Flashcards in Micro: Genital Ulcers Deck (19)
How would you go about lab testing for various genital ulcers?
everyone gets HIV testing
HSV: viral culture, DFA, PCR
Chancroid: PCR - not routinely available
these and syphilis are "US"
What are general features of the Herpes virus?
large, enveloped, icosahedral capsids
lytic, persistent, and latent inf (EBV --> immortalizing)
What is the pathogenesis of HSV?
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)
How does HSV reactivate?
triggered by stress, trauma, fever, sunlight, menses, etc.
virus returns to initial site of inf - asymptomatic or vesicular lesions w virions
How does HSV evade immune system?
obstruct pathway leading to CD8 T cell recognition
spreads directly cell to cell, avoiding Ab neutralization
What are big differences in HSV-1 vs. HSV-2?
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
What are the primary and relapsing symptoms seen in HSV1?
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
What are the primary and relapsing symptoms seen in HSV2?
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
What syndromes are associated with HSV1?
gingivostomatitis, orolabial herpes, keratitis, encephalitis, aseptic meningitis, esophagitis (HIV), hepatitis, whitlow
What syndromes are associated with HSV2?
genital, oropharyngeal and neonatal herpes, aseptic meningitis, autonomic neuropathy, Mollaret's meningitis
What is neonatal herpes?
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
How is HSV diagnosed?
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
How is genital herpes managed?
antiviral chemo - doesn't treat latent virus but helps w recurrences
acyclovir, valacyclovir, famciclovir
How do the drugs against herpes work?
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
What is chancroid?
incubation 5-7 days
painful papules that ulcerate w/i 48 hrs (kissing lesions)
tender regional lymphadenopathy - spontaneous rupture, purulent drainage
What causes chancroid?
Haemophilus ducreyi = gram- coccobacillus, chocolate agar, high CO2, gram stain = "school of fish"
What are the CDC definitions of haemophilus ducreyi?
definite: culture +
probable: one or more painful genital ulcers, no evidence of T. pallidum 7 days after onset, clinical picture, HSV testing negative
What is the epidemiology of chancroid?
mostly Asia and Africa, uncommon in U.S.
if here, mostly from returning travelers