Common STIs Flashcards
Chlamydia, gonorrhoea, bacterial vaginosis, trichomoniasis, herpes simplex
What is the most prevalent STI in the UK?
chlamydia
What pathogen causes chlamydia?
Chlamydia trachomatis - an obligate cellular pathogen
What proportion of young women in the UK have chlamydia?
1 in 10
What is the incubation period of chlamydia?
7-21 days
What makes it hard for chlamydia to be diagnosed/ an incubation period established sometimes?
a large percentage of cases of chlamydia are asymptomatic
In what proportion of women is chlamydia asymptomatic?
70%
In what proportion of men is chlamydia asymptomatic?
50%
What are 6 symptoms of chlamydia in females?
- Vaginal discharge
- Dysuria (can cause sterile pyuria)
- Vague lower abdominal pain
- Fever
- Intermenstrual or postcoital bleeding
- Deep dyspareunia
What are 5 symptoms of chlamydia in males?
- Classical urethritis
- Dysuria
- Urethral discharge
- Epididymo-orchitis - unilateral testicular pain ± swelling
- Fever
What are 4 features of chlamydia that may present in both sexes?
- Reactive arthritis (conjunctivitis, arthritis, urethritis)
- Upper abdominal pain due to perihepatitis (Fitz-Hugh Curtis syndrome)
- Proctitis with mucopurulent discharge (rectal chlamydia after anal intercourse)
- Pharyngeal infection
What are 7 potential complications of chlalmydia?
- Epididymitis
- Pelvic inflammatory disease
- Endometritis
- Increased incidence of ectopic pregnancies
- Infertility
- Reactive arthritis
- Perihepatitis (Fitz-Hugh Curtis syndrome)
What is the investigation of choice for chlamydia?
- NAAT: nucleic acid amplification tests
- Urine (first void urine sample), vulvovaginal swab or cervical swab may be tested using NAAT
What investigation for chlamydia is first line in women?
NAAT technique using vulvovaginal swab
What investigation for chlamydia is first line in men?
First void urine sample for NAAT
What are 3 samples that can be used for NAAT to diagnose chlamydia?
- Vulvovaginal swab
- Cervical swab
- First void urine sample
When should chlamydia testing be carried out?
2 weeks after possible exposure
What screening for chlamydia is available and for what age group?
National Chlamydia Screening Programme - open to all men and women aged 15-24 years
What type of screening programme is the National Chlamydia Screening Programme?
heavily relies on opportunistic testing
What is a typical sign of chlamydia on a swab?
red inclusion bodies red
What is now the first line treatment for chlamydia?
doxycycline 7 day course
Why has first line management of chlamydia changed?
changed from azithromycin to doxycycline due to concerns about Mycoplasma genitalium - infetion often co-existent in patients with chlamydia, evidence of rising macrolide resistance
What is second-line treatment for chlamydia if doxycycline is contraindicated/ not tolerated?
azithromycin 1g od for one day, then 500mg od for 2 days
What is the drug of choice to treat chlamydia in pregnancy and what dosing?
azithromycin 1g stat
What are 3 options for treatment of chlamydia in pregnancy?
azithromycin, erythromycin or amoxicillin
What must always be done in addition to drug treatment for chlamydia?
contact tracing/ partner notification
What are the 2 choices of providers for initial partner notification when a patient is diagnosed with chlamydia?
- Trained practice nurses with support from GUM
- Referral to GUM
Which partners must be notified in the case of a male patient with urethral symptoms diagnosed with chlamydia?
all contacts since and in the four weeks prior to the onset of symptoms
What is the partner notification for women and asymptomatic men who are diagnosed with chlamydia?
all partners from last 6 months or most recent sexual parter (if none in past 6 months)
What should be offered to contacts of confirmed chlamydia cases?
offer treatment prior to results of their investigations being known (treat then test)
What causes gonorrhoea?
gram-negative diplococcus Neisseria gonorrhoeae
Where can acute gonorrhoea infection occur?
on any mucous membrane surface, typically genito-urinary but also rectum and pharynx
What is the incubation period of gonorrhoea?
2-5 days
What are 2 key symptoms of gonorrhoea in males?
- urethral discharge
- dysuria
What are the symptoms of gonorrhoea in females?
cervicitis e.g. leading to vaginal discharge
How to rectal and pharyngeal gonorrhoeal infection often present?
often asymptomatic
Why is immunisation not possible and reinfection common with gonorrhoea?
variation of type IV pili (proteins which adhere to surfaces) and Opa proteins (surface proteins which bind to receptors on immune cells)
What are 6 possible complications of gonorrhoea?
- Urethral strictures
- Epididymitis
- Salpingitis
- Infertility
- Disseminated gonococcal infection
- Gonococcal arthritis (septic arthritis)
What is now the treatment of choice for gonorrhoea?
Single dose of IM ceftriazone 1g (without azithromycin)
if sensitivities known (and organism sensitive to ciprofloxacin) then single dose of oral ciprofloxacin 500mg should be given
If the first line treatment for gonorrhoea (IM ceftriazone 1g) is refused (e.g. needle phobic) what is second line treatment?
oral cefixime 400mg (single dose) + oral azithromycin 2g (single dose)
What is the most common cause of septic arthritis in young adults?
gonococcal infection
What is thought to be the pathophysiology of DGI?
haematogenous spread from mucosal infection (e.g. asymptomatic genital infection)
What may be the classic triad of symptoms initially in disseminated gonococcal infection (DGI)?
