STIs Flashcards
Syphilis species
Treponema pallidum
Gonorrhea species
Neisseria gonorrhoeae
Nongonococcal urethritis species
Chlamydia trachomatis
Ureaplasma urealyticum
Mycoplasma genitalium
Chancroid species
Haemophilus ducreyi
Granuloma inguinale species
Calymmatobacterium granulomatis
Ulcerative STDs
Syphilis
Chancroid
Genital herpes
Non-ulcerative STDs
Gonorrohea
Trichomoniasis
Chlamydia
“The great impostor”
Syphilis
T. pallidum morphology
Gram negative
Spirochete w/ slow rotational motility
Obligate internal parasite
T. pallidum virulence
Outer membrane proteins
Hyaluronidase
Fibronectin coat (antiphagocytic)
Cause of lesions in syphilis
Inflammatory response
Transmission of syphilis
- Direct sexual contact w/ person who has active primary or secondary lesion***
- Needle sharing
- Transplacental
Stages of syphilis
Primary
Secondary
*Latent
Tertiary
Primary syphilis
- Local multiplication and infiltration of nearby LN
- Primary lesion: CHANCRE
Untreated lesion heals in 3-8 weeks
Chancre formation
Principal lesion of PRIMARY syphilis:
- Starts as papule
- Superficial erosion
- Scanty serous exudate may occur, w/ formation of a thin, grayish, hemorrhagic crust
- Base is usually smooth, and the border is raised, firm, and indurated
Secondary syphilis
Dormancy for 2-10 weeks:
- MACULOPAPULAR RASH: superficial lesions of HIGH infectivity
- CONDYLOMATA LATA: mucosal warty lesion
- Immune complexes form in anteriolar walls
Latent syphilis
- Absence of clinical signs and symptoms
- Early latency (w/in 1 year of infection): relapse possible
- Late latency (>1 yr after infection): immunity to relapse
Tertiary syphilis
Manifests 5-20 yr after infection:
- Neurosyphilis (neuro changes and cortical degeneration)
- Cardiovascular syphilis (aneurysm of ascending aorta)
- Granulomata (gummas) in any tissue (esp. skin, bone, joints) = late/benign syphilis
Congenital Syphilis
- Maculopapular cutaneous lesions
- Nasal obstruction w/ mucoid discharge (infectious)
- Osteitis of nasal bones
- Neurosyphilis
- HUTCHINSON’S TRIAD
*Earlier onset of symptoms after birth = worse prognosis
Hutchinson’s Triad
Notched incisors
Interstitial keratitis
8th nerve deafness
Syphilis diagnosis
- Darkfield microscopy or direct immunofluorescence
- Nontreponemal tests (screening)
- Treponemal tests (confirmation)
Nontreponemal tests
VDRL, RPR
Treponemal tests
FTA-ABS, MHA-TP
N. gonorrhoeae morphology
Gram negative
Diplococcus
Kidney bean shaped
Fastidious growth requirements
N. gonorrhoeae virulence
- Antigenic variation of pili
- Nonpiliated phase variants
- Porin protein and other proteins for attachment
- IgA protease
- Plasmid and chromosome mediated resistance to abx
Highest rate of gonorrhea infection
Adolescents
Reservoir for gonorrhea
Asymptomatic patient
Clinical presentation of gonorrhea
Wide spectrum:
- Varying locations
- Females: Presence in endocervix w/ urethral colonization
- Males: Presents in anterior urethra w/ mucopurulent discharge
Complications of Gonorrhea
- Local effects
- PID (most common)
- Disseminated gonococcal infection (DGI)
Disseminated gonococcal infection (DGI)
Bacteremia leads to widespread infection:
- Fever rash (arthritis-dermatitis syndrome)
- Endocarditis
- Meningitis
- Purulent arthritis*** (most common)
Gonorrhea diagnosis
Gram stain is problematic (hiding intracellularly)
Culture:
- Agglutination, DNA probe, biochemical tests for confirmation
