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Tired of being confused by syphilis serologies?!
Want more info on who needs an LP?
To complement our newest episode, here are some infographics & pearls about syphilis covered by Khalil Ghanem and @ZachLorenzMD in this 🧵
#IDTwitter #IDMedEd @ID_fellows @MedTweetorials
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First, let's start with four rules to understand and master syphilis serologies from Khalil!
#IDTwitter #IDMedEd
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There are 2 algorithms - do you know what your lab uses?
📘Trad'l starts with nontrep test ➡️then uses trep test to confirm dx
◀️Reverse sequence starts with TT➡️then use NTT to stage your pt
Use this diagram to help sort the possible scenarios 👇
More on those FP/FN next
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To really hammer this home, check out this chart as well, which includes false positives.
⭐️What is a prozone effect? FN result due to high Ab titers that interfere with the Ag/Ab complex formation (imbalance of Ag and Ab)➡️if you suspect, discuss with lab to dilute specimen
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A pearl from Khalil in the episode: in secondary syphilis, usually everyone has reactive serologies!
If they don't, think about the prozone phenomenon and reconsider what might be going on (that isn't syphilis!)
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Moving to the next question: who needs an LP in syphilis? We know that CSF exam is necessary with neuro sxs, but what about these other situations that often come up?
Check out this guide below based on what Khalil discussed in this episode
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📌Remember that no single test can be used to diagnose neurosyphilis (combo of CSF testing + reactive serology + neuro s/s)
▪️50% of neurosyphilis cases have negative CSF VDRL (highly specific but insensitive)
▪️CSF trep tests are very sensitive but not specific
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📌Last note on neurosyphilis: CSF pleiocytosis is a sensitive test (although not specific)
Listen to the ep. if you haven't already!
🍎podcasts.apple.com/us/podcast/sai…
Or wherever you listen to 🎙️febrilepodcast.captivate.fm/listen
Let me know if you have other tips or recs for these notes!
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⭐️A great overview of syphilis from our guest: pubmed.ncbi.nlm.nih.gov/32101666/
⭐️2021 CDC STI GL: cdc.gov/std/treatment-…
⭐️Check out the @IDSAMedEdCOP Chalk Talk on syphilis from @Darcy_ID_doc for another ID fellow resource for teaching about serologies
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