Sexually Transmitted Infections

Question 1

What are the main presentations of STIs?

Answer 1

vaginal or urethral discharge, genital lesion, dermatalogical presentation, generalised presentation (syphilis) or PID

Question 2

What are the diagnostic tools for STIs?

Answer 2

microscopy, culture, serology, PCR

Question 3

What is the urethral discharge for neisseria gonorrhoea?

Answer 3

thick, creamy and painful

Question 4

What is the gram stain of neisseria gonorrhoea?

Answer 4

intracellular gram negative diplococci - characteristic gram stain of neutrophils packed with organisms

Question 5

Where does neisseria gonorrhoea adhere to?

Answer 5

the columnar epithelial cells that line the urethra and cervix - as cells become more squamous in the cervix with age you’re less likely to be infected

Question 6

What is the incubation period of neisseria gonorrhoea?

Answer 6

2-7 days

Question 7

How commonly is neisseria gonorrhoea asymptomatic in females?

Answer 7

80%

Question 8

Why is there increasing antibiotic resitance of neisseria gonorrhoea?

Answer 8

because it can exchange genetic material with other non pathogenic neisseria that are commensals

Question 9

Where can neisseria gonorrhoea disseminate to?

Answer 9

arthritis, maculopapular rash, meningitis, endocarditis, epididymitis and peri-hepatitis

Question 10

How can gonorrhoea cause infertility?

Answer 10

if it results in PID and causes tubule scarring

Question 11

What is the presentation of PID?

Answer 11

pelvic tenderness, discharge, fever, palpation of cervix induces pain and can see fluid abscess on imaging

Question 12

What is neonatal gonococcal opthalmia?

Answer 12

babies born to a mother with gonorrhoea get a purulent conjunctivitis in the first week of life which can lead to scarring of the cornea and blindness

Question 13

What is the treatment for neonatal gonococcal opthalmia?

Answer 13

cefotaxime for 7 days and regular eye irrigation + treat mother and contacts

Question 14

Why is PCR a good diagnostic test?

Answer 14

because it only requires a 10mL first void urine sample compared to a urethral swab which is more unpleasant

Question 15

What is the selective media for culture of neisseria gonorrhoea?

Answer 15

thayer-martin agar - contains colistin to inhibit gram negatives, vancomycin to inhibit gram positives and nyastatin to inhibit the yeast

Question 16

What is the disadvantage of PCR as a test for gonorrhoea?

Answer 16

cant get antibiotic resistance results

Question 17

What is the treatment for neisseria gonorrhoea?

Answer 17

ceftriaxone (beta lactam) and azithromycin (macrolide) - using two different mechanisms delays resistance and azithromycin is also used to treat chlamydia which is useful because coinfection is common

Question 18

How do you prevent gonorrhoea?

Answer 18

barrier contraception and contact tracing

Question 19

What type of organism of chlamydia trachomatis?

Answer 19

an obligate intracellular parasite - a gram negative bacteria

Question 20

Where does chlamydia trachomatis adhere to?

Answer 20

the columnar epithelium

Question 21

Which serovars of chlamydia trachomatis cause genital infections?

Answer 21

D-K

Question 22

Describe the life cycle of chlamydia trachomatis

Answer 22

elementary bodies (the infectious form of the organism) enter cells and form reticulate bodies which replicate and eventually rupture the cell to release the infectious elementary bodies which are in the body secretions

Question 23

What does chlamydia cause in women?

Answer 23

cervicitis, endometritis, discharge, dysuria, irregular bleeding, can cause PID - although it is very commonly asymptomatic

Question 24

What does chlamydia cause in men?

Answer 24

urethritis - dysuria, meatal erythema, clear urethral discharge, testicular pain, prostatitis

Question 25

What is lymphogranuloma venereum?

Answer 25

an infection caused by a different serotype of chlamydia which starts off as an ulcerative genital lesion which then spreads to lymph nodes

Question 26

What are the symptoms of neonatal chlamydia?

Answer 26

conjunctivitis that is thin and sometimes haemmorhagic from 2-28 days and pneumonia with a staccato cough at 2-8 weeks

Question 27

What is the treatment for chlamydia?

Answer 27

azithromycin or doxycycline

Question 28

What type of organism is trichomonas vaginalis?

Answer 28

a flagellated protozoon

Question 29

What are the symptoms of trichomonas vaginialis (if its not asymptomatic)?

Answer 29

frothy, green-yellow vaginal discharge, more alkaline pH in the vagina, cervical erythema and friability, pruritus, dysuria, abdominal pain

Question 30

Why does a trichomonas vaginalis infection put you at risk of HIV?

Answer 30

because of the genital inflammation it causes

Question 31

What are the laboratory tests for trichomonas vaginalis?

Answer 31

wet prep microscopy to look for the motility, PCR and can sometimes be seen on pap smear

Question 32

What is the treatment for trichomonas vaginalis?

Answer 32

metronidazole or tinidazole

Question 33

What does treponema pallidum cause?

Answer 33

syphilis

Question 34

What is the classic presentation of syphilis?

Answer 34

3 stages - primary stage of an ulcer (shanka) 2-3 weeks after exposure which then heals, followed by a secondary stage of a rash, lymphadenopathy, abdominal pain and allopetia, followed by an early latent phase (where still infectious) and a late latent phase (where less infectious) and then a tertiary phase which involves a gumma (growth) particulary in joints, aorta or brain

Question 35

Why is microscopy of syphilis difficult?

Answer 35

because the sample has to be taken from the primary shanka and the organisms are very thin so difficult to visualise

Question 36

What are the two types of serological tests for syphilis?

Answer 36

non treponemal and treponemal tests

Question 37

What is the use of non treponemal tests?

Answer 37

look for active disease by looking for biomarkers released in infection - useful for screening and monitoring therapy

Question 38

What is the use of treponemal tests?

Answer 38

looks for the actual antigen - they become postive earlier and are positive for life so can be used for antenatal screening and then followed up with a non treponemal test

Question 39

What type of organism is mycoplasma genitalium?

Answer 39

a molecute - no cell wall - flask shaped

Question 40

Why is mycoplasma genitalium not widely tested?

Answer 40

because its difficult to culture and the NAAT arent widely available

Question 41

What does mycoplasma genitalium cause in men?

Answer 41

urethritis

Question 42

What does mycoplasma genitalium cause in women?

Answer 42

cervicitis, acute endometritis, PID

Question 43

How long does mycoplasma genitalium persist for?

Answer 43

3-6 months

Question 44

What is mycoplasma genitalium associated with?

Answer 44

preterm labour and HIV transmission

Question 45

What is the treatment of mycosplasma genitalium?

Answer 45

azithromycin but has high failure rates so may need to use moxifloxacin

Question 46

What type of organism is treponema pallidum?

Answer 46

spirochaete bacterium - gram negative