STIs Flashcards
What is the most commonly reported bacterial STI in sexual health clinics?
Chlamydia = 70-80% of women and 50% men are asymptomatic
What causes chlamydia?
Gram negative obligate intracellular bacterium = very small and stain poorly
What are the modes of transmission for chlamydia?
Vaginal, oral, anal
What age group has the highest incidence of chlamydia?
Age 20-24
How common is PID as a result of chlamydial infection?
9% of women with chlamydia will go on to develop PID = 10x increase in ectopic pregnancy and 15-20% risk of tubal factor infertility with PID
What is the prognosis of chlamydia?
Some can clear infection naturally = good TH1 and gamma interferon
Abnormal host immune response confers damage
What is the primary target of chlamydia?
Mucosal epithelial cells = replicates within vacuole
What is the presentation of chlamydia in females?
Post-coital or intermenstrual bleeding, lower abdominal pain, dyspareunia, mucopurulent cervicitis
What is the presentation of chlamydia in males?
Urethral discharge, dysuria, urethritis, proctitis, epididymo-orchitis
What are some complications of chlamydia?
PID = chlamydia causes 50% of cases
Tubal damage, chronic pelvic pain, adult conjunctivitis
Reiter’s syndrome = more common in men
Transmission to neonate, Fitz-Hugh-Curtis syndrome
Who should be tested for chlamydia?
Stop testing in women >age 25 with vaginal discharge
Test women who have had chlamydia in past year
How common is reinfection with chlamydia?
1 in 5 women with diagnosed and treated with chlamydia are likely to become re-infected within 10 months after initial treatment
What is LGV?
Serovars of chlamydia trachomitis (L1-L3) = common in male/male sex
What are some features of LGV?
High risk of concurrent STIs = 67% have HIV
Symptoms = rectal pain, discharge, bleeding
How is chlamydia diagnosed?
Test 14 days following exposure
Nucleic acid amplification test = vulvovaginal swab for females and first void urine in males
What swabs should be added when testing for chlamydia if male/male receptive anal sex?
Add rectal swab
How is chlamydia treated?
Doxycycline 100mg twice daily for 1 week
Azithromycin 1g starting followed by 500mg daily for 2 days
What is mycoplasma genitalium?
Emerging sexually transmitted pathogen = associated with non-gonococcal urethritis and PID
What are some features of mycoplasma genitalium?
Prevalence of 1-2% of population
Asymptomatic carriage
Tested for using nucleic acid amplification
High levels of macrolide estimated at 40%
What causes gonorrohea?
Gram negative intracellular diplococcus
What are the primary sites of gonorrhoea infection?
Mucous membranes of urethra, endocervix, rectum and pharynx
What is the incubation period for urethral gonorrhoea in men?
Short incubation = 2-5 days
What is the risk of spreading gonorrhoea to a partner?
20% risk from infected woman to uninfected male
50-90% risk from infected man to uninfected female
What is the presentation of gonorrhoea in men?
Asymptomatic in <= 10% = pharyngeal and rectal infections usually asymptomatic
Urethral discharge in >80%
Dysuria
What is the presentation of gonorrhoea in women?
Asymptomatic in up to 50% = pharyngeal and rectal infections usually asymptomatic
Increased or altered vaginal discharge in 40%
Dysuria and pelvic pain (<5%)
How common are complications from gonorrhoea?
Occur in 3% of females and <1% of males
What are some lower genital tract complications of gonorrohea?
Bartholinitis, tysonitis, periurethral abscess, rectal abscess, epididymitis, urethral stricture
What are some upper genital tract complications of gonorrhoea?
Endometritis, PID, hydrosalpinx, infertility, ectopic pregnancy, prostatitis
What tests can be done for diagnosing gonorrhoea?
Nucleic acid amplification test = >96% sensitivity
Microscopy and culture
When is microscopy done for gonorrhoea?
Symptomatic testing = urethral has 90-95% sensitivity, endocervical has 37-50% sensitivity
When is culture done for gonorrhoea?
If microscopy positive or if contact of case = urethral has >95% sensitivity, endocervical has 80-92% sensitivity
What is the treatment of gonorrhoea?
First line = IM ceftriaxone 500mg
Second line = oral cefixime 400mg (only if IM contraindicated or refused)
When do you do test of cure for gonorrhoea?
After two weeks of treatment
What kind of infections may cause genital herpes?
Primary infection, non-primary first episode, recurrent infection
How long does genital herpes last for?
Incubation period of 3-6 days
Duration of 14-21 days
What are the symptoms of genital herpes?
Blistering and ulceration of external genitalia, pain, external dysuria, vaginal/urethral discharge, local lymphadenopathy, fever, myalgia
What are some features of recurrent episodes of genital herpes?
