L36 - Sexually transmitted diseases Flashcards

1
Q

Define the reservoir, site of entry and transmission of STDs?

A

Reservoir = asymptomatic human carriers, do not survive in environment

Entry:

  • Mucous membrane +/- trauma
  • Minute abrasion in skin surface
  • Local sites: vagina, cervix, urethra, rectum, pharynx, eye)
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2
Q

Define the public health centers for STD?

A

Department of health Social hygiene clinics

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3
Q

Most common STI in HK?

A

Non-gonococcal urethritis/ nonspecific genital infection by Chlamydia trachomatis

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4
Q

3 typical clinical presentation features of STDs?

A
  1. Urethral discharge (urethritis/male).
  2. Genital ulcer (male and female)
  3. Genital lumps (male/female)
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5
Q

List 2 main pathogens that cause urethral discharge/ urethritis?

A
  • Neisseria gonorrhoeae
  • Chlamydia trachomatis

(Asymptomatic: Ureaplasma urealyticum, Mycoplasma genitalium)

(Rare: Herpes Simplex virus, Trichomonas vaginalis, yeasts)

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6
Q

Compare gonococcal and Non-gonococcal urethritis: onset, incubation period, relapse?

A

Gonococcal:

  • 2-5 days
  • Abrupt onset
  • Rare relapse

Non-gonococcal:

  • 7-14 days
  • Gradual onset
  • Common relapse
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7
Q

Compare gonococcal and Non-gonococcal urethritis: dysuria, discharge?

A

Gonococcal:

  • Prominent dysuria
  • Copious discharge

Non-gonococcal:

  • Mild dysuria
  • Scanty, non-purulent discharge
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8
Q

List infections caused by Chlamydia trachomatis serotype A,B,C?

A

Trachoma

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9
Q

List infections caused by Chlamydia trachomatis serotype D to K?

A

Cervicitis, urethritis, pelvic inflammatory disease, neonatal pneumonia

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10
Q

List infections caused by Chlamydia trachomatis serotype L?

A

Lymphogranuloma venereum (LGV)

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11
Q

List infections caused by Chlamydophila/ Chlamydia pneumoniae?

A

Respiratory tract infection (not genital)

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12
Q

How to clinically establish presence of urethritis?

A
  1. P/E
  2. Microscopy: swab for anterior surface of urethra, anal mucosa, endocervix:
    - 1st swab for Gonococcal culture
    - 2nd swab for Chlamydia culture
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13
Q

Which serotypes of chlamydia cause STDs?

A

D to L

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14
Q

Define the medium and culture for gonococcal urethritis?

A

Modified Thayer-Martin medium (nutritive culture media with antibiotics): small, grayish-white mucoid colonies

Incubation: 35 oC, CO2 enriched, humid atmosphere

Never refrigerate, immediate culture

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15
Q

Define the medium and culture for Chlamydial urethritis?

A
  • Need special transport medium and cell culture: McCoy Cell Line shows Chlamydia inclusion bodies
  • Can refrigerate for 24h
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16
Q

Name one test for rapid chlamydia urethritis Dx and give 2 limitations?

A

Antigen detection e.g. Chlamydiazyme

–Less sensitive than culture

–False-positive results from cross reacting bacterial species

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17
Q

Describe the morphology of gonococci and gram stain?

A

Gram-negative diplococci

small mucoid colonies

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18
Q

Pharyngeal gonorrhoea is often asymptomatic in normal adults. T or F?

A

True

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19
Q

Name one test for pharyngeal gonorrhea?

A

Direct fluorescent antibody (DFA) for gonococcal pharyngitis

20
Q

Name one test for detecting both gonococcal and chlamydial urethritis simultaneously? Give 2 advantages?

A

nucleic acid amplification tests (NAAT): e.g. PCR

Higher sensitivity than culture
Performed on non-invasive specimens (e.g. first-void urine)

21
Q

Treatment for urethritis?

A
  • Single dose oral azithromycin/ 7 days oral doxycycline for chlamydial
  • Single dose intramuscular ceftriaxone for gonococcal
22
Q

List 5 common genital ulceration diseases?

A
  • Herpes simplex
  • Syphilis (Treponema pallidum)

Chancroid
Lymphogranuloma venereum (LGV)
Donovanosis

23
Q

Which serotype of HSV causes most genital ulceration?

A

HSV Type I (10%)

HSV Type II (90%)

24
Q

Morphology of Treponema pallidum?

