Sexually Transmissible Infections Flashcards
What are sexually transmissible infections (STIs)?
Infections transmitted primary during sexual contact
What are the routes of transmission for STIs?
Oral-genital contact
Vaginal intercourse
Anal intercourse
Anilingus
How are STIs detected?
Microscopy
Culture
Serology
Nucleic acid amplification tests
What are the 5 P’s of a sexual history?
Partners - Male/female/both - Number Pregnancy prevention Protection from STIs Practices Past history of STIs
What is the cellular morphology of Neisseria gonorrhoeae?
Intracellular Gram negative diplococci
What cells do N gonorrhoeae enter and how?
Adhere to columnar epithelial cells via pilli
Enter cells around cervix and urethra
Can also survive in neutrophils
What is the incubation period for N gonorrhoeae?
2-7 days
What proportion of infections ins asymptomatic?
80% in females
10% in males
What symptoms does N gonorrhoeae cause?
Pain
Discharge
What disseminated diseases can N gonorrhoeae cause?
Arthritis Maculopapular rash Meningitis Endocarditis Epididymitis Peri-hepatitis
When is risk of disseminated disease with N gonorrhoeae greater?
Post menses
When can pelvic inflammatory disease develop after an gonococcal infection?
1-2 weeks
What can pelvic inflammatory disease cause?
Tubal scarring
Infertility
What is neonatal gonococcal ophthalmia?
Gross purulent conjunctivitis
When does neonatal gonococcal ophthalmia develop?
Day 2-5 of life
What does neonatal gonoccocal ophthalmia cause?
Mild disease indistinguishable from other causes of conjunctivitis
Perforation of front of eye and blindness
What is the treatment for gonococcal ophthalmia?
IV cefotaxime, 7 days
Irrigate eyes regularly
Treat mother and sexual contacts
What specimens can be taken for the diagnosis of gonorrhoea?
Cervical swab into charcoal transport Male urethral swabs Urine Other specimens - Conjunctiva - Pharynx - Skin lesions - Anal - CSF - Blood - Synovial fluid
What are the lab investigations for the diagnosis of gonorrhoea?
Non-selective: CHB in CO2
Selective: Thayer-Martin agar
Culture for antibiotic sensitivities
What antimicrobials are found in Thayer-Martin agar?
Colistin - kills Gram negative bacteria
Vancomycin - kills Gram positive bacteria
Nystatin - kills fungi
In what proportion of gonorrhoea cases is there a co-infection with chlamydia?
50%
What is the treatment for gonorrhoea?
Ceftriaxone
Azithryomycin - also kills chlamydia
How do you prevent gonorrhoea?
Barrier contraception
Contact tracing
Which organism causes chlamydia?
Chlamydia trachomatis
What are the signs and symptoms of cervicitis?
Swollen Red Friable Columnar epithelium exposed Bleeds easily when touched
What is the cellular morphology of C trachomatis?
Obligate intracellular bacteria
What cell type does C trachomatis invade?
Columnar epithelium
What serovars of C trachomatis causes genital infection?
D-K
What serovars of C trachomatis cause lymphogranuloma venereum (LGV)?
L 1-3
What serovars of C trachomatis cause ocular infection (trachoma)?
A-C
How long is the life cycle of C trachomatis?
48-72 hrs
What are the two forms of C trachomatis during its life cycle?
Elementary bodies - Infectious - Non-replicating - Hardy Reticulate bodies - Metabolically active - Replicate
What is the life cycle of C trachomatis?
- Attachment and entry of elementary body to target cell
- Formation of reticulate body
- Binary fission of reticulate bodies
- Reorganisation of reticulate bodies into elementary bodies
- Multiplication ceases
- Release of elementary bodies
What is the most common STI?
Chlamydia
What does chlamydia cause in males and females?
Males: urethritis
Females: cervicitis
Is chlamydia always symptomatic?
No, frequently asymptomatic
What are the clinical findings of chlamydia in males?
Dysuria Meatal erythema Clear urethral discharge - Not as purulent as gonorrhoea Testicular pain Prostatitis
What are the clinical findings of chlamydia in females?
Cervicitis, endometritis/vaginal discharge Urethritis/dysuria Irregular bleeding Pelvic pain and dyspareunia Pelvic inflammatory disease - Acute - Chronic
What is LGV?
Invasive lymphatic infection
What are the clinical features of GLV?
Ulcerative genital lesion, similar to chancre of syphilis
Suppurative inguinal lymphadenopathy
Systemic symptoms
Men who have sex with men: proctocolitis
What is proctocolitis?
Inflammation of rectum and colon
Where is LGV endemic?
Africa
India
Southeast Asia
South America
What is the rate of vertical transmission of chlamydia?
50%
What does neonatal chlamydia present as?
Conjunctivitis
Pneumonia
When does conjunctivitis caused by neonatal chlamydia appear?
