STIs Flashcards
Define commensal micro-organism
Micro-organism that derives food/benefits from another organism without harming or benefiting it
Define pathogen
A micro-organism that causes disease
Define infection
Invasion/multiplication of the body by an organism that is not usually found on it
Define sexually transmissible micro-organism
Virus, bacteria, parasite which is spread by means of sexual contact (can be commensal or pathogenic)
Define STI
An infection caused by a pathogen which is spread by sexual contact and is unlikely to be spread by other means
Define STD
Disease resulting from an STI e.g. genital warts, PID
What bacteria are considered STIs?
Neisseria gonorrhoea Chlamydia trachomatis Klebsiella granulomatis Mycoplasma genitalium Treponema pallidum
What viruses are considered STIs?
Molluscum contagiosum
HSV
HIV
HPV
What parasites are considered STIs?
Pthirus pubis
Sacroptes scabei
Trichomonas vaginalis
What are some common features of STIs?
Transmissible, manageable, often asymptomatic and avoidable
List the different types of sexual contact from highest risk of catching an STI to lowest risk
Fisting/traumatic sex Group sex Anal sex Vaginal sex Oral sex Touching someone's genitals with your own Mutual masturbation
What can be spread from genital contact only?
Pthirus pubis (public lice)
Scabies (sacroptes scabeii)
Warts (HPV 6 and 11)
HSV types 1 and 2
What tends to be spread through blood transmission/group sex?
Hep C
Why are STIs important?
They can kill, cause unpleasant symptoms, psychological distress and are costly and v. common
What are symptoms of STIs?
Ulceration (syphilis, herpes, chancroid)
Lumps (HPV 6 and 11)
Discharge (penis, rectum, vagina, eye)
Rashes (itchy/non-itchy, genital or trunk in HIV)
Systemic symptoms: fever, rash, lymphadenopathy, malaise, infertility, cervical cancer, adverse pregnancy outcomes
Why do diagnoses of STIs change over time?
- true change in no of cases (e.g. more condom use, more MSM, more sex and more partners, vaccination)
- change in no of diagnoses without change in no of cases (more awareness –> more tests –> more diagnoses) & better tests
Explain cores and assertive mixing
Some people have sex only with people similar to them
–> high prevalence in a certain group but limited spread
E.g. syphilis in those who exchange sex for drugs
Explain chains and random mixing
Some groups are v. large, e.g. heterosexual men and woman –> low prevalence but wider dissemination along chains
What is important to do in managing STIs?
Partner notification
Diagnosis and treatment
Health promotion
What are the two forms of partner notification?
Patient tells contact - client referral (preferred)
NHS tells contact - provider referral
What causes gonorrhoea?
Neisseria gonorrhoeae
What are the symptoms of gonorrhoea?
M: asymptomatic or thick, yellow discharge
W: asymptomatic, vaginal discharge, dysuria, IMB/PCB
What are the complications of gonorrhoea?
M: epididymitis
W: PID/Bartholin’s abscess
B: acute monoarthritis
How do you diagnose gonorrhoea?
Nucleic acid amplification test
What is the treatment for gonorrhoea?
500mg ceftriaxone IM + 1g azithromycin
What causes chlamydia?
Chlamydia trachomatis
What are the symptoms of chlamydia?
M: asymptomatic mostly, or watery discharge, dysuria
W: mostly asymptomatic, vaginal discharge, dysuria, IMB/PCB
B: conjunctivitis
What are the complications of chlamydia?
M: epididymitis
W: PID, ectopic, infertility
B: reactive arthritis/Reiter’s syndrome (urthritis/cervitis, arthritis, conjunctivitis)
How do you diagnose chlamydia?
NAAT
How do you treat chlamydia?
Azithromycin 1g po 1x
Doxycycline 100mg bd 1xwk if rectal infection
What causes herpes?
HSV 1 and 2
What are the symptoms of herpes?
Asymptomatic, recurrent symptoms monthly/annually
Burning/tingling –> blistering and tender ulceration
Inguinal lymphadenopathy flu like symptoms, dysuria, neuralgic pain in back, pelvis and legs
What are complications of herpes?
Autonomic neuropathy (urinary retention), neonatal infection, secondary infection
How do you diagnose herpes?
Clinical or swab from lesion and PCR
What is the treatment for herpes?
1st outbreak - acyclovir 400mg tds 5 days, lidocaine ointment
Infrequent outbreaks - lidocaine, acyclovir 1.2g 1-3d
Frequent outbreaks - acyclovir 400bd long term suppression
What causes trichomoniasis?
Trachomonas vaginalis
What are the symptoms of trichomoniasis?
Usually asymptomatic in men
W: profuse, thin, watery discharge - green, frothy, smelly, vulvitis
What are the complications of trichomoniasis?
Miscarriage/preterm labour
How do you diagnose trichomoniasis?
PCR on swab
How do you treat trichomoniasis?
Metronidazole 400mg bd 5d/2g single dose
What causes anogenital warts?
HPV 6 and 11
What is the appearance of anogenital warts?
Cauliflower lumps with itching and bleeding
How do you diagnose anogenital warts?
Appearance
Can biopsy if they look unusual
How do you treat anogenital warts?
Podophyllotoxin, imiquimoid, cryotherapy, diathermy, scissor removal
What causes syphilis?
Treponema pallidum
What is the presentation of syphilis?
Primary - chancre
Secondary - rash, mucosal ulceration, neuro symptoms, patchy alopecia
Early latent - no symptoms <2y
Late latent - no symptoms >2y
Tertiary - neurological, CV, gummatous disease & skin lesions
In which group of people is syphilis most common?
MSM
What are the complications of syphilis?
Neurosyphilis - cranial nerve palsies
Cardiac/aortic involvement
How do you diagnose syphilis?
Serology for TP
PCR from ulcer sample
How do you treat syphilis?
Early (<2y + no neuro involvement) - benzathine penicillin 2.4MU IM once or doxycycline 100mg bd po 2wks
Late (>2y + no neuro involvement) - benzathine penicillin 2.4MU x3 or doxycycline 100mg bd po 28 days
