Sexually Transmitted Infection Flashcards
Commonest STI?
Chlamydia
Chlamydia trachomatis appearance on gram stain
Obligate intracellular organism
Doesn’t stain on gram stain
What is Chlamydia trachomatis divided into?
What is the clinical implication of this?
Serovars
Serovars A-C = eye infection
Serovars D-K = genital infection
Serovars L1-3 = lymphogranuloma venereum
Symptoms of chlamydia?
Pain
Dysuria/Dyspareunia
Vaginal bleeding (post-coital/intermenstrual)
How long does chlamydia take to show symptoms?
Might never show symptoms
Commonly asymptomatic
What microorganism is responsible for chlamydia infection?
chlamydia trachomatis
chlamydia is always sexually transmitted. true or false?
False
Mothers can transfer to neonates during childbirth
How does neonatal chlamydia present?
Conjunctivitis
Pneumonia
What is lymphogranuloma venereum?
What microoganism causes it?
Chlamydia infection of lymphatics
Occurs when microbe crosses anal mucous membrane and is taken up by lymphatics
chlamydia trachomatis L1,2,3
Man presents with dysuria 4 months after successful treatment of an STI.
Diagnosis?
What else would be expect to see?
What do you think the STI was?
Reactive arthritis
Arthritis, conjunctivitis, urethritis
Chlamydia
First and second line treatments for chlamydia.
1st: doxycycline (7 days)
2nd: azithromycin (3 days)
What organism causes gonorrhoea?
Neisseria gonorrhoeae
Neisseria gonorrhoeae appearance on gram stain.
Gram negative intracellular diplococcus
What organism can be cultured on chocolate agar?
Neisseria gonorrhoeae
Presentation of gonorrhoea.
Discharge (vaginal, urethral pus)
Pain
Dysuria
First and second line treatments for gonorrhoea.
1st: IM ceftriaxone
2nd: oral cefixime
What do these viruses cause?
HSV-1
HSV-2
HPV-6
HPV-11
HSV-1: genital herpes
HSV-2: genital herpes
HSV-6: genital warts
HSV-11: genital warts
What makes someone with HSV infectious?
Viral shedding
What HSV virus most commonly undergoes viral shedding?
What is the clinical implication of this?
HSV-2
In general, this means they are more contagious (particularly in first year of infection)
Why must a patient be symptomatic when they are viral shedding?
They don’t have to be
This isn’t true
Viral shedding can occur asymptomatically
How does primary genital herpes infection present?
Painful blistering
Pain, dysuria, discharge
Systemic symptoms
How do you diagnose genital herpes?
Swab re-roofed ulcer for PCR
Why can genital herpes be recurrent?
Migrates to dorsal root ganglion
How do you treat primary genital herpes infection?
oral acyclovir (lignocaine for pain)
How does a relapse of genital herpes infection present?
Small unilateral ulcers
Mild tingling
Few systemic symptoms
How do you manage a patient with herpes in pregnancy?
Treat all herpes with acyclovir during pregnancy
If history of recurrent infection, treat prophylactically from 36 weeks gestation
What microbe is responsible for syphilis infection?
Treponema pallidum
How does treponema pallidum appear on gram stain?
Doesn’t stain on gram stain
Spirocheate organism
Describe the stages of syphilis infection and when they occur.
Primary: painless chancre at site of contact (~2 weeks post infection)
Secondary: erythematous palmoplantar rash, snail track ulcers and flu (~4 months post infection and pass over a few weeks)
Latent: asymptomatic (can last decades)
Late: life threatening cardiovascular and neurological damage (long time after initial infection)
What is the simplest test to do in suspected syphilis?
Swab chancre for PCR
What blood tests can you order for suspected syphilis?
What do they tell you?
IgM/IgG ELISA test
- screening test
TPPA/TPHA
(treponema pallidum particule/haem-agglutination assay)
- positive result confirms infection
- may be positive for life after infection
VDRL/RPR
(venereal disease research laboratory test / rapid plasma reagin)
- non specific test
- used to monitor treatment response
Dark ground microscopy can be used to see which type of organism?
Treponema pallidum
Management of syphilis.
IM benzathine benzylpenicillin
long acting
5% of people with HPV ___ infection go onto develop genital warts. True/false?
False
1%
____ = 6/11
How do you manage genital warts?
Topical podophyllotoxin
Screen for other STIs
Viruses causing
- genital warts
- genital herpes
warts: HPV 6/11
herpes: HSV 1/2
Increased sexual partners increases risk of bacterial vaginosis. True/false?
True
Not a sexually transmitted infection but lots of partners increases risk
What are the normal vaginal flora?
Lactobacilli
Produce lactic acid
What do the normal vaginal flora produce and what does this do?
Lactobacilli produce lactic acid to suppress growth of other microbes
What can be seen on microscopy in bacterial vaginosis?
Lactobacilli replaces by clumps of coccobacilli
Clue cells - clumps obscure edges of vaginal epithelial cells
How do you treat bacterial vaginosis?
Metronidazole
In what infection would you consider the whiff test?
What does it involve and show?
Bacterial vaginosis
Adding potassium hydroxide to vaginal discharge produces fishy odour
How does bacterial vaginosis present?
Vaginal discharge
What microorganism causes trichomoniasis?
Trichomonas vaginalis
Single celles protozoa
In what condition might you see an alkaline vagina?
What is the normal pH?
Trichomoniasis
(pH>5)
3.5-4.5
How might trichomoniasis present?
Vaginal discharge (thin, frothy, fishy)
Itchy vagina
How do you treat trichomoniasis?
Metronidazole
What is the name of the emerging sexually transmitted pathogen which may be a big problem in the future?
Mycoplasma Genitalium
What is PID and what causes it?
• Ascending infection of the female reproductive tract
Chlamydia, gonorrhoea (bacterial vaginosis)
How does PID present?
In a very varied way (from asymptomatic to severe)
Pelvic pain, abnormal discharge, fever, N+V
How do you treat PID?
Metronidazole + ofloxacin
What is the nucleic acid amplification test (NAAT)?
What does it test for?
Sensitive PCR test
Both chlamydia/gonorrhoea in one test
Where would you take the sample from in NAAT from
- male?
- female?
Where else might you swab and why?
M: first pass urine
F: vuvlovaginal swab
Rectum, pharynx (MSM)
Although asympomatic, pharngeal gonococcal infection sustains gonorrhoea infection in general population
“2 kidney beans” on microscopy?
Gonorrhoea
Benefits/disadvantages of NAAT v culture?
Benefts
- NAAT is more sensitive
- culture can test for antimicrobial resistance
Disadvantages
- difficult to grow on culture
What infection requires a test of cure?
Gonorrhoea
