ic18 STI

Question 1

Out of Gonorrhea, Chlamydia, Syphilis, Genital Herpes, which are caused by bacteria or virus?

and what bacteria / virus?

Answer 1

Bacteria
Gonorrhea: Neisseria Gonorrhoeae
Chlamydia: Chlamydia Trachomatis
Syphilis: Treponema Pallidum

Virus
Herpes: HSV-2

Question 2

name 1 STI caused by fungi and 1 caused by parasites

Answer 2

vaginal candidiasis (candida albicans)
scabies (sarcoptes scabiei)

Question 3

What tests to diagnose Gonorrhea?

What symptoms are there (3 points)

Answer 3

Gram stain, Culture, NAAT (nucleic acid amplification test)

Purulent urethral discharge / Mucopurulent vaginal discharge
Dysuria
Urinary frequency

Question 4

Treatment for Gonorrhea

2nd line for Gonorrhea

Answer 4

Should treat for Chlamydia at the same time
First line
IM Ceftriaxone 500mg single dose
+
Chlamydia
PO Doxycycline 100mg BD for 7 days

(2nd line)
AG240
PO Azithromycin 2g single dose + IM Gentamicin 240mg single dose
+
Chlamydia treatment
PO Doxycycline 100mg BD for 7 days

Question 5

General management of sex partners

Answer 5

Should treat sex partners of past 60 days

If single dose, abstain from sexual activities for 7 days after treatment

If 7 day course eg. Doxycycline, abstain until finish 7 day course

Abstain until all sexual partners have been treated

Question 6

What causes Chlamydia?

How to diagnose Chlamydia

Answer 6

Chlamydia Trachomatis

NAAT

Question 7

Treatment for Chlamydia

What if first line is not available?

Answer 7

DAL7

PO Doxycycline 100mg BD for 7 days

PO Azithromycin 1g single dose
OR
PO Levofloxacin 500mg OD for 7 days

Question 8

What bacteria causes Syphilis?

How to diagnose Syphilis?

Answer 8

Treponema pallidum

Darkfield microscopy of exudate
Treponemal test
Non-treponemal test

Question 9

General idea of Treponemal and Non-treponemal tests

Answer 9

Using treponemal / nontreponemal antigen to detect antibodies

Question 10

What is Treponemal test be used for?
Isit used to confirm diagnosis or response to treatment? Why?

Answer 10

Used to confirm diagnosis

Not used for monitoring response to treatment as it can remain active for life

Question 11

What is the antigen used in non-treponemal test

General idea of non-treponemal test?

Answer 11

Cardiolipin

To produce the most dilute serum concentration with a positive reaction eg. 1:16 positive means 1:32 is negative

Declines after treatment, hence is used to measure response to therapy

Question 12

What is non-treponemal test used to monitor

Which is a better result, 1:8 or 1:32?

Answer 12

Used as a tool to monitor response to treatment

We will want a less dilute antibody titre
1:8 is better than 1:32 as it means that I dont have as much antibodies in the blood, hence need a higher concentration to detect enough antibodies

Question 13

Main difference between the use of Treponemal test and Non-treponemal test

Answer 13

Treponemal test can stay (+) for life, hence is used to confirm diagnosis only

Non-treponemal test will decline over time, hence is used to monitor response to treatment

Question 14

Treatment for Syphilis for Primary, Secondary or Early latent infection (<1 year duration)

Answer 14

IM Benzathine Pen G 2.4m units for 1 dose
(Pen allergy) PO Doxycycline 100mg BD x 14 days

Question 15

Treatment for Syphilis for Late latent (> 1 year), Tertiary, or Unknown duration

Answer 15

IM Benzathine Pen G 2.4m units once a week for 3 doses
(Pen allergy) Doxycycline 100mg BD x 28 days

Question 16

Treatment for Neurosyphilis

Answer 16

[Always treat for 10-14 days]
IV Crystalline Pen G 3-4m units Q4H

IM Procaine Pen G 2.4m units + PO Probenecid 500mg QD

(Pen allergy) IV / IM Ceftriaxone 2g

Question 17

Monitoring for therapeutic response for syphilis

Answer 17

Neurosyphilis: use CSF fluid
The rest (primary, secondary, latent): Use blood

Monitor at 6, 12, 24 months
Treatment success = Decrease of antibody titre by at least 4x (1:64 to 1:16)

