Week 2 STDs Flashcards
What are the common bacteria causing STDs?
- Chlamydia: Chlamydia trachomatis
- Gonorrhea: Neisseria gonorrhea
- Syphilis: Treponema pallidum
What are the common viruses causing STDs?
- Herpes: HSV-1, HSV-2
- HPV: Human Papilloma Virus
- HIV
What are the common parasites causing STDs?
- Trichomoniasis: Trichomonas vaginalis
- Scabies: Sarcoptes scabeiei
- Pubic lice
Cause of chlamydia?
Chlamydia trachomatis
Obligate intracellular bacteria
s/s of Chlamydia? (IMPT)
- 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
What are some s/s of urethritis?
- Urethral discharge
- Dysuria
- Pyuria
- Symptoms similar to UTI
What are some complications of chlamydia? (IMPT)
- 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
How is chlamydia diagnosed? (IMPT)
- PCR test (as routine culture not available)
- Specimen types:
~ Endocervical swab (for women)
~ First-catch urine (men and woman)
~ Urethral swab (for men)
Why is first-catch urine taken to diagnose chlamydia instead of mid-stream urine?
Causative bacteria will often be found in the urethra itself
Cause of gonorrhea?
Neisseria gonorrhea
Gram-negative diplococci
Fastidious
s/s of gonorrhea in men? (IMPT)
Early & symptomatic
- Urethritis
- Epididymitis / prostitis
s/s of gonorrhea in women? (IMPT)
Mostly asymptomatic carries or atypical
- Urethritis
- Pelvic inflammatory disease
- Cervicitis/vaginitis
s/s of extra-genital gonorrhea? (IMPT)
- Pharyngitis
- Conjunctivitis
- Disseminated gonococcal infection (bloodstream infection, skin rash, arthritis, fever)
Diagnosis of gonorrhea?
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
Cause of syphilis?
Treponema pallidum
Highly mobile bacteria (can move like a corkscrew)
How is syphilis transmitted?
- Intimate contact with infectious lesions
- Blood transfusions
- Transplacental /congenital syphilis
What are the 3 stages of syphilis? (IMPT)
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
Diagnosis of syphilis? (IMPT)
- Serology
- Screening test (non-treponema antibody testing)
- Confirmatory test (Treponemal-specific antibody testing)
~ e.g. enzyme-immunoassay, TPPA
Cause of Herpes?
1) Herpes Simplex Virus-1
- Oral herpes / cold sores if oral-oral contact
- Genital herpes if oral-genital contact
2) HSV-2
- Genital herpes
Stages of herpes? (IMPT)
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
Diagnosis of herpes?
- In universal transport media (UTM) for PCR or NAAT (most common)
- In viral transport media (VTM) for viral cultures
Cause of HPV?
- Human papilloma virus
- By direct skin-skin contact (sex, touching infected area, mother to baby)
Stages of HPV infection?
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
How to prevent HPV?
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
Diagnosis of HPV?
- PCR / NAAT
- High-risk serotype testing
- Cervical cytology (study of cells)
Cause of Trichomoniasis?
- Trichomonas vaginalis
- Single-celled parasite
s/s of Trichomoniasis?
- Women affected more than men
- Mostly asymptomatic
- Malodorous discharge
- Urethritis
- Vaginitis
- Itching
Diagnosis of trichomoniasis?
- Microscopy of vaginal secretions
- PCR / NAAT
- Rapid antigen test (binds to antigens on cells)
