Microbiology of your ulcerated (and cottage cheese) junk

Question 1

What microbes cause ulcerative STIs?

Answer 1

Haemophilus ducreyi
Treponema pallidum
Chlamydia trach. (LGV)
Other treponemes

Question 2

What causes chancroid?

Answer 2

H. ducreyi

Question 3

How do you diagnose chancroid?

Answer 3

1. No evidence of T. pallidum infection by DFM of exudate or DFA-TP
2. Presentation of ulcers not typical for HSV or HSV culture negative
3. Confirm by culturing on Fildes-enriched gonococcal media (blood, AA, vitamins, serum) in a 10% CO2 atmosphere at 33-35C.

Question 4

Name three pathogenic spirochetes

Answer 4

Treponema
Borrelia (lyme disease)
Leptospira (zoonotic diseases)

Question 5

Which spirochetes can be seen on light-field microscopy?

Answer 5

Borrelia is the only one large enough

Others must be visualized via dark field microscopy or with special stains

Question 6

How do you diagnose T. palladium?

Answer 6

Can’t be cultured
Darkfield microscopy or fluorescent antibody staining
Treponemal and non-treponemal serologic tests

Question 7

What’s the 50% infectious dose for syphilis?

Answer 7

<100 organisms
easily infects mucus membranes
small cuts and abrasions make it easier

Question 8

What are three methods by which syphilis can be spread?

Answer 8

Sexual
Congenital
Direct contact/inoculation

Question 9

What are the lesions of primary, secondary, and tertiary syphilis?

Answer 9

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

Question 10

What are non-treponemal serologic tests?

Answer 10

VDRL, RPR, USR, TRUST
Based on Antibody lipid response
Sensitive for current infection but not specific

Question 11

What are treponemal serologic tests?

Answer 11

FTA-ABS
TP-PA
EIA
Used for definitive diagnosis of syphilis

Question 12

Other than contraception, what’s the most common reason women seek GYN care?

Answer 12

Vaginitis

Question 13

What are three infective causes of vaginitis?

Answer 13

Bacterial vaginosis 40-50%
Cadidiasis 20-25%
Trichomoniasis 15-20%

Question 14

What is the cause of bacterial vaginosis and what predisposes women to this condition?

Answer 14

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

Question 15

What is normal vaginal pH and how do lactobacilli contribute?

Answer 15

Less than 5. Usually 4.5
Lactobacilli produce acid by fermentation
Produce H2O2

Question 16

Diagnostic findings of BV:

Answer 16

Elevated pH
Clue Cells (epithelium covered in gm+ rods)
Amine odor
Culture positive for Gardnerella vaginalis

Question 17

Treatments for BV, Cadida, and Trichomonas? Which needs partner treatment?

Answer 17

Metroniadazole for BV and Trichomonas
Candida needs vaginal or systemic azoles
Trichomonas needs partner treatment to prevent recurrent infection.

Question 18

What are the sx of a yeast infection?

What are risk factors for yeast overgrowth?

Answer 18

vulvovaginal itiching
thick white curdy discharge
burning on urination

changes in hormone status
DM
immunoompromised

Question 19

How do you diagnose yeast infection?

Answer 19

Microscopic Dx of budding yeast
Culture, PCR, and Probes work too
self diagnosis often confused with BV

Question 20

What are the characteristics of Trichomonas vaginalis?

Answer 20

Flagellated protozoan
Replicates by binary fission
Aerotolerant anaerobe
Human vagina is the reservoir

Question 21

What are some similarities between T. vaginalis and BV?

What’s the big difference?

Answer 21

Increased vaginal pH
Similar symptoms
Similar risks with infection
Inflammatory response is seen in Trichomoniasis

Question 22

What are the risks of BV and T. vaginalis infection?

Answer 22

Premature birth
Postpartum complications
Increased risk of other STDs

Question 23

How does metronidazole work?

Answer 23

Prodrug activated by reduction
Once activated imidazole attacks DNA
Works well on anaerobic bacteria and protozoans