Lec20 Bacterial STDs Flashcards
What bacteria causes syphilis?
- treponema pallidum
What are micro features of treponema pallidum?
- spirochete
What are the high risk groups for syphilis?
- MSM, drug users, multiple sexual partners, common in HIV patients
What are the routes of syphilis transmission
- sexual transmission: penetration via small abrasion on skin or mucus membrane
- during early spirochetemia when negative RPR syphilis test, can be transmitted via blood transfusion
- congenital [via placenta]
What are the four stages os syphilis?
primary, secondary, latent, late
How do you diagnose T. pallidum?
- direct visualization of spirochete [darkfield microscopy, silver staining]
- serologic testing
Can you diagnose T. pallidum from culture?
NO - T. pallidum does not grow in culture
What 3 types of serologic testing for syphilis?
- RPR [inexpensive but non-specific, can be negative just after infection]
- specific treponemal antibody test
- syphilis IgG
What is RPR?
- rapid plasminogen reagin
- uses cardiolipin Ag and charcoal to test for reagin Ab
- Charcoal gets trapped in latice from Ag-Ab rxn and seen microscopically
- reagin antibodies develop from scell breakdown and always seen in syphilis
What are downsides of RPR?
- very sensitive but not specific for syphilis
- positive RPR needs to be confirmed with specific treponemal antibody test
- get false positive from: some viral infections, TB, malaria, pregnancy, IDU [intravenous drug use], autoimmune diseae, other treponemal infections
What is the prozone effect?
- when excess Ab, huge antibody titiers interfere with creation of Ag-Ab lattice
- get false negative on RPR test
- can sometimes occur in secondary syphilis
- seen mostly in HIV + sisnce have broad polyclonal antibody response
What are signs of primary syphilis?
- presence of chancre lesion
- negative RPR early on
- may not notice chancre because its painless
- as chancre is healing, spirochetes enter blood stream and cause dissemination [spirochetemia] leading to secondary syphilis symptoms in half of patients
What are characteristics of chancre lesion?
- sign of primary syphilis
- painless
- smooth ulcer with firm borders
- no exudates
- associated with painless lymphadenopathy
- heals on its own in 3-6 wks
What is differntial diagnosis from a primary chancre?
- chancroid
- lymphogranuloma verenum [LGV]
- herpes virus infection
- traumatic lesion
What are signs of secondary syphilis?
- period with highest spirochete antigen load
- rarely can get prozone phenomemon [esp. with HIV]
- if untreated can get secondary syphilis recurrences in 25%
- rash [palm and sole involvement, trunk], fever, malaise, weight loss, diffuse painless LAD [lymphadenopathy], pharyngitis, arthralgias [joint pain]
- asymptomatic CNS in some [elevated protein or plecytosis, sometimes symptoms of meningitis]
- eye involvement [uveitis]
- eventually immune beats and symptoms dissipate
What are condylomata lata?
- large moist infectious plaques in places where skin rubs [axilla, etc]
What is latent syphilis?
- period after infection when patient is asymptomatic but has reactive specific anti-treponemal antibody test
What are you looking for in LP for syphilis?
- do it on pts with neuro/behavioral changes, with HIV, and failed treatment on penicilin G
- looking for: leucocytosis, high protein or positive VDRL
How do you treat syphilis pt with positive lumbar puncture?
- IV penicillin [PCN] for 10-14 days
- then weekly intramuscular PCN
What is late syphillis?
- years to decades after infection
signs:
- aortitis
- CNS complications [meningo-vascular syphilis, general paresis = dementia/psychosis, tabes dorsalis = degeneration of nerves of dorsal columns of spinal cord]
- gumma formation [tumor like balls of inflammation, usually on bones
What is normal treatment for syphilis [primary, secondary, latent, late]? Other alternatives?
primary/secondary: single injection benzathine penicillin
latent: weekly benzathine penicillin
late: IV penicillin
No substitute for penicillin in late disease
for other stages can use: doxycyclin
What syndomres asociated with chlamydia trachomatis?
- genital infection
- infant pneumonia + conjuncitivits
- ocular trachoma
What is ocular trachoma?
- chronic follicular conjuncitivitis caused by chlamydia trachomatis
- causes scarring of cornea so get vision loss –> blindness
- spread from eye to eye or via autoinoculation from genital secretions
What are the two biotypes of C. trachomatis and what do they cause?
trachoma biotype: causes all genital infections except LGV
LGV biotype: causes lymphogranuloma venereum [LGV]
What is the most common bacterial STD in the US?
C. trachomatis
What are affects of C. trachomatis in men? women?
men: causes urethritis, epididymitis
women: causes urethritits, cerviciits, acute salpingitis [chronic can lead to infertility]
- large proportion of cases asymptomatic
How is chlamydia trachomatis spread?
- infection occurs via abrasion
- can also be transmitted via direct inoculation into eyes or via respiratory tract in birth canal
What is pathogenesis of chlamydia trachomatis?
