2 STIs Flashcards
Causative agent of syphilis
Treponema pallidum
Causative agent of gonorrhea
Neisseria gonorrhoeae
Causative agent of lymphogranuloma venereum or nongonococcal urethritis
Chlamydia trachomatis
Ureaplasma urealyticum
Mycoplasma genitalium
Causative agent of chancroid
Haemophilus ducreyi
Causative agent of granuloma inguinale
Calymmatobacterium granulomatis
Which STDs are ulcerative?
Syphilis
Chancroid
Genital herpes
Which STDs are nonulcerative?
Gonorrhea
Trichomoniasis
Chlamydia
Treponema also causes non-STD diseases such as…
Yaws
Pinta
Bejel
Occur in developing countries and direct contact (person-to-person transmission)
“The great imposter”
Syphilis (Treponema pallidum)
What does the Treponema pallidum bacteria look like?
Gram negative spirochete w/ a slow rotational motility
Obligate internal parasite requiring a mammalian host
Treponema pallidum
No vaccine possible b/c we don’t develop good antibodies to it (since it’s intracellular)
Virulence factors for T. pallidum
Outer membrane proteins promote adherence to host cells
Hyaluronidase may facilitate perivascular infiltration
Fibronectin coat is antiphagocytic - prevents it from looking foreign to the immune system
Syphilitic lesions are primarily the result of …
The inflammatory response
Acquisition of syphilis is usually via …
Direct sexual contact w/ a person who has an active 1˚ or 2˚ lesion
Other acquisition via nongenital contact - lesion near mouth, needle sharing, transplacental transmission
Which stage of syphilis?
Local multiplication and dissemination to nearby lymph nodes and other sites via blood
Primary
Which stage of syphilis?
Indurated swelling develops and surface necrosis results in chancre formation (may not be visible)
Primary
Which stage of syphilis?
Untreated lesion heals in 3-8 weeks w/ fibrosis
Primary
What is the syphilis chancre?
Principle lesion of primary syphilis
Typically begins as a papule that passes through a series of evolutional stages
Superficial erosion —> scanty serous exudate —> thin, grayish, slightly hemorrhagic crust —> base usually smooth, and the border raised, firm, indurated
The period between primary and secondary stages of syphilis is usually …
2-10 weeks
Which stage of syphilis?
Development of superficial, mucocutaneous maculopapular rash
Secondary
Which stage of syphilis?
Mucosal warty lesions (condylomata lata)
Secondary
Which stage of syphilis?
Immune complexes form in arteriolar walls
Secondary
Which stage of syphilis?
Absence of clinical signs/symptoms
Latency
Early syphilis latency
Within 1 year of infection
Recrudescence of active secondary syphilis
Late syphilis latency
> 1 year after infection
Immunity to relapse and reinfection
Spontaneous cure in _____ of syphilis cases
1/3
Seropositivity w/o Disease in ____ of syphilis cases
1/3
Tertiary syphilis develops in _____ of cases
1/3
Which stage of syphilis?
5-20 years after infection
Tertiary
Which stage of syphilis?
Meningovascular changes w/ focal neurologic changes and cortical degeneration
Tertiary
This specifically is neurosyphilis
Which stage of syphilis?
Cardiovascular changes w/ aneurysm of ascending aorta
Tertiary
Which stage of syphilis?
Granulomata (gummas) in any tissue, but especially in skin, bones, joints
Tertiary
When do you usually see changes in infants with congenital syphilis?
After the fourth month, but infection probably occurred earlier
What indicates a poor prognosis for congenital syphilis?
Earlier onset of symptoms after birth
Most infants are born heathy and develop SSx at ~3 weeks of age
What SSx do you see in infants with congenital syphilis?
Maculopapular cutaneous lesions
Nasal obstruction w/ mucous discharge (infectious)
Osteitis of nasal bones
Neurosyphilis
What is Hutchinson’s triad?
Notched incisors, interstitial keratitis, 8th nerve deafness
Until proven otherwise, every genital lesion should be considered …
Syphilitic
What do you have to do to visualize treponema bacteria?
Darkfield microscopy or direct immunofluorescence from 1˚ or 2˚ lesions
Most cases of syphilis are diagnosed…
Serologically
Nontreponemal tests (VDRL, RPR) are non specific screening tests but cheap first pass
Treponemal tests for specific antibodies (FTA-ABS, MHA-TP) - confirmatory for positive screening tests
How do you treat syphilis
Penicillin
Gram-negative diplodocus w/ kidney bean shaped cells
Neisseria gonorrheae
Has fastidious growth requirements
What are the virulence factors for neisseria gonorrheae?
Antigenic variation of pili (confuses immune system)
Nonpiliated phase variants (no antibodies made)
Porin protein and other proteins for attachment
IgA protease***
Plasmid and chromosome-mediated resistance to penicillins, tetracyclines, spectinomycin, and fluoroquinolones
Who has the highest rate of gonorrhea infections?
