Microbio - STIs

Question 1

What pathogen causes Chlamydia?

Answer 1

Chlamydia trachomatis

Question 2

What type of pathogen is Chlamydia?

Answer 2

obligate intracellular Gram –ve pathogen

(cannot be cultured on agar)

Question 3

Chlamydia presentation

Answer 3

Asymptomatic (80%F, 50%M)

F: vaginal discharge, abnormal bleeding, abdo pain (-> PID)
M: urethral discharge, dysuria

Question 4

What is chlamydia serotypes A, B, C?

Answer 4

Trachoma - infx of eyes -> can cause blindness

Question 5

What is chlamydia serotypes D-K?

Answer 5

genital chlamydia, ophthalmia neonatorum

Question 6

What is chlamydia serotypes L1, L2, L3?

Answer 6

lympho-granuloma venereum (LGV) -> lymphatic infx –> +++lymphadenopathy

Question 7

*Chlamydia investigations

Answer 7

Genital swabs / urine sample –> NAAT (nucleic acid amplification tests)

As can’t culture on Agar

Question 8

Chlamydia treatment

Answer 8

1) Doxycycline
2) Azithromycin (if preg)

Question 9

Complications of chlamydia

Answer 9

• !PID -> infertility, ectopic pregnancy, chronic pelvic pain
• Epididymitis
• Reactive arthritis
• Adult conjunctivitis, ophthalmia neonatorum

Question 10

*What pathogen causes Gonorrhoea?

Answer 10

Neisseria gonorrhoeae

(obligate intracellular Gram –ve diplococcus)

Question 11

Gonorrhoea presentation

Answer 11

F: many asymptomatic / vaginal discharge, abnormal bleeding, pain
M: urethral discharge (copious)

Question 12

Gonorrhoea investigations

Answer 12

swabs / urine sample -> culture / NAAT

Question 13

Gonorrhoea treatment

Answer 13

IM ceftriaxone

or PO Cefixime + azithromycin

Question 14

*What pathogen causes Syphilis?

Answer 14

Treponema pallidum

(obligate Gram –ve spirochaete - spiral shape)

Question 15

Types of Syphilis (4)

Answer 15

1. Primary
2. Secondary
3. Latent
4. Tertiary

Question 16

*Primary syphilis presentation

Answer 16

Painless solitary (indurated) genital ulcer (chancre)
May persist 4-6wks

Question 17

*Secondary syphilis presentation

Answer 17

Bacteraemia after 1-6 months-> fever, lymphadenopathy
Rash on palms and soles
Condyloma acuminate (genital warts)
Snail track ulcers

Question 18

Latent syphilis presentation

Answer 18

Asymptomatic

Question 19

Tertiary syphilis presentation

Answer 19

2-30yrs later -> 3 different syndromes:

1. Gummatous: skin/bone/mucosal granulomas
2. Cardiovascular: mimics any cardiac disease; aortic root dilatation
3. Neurosyphilis: dementia, tabes dorsalis, Argyll-Robertson pupil (accomodates but doesn’t react to light)

Question 20

Syphilis investigations

Answer 20

• Dark-ground microscopy from primary lesions -> visualise Treponemes
• Antibody tests (use both)
  1. Non-Treponemal tests:
  Detect antibodies against non-specific antigens
  e.g. VDRL test, RPR test
  False positives are common (need to confirm with treponemal test)
  Titre falls in response to treatment -> can be used to monitor response

2. Treponemal tests:
   Detect antibodies against specific antigens from T. pallidum
   e.g. EIA, FTA, TPHA, TP-PA
   More specific than non-treponemal
   Remains positive for years (even after treatment)

Question 21

Syphilis management

Answer 21

IM benzathine penicillin STAT

Question 22

*What is genital warts cuased by?

Answer 22

HPV

Question 23

*What can be found on wet slide microscopy?

Answer 23

• Candida
• BV
• Trichomoniasis

Question 24

*Trichomonas mx

Answer 24

Metronidazole

Question 25

Trichomonas findings

Answer 25

• pH>4.5
• Strawberry cervix
• Flagellated protozoa

Question 26

PID Mx

Answer 26

Doxy + ceftriaxone + metronidazole

Question 27

*HSV Ix

Answer 27

NAAT

Question 28

*BV Mx

Answer 28

Metronidazole

Question 29

*Ix for invasive candida albicans

Answer 29

Beta-D-Glucan