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