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Micro - Spirochetes (ii) Treponema Pallidum (Intro (causes (endemic…
Micro - Spirochetes (ii) Treponema Pallidum
Intro
causes
syphilis
endemic treponemal disease (not an STI)
yaws
most common
esp in children
skin + bone lesions that look similar to syphilis but aren't on genitals
bejel
won't grow in lab
obligate human pathogen (can't survive outside host)
4th most common curable STI (after chlamydia, gonorrhoea + trichomoniasis parasite)
spread mostly via sex
esp in gay men
30% infection risk from single sexual contact with an infected person
people with an active genital lesion are more likely to get other STIs
2nd most common route of speed = transplacental
congenital syphilis
IU acquisition of intellectual disabilities
not txable with antibiotics
incidence increasing in Ire (partially due to artefact - case definition changed)
bigger problem in developing world
portal of entry = contact with mucous membrane/lesion, or transplacental
disseminates from inoculation site to bloodstream
incubation period = 10-90 days
binds to vasc endothelial cells + goes between tight junctions
prolifs in blood vessel wall
tissue necrosis + ulceration
formation of primary chancre
painless so patients usually don't present
can be on ext genitals (penis/labia) or int (cervix - woman won't know she has one)
can be extra-genital (e.g. lip due to oral sex)
resolve by themselves
highly infectious (as well as lesions from secondary syphilis)
no vaccine
preventable with condoms
Phases/types of syphilis
primary
completely curable
progresses to secondary in 4-10 wks (usually 8)
secondary
ILI (fever, headache, bone/joint pain)
more systemic
rash on soles + palms appears 3-4 days later
condylomata lata (wart-like lesions on genitals)
other manifestations
splenomegaly
lymphadenopathy
CNS involvement (e.g. meningitis)
mucous patch on tongue
highly infectious
still curable
resolves on its own + becomes latent
latent
can last up to 40 yrs
early latent period: 1st yr after secondary syphilis resolves
recurrences of infectious lesions common
still infectious
late latent period
asymptomatic
non-infectious
tertiary
gummata
granulomatous lesions on skin/bone
neurosyphilis
tabes dorsalis (aka syphilitic myopathy)
slow demyelination of neural tracts in dorsal columns
responsible for proprioception, vibration, discriminative touch
general paresis of the insane (cerebral atrophy)
CV syphilis
aortitis
aortic aneurysm or insufficiency
presentation can be v non-specific (syphilis = the great imitator)
congenital
due primary/secondary syphilis untxed in pregnancy (earlier tx -> better outcome)
25% stillbirth risk
risk of death after delivery
rhinorrhoea (syphilitic snuffles), poor feeding, rash on palms + soles, hepatosplenomegaly, bone abnormalities, poor neurological + developmental outcomes
routine antenatal serological screening in Ire
if +ve Tx mam with IM penicillin
Dx
clinical suspicion, serology, x-rays, lumbar puncture (assesses neurological involvement)
Tx = 10 days IV/IM penicillin
Serological syphilus tests
low detection rates in primary
nearly 100% sensitive in secondary
non-treponemal
sensitive but not specific (false +ves for cross-reactive Igs in other conditions)
e.g. RPR (rapid plasma regain) - also assesses Tx response
treponemal
e.g. TPPA (treponema pallidum particle agglutination)
specific Igs
doesn't distinguish between active + txed infection
guidelines in Ire
do enzyme immunoassay (EIA) for IgM/IgG (treponemal test)
if +ve do TPPA + RPR
if both -ve then assume EIA was a false +ve, if TPPA +ve but RPR -ve its a txed syphilis infection
always correlate with clinical findings + patient's risk
sensitivity decreases a bit in tertiary
Tx
1st line = penicillin
use doxycycline in a penicillin allergy
contact tracing NB but can be difficult due to long latency + incubation period
penicillin is the only thing that works for neurosyphilis
Jarisch-Herxheimer reaction may occur with Tx
reaction to endotoxin-like products released after spirochete death
usually not life-threatening
NOT AN ALLERGIC REACTION TO THE DRUG
fever, chills, rigors, hypotension, headache, tachycardia, hyperventilation, vasodilation (flushing), myalgia, exacerbation of skin lesions, anxiety