Sexually Transmitted Infections Flashcards
What are sexually transmitted infections?
STI’s are infections transmitted primarily during sexual contact; commonly by any of the following routes of transmission:
- Oral-genital contact
- Vaginal intercourse
- Anal intercourse
- Anilingus
What are the common patterns of STI infections?
Vaginal / Urethral Discharge
Genital Lesions
Warts
**Pelvic Involvement Disorders (PID) **
Dermatological Conditions
Chacterise the microbe Neisseria gonorrhoeae
Neisseria gonorrhoeae is a **gram negative diplococci **
It adheres to columnar epithelial cells ( of which there are more of in younger women - may contribute to increased prevalence )
Have a **short incubation period of 2-7 **
Asymptomatic infection common in females (80%) but not males (urethritis) **(10%) **
There is increasing antibiotic resistance in Neisseria gonorrhoeae - largely due to the exchanging of genes beween respiratory microflora Neisseria with pathogenic STI Neisseria
What are the pathological consequences of a gonorrhoea infection?
If untreated, gonorrhoea can progress to result in:
Dissemination (0.5-3% of cases)
- **Arthritis **
- Disseminated maculopapular rashes
- Meningitis
- Endocarditis
-
Peri-hepatitis / Violin-string adhesions / Fitz Hugh Curtis Syndrome
- Organism capable of entering the abdominal cavity after ascending the fallopian tubes and creating adhesions of the liver ( a consequence of PID )
- Epididymitis
Pelvic Inflammatory Disease
- Tubal scarring
- Infertility (10-20%)
What is neonatal gonococcal opthalmia?
Neonatal gonococcal opthalmia is a gross purulent conjuctivitis
Is a aquired in the process of birth ( to a gonorrhoea infected mother) before becoming symptomatic in day 2-5 of life
Mild neonatal gonococcal opthalmia is indistinguishable from other causes of conjunctivitis
Treatment involves:
- IV cefotaxime (50mg/kg)
* No need for topical antibiotic treatment unlike other more common conjunctivitis - Irrigate eyes regularly
- Treat mother and sexual contacts
What diagnostic testing is involved in gonnorhoea diagnosis?
Diagnostic Specimens:
- Cervical Swab / Urethral Swabs
- Urine Sample
- Other as relevant: conjunctiva, pharynx, skin lesions, anal swab, blood specimens, synovial fluid
Culture media:
- Selective: Thayer-Martin Agar (colistin, vancomycin and nystatin)
- Non-selective : Chocolate blood agar in CO2
Nucleic acid amplification tests (NAAT)
- Combined Chlamydia and Neisseria detection from wither genital or first void urine samples
- Chlamydia co-infections ~50% of cases
How do you treat and prevent Gonnorrhoea?
Ceftriaxone (500mg) IM/IV + Azithromycin 1g oral (in case of chlamydia co-infection)
To prevent it:
- Barrier contraception
- Contact tracing
- Vaccine (in development)
Characterise the microbe **Chlamydia trachomatis **
**Chlamydia trachomatis **is an obligate intracellular parasite
The parasite *adheres to an invades columnar epithelium *
Different serotypes of the microbe cause different diseases:
D-K = genital infection ; L1-L3 = Lymphogranuloma Venereum (LGV) ; A-C = Trachoma
Discuss the life cycle of **chlamydia **
There are two forms of the chlamydia microbe:
Elementary Bodies: infectious, non-replicating and hardy
Reticulate Bodies: metabolically active and replicating
The life cycle consists of:
- Infectious elementary body attachment and entry to target columnar epithelial cell
- Formation of reticulate body
- Binary fission of reticulate body to replicate
- Reorganisation of reticulate bodies into elementary bodies
- Vast quantities of elementary bodies in cytoplasmic inclusion of host cell
- Rupture of host cell and release of infectious elementary body
Discuss the epidemiology and clinical signs of Chlamydia
Chlamydia is the most common STI
Causes cervicitis in females (although often asymptomatic) and urethritis in males
Male signs:
- Dysuria
- Meatal erythema
- Clear urethral discharge
- Testicular pain
- Prostatitis
Female signs:
- _Cervicitis / endometritis _
- Vaginal discharge
- Urethritis / Dysuria
- Irregular bleeding
- Pelvic pain and dysparenuia (painful intercourse)
- Pelvic inflammatory disease (acute + chronic)
What is lymphogranuloma venereum (LGV)?
** Lymphogranuloma venereum **is an **invasive lymphatic infection **caused by chlamydia
It generally results from chlamydia infecting or causing an ulcerative genital lesion before travelling via the lymphatics to cause suppurative inguinal lymphadenopathy
It is endemic in Africa, India, SE Asia and South America
Discuss Neonatal Chlamydia
Neonates can become infected with chlamydia by their positive mothers during passage through the birth canal.
50% of births to Chlamydia positive mothers result in neonatal Chlamydia
Presents as conjunctivitis (25%) or pneumonia (10%)
Must treat the child and the parents
What investigations are relevant to diagnosing Chlamydia
Cervical / urethral / anal swab
Urine
Nucleic Acid Detection
Culture is not routine
Note: test of cure is required post-procedure and during pregancy screening
How is Chlamydia treated?
Azithromycin (1g oral x 2 doses one week apart) or Doxycycline ( 100mg oral bidaily 10-14 days -not to be used in pregnant women because the tetrocyclins stain the teeth of developing foetus)
In **severe chylamydia PID = **500mg Azithromycin IV daily 14 days
- Must contact trace partners
- Must be doctor notified
- Test-of-cure = 4-6 weeks
- Advise retest in 3 months
- Repeated episode of chlamydia can cause scarring of the infected regions
Characterise the **Trichomonas Vaginalis **microbe in STIs
Trichomonas Vaginalis is a flagellated protozoon that transmitted sexually
It is frequently asymptomatic - but when symptomatic it causes a characterisitc Frothy green-yellow vaginal discharge
**It is a marker of high risk sexual activity **and is associated with:
- greater rates of HIV acquisition
- non-steady sexual partner
- marijuana use
- elevated rates in indigenous communites
It causes cervical erythema & friability, pruritis, dysuria and abdominal pain
Testing =
- High vaginal swab + culture
- Urine - PCR
- Can be seen on Pap smears
Treatment =
- Metronidazole (not well tolerated due to metallic taste in mouth)
- Tinidazole
- Note: resistance development is increasingly common
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