Describe the routes of transmission for STIs?
Describe the agent of gonorrhea?
Gram negative diplococci
What does neisseria gonorrhoeae adhere to in the body to cause infection?
Columnar epithelial cells (line urethra and cervix)
Describe the incubation period for gonorrhea?
Describe the presentation of gonorrhea?
Asymptomatic common in females (80%)
Urethritis and thick urethral discharge in males
Infection in throat (difficult to distinguish from other causes of pharyngitis)
Describe the antibiotic resistance levels of neisseria gonorrhoeae?
Why does this occur?
Increasing levels of antibiotic resistance
Able to exchange antibiotic resistance genes with other neisseria (eg. meningitidis) that colonise mouth
Describe the possible consequences of dissemination of gonorrhoea?
In how many cases does this occur?
Dissemination occurs in 0.5-3% if untreated
Peri-hepatitis (Fitz-Hugh-Curtis syndrome)
Pelvic Inflammatory Disease (> tubal scarring, infertility)
Describe the symptoms of Pelvic Inflammatory Disease?
Describe the pathology of Fitz-Hugh-Curtis syndrome?
Gonorrhoea > ascends up Fallopian tubes > enters abdominal cavity > liver adhesions > hepatitis> derangement in LFTs
Describe the possible consequences of a mother with gonorrhoea delivering a baby naturally?
Neonatal gonococcal opthalmia
Gross purulent conjunctivitis
If untreated > perforation and blindess
Describe the treatment of neonatal gonococcal opthalmia?
IV cefotaxime for 7 days
Irrigate eyes regularly
No topical treatment
Also treat mother and sexual contacts
Why is it important to distinguish neonatal gonococcal opthalmia from other causes of conjuntivitis?
Other conjunctivitis only requires topical treatments, whereas NGO requires systemic treatment
NGO can lead to blindness if untreated
Describe the major diagnostic specimens that can be collected for investigation of gonorrhoea?
Cervical swab in charocal transport medium (female)
Urethral swab (male)
First void urine
Describe the laboratory investigations that can be performed for investigation of gonorrhoea?
Non-selective: CBA in CO2
Selective: Thayer-Martin agar (inhibits growth of normal)
Culture for antibiotic sensitivities
NUCLEIC ACID AMPLIFICATION TESTS
Describe the treatment for gonorrhoea?
Ceftriaxone 500mg IV/IM and Azithromycin 1g oral
Combination used to delay emergence of resitance
Azithromycin also treats chlamydia (coinfection common)
How can gonorrhoea be prevented?
Describe the agent that causes chlamydia?
Obligate intracellular parasite
Serovars D-K cause genital infection
Describe the different stages of chlamydia trachomatis?
Elementary bodies: infectious, non-replicating, hardy
Reticulate bodies: metabolically active, replicate
Describe the life cycle of chlamydia?
Elementary body infects columnar epithelium of target > reticulate body froms in cell > replication > reticulate bodies reorganise into elementary bodies > elementary bodies released
What is the most common STI?
Describe the presentation of chlamydia?
Describe the possible clinical findings for chlamydia?
Clear urethral discharge
Cervicitis, endometritis, vaginal discharge
Pelvic pain and dyspareunia
What is LGV?
Invasive lymphatic infection caused by chlamydia
How commonly is chlamydia transferred to neonates?
Describe the consequences of neonatal chlamydia?
25% conjunctivitis: thin, haemorrhagic
10% pneumonia: 3-4 months incubation, staccato cough
Describe the laboratory investigation of chlamydia?
Sample: cervical/urethral/anal swab or first void urine
Tests: NA detection (not culture)
TEST OF CURE REQUIRED (post procedure and pregnancy)
When and why is test of cure required in chlamydia?
Post procedure and in pregnancy
Chance of reinfection or lack of response to initial treatment
Describe the treatment for chlamydia?
Azithromycin 1g oral, 2 doses 1 week apart
Doxycycline 100mg oral twice daily, 10-14 days
Severe chlamydia PID: azithromycin 500mg IV daily, 14 days (step down to oral when well)
Treat sexual contacts
Test of cure
Describe trichomonas vaginalis?
Flagellated protozoan > motile
Describe the presentation of infection with trichomonas vaginalis?
Frothy, green-yellow vaginal discharge
Pruritis, odour, dysuria, abdominal pain
Describe the possible appearance of the cervix after infection with trichomoas vaginalis?
Cervical erythema and friability
Describe the effect of trichomonas vaginalis on the pH of the vagina?
pH > 5
Becomes more alkaline
What is infection with trichomonas vaginalis a marker for?
High risk sexual activity
Describe the prevalence of trichomonas vaginalis infection?
About 5% sexually active women
Describe a possible consequence of trichomonas vaginalis infection?
How does this occur?
Genital inflammation > doubled risk HIV acquisition
Which groups of people is trichomonas vaginalis infection associated with?
Describe the laboratory testing for trichomonas vaginalis?
High vaginal swab > microscopy, culture
Urine > PCR (expensive for this infection)
Sometimes seen on Pap smear
Describe the treatment for infection with trichomonas vaginalis?
Metronidazole 2gm orally singly
Tinidazole 2 gm orally singly
Or smaller doses for better SE tolerance
Follow up testing (may have resistance)
Why is follow up testing required after treatment of trichomonas vaginalis infection?
May have antibiotic resistance
Describe the agent that causes syphilis?
Describe the stages of syphilis?
Primary: ulcer (Chancre) on genitals, 2-3 weeks after exposure
Secondary: ulcer heals > rash, lymphadenopathy, abdominal pain, alopecia
Tertiary: can lead to neurosyphilis
Describe the laboratory testing for syphilis?
Microscopy: difficult to see, don't Gram stain
Serology: non-treponemal and treponemal tests
Describe the non-treponemal tests that are used for investiagting syphilis/t.pallidum?
Ab to cellular lipids and lecithin
Positive 4-8 weeks post-infection
useful for screening and monitoring therapy
Describe the treponemal tests that are used to investigate syphilis/t.pallidum?
Detect antigens on organism itself
Positive slighlty earlier and for life
Describe mycoplasma genitalium?
No cell wall
Flask shaped (protusion for attachment to columnar mucosa)
Describe the prevalence of mycoplasma genitalium?
What is the main diagnostic tool for mycoplasma genitalium?
Nucelic acid detection
Difficult to culture
No cell wall > no Gram stain
Describe the presentation of infection with mycoplasma genitalium?
May predispose to HIV transmission
Describe the treatment for mycoplasma genitalium?
Azithromycin 1gm (15-30% failure)
Moxifloxacin 400mg daily, 7-10 days (expensive, failures described)
List the indications for STI testing?
Symptomatic patient investigation
Screening for asymptomatic infection
Blood and organ donation