Sexually Transmitted Infections 1 Flashcards
STIs - epidemiology
*STIs are very common and very expensive
*most STIs are asymptomatic
*people of all backgrounds and economic levels affected
examples of bacterial STIs
*syphilis
*gonorrhea
*Chlamydia trachomatis
*chancroid
*agents of NGU
*shigellosis
*salmonellosis
*campylobacteriosis
*MRSA
examples of fungal STIs
*candida species
*blastomycosis
examples of viral STIs
*hepatitis (A, B, C, E)
*HSV
*HIV
*CMV
*HPV
*Kaposi’s sarcoma (HHV-8)
STIs - prevalence/incidence
*most common STI = HPV
*most common BACTERIAL STI = Chlamydia
*most common parasitic STI = Trichomoniasis
urethritis - clinical presentation
*typically presents with urethral discharge (mucoid, mucopurulent, or purulent)
-mucoid = NGU (Chlamydia)
-purulent = Gonorrhea
*often accompanied by dysuria
*asymptomatic in 10% of cases
urethritis - common causes
1. Gonorrhea
2. Chlamydia
3. Trichomonas vaginalis
4. Mycoplasma genitalium
5. Ureaplasma urealyticum
6. HSV (herpes simplex virus)
7. adenovirus
cervicitis - clinical syndrome
*clinical findings:
-mucopurulent or purulent cervical discharge
-easily induced cervical bleeding
*nonspecific symptoms: abnormal vaginal discharge, intermenstrual bleeding, dysuria, lower abdominal pain, dyspareunia
*50% of women with clinical cervicitis have no symptoms
cervicitis - common causes
1. Gonorrhea
2. Chlamydia
3. Trichomonas vaginalis
4. HSV
most common bacterial STI in the US
*Chlamydia (C. trachomatis)
Chlamydia trachomatis - risk factors
*women > men
*young age (<25) [due to risky behaviors & cervical ectopy - columnar epithelial cells on ectocervix]
*new or multiple sex partners
*oral contraceptive use (cervical ectopy)
*inconsistent use of barrier contraceptives
*history of STI
*presence of another STI
Chlamydia trachomatis - transmission
*highly transmissible (infection rates in partners > 50%)
*incubation period 7-21 days
*significant asymptomatic reservoir
*re-infection is common
*thought to be more efficient transmission from man to woman
*perinatal (vertical) transmission:
-neonatal conjunctivitis in 30-50% of exposed babies
-neonatal pneumonia in 3-16% of exposed babies
Chlamydia - genus & species
*genus: Chlamydia
*species:
1. C. psittaci → psittacosis
2. C. pneumoniae → pneumonia, bronchitis, pharyngitis
3. C. trachomatis → trachoma, oculogenital infection (Serotypes D-K), LGV
human diseases caused by Chlamydia trachomatis: serotypes A, B, Ba, C
*hyperendemic blinding trachoma
human diseases caused by Chlamydia trachomatis: serotypes D-K
*oculogenital infections:
1. inclusion conjunctivitis
2. nongonococcal urethritis
3. cervicitis
4. salpingitis
5. proctitis
6. epididymitis
7. pneumonia of the newborn
human diseases caused by Chlamydia trachomatis: serotypes L1, L2, L3
*lymphogranuloma venereum (LGV)
Chlamydia - microbiology
*obligate intracellular bacteria:
-needs host ATP
-gram negative-like cell wall
-not visible on gram stain
*target = columnar, squamocolumnar epithelium:
-cervix, upper genital tract, conjunctiva, urethra, rectum
*immunity: re-infection common with little protection from antibody response
Chlamydia - life cycle
- EB attaches to and enters a cell to replicate
- strong immune response results → damage and scarring at site
- within 8 hours, EB transforms into a RB, which begins to multiply within an isolated area called an inclusion
- within 24 hours, some RBs change back to EBs
- eventually, the cell wall bursts and the EBs are released into adjacent cells or transmitted to infect another partner/site
EB (elementary body) - attach to cells
RB (reticulate body) - multiply in cells
Chlamydia - elementary bodies (EB)
*elementary body (EB): small, infectious particle found in secretions
*ENTER the cells
Chlamydia - reticulate bodies (RB)
*metabolically active, non-infectious form of the bacteria that REPLICATE inside of the host cell
Chlamydia - diagnosis
*nucleic acid amplification test (NAATs):
-amplify and detect organism-specific genetic material (nucleic acids)
-high sensitivity and specificity
-can detect N. gonorrhea in same specimen
*collection of sample:
-first catch urine (males or females)
-urethral swabs (males)
-endocervical or vaginal swabs (female)
-rectal swab (males or females)
Chlamydia - screening
*screen all sexually active women aged < 25 and those at increased risk (any age) using NAATs
*increased risk of infection:
-new sex partner
-more than one sex partner
-sex partner with concurrent partners
-sex partner who has an STI
Chlamydia - treatment
*DOXYCYCLINE is treatment of choice
Chlamydia - reactive arthritis
*a systemic disease complication associated with Chlamydia (others: yersinia, campylobacter)