Adolescents
What is the major reservoir for gonorrhea?
Asymptomatic patients - almost 50% of infected women are asymptomatic
How is gonorrhea transmitted?
Genital, oral-genital, and rectal intercourse
No sexual transmission is extremely rare
Attachment of N. gonorrhoeae to host cell is via…
Pili and surface protein
Bacteria alter their surface properties as an adaptation to the host environment
Nonimmunity to N. gonorrhoeae is due to …
Antigenic variation of pili and surface proteins —> retardation of phagocytes activity
How do N. gonorrhoeae bacteria injury host cells?
Lipooligosaccharide and peptidoglycan
It then spreads to other tissues via Pilar attachment
Where can you get gonorrhea?
Eyes, mouth, urethra, vagina, rectum
Basically any mucosal surface
What is the typical present of gonorrhea in females?
Presence in endocervix (cervicitis) accompanied by urethral colonization
What is the typical presentation of gonorrhea in males?
Presence in anterior urethra with much purulent discharge
Most common complication of gonorrhea in 10-20% of acute infections
Acute salpingitis or PID
Presents w/ pain, dyspareunia, abnormal menses, bleeding, etc
What is salpingitis?
Spread of gonorrheal infection along Fallopian tubes
Can also spread into pelvic cavity —> peritonitis and abscesses
What are the long-term sequelae of acute salpingitis/PID?
Chronic pelvic pain, infertility, and ectopic pregnancy secondary to scarring of tubes
What is DGI?
Disseminated Gonococcal Infection
Any of the forms of N. gonorrhoeae infection can lead to bacteremia
SSx: Fever rash (arthritis-dermatitis syndrome)
Metastatic infections (endocarditis, meningitis) can also occur but PURULENT ARTHRITIS is more common (30-40% of DGI)
Only _____ % of gonococcal infections yield gram negative results
~60% - the gram stain of the exudate varies in sensitivity
What is the gold standard for diagnosing Gonorrhea?
Nuclei acid amplification (PCR)
Can also use agglutination, DNA probe, biochemical tests but PCR is best
How do you treat gonorrhea?
3rd gen cephalosporin
If resistant, go with 4th gen cephalosporin or FQ
Widespread resistance to penicillin and FQs so do a culture and sensitivity
What are the top three species that cause nongonococcal urethritis?
Chlamydia trachomatis
Ureaplasma urealyticum
Mycoplasma genitalium
The last two are more chronic infections b/c no cell wall
What is Psittacosis?
Respiratory, zoonotic atypical pneumonia caused by Chlamydia psittaci
Which chlamydial organism can cause acute PNA?
Chlamydophila pneumoniae
Hard to ID b/c very small, obligate intracellular organism
No long lasting immunity or vaccine
Trachoma, inclusion conjunctivitis, lymphogranuloma venereum and nongonoccal urethritis are all due to…
Chlamydia trachomatis
Super small, gram-negative, obligate intracellular bacteria
Chlamydia trachomatis
This bacteria is metabolically deficient and requires host-derived ATP to survive, so you can identify it by looking for INCLUSIONS
Chlamydia trachomatis
What is the unique replication cycle for chlamydia trachomatis?
Infectious form = elementary body
Fragile intracellular form = reticulate body
Highest prevalence for Chlamydia trachomatis is among…
Teenagers
Ascension of Chlamydia trachomatis bacteria in female patients leads to …
Salpingitis and PID
Complications of scarring in chronic/repeat infections include sterility and ectopic pregnancy
> 50% of infants born to mothers infected with Chlamydia trachomatis show…
Evidence of infection, usually INCLUSION CONJUNCTIVITIS and 5-10% present with PNA
What is the clinical spectrum of chlamydia trachomatis?
Resembles that of N. gonorrhoeae
Urethritis (often asymptomatic) and epididymitis in males
WATERY discharge (not mucous like in gonorrhea)
Cervicitis, salpingitis, and PID in women
Strains of Chlamydia trachomatis that become chronic may be due to…
A gene that encodes for a toxin that functions like Toxin B of C. diff
Protein scaffolding of the infected cells collapse, causing mucosal cells to separate from each other
What is the gold standard for diagnosing Chlamydial infections?
Isolation in cell culture is technically the gold standard (but doesn’t work all the time)
Have to use immortalized cell lines and detect INTRACELLULAR INCLUSIONS, then look for clearing zones
Sensitivity is less than 85%
Nucleic acid probes are very sensitive for Chlamydial infections, but…
They are sensitive for the genes but not for the different Chlamydial species, so you need clinical SSx to diagnose this way
LOTS OF FALSE POSITIVES on the antigen test so just don’t.
How do you treat Chlamydial infections?
