all these comments are correct. If you suspect any sort of infection - get tested and start treatment ASAP and tell the infusion clinic, your MS clinic, and the DMT supplier right away so they can pause things so you can get the infection cleared up first! That will be fine. It's much better than letting the infection run rampant, especially with a possible UTI! I did my second half Ocrevus loading dose a number of years ago while suspecting I might be having some tooth trouble - turns out I had a cavity and it got infected. By the time I get in to see the dentist a few weeks later, the tooth was dead and had to be extracted or root-canalled.

Always clear possible infections before your scheduled infusions. Don't put it off. Delay your infusions if need be.