Week 2 STDs

Question 1

What are the common bacteria causing STDs?

Answer 1

• Chlamydia: Chlamydia trachomatis
• Gonorrhea: Neisseria gonorrhea
• Syphilis: Treponema pallidum

Question 2

What are the common viruses causing STDs?

Answer 2

• Herpes: HSV-1, HSV-2
• HPV: Human Papilloma Virus
• HIV

Question 3

What are the common parasites causing STDs?

Answer 3

• Trichomoniasis: Trichomonas vaginalis
• Scabies: Sarcoptes scabeiei
• Pubic lice

Question 4

Cause of chlamydia?

Answer 4

Chlamydia trachomatis

Obligate intracellular bacteria

Question 5

s/s of Chlamydia? (IMPT)

Answer 5

• Genital chlamydia mostly asymptomatic but:

-Urethritis very common in infected males (occasionally females)
- Pelvic inflammatory disease common in females

• Males -> Epididymitis/prostitis, pharyngitis/conjunctivitis amd cervicitis

Question 6

What are some s/s of urethritis?

Answer 6

• Urethral discharge
• Dysuria
• Pyuria
• Symptoms similar to UTI

Question 7

What are some complications of chlamydia? (IMPT)

Answer 7

• Pelvic inflammatory disease leading to:
  ~ Infertility
  ~ Tubo-ovarian abscess
  ~ Ectopic pregnancy
  ~ Chronic pelvic pain
• Infection during pregnancy leading to:
  ~ Premature rupture of woman’s membranes, preterm delivery and low birth weight infants
  ~ Chlamydia trichomatis can be acquired through infected birth canal
  ~ Neonatal conjunctivitis and pneumonia

Question 8

How is chlamydia diagnosed? (IMPT)

Answer 8

• PCR test (as routine culture not available)
• Specimen types:
  ~ Endocervical swab (for women)
  ~ First-catch urine (men and woman)
  ~ Urethral swab (for men)

Question 9

Why is first-catch urine taken to diagnose chlamydia instead of mid-stream urine?

Answer 9

Causative bacteria will often be found in the urethra itself

Question 10

Cause of gonorrhea?

Answer 10

Neisseria gonorrhea

Gram-negative diplococci

Fastidious

Question 11

s/s of gonorrhea in men? (IMPT)

Answer 11

Early & symptomatic
- Urethritis
- Epididymitis / prostitis

Question 12

s/s of gonorrhea in women? (IMPT)

Answer 12

Mostly asymptomatic carries or atypical
- Urethritis
- Pelvic inflammatory disease
- Cervicitis/vaginitis

Question 13

s/s of extra-genital gonorrhea? (IMPT)

Answer 13

• Pharyngitis
• Conjunctivitis
• Disseminated gonococcal infection (bloodstream infection, skin rash, arthritis, fever)

Question 14

Diagnosis of gonorrhea?

Answer 14

Swab or pus specimen in special transport medium (as bacteria is fastidious) for
- C&S
~ Sensitivity testing more important as N. gonorrhea is now more drug-resistant

Urine or swab for
- Nucleic acid amplification test (NAAT) / PCR

Question 15

Cause of syphilis?

Answer 15

Treponema pallidum

Highly mobile bacteria (can move like a corkscrew)

Question 16

How is syphilis transmitted?

Answer 16

• Intimate contact with infectious lesions
• Blood transfusions
• Transplacental /congenital syphilis

Question 17

What are the 3 stages of syphilis? (IMPT)

Answer 17

1) Primary
- Painless sores/chancres at local site
- Sores may turn into ulcers
- Resolves in 3-6 weeks

2) Secondary
- Occurs 2-8 weeks after the chancre appears
- Disseminates throughout the body
- Manifests as rashes, pustular lesions, fever, malaise or lymphadenopathy
- In the groin or moist areas, lesions may coalesce (come together to form a big mass) to for infectious plaques called condylomata lata
- Resolves in 2-10 weeks

3) Tertiary
- Occurs 1-30 years after exposure
- Bacteria may remain in the body, asymptomatic even with primary or secondary syphilis
- Neurosyphilis occurs if bacteria invades the CNS
- CVS syphilis can occur, leading to aneurysms or aortitis

Question 18

Diagnosis of syphilis? (IMPT)

Answer 18

• Serology
• Screening test (non-treponema antibody testing)
• Confirmatory test (Treponemal-specific antibody testing)
  ~ e.g. enzyme-immunoassay, TPPA

Question 19

Cause of Herpes?

Answer 19

1) Herpes Simplex Virus-1
- Oral herpes / cold sores if oral-oral contact
- Genital herpes if oral-genital contact

2) HSV-2
- Genital herpes

Question 20

Stages of herpes? (IMPT)

Answer 20

1) Primary
- Commonly asymptomatic or has mild symptoms only
- Presents as painful blisters/ulcers at the site of infection and crusting
- Eye infections (herpetic keratitis)
- CNS infections (meningitis, encephalitis)
- Neonatal infection

2) Latency stage
- Remains latent and present for life
- Potential for recurrence or reactivation of the virus

3) Reactivation stage
- Same spectrum of infections as primary infection
- Accounts for greater proportion of encephalitis infx

Question 21

Diagnosis of herpes?

Answer 21

• In universal transport media (UTM) for PCR or NAAT (most common)
• In viral transport media (VTM) for viral cultures

Question 22

Cause of HPV?

Answer 22

• Human papilloma virus
• By direct skin-skin contact (sex, touching infected area, mother to baby)

Question 23

Stages of HPV infection?

Answer 23

1) Primary
- May be asymptomatic or with mild symptoms
- May present with warts at genital area

2) Spontaneously resolves OR

3) Persistent infection
- Due to infection with high risk HPV types
- Increased risk of cervical, anal, oro-pharygeal cancer

Question 24

How to prevent HPV?

Answer 24

1) Primary (at HPV infx)
- Vaccination, condom promotion, sexuality education

2) Secondary (at precancer)
- Cervical screening
~ Recommended for 30-49 y/o
~ Every 5 years

3) Tertiary (at cancer stage)
- Treatment of cancer

Question 25

Diagnosis of HPV?

Answer 25

• PCR / NAAT
• High-risk serotype testing
• Cervical cytology (study of cells)

Question 26

Cause of Trichomoniasis?

Answer 26

• Trichomonas vaginalis
• Single-celled parasite

Question 27

s/s of Trichomoniasis?

Answer 27

• Women affected more than men
• Mostly asymptomatic
• Malodorous discharge
• Urethritis
• Vaginitis
• Itching

Question 28

Diagnosis of trichomoniasis?

Answer 28

• Microscopy of vaginal secretions
• PCR / NAAT
• Rapid antigen test (binds to antigens on cells)