STI's Flashcards
What is the primary mode of transmission of STI’s ?
Human-human transmission (sexual intercourse)
Go over the general principles of STI’s
- Immunity is rare
- Reinfection is common
- Co-infections are common - STI ppathogens move together e.g. chlamydia and gonorrhoea
- Vaccines have been difficult to develop
What are the typical organisms which colonise the vaginal flora
Lactobacillus spp. predominate and are protective e.g L.crispatus and L. jensenii.
Other organisms:
- +/- Group B beta-haemolytic Streptococcus
- +/- Candida spp. (small numbers)
- +/-Strep “viridans” group
What is the normal pH of the vagina and why?
- ACID pH is Normal (4 to 4.5)
- This is because the Lactobacillus spp. produce Lactic acid +/- hydrogen peroxide
What is the most common cause of candida infections ?
Candida albicans
What percentage of females are colonised with small numbers of Candida albicans?
30%
List the predisposing factors to a candida infection
- Recent antibiotic therapy
- High oestrogen levels (pregnancy, certain types of contraceptives)
- Poorly controlled diabetes
- Immunocompromised patients
Describe the presentation of a candida infection
- Intensely itchy white vaginal discharge (cottage cheese appearance)
- +/- occasionally pain on intercourse or urination
How is a candida infeciton diagnosed?
- 1st line = clinical diagnosis
- 2nd line = high vaginal swab for culture if the diagnosis if uncertain, or women who have severe or recurrent symptoms, or if there is treatment failure
What is the treatment for a candida infection?
- Oral Fluconazole AND
- Clotrimazole cream daily or Clotrimazole pessary + clotrimazole cream daily
What is shown in this pic
Candida balanitis - this is inflammation of the glans of the penis +/- the foreskin.
What are the signs/symptoms of candida balanitis ?
- A red, inflamed ‘spotty’ rash on the head and shaft of the penis or under the foreskin
- Itching or burning in the affected area
- A white, clumpy or yellowish discharge from the affected skin or from under the foreskin
What is the most common cause of candida balanitis ?
Non-specific dermatitis +/- candida albcians infection
What is the treatment of candida balanitis ?
Topical hydrocortisone + clotrimazole cream
What is the causative organism of gonorrhoea ?
Neisseria gonorrhoeae
Describe the microscopic appearance of gonorrhoea
Gram -ve intracellular dipplococci - Look like “2 kidney beans facing each other”
Note also a fastidious organism so doesnt survive outside ideal growth conditions
What part of the body does gonorrhoea infect?
The urethra, rectum, throat & eyes (♂&♀) endocervix (♀) (same as chlamydia)
What is the incubation period of gonorrhoea infections ?
2-5 days
Describe the presentation of gonorrhoea
Men:
- Urethral infection - purluent discharge and dysuria, asymptomatic (<10%).
- Rectal & pharyngeal infections - usually asymptomatic; may cause anal discharge (purulent) or perianal/anal pain (proctitis), pruritus, bleeding, tenesmus.
Women:
- Endocervical infection - frequently asymptomatic (up to 50%); may get increased or altered vaginal discharge, +/- sometimes lower abdominal/pelvic pain, intermenstrual bleeding or menorrhagia.
- Urethral infection - cause of dysuria (10-15%) without frequency.
- Rectal and pharyngeal infections - usually asymptomatic.
What are the potential complications of gonorrhoea infection?
What is shown in the pic and what infection can cause these complications
Bartholinitis (right) and tysonitis (left)
What is the treatment of gonorrhoea ?
- 1st line = IM ceftriaxone + oral azithromycin
- 2nd line = Oral cefixime + azithromycin
Why is azithromycin given in the treatment of gonorrhoea ?
Because there is often co-infection with chlamydia
Due to the high antibiotic resistance of gonorrhoea what is required following treatment ?
Test of cure to be sure patient is cured
What is the most common sexually trasmitted infection ?
Chlamydia
What parts of the body can chlamydia infect?
The urethra, rectum, throat & eyes (♂&♀) endocervix (♀) (same as gonorrhoea)
What is the causative organism of chlamydia ?
Chlamydia trachomatis
What is the microscopic appearance of chlamydia trachomatis ?
Obligate intracellular bacteria with biphasic life cycle - does not gram stain
What are the 3 serological groupings of chlamydia trachomatis and the pathologies they cause?
- Serovars A-C = Trachoma (eye infection) (NOT an STI)
- Serovars D-K = Genital infection
- Serovars L1-L3 = Lymphogranuloma venereum
Who does Lymphogranuloma venereum (chlamydia trachomatis L1-3) mainly affect and how does it present?
- MSM (often HIV+) - it can cause proctitis ==> screening rectum important in MSM
- Presents with rectal pain, discharge and bleeding
What complications can LGV chlamydia result in ?
- Ulcers
- Abscesses
- Strictures
- Fistulae
What are the clinical features of chlamydia ?
In men:
- Anterior urethritis
- Dysuria
- Watery discharge
- Ascending infection can lead to Epididymo-orchitis
- Proctitis (LGV) - MSM
In women:
- Post coital or intermenstrual bleeding
- Lower abdominal pain
- Dyspareunia
- Mucopurulent cervicitis (from endocervix) – it is yellow or green, if this is present then worry about PID
- Watery vaginal discharge
- Ascending infection can lead to salpingitis
What are the clinical features of rectal chlamydia (not talking about LGV chlamydia here)
- 70% asymptomatic
- Milder than gonorrhoea
- Anal discomfort/itch, discharge
- Associated symptoms
What is the key thing to remember about the presentation of chlamydia ?
Many patients are asymptomatic - famles 70%, males 50%
What are the complications of chlamydia infection which can develop?
- PID (CT accounts for 50% of cases) ==> Tubal damage (infertility, ectopic pregnancy)
- Chronic pelvic pain
- Transmission to the neonate (17% conjunctivitis, 20% pneumonia)
- Adult conjunctivitis
- Sexually acquired reactive arthritis (SARA) /Reiter’s syndrome (commoner in men). – hence in a young man with joint pain its important to take a sexual history
- Fitz-Hugh-Curtis Syndrome (Perihepatitis) – piano string adhesions involving the liver capsule
What is reiters syndrome
- It is a reactive arthritis which can affect the joints & tendons, cause urinary symptoms & affect the eyes.
- It primary affects the joints and tendons causing pain & joint swelling
- It occurs in men primarily, often within 4 weeks of an infection typically an STI such as chlamydia
What is the treatment of chlamydia ?
- 1st line = Doxycycline (7 days)
- 2nd line = Azithromycin (2 days)
What are the symptoms of epididymo-orchitis ?
- scrotal pain (usually unilateral), and swelling
- +/- symptoms of UTI (dysuria, urgency, frequency) or urethritis (dysuria or urethral discharge)
What investigations and management is given for epididmyo-orchitis ?
Send MSSU, gonorrhoea & chlamydia tests.
- If STI likely (35 or new partner in last 3mth) give doxycycline
- If UTI likely (>35 and no new partner) give ofloxacin or ciprofloxacin
What is the treatment of chlamydia in pregnancy ?
1st line = azithromycin or erythromycin
Test of cure at 3 weeks after end of treatment + rescreen in 3rd trimester
What is the treatment of LGV ?
3 weeks of doxycyline
How is chlamydia and gonorrhoea diagnosed ?
- 1st line = Combined NAATs or PCR - tests for both organisms
- 2nd line = a culture & microscopy should be taken for all those +ve for gonorrhoea before prescribing antibiotics (due to resitance, done on male urethral and female endocervical swabs, not HVS)