Azithromycin or tetracycline (but send for MIC)
The main reservoir for Ureaplasma urealyticum is…
Genital tract of sexually active persons (really any mucosal surface)
Colonization is present in >80% of persons who have had 3 or more sex partners
Responsible for ~50% of nongonococcal, no Chlamydial urethritis in men
Cause of chorioamnionitis and postpartum fever in women
Ureaplasma urealyticum
What are the three species of trichomonas found in humans?
Trichomonas tenax - commensalism in MOUTH
Trichomonas hominis - commensalism in INTESTINE
Trichomonas vaginalis - STD
Tenax and hominis are both part of normal flora and harmless but vaginalis is always pathogenic
Giant flagellated protozoan —> vaginitis
Trichomonas vaginalis
It is an extracellular anaerobic trophozoite
What is the life cycle of Trichomonas vaginalis?
Trophozoite is acquired via sexual intercourse
Parasite establishes on the mucosa and multiplies
Parasite is transmitted to sexual partner
Not a huge amount of tissue damage until it progresses
How does trichomoniasis present in males?
Usually asymptomatic
Scanty, clear to mucopurulent discharge in the event they do have Sx
How does trichomoniasis present in females?
Profuse vaginal discharge - frothy and malodorous (smells “amine”)
Creates an environment for bacterial vaginosis b/c it changes pH
How is trichomoniasis diagnosed?
Wet mount exam - easy to see on microscopy
Culture on diamonds media is more sensitive but takes a long time
Monoclonal antibody methods and DNA probe tests available as well
How do you treat trichomoniasis?
Metronidazole
Overgrowth of opportunistic pathogen in vagina due to change in pH
Bacterial Vaginosis
NOT an STI but more common with Hx of previous STDs, Hx of sexual activity, and current use of intrauterine devices
pH in normal vagina vs vaginosis
Normal <4.5
Vaginosis 5.0-6.0
Presence of clue cells
Distinguishes Vaginosis from normal vaginal secretions
What are the criteria for diagnosing bacterial vaginosis?
(Pick any three)
Homogenous quality of secretions
Presence of clue cells***
Release of fishy amine odor when 10% KOH is added
Vaginal pH >4.5
Presence of curved gram negative or gram variable rods
Color of discharge in vaginosis and trichomoniasis
Vaginosis = gray Trichomoniasis = yellow-gray
Both thin and homogenous
Both respond to metronidazole
Most commonly encountered opportunistic mycoses worldwide
Candidiasis
Normal fungal flora of the skin, mucous membranes
Colonize mucosal surfaces soon after birth (~45 min)
Underlying causes of candidiasis
Absence of competing normal flora
Introduction to abnormal site
“Pathologic” change in microenvironment (ie pH change after STI)
Inborn or acquired immune defect
Use of broad-spectrum abx
80-90% of vulvovaginal candidiasis are due to…
Candida albicans
Remainder are due to C. tropicalis or C. glabrata
Clinical presentation of candidiasis
Thick, white, frothy discharge in women with NO ODOR
Can be considered an STI but usually an endogenous infection
Itching, irritation, burning sensation after intercourse or urination, vaginal pain and soreness
What helps Candida albicans attach to host?
GERM TUBE
How is candida diagnosed?
Direct microscopic exam
Gram stained samples —> large G(+) yeast cells
Culturing candida
Chromagar —> hyphae, pseudohyphae, and GERM TUBES
How is Candidiasis treated?
Topical cream (Miconazole) or oral fluconazole
What species causes chancroid?
Haemophilus ducreyi
Routinely mistaken for syphilis
Chancroid is more common in what locations?
Tropical countries
Female patients with chancroid are more likely to be…
Asymptomatic or have nondescript lesion
What does the chancroid lesion look like?
Tender papule on the genitalia that develops into a tender ulcer with sharp margins
Much angrier, painful, and more likely to spread than syphilis
Ulcer is PAINFUL, bleeds readily, and LACKS INDURATION
May also have regional adenoma they and bubo development
Chancroid development is quick or slow?
Quick - 3-5 days post infection
Vesicle or papule quickly progresses to postulation and ulceration
Can autoinoculate —> multiple ulcers if untreated
How do you diagnose chancroid?
ID of H. ducreyi from genital ulcer or swollen lymph node
There’s also a PCR-based method
How do you treat chancroid?
Varies based on susceptibility testing
3rd gen cephalosporins are still effective
Syndrome unrelated to surgery or pregnancy that results when microorganisms ascend to the endometrium, Fallopian tubes, and contiguous pelvic structures
Pelvic Inflammatory Disease
Produces one or more of the following - endometriosis, salpingitis, pelvic peritonitis, tuboovarian abscess
Usually due to N. gonorrhoeae or C. trachomatis
Clinical manifestations of PID
Lower abdominal pain Abnormal vaginal discharge Painful intercourse Increased pain during menstruation Irregular menstruation Fever/chills Scarring