A

Spirochete:

 Helical, slender, long cells

 Flagella within periplasm

25
Q

List the STDs causing multiple genital ulcers vs those causing single?

A

Single: Syphilis, LGV

Multiple: Genital herpes, Chancroid, Donovanosis

26
Q

Ddx STDs causing genital ulcers based on lymph tenderness/ adenopathy?

A

Tender - Genital herpes, Chancroid, LGV

Non-tender - Syphilis, Donovanosis

27
Q

Describe the edge, base and lymphadenopathy of genital ulcers by Herpes?

A

Edge: Soft (rim of inflammation)

Base: Clean

Lymphadenopathy: tender

28
Q

Describe the edge, base and lymphadenopathy of genital ulcers by Syhilis?

A

Edge: Indurated (elevated)

Base: Clean

Lymphadenopathy: Indolent

29
Q

Describe the edge, base and lymphadenopathy of genital ulcers by Chancroid?

A

Edge: Soft

Base: Dirty, Gray

Lymphadenopahty: tender

30
Q

Describe the edge, base and lymphadenopathy of genital ulcers by Donovanosis?

A

Edge: Serpinginous (wavy), white

Base: BEEFY RED** granulation tissue

Lymphadenopahty: Erosive lesion over nodes

31
Q

Describe the edge, base and lymphadenopathy of genital ulcers by LGV

A

Edge: soft

Base: eroded papule

Lymphadenopahty: PROMINENT* tender

32
Q

Lab Dx tests of Herpes?

A

TZANCK SMEAR: identify multinucleated giant cells via Wright or Giemsa stain

Viral culture

33
Q

Describe how herpes can cause recurrent infection?

A

Mucocutaneous infection
» spread to local sensory nerve endings
» Maintain neuronal latency
» Reactivation and distal spread again

34
Q

Lab dx test for Syphilis?

A

Serology- detect specific antibodies:

1) Non-trepenamal specific test: Time-specific: VDRL, RPR tests
2) Treponemal specific tests: syphilis specific: TPPA, FTA-abs, EIA-syphilis test

Need both for Dx**

35
Q

Antibody detection can Dx syphilis as soon as genitla ulcerations appear. T or F? exam

A

False

Ulceration/ primary syphilis may appear before development of detectable antibodies

36
Q

Describe the time course of syphilis infection? exam

A

[Early syphilis (<2 years)]
Infection
» primary syphilis (9-90 days)

> > secondary s. (6 weeks to 6m)

> > Early latent up to 2 years

[Late syphilis (>2 years)]

> > Late latent (3 to 30 years)**

37
Q

Disease outcome of syphilis?

A

 1/3: spontaneous cure
 1/3: persistent latent
 1/3: tertiary syphilis

Infectivity decrease rapidly with time

38
Q

Describe the pathological damage caused by primary and secondary syphilis?

A

Primary = Local multiplication > ulceration > healing

Secondary = Bloodstream dissemination > Localized at BV > lesion in skin, mucosa, LN, CNS

39
Q

Which organs are involved in latent syphilis?

A

spleen, lymph nodes

40
Q

How to clinically Dx Chancroid? Treatment?

A
  • P/E: tenderness, ulceration, base, edge…etc
  • Due to unreliable culture: Dx if no evidence of syphilis and HSV

–single dose of azithromycin or single dose Ceftriaxone

41
Q

Treatment options for genital ulceration?

A

Single dose azithromycin + single dose Ceftriaxone

covers Gonorrhoea, Chlamydia trachomatis, Chancroid

Must always consider asymptomatic syphilis or HIV

42
Q

How to Dx Genital lumps?

A
  • No culture
  • No routine serology tests: only test if high-risk HPV suspected
  • Dx based on exam and clinical presentation **
43
Q

Causative pathogen of genital lumps?

A

Human papilloma virus (HPV): > 100 types

causing genital warts

44
Q

Which serotypes of HPV mainly cause mucotaneous diseases at genitals?

A
  • Genital warts = 6, 11 ***

* Laryngeal papillomata = 6, 11 •Oral papillomata = 6, 11, 16, 18,

45
Q

Incubation period of HPV and disease course?

A

Incubation period 1 to 6 month

Most HPV infections are selflimited and are asymptomatic

46
Q

Clinical presentation of genital lumps caused by HPV?

A

Superficial, clusters of warts with grey appearance

on the penis, vulva & perianal regions.

47
Q

Which HPV serotypes should be screened by serology?

A

HPV types associated with cervical cancer (esp. 16 & 18)