- PCR is GOLD STANDARD
Etiology of nongonococcal urethritis
C. trachomatis
Ureaplasma urealyticum
Mycoplasma genitalium
C. trachomatis morphology
Gram negative
Metabolically deficient*** (require host DNA)
Obligate intracellular bacteria
Elementary body
Infectious form of C. trachomatis
Reticulate body
Intracellular form of C. trachomatis
C. trachomatis complications
PID
Sterility
Ectopic pregnancies
Inclusion conjunctivitis and pneumonia (newborns)
Causes of PID
N. gonorrhoeae
C. trachomatis
Chlamydia clinical presentation
ASYMPTOMATIC urethritis and watery discharge (males)
Cervicitis, saplingitis, PID (females)
*Some serotypes cause lymphogranuloma venereum
Cause of chronic inflammation with chlamydia
Toxin producing strains
Chlamydia diagnosis
GOLD STANDARD - Isolation in cell culture:
- Human immortalized cell lines
- INCLUSION BODIES
Noncultural tests:
- Antigen detection (less sensitive)
- PCR (95% sensitivity!)
Ureaplasma urealyticum reservoir
Genital tract of sexually active persons (>80% of people with 3 or more sex partners)
Ureaplasma urealyticum key notes
- Responsible for 50% of nongonococcal, nonchlamydial urethritis in men
- Cause of chorioamnionitis and postpartum fever in women
Trichomonas vaginalis morphology
LARGE flagellated protozoan
Exists only as a trophozoite
Extracellular anaerobe
Trichomonas transmission
ONLY sexual contact
Trichomonas presentation
Male: Asymptomatic to scanty, clear mucopurulent discharge
Female: Profuse vaginal discharge (frothy and malodorous)
Diagnosis of trichomonas
- Wet mount for examination
- Culture (more sensitive)
- Monoclonal antibodies
- DNA probe test (Affirm VP III)
Cause of bacterial vaginosis
Overgrowth of opportunistic pathogen in vagina due to change in pH
NOT AN STI***
Vaginal secretions of bacterial vaginosis (labs)
Elevated pH: 5.0-6.0
CLUE CELLS present
Criteria for bacterial vaginosis diagnosis
Pick any three:
- Homogenous quality of secretions
- CLUE CELLS
- Fishy amine odor when 10% KOH added
- pH >4.5
- Presence of curved gram negative or gram variable rods
Cause of yeast infections
Candida albicans (80-90%)
C. tropicalis
C. glabrata
Can be an STD***
Yeast infection clinical presentation
- Thick, white, frothy discharge WITHOUT ODOR
- Itching, irritation
- Burning sensation during intercourse or urination
- Vaginal pain and soreness
Candida diagnosis
- Microscopy
- Gram stained shows large “G+” cells
- Chromagar
- Germ tube culture
Haemophilus ducreyi morphology
Gram negative
Coccobacillus
Non-motile
Chancroid lesion
“Soft chancre”:
- Develops quickly (3-5 days)
- Papule quickly progresses to pustulation and ulceration
- Progressive enlargement w/ autoinoculation
- Ulcer is painful and tender, bleeds readily and lacks induration!***
Diagnosis of chancroid
- Identification of H. ducreyi from genital ulcer or swollen LN
- Media needs growth supplements (chocolate agar)
- PCR available (false positive with other haemophilus spp)
Risk factors for PID
- STD (esp. gonorrhea or chlamydia) present
- Prior PID
- Sexually active adolescent
- Multiple sex partners
- Frequent douching
Clinical manifestations of PID
Lower abdominal pain Abnormal vaginal discharge Painful intercourse Dysmenorrhea Irregular menstruation Fever/chills Scarring
Diagnosis of PID
Clinical signs with evidence of inflammation - fever, leukocytosis, and/or elevated ESR
