Micro: Genital Ulcers

Question 1

How would you go about lab testing for various genital ulcers?

Answer 1

everyone gets HIV testing
HSV: viral culture, DFA, PCR
Chancroid: PCR - not routinely available
these and syphilis are “US”

Question 2

What are general features of the Herpes virus?

Answer 2

large, enveloped, icosahedral capsids
dsDNA, linear
lytic, persistent, and latent inf (EBV –> immortalizing)

Question 3

What is the pathogenesis of HSV?

Answer 3

inf and replication in mucoepithelial - lytic inf, persistent inf in lymphocytes and macrophages
inf of innervating neuron - retrograde back to ganglion for latent (sacral and trigeminal)

Question 4

How does HSV reactivate?

Answer 4

triggered by stress, trauma, fever, sunlight, menses, etc.

virus returns to initial site of inf - asymptomatic or vesicular lesions w virions

Question 5

How does HSV evade immune system?

Answer 5

obstruct pathway leading to CD8 T cell recognition

spreads directly cell to cell, avoiding Ab neutralization

Question 6

What are big differences in HSV-1 vs. HSV-2?

Answer 6

glycoprotein gG1 vs. gG2
higher seroprevalence vs. lower
most acquired by 30 as saliva (families, kids) vs. most acquired in adolescence/early adulthood as STD
prior partial immunity to HSV-1 provides partial protection to HSV-2

Question 7

What are the primary and relapsing symptoms seen in HSV1?

Answer 7

primary: incubation 6-8 days, oral mucosa replication, mild fever and sore throat, ascends sensory nerves to trigeminal ganglion
Relapse: at vermillion border, often prodrome of itching, burns, pins and needles

Question 8

What are the primary and relapsing symptoms seen in HSV2?

Answer 8

primary: incubation 3-7 days, painful vesicles, regional LAD, maybe systemic symptoms, ascends sensory nerves to sacral root ganglia, duration 2 wks
relapse: frequent, shorter duration than first episode, prodrome common

Question 9

What syndromes are associated with HSV1?

Answer 9

gingivostomatitis, orolabial herpes, keratitis, encephalitis, aseptic meningitis, esophagitis (HIV), hepatitis, whitlow

Question 10

What syndromes are associated with HSV2?

Answer 10

genital, oropharyngeal and neonatal herpes, aseptic meningitis, autonomic neuropathy, Mollaret’s meningitis

Question 11

What is neonatal herpes?

Answer 11

mostly during childbirth
higher risk in moms who acquire HSV2 near term, lower risk in those w recurrent lesions and Abs
skin/eye/mouth dz, meningoencephalitis, multiorgan dissemination

Question 12

How is HSV diagnosed?

Answer 12

clinical appearance of lesions, viral culture w typing, Tzanck smear
ELISA, IFA, DFA, PCR
type specific serology: primary inf or epidemiology, recurrence doesn’t correlate w rise in titers

Question 13

How is genital herpes managed?

Answer 13

antiviral chemo - doesn’t treat latent virus but helps w recurrences
acyclovir, valacyclovir, famciclovir

Question 14

How do the drugs against herpes work?

Answer 14

all are phosphorylated by viral thymidine kinase - incorporate into viral DNA and prevent elongation
resistance if mutations in viral thymidine kinase
second line = foscarnet, cidofovir

Question 15

What is chancroid?

Answer 15

incubation 5-7 days
painful papules that ulcerate w/i 48 hrs (kissing lesions)
tender regional lymphadenopathy - spontaneous rupture, purulent drainage

Question 16

What causes chancroid?

Answer 16

Haemophilus ducreyi = gram- coccobacillus, chocolate agar, high CO2, gram stain = “school of fish”

Question 17

What are the CDC definitions of haemophilus ducreyi?

Answer 17

definite: culture +
probable: one or more painful genital ulcers, no evidence of T. pallidum 7 days after onset, clinical picture, HSV testing negative

Question 18

What is the epidemiology of chancroid?

Answer 18

mostly Asia and Africa, uncommon in U.S.

if here, mostly from returning travelers

Question 19

What causes granuloma inguinale?

Answer 19

klebsiella granulomatosis

difficult to culture - diagnosis requires seeing intracellular inclusions (Donovan bodies = “safety pins”)