2-28 days
When does penuomonia caused by neonatal chlamydia appear?
2-8 weeks
What are the lab investigations for the diagnosis of chlamydia?
Cervical/urethral/anal swab Urine Nucleic acid detection Test of cure needed - Post-procedure; eg: IUD insertion - Pregnancy
What is the mainstay of chlamydia identification?
Nucleic acid detection
Why is chlamydia culture not routine?
Needs cell culture techniques
What is the treatment for chlamydia?
Azithromycin, oral OR Doxycycline, oral - Less well tolerated Contact trace partners Notifiable disease Test of cure in 4-6 weeks Advise retest in 3 months
What is the treatment for severe chlamydia causing pelvic inflammatory disease?
Azithromycin, IV > step down to oral when well
What can repeated episodes of chlamydia cause?
Scarring
What is the cellular morphology of Trichomonas vaginalis?
Flagellated protozoan
Can you get female to female transmission of T vaginalis?
Yes
Can you get male to male transmission of T vaginalis?
Very rare
Can T vaginalis be asymptomatic?
Yes, frequently
How is T vaginalis transmitted?
Sexually
What are the clinical features of a T vaginalis infection?
Vaginal discharge - Frothy - Green-yellow - Smelly, fishy odour Cervical erythema and friability Pruritis Dysuria Abdominal pain
What is the presence of T vaginalis a marker for?
High risk sexual activity
Possibility of other STIs
- Chlamydia
- Gonorrhoea
What does the genital inflammation caused by T vaginalis increase the risk of acquiring?
HIV
How does a T vaginalis infection increase the risk of HIV acquisition?
In females: shed more HIV virions
If males HIV positive, females more susceptible
What is a T vaginalis infection associated with?
Non steady partner
Older partner
Marijuana use
In which demographic does T vaginalis have an increased prevalence?
Indigenous community
What are the lab investigations for T vaginalis?
High vaginal swab - Wet prep microscopy to detect motility - Culture Urine - PCR Sometimes seen on Pap smear
What is the treatment for T vaginalis?
Metronidazole, oral Tinidazole, oral Clindamycin cream Treat partners Follow up testing
Why is follow up testing required after treatment for a T vaginalis infection?
May have resistance
What is the causative organism of syphilis?
Treponema pallidum
What are the clinical features of primary syphilis?
Lesions at site of inoculation on mucous membranes
5 weeks after inoculation
Chancres = painless ulcers
What are the clinical features of secondary syphilis?
3-6 months after primary lesions healed Fever Rash Alopecia Some hepatitis
What are the stages of syphilis?
Primary Secondary Early latent Late latent Tertiary
How is T pallidum detected in the lab?
Microscopy - Hard to see on light microscopy - Can use dark field microscopy Serology - Non-treponemal tests - Treponemal tests
What non-treponemal test is used regularly?
RPR
Describe non-treponemal tests
Abs to cellular lipids and lecithin
Positive 4-8 weeks post infection
70% positive within 2 weeks of chancre
100% positive fr secondary and latent
What are non-treponemal tests useful for?
Diagnosis
Monitoring therapy
What can cause false positive reactions in non-treponemal tests?
Connective tissue disorders
Viral infections
IV drug use
Pregnancy
What can cause false negative reactions in non-treponemal tests?
Prozone effect
- Excess Abs can give negative results
What are treponemal tests used for?
Screening
What is the most regularly used treponemal test?
EIA
What doesn’t Mycoplasma genitalium have which other bacteria doo?
Cell wall
Can M genitalium be cultured?
Not easily
- Fastidious
- Difficult to culture > takes 1-2 months to grow
What is the mainstay of diagnosis of M genitalium?
NAAT
What samples are used for the diagnosis of M genitalium?
Ist void urine
Vaginal swab
How is M genitalium transmitted?
Sexually
What is the antibiotic susceptibility of M genitalium?
Antibiotic resistant
What is the clinical presentation of M genitalium?
Males: urethritis - 50% asymptomatic Females - Cervicitis - Acute endometritis - Pelvic inflammatory disease, especially post termination of pregnancy
How long can an M genitalium infection persist for?
3-6 months
What may an M genitalium infection predispose you to?
HIV transmission
How can azithromycin resistance be tested for in M genitalium?
Whilst doing NAAT
What is the treatment for an M genitalium infection?
Azithromycin
What is the failure rate of azithromycin as a treatment for an M genitalium infection?
15%
What can be used in treatment if M genitalium is resistant?
Moxifloxacin
What are the limitations of the use of moxifloxacin?
Expensive
Failures described
Not safe in pregnancy
What are the indications for STI testing?
Symptomatic patient Screening for asymptomatic infection Pre-pregnancy Antenatal screening Blood and organ donation Contact tracing Epidemiological surveillance
