Microbio: STIs

Question 1

What type of bacteria is chlamydia trachomatis?

Answer 1

obligate intracellular Gram –ve pathogen.

Cannot be cultured on agar

Question 2

What are the symptoms of chalmydia trachomatis?

Answer 2

Asymptomatic (80% females, 50% males)

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

Question 3

How can chlamydia be classified?

Answer 3

Serovars A, B, C: trachoma (Eye infection)

Serovars D-K (MAIN): genital chlamydia, ophthalmia neonatorum (sticky eye in neonates)

Serovars L1, L2, L3: lympho-granuloma venereum (LGV) - tropical

Question 4

How is chlamydia diagnosed?

Answer 4

Genital swab (F) / urine sample (M) –> NAAT (nucleic acid amplication tests)

This is done as it cant culture on agar

Question 5

Mx of chlamydia?

Answer 5

Azithromycin 1g stat - increasing resistence
or
Doxycycline 100mg 7d

Question 6

What are the complications of chlamydia infection?

Answer 6

PID -> infertility, ectopic pregnancy, chronic pelvic pain

Epididymitis

Reiter’s syndrome - reactive arthritis

Adult conjunctivitis, ophthalmia neonatorum

Question 7

What type of bacteria is neisseria gonorrhoeae?

Answer 7

Obligate intracellular Gram –ve diplococcus

Question 8

What are the main symptoms of gonorrhoea?

Answer 8

M: urethral discharge (MAIN - copious amounts)

F: vaginal discharge, abnormal bleeding, pain

Question 9

How is gonorrhoea diagnosed?

Answer 9

Swabs / urine sample -> culture / NAAT (preferred)

Question 10

How is gonorrhoea treated?

Answer 10

Ceftriaxone 250mg IM STAT

Question 11

What organism causes syphilis infection? what type of organism is this?

Answer 11

Treponema pallidum which is a gram -ve spirochaete

Question 12

What are the different types of syphillis infection?

Answer 12

Primary Syphilis

Secondary Syphilis

Latent Syphilis

Tertiary Syphilis

Question 13

What are the features of second syphilis?

Answer 13

Primary goes systemic -> Bacteraemia after 1-6 months -> fever, lymphadenopathy

Rash on palms and soles (MAIN)

Condyloma acuminate (genital warts)

Question 14

What are the features of latent syphilis?

Answer 14

Asymptomatic

Question 15

What are the features of tertiary syphilis?

Answer 15

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

Question 16

What is argyll-robertson pupil?

Answer 16

Argyll-Robertson pupil = accommodates but does not react

This is seen as a feature of tertiary syphilis (neurosyphilis)

Question 17

What is Tabes dorsalis?

Answer 17

Tabes dorsalis = weakness, sensory ataxia, numbness

This is seen as a feature of tertiary syphilis (neurosyphilis)

Question 18

How is syphilis diagnosed?

Answer 18

IF PRIMARY LEISONS PRESENT:
Dark-ground microscopy from primary lesions -> visualise Treponemes

IF AFTER PRIMARY:
Antibody tests: (need to do both)
-
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

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 19

Why in patient presenting after primary leisons have disappeared do you need to do both antibody tests for syphilis?

Answer 19

Non-treponemal tests = detect ab against non-specific antigens however false positives are common

Treponemal tests = more specifc (only issue is can be positive for years after, even w treatment)

Question 20

What is the mx of syphilis?

Answer 20

IM benzathine penicillin STAT

Question 21

A 22yo female attends GUM clinic and is diagnosed with chlamydia. Which treatment is most appropriate?

a) Azithromycin 100mg BD 7d
b) Azithromycin 1g STAT
c) Doxycycline 100mg OD 3d
d) Doxycycline 1g STAT
e) Co-amoxiclav 625mg TDS 7d

Answer 21

b) Azithromycin 1g STAT

Question 22

A man presents to GUM clinic with fever, widespread lymphadenopathy and a rash on his palms and soles. You suspect syphilis. Which clinical stage of syphilis does he have?

a) Primary syphilis
b) Secondary syphilis
c) Tertiary syphilis
d) Latent syphilis
e) Gummatous syphilis

Answer 22

b) Secondary syphilis