More common with HSV-2 Often misdiagnosed as thrush Usually unilateral small blisters and ulcers Minimal systemic symptoms Resolves within 5-7 days
What do you swab for diagnosing genital herpes?
Swab base of ulcer for HSV PCR
What is the treatment for genital herpes?
Oral aciclovir 400mg 3x for five days a week
Consider topical lidocaine 5% ointment if very sore
Saline bathing and analgesia
What are some features of viral shedding in genital herpes?
Higher in HSV2 and reduced by suppressive therapy
More frequent in 1st year of infection
More common in people with frequent recurrences
When would you consider giving suppressive therapy for genital herpes?
If patient has 6 or more attacks per year
How does genital herpes affect pregnancy?
50% risk of transmission if primary HSV
70% of babies have localised CNS or disseminated disease
Disseminated HSV more common in preterm infants
What is the most common viral STI in the UK?
HPV = lifetime risk of up to 80%
How many genotypes are there of HPV that could cause an STI?
> 40 genotypes that infect anogenital epithelium
Low risk = types 6, 11, 42, 43 and 44
High risk = types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68
What are some types of infection that different HPV genotypes can cause?
Anogenital = types 6 and 11
Palmoplantar warts = types 1 and 2
Cellular dysplasia = type 16
Cervical, anal, penile, vulval and oropharyngeal = type 18
What is the incubation period for HPV?
3 weeks up to 9 months
What is the prognosis of HPV?
20-34% will clear spontaneously
60% clear with treatment
20% are treatment-resistant
What causes over 90% of anogenital warts?
HPV types 6 and 11
What are the treatments for HPV?
Imiquimod = can be used for all anogenital warts but not licensed for pregnancy
Podophyllotoxin = not for extra-anogenital use, not licensed for pregnancy
Cryotherapy and electrocautery
Who is vaccinated against HPV?
Girls aged 11-13, adolescent boys, gay men
What causes syphilis?
Treponema pallidum bacteria
How is syphilis transmitted?
Through sexual contact, during birth, through placenta, via blood transfusion = classed as congenital or acquired
What types of syphilis are infectious?
Infectious = primary, secondary, early latent Non-infectious = late latent, tertiary
What is the incubation period of primary syphilis?
Incubation from 9-90 days = mean is 21 days
What are the symptoms of primary syphilis?
Non-tender local lymphadenopathy
Lesion known as primary chancre = painless and at site of inoculation (90% are genital)
What is the incubation period of secondary syphilis?
incubation of 6 weeks -6 months
How may the skin be involved in secondary syphilis?
Macular, follicular or pustular palmoplantar rash
What are the symptoms of secondary syphilis?
Rash, lesions of mucous membranes, generalised lymphadenopathy, patchy alopecia, condylomata lata
What is condylomata lata?
Most highly infectious lesion of syphilis = exudes serum filled with treponemes
How is syphilis diagnosed?
Samples from lesions or infected lymph nodes used for dark field microscopy or PCR
Serological testing for antibodies
What are some serological tests done for syphilis?
Non-treponemal = VDRL, RPR Treponemal = TPPA, INNO-LIA, FTA abs
What is the screening test done for syphilis?
ELISA enzyme immunoassay
What is the treatment for syphilis?
Early syphilis = 2.4 MU benzathine penicillin x1
Late syphilis = 2.4 MU benzathine penicillin x3
How long do you follow up syphilis patients for?
Until RPR is negative or serofast = titres should decrease by fourfold by 3-6 months in early syphilis
When does syphilis relapse occur?
If titres increase by fourfold
What STIs are tested for in an STI screen?
Gonorrhoea, chlamydia, syphilis and HIV
What samples are taken for gonorrhoea and chlamydia?
Vulvovaginal swab = women
First pass urine sample = men
Rectal and throat swab = male/male sex, gonorrhoea on microscopy and gonorrhoea contacts
What symptomatic sampling can be done for vaginal/urethral discharge?
Cervical and urethral microscopy = gram stain Vaginal microscopy (gram stain, wet prep) and narrow range pH Amies swab = HVS culture and sensitivity
When would you take an Amies swab?
Recurrent or persistent discharge Vaginitis of unknown cause Pregnant or post partum Post gynaecological surgery or instrumentation Signs and symptoms of PID
How is PID treated?
Ceftriaxone 1g IM, doxycycline 100mg twice daily for two weeks and metronidazole 400mg twice daily for two weeks
What are the serovars of chlamydia?
A-B = endemic trachoma (ocular infections) D-K = urethritis, PID, epididymo-orchitis, neonatal pneumonia and conjunctivitis L1-3 = lymphogranuloma venereum
How does gonorrhoea presentation vary depending on the site that is infected?
Urethral = discharge in >90%, dysuria Pharyngeal/rectal = mostly asymptomatic Endocervical = discharge in 50%, irregular bleeding, external dysuria
