STI Flashcards
What is the cause of bacterial vaginosis?
Gardnerella vaginallis
What is the damsel criteria for bacterial vaginosis?
- Thin, white homogenous discharge
clue cells on microscopy: stippled vaginal epithelial cells - Vaginal pH > 4.5
- Positive whiff test (addition of potassium hydroxide results in fishy odour)
How is bacterial vaginosis treated?
Metronidazole
70-80% initial cure rate
relapse rate > 50% within 3 months
the BNF suggests topical metronidazole or topical clindamycin as alternatives
What is the buzz word for bacterial vaginosis?
Clue cells
What is the complicating factor of bacterial vaginosis in pregnancy?
Risk in preterm labour, low birth weight and chorioamnionitis, late miscarriage
Can metronidazole be used in pregnancy?
Yes.
What are clue cells?
Clue cells - epithelial cells develop a stippled appearance due to being covered with bacteria
How does trichomonas vaginalis differ from bacterial vaginosis?
BV:
- White discharge
- Clue cells
Both:
- pH > 4.5
- Offensive discharge
Trichomonas:
- Frothy yellow/green discharge
- Vulvovaginitis
- Strawberry cervix
- Wet mount: motile trophozoites
What STI is caused by gram negative diplococcus?
Neisseria gonorrhoeae.
What is the incubation period of gonorrhoaeae?
2-5 days
What are the features of Neisseria gonorrhoeae?
Males: urethral discharge, dysuria
Females: cervicitis e.g. leading to vaginal discharge
rectal and pharyngeal infection is usually asymptomatic
Why is gonorrhoea vaccination challenging?
antigen variation of type IV pili (proteins which adhere to surfaces) and Opa proteins (surface proteins which bind to receptors on immune cells)
How is gonnorhoeae treated?
IM ceftriaxone 1 gram
Alertnative:
Oral cefixime 400mg (single dose) + oral azithromycin 2g (single dose)
What are the most common causes of septic arthritis in young people?
Disseminated gonococcal infection (DGI) and gonococcal arthritis
What are the features of a disseminated gonococcal infection? It’s a triad
Tenosynovitis
Migratory polyarthritis
Dermatitis (lesions can be maculopapular or vesicular)
Why is doxycycline the new treatment for chlamydia?
Macrolide resistance
now preferred to azithromycin due to concerns about Mycoplasma genitalium. This infection is often coexistant in patients with Chlamydia and there is evidence of rising levels of macrolide resistance, hence why doxycycline is preferred
What is the most prevalent STI in the UK?
Chlamydia
What are the features of chlamydia?
women: cervicitis (discharge, bleeding), dysuria
men: urethral discharge, dysuria
What are the complications of chlamydia?
epididymitis
pelvic inflammatory disease
endometritis
increased incidence of ectopic pregnancies
infertility
reactive arthritis
perihepatitis (Fitz-Hugh-Curtis syndrome)
What are the first line investigations for chlamydia?
Female: Vulvalvaginal swb
Men: Urine test
Nucleic acid amplification testing
How should chlamydia be treated?
Doxycycline
How should someone who is pregnant be treated for chlamydia?
Erythromycin
Amoxicillin
Azithromycin (best choice)
How should men with urethral symptoms be contact traced?
All contacts since, and in the four weeks prior to, the onset of symptoms
How should women and asymptomatic men be contact traced?
All partners from the last six months or the most recent sexual partner should be contacted
What are the features of genital herpes? What is the underlying infection?
Painful ulcers - Multiple
Caused by HSV2
Primary attack associated with fevers and pain
What is the feature of chancroid ulcer?
Genital ulcers associated with unilateral, painful inguinal lymph node enlargement.
Ulcers typically have a sharply defined, ragged, undermined border.
What causes a chancroid ulcer?
Haemophilus Ducreyi
What are the phases of lymphogranuloma venereum? What is the causative agent?
stage 1: small painless pustule which later forms an ulcer
stage 2: painful inguinal lymphadenopathy
stage 3: proctocolitis
Chlamydia trachoma’s
What is pelvic inflammatory disease?
inflammation of the female pelvic organs including the uterus, fallopian tubes, ovaries and the surrounding peritoneum
*Usually from infection of endocervix
What causes pelvic inflammatory disease?
Chlamydia trachomatis (Most common cause)
Neisseria gonorrhoeae
Mycoplasma genitalium
Mycoplasma hominis
What are the features of pelvic inflammatory disease?
Lower abdominal pain
Fever
Deep dyspareunia
Dysuria and menstrual
Vaginal or cervical discharge
Cervical excitation
What is the treatment for PID?
oral ofloxacin + oral metronidazole
OR
intramuscular ceftriaxone + oral doxycycline + oral metronidazole
How do you test for syphilus?
- Non- treponemal test:
- Not specific for syphilis
- based upon the reactivity of serum from infected patients to a cardiolipin-cholesterol-lecithin antigen
assesses the quantity of antibodies
-negative after treatment
Tests: 1. rapid plasma reagin (RPR), and 2. Venereal Disease Research Laboratory (VDRL) - Treponemal specific test:
- Specific to syphikus
- Qualitative only and are reported as ‘reactive’ or ‘non-reactive’
- examples include: TP-EIA (T. pallidum enzyme immunoassay), TPHA (T. pallidum HaemAgglutination test)
What does a Positive non-treponemal test + positive treponemal test mean?
Consistent with active infection
What does a Positive non-treponemal test + negative treponemal test mean?
Consistent with false positive
What does a Negative non-treponemal test + positive treponemal test mean?
Consistent with treated syphilus
Can chlamydia be diagnosed by gram stain?
No - it does not gram stain
What is the gram stain of gonorrhoea?
Gram negative diplococcus
How do you treat trichinas vaginalis?
Oral metronidazole for 5-7 days, although the BNF also supports the use of a one-off dose of 2g metronidazole
What is the gram stain of gardnerella?
Gardnerella vaginalis is a coccobacillus which can appear as both gram-positive or occasionally gram-negative due to its very thin wall.
Painless penile ulcer + painful inguinal lymphadenopathy?
Lymphogranula venereum
Painless penile ulcer + painless inguinal lymphadenopathy?
Syphilus
What is non-specific urethritis?
Non-gonococcal urethritis (NGU, sometimes referred to as non-specific urethritis) is a term used to describe the presence of urethritis when a gonococcal bacteria are not identifiable or the initial swab.
Causes of non-specific urethritis?
Chlamydia trachomatis - most common cause
Mycoplasma genitalium - thought to cause more symptoms than Chlamydia
Management of non-specific urethritis?
Doxycycline or azithromycin
What is the cause of multiple painless genital ulcers, known as granuloma inguinale?
Klebsiella granulomatos