- Tenosynovitis
- Migratory polyarthritis
- Dermatitis (lesions can be maculopapular or vesicular)
What are 3 later complications of DGI?
- Septic arthritis
- Endocarditis
- Perihepatitis (Fitz-Hugh-Curtis syndrome)
What is trichomonas vaginalis?
highly motile, flagellated protozoan parasite - sexually transmitted infection
What are 4 features of trichomonas vaginalis in women?
- Vaginal discharge: offensive, yellow/green, frothy
- Vulvovaginitis
- Strawberry cervix
- pH >4.5
What is the presentation of trichomonas vaginalis in men?
usually asymptomatic but may cause urethritis
What investigation can show the appearance of trichomonas and what will it show?
microscopy of a wet mount: motile trophozoites
What are 2 treatment options for trichomonas vaginalis?
- Oral metronidazole for 5-7 days
- One-off dose of 2g metronidazole
What is the histological appearance of trichomonas vaginalis?
largely transparent core with finely granular esoinophilis cytoplasm. surrounded by neutrophils with segmented nuclei
What is bacterial vaginosis?
overgrowth of predominantly anaerobic organisms such as Gardnerella vaginalis
leads to consequent fall in lactic acid produced aerobic lactobacilli, resulting in a raised vaginal pH
Is bacterial vaginosis sexually transmitted?
no BUT seen almost exclusively in sexually active women
In what proportion of women is bacterial vaginosis asymptomatic?
50%
If bacterial vaginosis is symptomatic, how does it present?
vaginal discharge: fishy, offensive. thin, white, homogenous
What is the appearance of bacterial vaginosis on microscopy?
clue cells: epithelial cells develop stippled appearance due to being covered with bacteria.
What is the name of the criteria used to diagnose bacterial vaginosis?
Amsel’s criteria
What are Amsel’s criteria to diagnose bacterial vaginosis?
3 of the following 4 should be present:
- 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)
What is the management of bacterial vaginosis?
oral metronidazole for 5-7 days
What is the success rate of treatment of BV with oral metronidazole?
70-80% initial cure rate; relapse rate >50% within 3 months
What are 2 alternatives to first line management for bacterial vaginosis?
- Topical metronidazole
- Topical clindamycin
What are 4 risks of bacterial vaginosis in pregnancy?
- Preterm labour
- Low birth weight
- Chorioamnionitis
- Late miscarriage
What is suggested about the management of bacterial vaginosis in pregnancy?
suggest oral metronidazole can be used throughout pregnancy
BNF still advises against use of high dose metronidazole regimes
What was previously thought to be the type of herpes that caused genital herpes?
HSV-2 and HSV-1 causes cold sores - but now known there is considerable overlap
What are 5 possible features of genital herpes?
- Painful genital ulceration
- Dysuria
- Pruritus
- Tender inguinal lymphadenopathy
- Urinary retention
How does the severity of the primary episode of genital herpes often compare with subsequent episodes?
primary often more severe than recurrent; systemic features e.g. headache, fever, malaise more common in primary episodes
What are 3 features that may be present with the primary episode of genital herpes but not recurrent episodes?
- Headache
- Fever
- Malaise
What is the investigation of choice for genital herpes?
nucleic acid amplification tests (considered superior to viral culture)
In addition to NAAT what other investigation may be performed in suspected genital herpes and why?
HSV serology: may be useful in certain situations such as recurrent genital ulceration of unknown cause
What are 4 aspects of the management of genital herpes?
- Saline bathing
- Analgesia
- Topical anaesthetic agents e.g. lidocaine
- Oral aciclovir
What treatment may be indicated in some patients with frequent exacerbations of genital herpes?
longer-term aciclovir
What is advised if a primary attack of herpes occurs during pregnancy?
elective C-section at term if occurs at greater than 28 weeks gestation
What is the management of women with recurrent genital herpes who are pregnant?
treat with suppressive thearpy, advise risk of transmission to baby is low
What are 2 STIs that can be detected using NAAT on an endocervical swab?
chlamydia
gonorrhoea
What are 4 vaginal conditions that can be detected using a high-vaginal charcoal media swab?
- Bacterial vaginosis
- Trichomonas vaginalis
- Candida
- Group B streptococcus
What STI can be detected using an endocervical charcoal media swab?
gonorrhoea
What are triple swabs vs double swabs?
- triple swabs: endocervical NAAT swab, high-vaginal charcoal media swab, endocervical charcoal media swab
- double swabs: endocervical NAAT swab, high vaginal charcoal media swab
What is the primary treatment for the first episode of genital herpes?
oral antivirals - treatment should commence within 5 days of start of episode or while new lesions forming
oral aciclovir 400mg tds for 5-10 days or 200mg 5x a day for 5-10 days
valaciclovir or famciclovir can also be used
What is the recommendation about topical antivirals for genital herpes?
not recommended as offer minimal benefit
What are 3 options for treatment of recurrent genital herpes?
- Self care alone may work
- Episodic antiviral treament if <6 attacks per year e.g. oral aciclovir 800mg tds for 2 days
- Suppressive antiviral tx if >6 attacks per year/psych distress/affecting social life e.g. aciclovir 400mg bd - continue for maximum of 1 year then stop to assess recurrence (for minimum of 2 recurrences)
If after stopping suppressive antiviral treatment for genital herpes there are high rates of recurrence, what is the management?
consider restarting suppressive antiviral treatment