*classic triad: inflammatory arthritis of large joints, inflammation of eyes (conjunctivitis or uveitis), urethritis/cervicitis
*other sx: swelling of digits, rash (can involve palms and soles), oral ulcerations
Chlamydia - neonatal considerations
*ophthalmia neonatorum / conjunctivitis 5-12 days after birth
*subacute afebrile pneumonia onset 1-3 months
*best prevention = prenatal screening and treatment of pregnant women
Neisseria gonorrhoeae (GC) - epidemiology
*2nd most common bacterial STI pathogen
*commonly overlaps with Chlamydia
*resurgence in high risk groups
*can have antibiotic resistance
Neisseria gonorrhoeae (GC) - microbiology
*gram-negative intracellular diplococcus
*infects mucus-secreting epithelial cells
*evades host response through alteration of surface structures
*contrast to Chlamydia: GC can be seen on gram stain (gram neg), Chlamydia can not
Neisseria gonorrhoeae (GC) - diagnostic tests
- culture = “gold standard”
-appropriate for multiple sites (including rectal, oropharyngeal, conjuctiva)
-susceptibility testing can be done - gram stain (gram negative)
- amplified tests (NAATs) = most common (also tests for Chlamydia); performed on swab of site or urine
Neisseria gonorrhoeae (GC) - treatment
*CEFTRIAXONE is treatment of choice
GC additional syndrome: Gonococcal conjunctivitis
*ophthalmia neonatorum (erythromycin ointment for all newborns)
*usually autoinoculation in adults
*s/s: eye irritation with purulent conjunctival exudate
*treatment: ceftriaxone
GC additional syndrome: pharyngeal infection
*may be sole site of infection if oral-genital contact is the only exposure
*most often asymptomatic ( > 90%)
*sx, if present, may include pharyngitis, tonsillitis, fever, cervical adenitis
*perform test-of-cure after treatment
disseminated gonococcal infection (DGI)
*occurs infrequently; women > men
*associated with gonococcal strains that produce bacteremia without associated urogenital sx
*clinical manifestations: skin lesions (eschar), ARTHRALGIAS, tenosynovitis, ARTHRITIS, hepatitis, meningitis, endocarditis (rare)
*screen all mucosal sites
*TERMINAL COMPLEMENT DEFICIENCY is a risk factor (including acquired form seen in SLE)
*requires extended treatment
gonorrhea/chlamydia additional syndromes: anorectal infection
*usually acquired by anal intercourse
*often asymptomatic (>90%)
*sx: anal irritation, painful defecation, constipation, scant rectal bleeding, painless mucopurulent discharge, tenesmus, anal pruritis
*evaluate utilizing anoscopic examination
*signs: mucosa may appear normal, or purulent discharge, erythema, or easily induced bleeding
*dx: NAAT testing for GC/Chl
gonorrhea/chlamydia additional syndromes: epididymitis
*epididymitis and epididymo-orchitis
*characterized by exquisitely tender or swollen testicles
*more common in young males (70% chlamydia, 30% GC); in older males, E.coli + STIs
pelvic inflammatory disease (PID) - overview
*encompasses endometritis and salpingitis
*most often due to chlamydia and gonorrhea (often polymicrobial: strep, gram negs, anaerobes)
*incidence decreasing due to screening
*clinical manifestations:
-lower abdominal pain
-adnexal tenderness
-cervical motion tenderness
-fever
-leukocytosis
pelvic inflammatory disease (PID) - long term sequelae
*tubal infertility
*ectopic pregnancy
*chronic pelvic pain
perihepatitis (Fitz-Hugh-Curtis Syndrome)
*complication of GC/chlamydia
*occurs in women
*complicates 10% of PID
*inflammation of the LIVER CAPSULE with adhesions, causing RUQ pain
*thought to be direct extension of pathogens
pelvic inflammatory disease (PID) - treatment
*ceftriaxone PLUS doxycycline PLUS metronidazole
Trichomonas vaginalis - microbiology
*flagellated anaerobic protozoa
*almost always sexually transmitted
*may persist for months to years in epithelial crypts and periglandular areas
*may be symptomatic or asymptomatic
*untreated trichomoniasis associated with pre-term rupture of membranes and pre-term delivery
Trichomonas vaginalis - clinical manifestations in women
*may be asymptomatic
1. vaginitis:
-frothy gray or yellow-green vaginal discharge
-pruritis
2. cervicitis:
-cervical petechiae (strawberry cervix) = classic presentation, occurs in minority of cases
*may also infect Skene’s glands and urethra
Trichomonas vaginalis - clinical manifestations in men
*cause of nongonococcal urethritis in males
*urethral trichomoniasis has been associated with increased shedding of HIV in HIV-infected men
*frequently asymptomatic
Trichomonas vaginalis - diagnosis
*vaginal pH > 4.5 often present
*positive amine test
*motile trichomonads seen on saline wet mount (low sensitivity)
*CULTURE has increased sensitivity
*Molecular tests (NAAT) have best performance characteristics
Trichomonas vaginalis - treatment
*METRONIDAZOLE is treatment of choice