- causes by inflammatory response rather than tissue destruction
What is life cycle of chlamydia?
- biphase life cycle
elemental body = extracellualr: attaches to and ingested by cells, surgives within phagosome by inhibiting phagolysosomal fustion via outer membrane proteins - differentiates into reticulate bodies = intracellular form: able to replicate within cell
What are signs and symptoms of chlamydia trachomatis?
- urethritis: pain/burning on urination, frequency
- epididymtis: painful swelling of epididymis, erythema of scrotum
- cervicitis: vaginal discharge, painful intercourse, irregular menses
- salpingitis: fever, chills, lower abdomen pain
What is lymphogranulomar vereneum?
- caused by C. trachomatis
- first stage: papule or ulcerative lesion
- second stage days - wks later: regional tender lymphadenopathy, lessions form abscesses, coalesce and form masses [bubos]
- third stage: granulomatous enlargement of external genitalia iwth ulceration
- can also have anal ulceration with adenopathy
How do you diagnose chlamydia?
- for urehtritis, cervicitis, salpingitis: do nucleic acid amplification test to detect DNA/RNA
- for lymphogranuloma venereum: do serum antibody assay for LGV serovars
What is therapy for chlamydia?
- treat empirically for chlamydia and GC
- normal: azithromycin or doxycycline [azi better]
- for neonatal: intravenous macrolide
- can also use fluoroquinolones
- azithromycin safe with pregnancy
What are micro properties of neisseria gonorrhea?
- bean shaped gram negative diplococci
- all oxidase positive, most catalase positive
- fastidious in nature, need nrutrients to grow –> use thayer martin media
How is neisseria gonorrhea spread?
- infection via sexual or perinatal transmission: M –> F higher risk than F–>M
What are the virulence factors of neisseria gonorrhea?
pili: important for attachment to host cell, motility, transfer genetic material
outer membrane protiens
- Opa: important for attachment to host cell
- Por B: prevents phagolysosome fusion
- RMP: stimulate blocking Abs –> reduce bactericidal activity
- lipooligosaccharides [LOS]: have endotoxin activity, cause cell death of mucosal cells
Who most commonly gets gonorrhea infection?
- risk: complement deficiency, promiscuity, no condoms
- adolescents and young adults
- common in MSM
What happens if untreated gonorrhea?
- chronic pelvic pain
- ectopic pregnancy or infertility
What are the symptoms of gonorrhea genital infection?
- urethritis: dysuria, purulent urethral discharge
- epididymitis
- cervicitis
- proctitis
- pharyngitis
- salpingitis [assocated with infertility]
- perihepatitis
- disseminated gonococcal infection [DGI]
What is PID? symptoms? exam?
- infection involving cervix, uterus, tubes, ovaries, pelvic peritoneum
- manifests as endometritis or salpingitis
- higher incidence in teen girls
- common with secondary bacterial super-infection
- symptoms: ab or pelvic pain, fever, chills, nausea, sepsis
- exam: adenexal tenderness, CMT, discharge
- long term causes ectopic rpegnancy/infertility
What is Fitz Hugh Curtis Syndrome? signs?
- there is a direct extension of gonorrhea from fallopian tubes to liver capsule
- get right upper quadrant pain or diffuse ab pain
- seen in women with acute PID
What is disseminated gonococcal infection?
- large spectrum of illness –> single large join arthritis, systemic febrile illness with toxicity, rahs, migratory polyarthritis
- due to bacteremia or immune complex deposition
- common in patients with terminal complement deficiency
What happens in GC in late pregnancy? How do you treat?
- newborn may get neonatal conjunctivitis –> untreated leads to blindness
- treat neonate with prophylactic antibiotic ointment
How can you diagnose GC? why two tests?
- culture AND NAAT [nucleic acid amplification test]
- NAAT won’t give you susceptibility data
- can have low yield cutlure in asymptomatic patients
What is the best way to culture for DGI?
- use thayer-martin agar [chocolate agar with Abx]
- collect from urethra/cervix, blood, pharynx, and rectum
What is treatment for gonorrhea?
- ceftriaxone + azithromycin [or ceft. + doxi in case chlamydia]
- if severe cephalosporin allergy: give azithro
- treat partner
- can’t use FQ or oral cefixime, resistance for PCN, tetracyclines, macrolides, fluoroquionolones, and more recently for cephalosporins
- high rates of resistance so need to test for susceptibility
What causes chancroid?
due to hemophilus ducreyi
asociated with drug use, sex trade, HIV transmission
What is sign of chancroid?
- ulcerative infection with painful adenopath
- painful ulcer, well circumscribes, necrotic base
How do you diagnose chancroid?
- culture of ulcer ecudate on chocolate agar
- if tender necrotic ulcer with lymphadenopathy and negative for syph/hsv
how do you treat chancroid?
azithromycin, ceftriaxone, or ciproflaxicin
