Microbiology of your ulcerated (and cottage cheese) junk Flashcards
What microbes cause ulcerative STIs?
Haemophilus ducreyi
Treponema pallidum
Chlamydia trach. (LGV)
Other treponemes
What causes chancroid?
H. ducreyi
How do you diagnose chancroid?
- No evidence of T. pallidum infection by DFM of exudate or DFA-TP
- Presentation of ulcers not typical for HSV or HSV culture negative
- Confirm by culturing on Fildes-enriched gonococcal media (blood, AA, vitamins, serum) in a 10% CO2 atmosphere at 33-35C.
Name three pathogenic spirochetes
Treponema
Borrelia (lyme disease)
Leptospira (zoonotic diseases)
Which spirochetes can be seen on light-field microscopy?
Borrelia is the only one large enough
Others must be visualized via dark field microscopy or with special stains
How do you diagnose T. palladium?
Can’t be cultured
Darkfield microscopy or fluorescent antibody staining
Treponemal and non-treponemal serologic tests
What’s the 50% infectious dose for syphilis?
<100 organisms
easily infects mucus membranes
small cuts and abrasions make it easier
What are three methods by which syphilis can be spread?
Sexual
Congenital
Direct contact/inoculation
What are the lesions of primary, secondary, and tertiary syphilis?
1-charcre 2-10 wks after infection, raised painless ulcer
2-condylomata lata, papulosquamous rashes of palms, soles, and genitals. Appear 2-10 wks after primary lesions vanish. extremely contagious
3-neurosyphilis, syphilitic aortitis. may occur years after infection
What are non-treponemal serologic tests?
VDRL, RPR, USR, TRUST
Based on Antibody lipid response
Sensitive for current infection but not specific
What are treponemal serologic tests?
FTA-ABS
TP-PA
EIA
Used for definitive diagnosis of syphilis
Other than contraception, what’s the most common reason women seek GYN care?
Vaginitis
What are three infective causes of vaginitis?
Bacterial vaginosis 40-50%
Cadidiasis 20-25%
Trichomoniasis 15-20%
What is the cause of bacterial vaginosis and what predisposes women to this condition?
Loss of lactobacilli and overgrowth of Mobiluncus and Gardnerella (anaerobes)
Caused by changes in hormone status (estrogen favors lactobacilli), sexual activity, and antibiotic therapy/douching
What is normal vaginal pH and how do lactobacilli contribute?
Less than 5. Usually 4.5
Lactobacilli produce acid by fermentation
Produce H2O2
Diagnostic findings of BV:
Elevated pH
Clue Cells (epithelium covered in gm+ rods)
Amine odor
Culture positive for Gardnerella vaginalis
Treatments for BV, Cadida, and Trichomonas? Which needs partner treatment?
Metroniadazole for BV and Trichomonas
Candida needs vaginal or systemic azoles
Trichomonas needs partner treatment to prevent recurrent infection.
What are the sx of a yeast infection?
What are risk factors for yeast overgrowth?
vulvovaginal itiching
thick white curdy discharge
burning on urination
changes in hormone status
DM
immunoompromised
How do you diagnose yeast infection?
Microscopic Dx of budding yeast
Culture, PCR, and Probes work too
self diagnosis often confused with BV
What are the characteristics of Trichomonas vaginalis?
Flagellated protozoan
Replicates by binary fission
Aerotolerant anaerobe
Human vagina is the reservoir
What are some similarities between T. vaginalis and BV?
What’s the big difference?
Increased vaginal pH
Similar symptoms
Similar risks with infection
Inflammatory response is seen in Trichomoniasis
What are the risks of BV and T. vaginalis infection?
Premature birth
Postpartum complications
Increased risk of other STDs
How does metronidazole work?
Prodrug activated by reduction
Once activated imidazole attacks DNA
Works well on anaerobic bacteria and protozoans
