Syphilis Treatment & Desensitization

[MudPhud20XX]

Kaplan says "Penicillin-allergic patients receive doxycycline for primary and secondary syphilis, but must be desensitized in tertiary syphilis. Pregnant patients must also undergo desensitization."

Can anyone explain the concept of "desensitization" here for both penicillin allergic pt and for pregnant patients? Why do pregnant patients also have to be desensitized?

Many thanks in advance.

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[Psai]

Doxycycline is a tetracycline class drug so it's bad for a kid's teeth and bones when they're growing. It discolors teeth. I'm not sure if it crosses the placenta but apparently it can go through milk.
Penicillin is a good drug to kill syphilis and you can desensitize people with allergies to it by giving them little by little so they can tolerate the doses that they need same as many other allergies.

 

[MudPhud20XX]

Doxycycline is a tetracycline class drug so it's bad for a kid's teeth and bones when they're growing. It discolors teeth. I'm not sure if it crosses the placenta but apparently it can go through milk.
Penicillin is a good drug to kill syphilis and you can desensitize people with allergies to it by giving them little by little so they can tolerate the doses that they need same as many other allergies.

Got it, so desensitization just simply means that you just give little bit at a time. thanks!

 

[Transposony]

Got it, so desensitization just simply means that you just give little bit at a time. thanks!

Incremental doses at specific intervals.
Just like allergy shots for seasonal allergies.

 

[SBR249]

Desensitization is the process of building up tolerance by gradually increasing the dose given over a short period of time. So you start with a tiny dose and then every few days give a bigger dose until the patient can tolerate a therapeutic dose.

FA2014 definitely lists tetracyclines as a drug to avoid during pregnancy because of bone and teeth effects on pg. 194 so that's why all pregnant patients get penicillin regardless of whether they are allergic or not. Desensitization for the allergic ones.

 

[dyspareunia]

We learned that doxy doesn't actually work in preventing prenatal syphilis. Yeah tetracyclines are contraindicated in pregnancy/children, but that's a secondary point in this case. Recall that in a few infections even pregnant women get doxy.. I think lyme dz is one of them, or maybe it's RMSF.