Question 18

5 stages of HSV infection

Answer 18

Primary mucocutaneous infection
Infection of nerve ganglia
Latency
Reactivation
Recurrent outbreak / flares

Question 19

Transmission of Genital herpes

Answer 19

Bodily fluids and skin to skin contact

Viral shedding from epithelial cells can occur → Transmissible even when asymptomatic

Question 20

Symptoms of genital herpes (in infection and prodromal stage)

Answer 20

Painful vesicles
Ulcerative lesions
Local itching, pain, tender inguinal lymphadenopathy
Flu-like symptoms during first days of lesions

Prodromal symptoms (occur before reactivation)
Mild burning
Itching, tingling
Symptoms less severe in recurrent disease

Question 21

How to diagnose Genital Herpes?

Answer 21

Virologic tests and Serologic tests

Virologic tests: Viral cell culture and NAAT

Serologic tests: HSV-1 and HSV-2 specific antibodies
Antibodies persists forever

Question 22

Why should serologic tests not be done for the first episode of genital herpes?

What does presence of HSV-2 antibodies confirm?

Answer 22

Antibody takes 6-8 weeks to be detected

Anogenital infection

Question 23

Non pharm management for genital herpes (4 points)

Answer 23

Warm saline bath to relieve discomfort
Analgesic, Anti-itch
Good genital hygiene
Counselling of shedding virus when asymptomatic, reactivation, triggers

Question 24

What is the MOA of Acyclovir?

Answer 24

Inhibit DNA polymerase, inhibit DNA synthesis and replication

Question 25

What are the 2 drugs for genital herpes and doses?

Counselling point

Answer 25

Acyclovir
PO 400mg TDS for 7-10 days
(for severe disease or complications that req hospitalisation) IV 5-10mg/kg TDS x 2-7 days + Oral until treat for 10 days

Valacyclovir (Valtrex)
PO 1g BD for 7-10 days

Counselling point: Drink enough water to prevent crystallisation in renal tubules

Question 26

What are the 2 ways to reduce recurrent herpes flares

Advantages of one over the other

Answer 26

Chronic suppressive therapy:
can reduce frequency of occurrences
decrease risk of transmission

Episodic therapy:
less costly, better compliance
but need to start within 1 day of lesion outbreak
does not reduce risk of transmission

Question 27

Dose for Chronic suppressive therapy

Answer 27

42 5111
PO Acyclovir 400mg BD
PO Valacyclovir 500mg OD
(at least 10 episodes per year) PO Valacyclovir 1g OD

Question 28

Dose for episodic therapy

Answer 28

(Acyclovir dose will be 2x higher than in chronic suppressive therapy)
2532
PO Acyclovir 800mg BD x 5 days OR TDS for 2 days

23115
PO Valacyclovir 500mg BD for 3 days OR 1g OD for 5 days

Question 29

Which STI can be passed through skin to skin contact?

Answer 29

Only Genital Herpes
hence can have viral shedding even though asymptomatic!

The rest are all mother to child, bodily fluids

Question 30

Which infections can diagnose using NAAT? Which cannot?

Answer 30

Can:
Gonorrhea
Chlamydia
Genital herpes

Cannot:
Syphilis

Question 31

When is Ceftriaxone used in STI?

Answer 31

1) First line for gonorrhea (IM 500mg single dose)
2) Neurosyphilis (if pt has pen allergy, IV / IM 2g daily x 10-14 days

Question 32

When is Doxycycline used for STI?

Answer 32

1) 1st line for Chlamydia

2) Syphilis, if patient has penicillin allergy, for primary / secondary / early latent → 14 days
or
late latent / unknown duration / tertiary → 28 days (basically not neurosyphilis can alr)

Question 33

When is Azithromycin used in STI?

Answer 33

1) Chlamydia 2nd line (PO 1g single dose)
2) 2nd line for Gonorrhea (PO 2g single dose, taken with Gentamicin IM 240mg single dose)

Question 34

What is considered treatment failure in Syphilis?

Answer 34

at 6 months
Still showing signs and symptoms of disease
Failure to get 4 fold decrease of antibody titre eg. 1:64 -> 1:16, or antibody titre increased
Could be due to undetected neurosyphilis