Sexually Transmitted Infections Flashcards
What are the standard STIs tested for?
Chlamydia
Gonorrhoea
HIV
Syphillis
How do you test for chlamydia and gonorrhoea?
NAAT
Increased sensitivity over culture
Where are NAAT samples taken?
Vulvovaginal swab or endocervical swab
Throat swab
Rectal swab
Urine - first void sample in males
What is a problem with NAAT?
It can detect dead organisms - wait 5 weeks to do cure test
How do you test for HIV/Syphilis?
Blood test
When a patient presents with discharge what tests can be done?
Cervical microscopy (gram stain)
Vaginal microscopy and pH (>4.5 in pathology)
Urethral microscopy (gram stain)
Amies swab
When should a amies swab be done?
High vaginal swab in HSV, unknown cause of discharge, pregnant, postpartum, post gynae, PID
What is the commonest STI in the UK?
Chlamydia
Where does chlamydia infect?
Columnar epithelium at mucosal site - urethra, rectum, throat, eyes, endocervix
How is chlamydia transmitted?
Vaginal, oral or anal sex
What percentage of patients with chlamydia are asymptomatic?
70-80% of women
50% of men
What are the symptoms of chlamydia?
Milky Discharge (men) Irregular bleeding (women) Abdominal pain (both) Dysuria (men)
What are the signs of chlamydia?
Urethritis
Cervicitis
Epididymo-orchitis
Proctitis (LGV)
Name the three serological groups of chlamydia
Serovars A-C - trachoma
Serovars D-K - genital infection
Servers L1-L3 - lymphogranuloma venereum
Describe lymphogranuloma venereum
Mainly in MSM, rectal pain, discharge and bleeding
67% also have HIV
Describe the bacteria chlamydia trachomatis
Obligate intracellular bacteria with biphasic life cycle, does not stain with gram stain - no peptidoglycan in cell wall. Cannot reproduce outside of host.
What is the treatment of chlamydia?
1st - doxycycline 100mg BD 7 days
2nd - azithromycin 1g stat followed by 500mg daily for 2 days
What is the treatment in PID?
Inpatient - ceftrixone, metronidazole, doxycycline
Outpatient - ofloxacin & metronidazole
State the complications of chlamydia
PID, tubal damage, conjunctivitis, pneumonia, reactive arthritis (righters), Fitz Huge Curtis
Describe Fitz Huge Curtis
Perihepatitis - piano string adhesions from liver
What is the testing advice for chlamydia?
14 days following exposure, >25 years old with discharge rarely chlamydia - high re-infection rate
Describe the action of bacteria neisseria gonorrhoea
Gram negative intracellular diplococcus - attaches to host epithelial cells and endocytose into the cell to replicate
Why does GC appear intracellularly on gram film?
Easily phagocytose by polymorphs
How does gonorrhoea present?
Mucopurulent urethral discharge, dysuria, endocervical - discharge, irregular bleeding, external dysuria, pharyngeal/rectal is usually asymptomatic
How is gonorrhoea investigated?
NAATs - urethral/endocervical swab
Microscopy if symptomatic
Culture is positive microscopy or GC contact - endocervical, rectal, throat swab
Why are cultures only done in the clinic?
GP were false negatives as the organism would die on the way to lab
How is gonorrhoea treated?
1st Ceftriaxone 1g IM
2nd Cefixime 400mg + azithromycin 2g
What is the incubation period for gonorrhoea?
2-5 days
What are the lower genital tract complications of gonorrhoea?
Bartholinitis Tysonitis Periurethral abscess Rectal abscess Epidiymitis Urethral stricture
What are the upper genital tract complications of gonorrhoea?
Endometritis PID Hydrosalpinx Infertility Ectopic pregnancy Prostatis
What is the new emerging STI?
Mycoplasma genitalium
How is mycoplasma genitalium managed?
NAAT test - high levels of macrolide resistance
What bacteria causes syphilis?
Treponema Pallidum Palldium subtype
How is syphilis transmitted?
Sex
During birth
Trans-placental
Describe primary syphilis
Organism multiples at inoculation site to form a chancre (90% genital) and then gets into the blood stream
What is the incubation period of primary syphilis?
9-90 days
Other than chancre what else can be present in primary syphilis?
Non-tender local lymphadenopathy
Describe secondary syphilis
Large number of bacteria circulating in blood with multiple manifestations at different sites
What is the incubation period for secondary syphilis?
6 weeks to 6 months
Describe the signs and symptoms of secondary syphilis
Snail track mouth ulcers Generalised rash (hands and feet) Malaise Anterior uveitis Cranial nerve lesion Condylomata lata
Describe condylomata lata
Highly infectious lesion exudes a serum teeming with treponemes
Describe latent syphilis
No symptoms but low level multiplication of spirochaete in intima of blood vessels
What happens in late syphilis?
