Seroma after intermuscular lipoma removal and colonized with MRSA. Should I be on antibiotics?

Thank you for sharing your question and I am sorry to hear of your seroma issues.  Unfortunately you did not mention the timing of the seroma development since removal of your lipoma but I will assume it is fairly recent.  As a result drainage of the seroma by reopening the incision and packing it is a good option at resolution and I would encourage a compression garment as well as any unnecessary movement of the bodypart.  As long as the wound remains open and draining it is unlikely to result in an infection that requires antibiotics, despite your MRSA colonization.  Be sure to maintain close follow up with your surgeon so that they can provide you with local wound care recommendations. 

I am sorry about your wound issues, but all will be well .Packing the wound and allowing it to heal from the inside out will prevent infection. Packing prevents the skin from healing before the cavity is healed and thereby eliminates infection potential. If your wound gets red or hot or the drainage is prurulent, (pus) your doctor with open the wound wider, pack it and add antibiotics. Otherwise antibiotics are not required. Good luck and take care.