Question on Bristle Worms

Over the last couple of weeks I have treated my main tank with Mardel
due to a die off of a lot of fish due to an Ich and/or a stage 2
bacterial infection.

Interesting enough, Now that I think back after looking at the dead
fish- with almost scares on their skins-I think now that the die off
may have also been due to a Bristle Worm not just Ich.

What I'm wondering is?
Now that the tank has been treated with an antibiotic (Mardel) could
it be that the Maracyn may have also killed off the Bristle Worm(s) if
there even was any in the tank?

According to the manufacture of the Mardel medication all inverts must
be removed prior to treatment. So what I'm hoping is that this
medication may have also wiped out any Bristle Worms?

Does anyone know about this? Or may have had any experience killing
off Bristle Worms.

THKS/Rick