Cardiovascular and neuromuscular complications
How is primary syphilis diagnosed?
Dark field microscopy
PCR
IgM
How is secondary and tertiary syphilis diagnosed?
Serology to detect antibodies
- non-treponemal (RPR - disease activity)
- treponemal
Describe the treatment of syphilis
Early - 2.4MU benzathine penicillin stat
Late - 2.4MU benzathine penicillin weekly x 3 weeks
What follow up should be done in syphilis?
Serology - RPR is negative, decrease by four fold by 3-6 months post treatment
What causes genital herpes?
HSV1 and HSV2
Describe the herpes virus
Enveloped virus containing double-stranded DNA transmitted by close contact with someone shedding the virus
Which virus is shed more easily?
HSV2
Describe the pathogenesis of herpes
- Virus duplicates in dermis and epidermis
- Gets into nerve endings of sensory and autonomic nerves
- Inflammation causes painful small vesicles which are easily reroofed
- Virus migrates to sacral root ganglion and hides from immune system
- Reactivation leads to genital herpes
What is the duration and incubation of primary herpes?
Incubation 3-6 days
Duration 14-21 days
How can primary herpes present?
Blistering, ulceration, pain, dysuria, discharge, lymphadenopathy, fever, malaise
Describe recurrent herpes
Usually HSV2 unilateral small blisters and ulcers, minimal systemic involvement - resolves in 5-7 days
How is herpes diagnosed?
Swab in virus transport medium of reroofed blister for PCR
How is herpes treated?
Aciclovir 400mg TDS 5 days
Topical lidocaine 5% ointment if painful
Saline bathing
Analgesia
What is the special circumstance for herpes treatment?
First episode in 3rd trimester within 6 weeks of delivery dates, ask if first episode - HSV NAAT and type specific serology for antibodies
Risk of neonatal herpes
State the differential diagnosis of genital lumps
- skin tags
- molluscum contagiosum (pox virus)
- spots of fordyce (blockage of sebaceous gland)
- pearly penile papules (normal)
What is the most common viral STI in UK?
HPV
What is the most oncogenic type of HPV?
Type 16
Which types of HPV cause warts and are low risk?
Type 6 and 11
Name the different features of HPV depending on type
- latent infection
- anogenital warts
- palmar and plantar warts (11 and 6)
- cellular dysplasia/intra-epithelial neoplasia (16 and 18)
What is the incubation period of HPV?
3 weeks to 9 months
Describe anogenital warts
Cauliflower lesions at sites of friction - HPV 6 and 11
What are the treatment options for HPV?
Podophyillotoxin - cytotoxic liquid
Imiquimod - immune modifier better for peri-anal disease and supports immune and superficial clearance
Cryotherapy - requires multiple treatments
Electrocautery
Who is given the HPV vaccination?
Girls 11-13
MSM
S1 boys
Describe pubic lice
Close genital skin contact, they bite and feed on blood causing itch
Female lay eggs and can survive unto 17 days
Males can survive for 22 days
How are pubic lice treated?
Malathion lotion
What bacteria are naturally present in the vagina?
Lactobacillus
Group B Strep
Candida
Strep viridian’s
Why is lactobacillus significant?
Produces lactic acid+/- hydrogen peroxide to create an acidic pH
What is the characteristic appearance of candida?
Budding yeast and hyphae
State the predisposing factors to candida?
Recent antibiotics
High oestrogen (pregnancy/contraception)
Poorly controlled diabetes
Immune-compromised patients
How does candida present?
Itchy cottage cheese white discharge
How is candida diagnosed?
Examination and high vaginal swab
How is candida treated?
Clotrimazole Pessary or cream
Oral fluconazole
What does candida look like in males?
Spotty rash of balanitis
Name a sexually transmitted parasite
Trichomonas vaginalis
How does Trichomonas vaginalis present?
Vaginal discharge and irritation in females
What is the diagnosis and treatment of Trichomonas vaginalis ?
Diagnosed with high vaginal swab for microscopy
Treatment with oral metronidazole
What is bacterial vaginosis?
Overgrowth of anaerobic bacteria - homogenous discharge may contain bubbles
Describe the microscopic appearance of bacterial vaginosis
Bacilli replaced with coccobacilli and few leukocytes
How does bacterial vaginosis present?
Asymptomatic, vaginal discharge, fishy odour particularly worse after sex/menstruation
What does bacterial vaginosis increase your risk of?
Upper tract infection, premature rupture of membranes and preterm delivery, increased risk of acquiring HIV
How is bacterial vaginosis treated?
Metronidazole 7 days
What is the relapse rate of bacterial vaginosis?
30%