (macular/follicular/pustular rash on hands and feet)
lesions of mucous membranes
generalized lympadenoathy
patchy alopecia
condylomata lata (most infectious lesion in syphilis, exudes a serum teeming with treponemes)
diagnosis of syphilis?
demonstrate treponema pallidum from lesions or infected lymph nodes
- via dark field microscopy or PCR
serological testing - detects antibodies to pathogenic treponemes
what serological tests are done for syphilis?
Non-specific
- VDRL
- RPR
specific
- TPPA (treponema pallidum particle agglutination)
- ELIZA/EIA (enzyme immunoassay - screening test)
- INNO-LIA (line immunoassay)
- FTA abs (fluorescent treponemal antibody absorbed)
treatment and follow up in syphilis?
early syphilis
- 2.4 MU benzathine penicillin X 1
late syphilis
- 2.4 MU benzathine penicillin X 3
syphilis follow up serologically?
continue until RPR is negative or serofast
- titres should decrease fourfold by 3-6 months in early syphilis
- relapse/reinfection defined as when titres increase fourfold
