Yep, it is not so much that Remicade is delivered by IV, but the type of drug that it is. The same issues would be present with the subcutaneous ones, like Humira or Simponi. But, not everyone has these problems. It is just important to be aware of the potential. I have been on one anti-TNF or another since 2005, but have not had any issues regarding infections. Sure, I get them, but they have not been persistent. I get my flu shot every year and the only infection I've had requiring antibiotics was a single case of bronchitis and occasional pouchitis. In each instance, antibiotics cleared them up quickly. So, it just depends.
I think the fact that you have an antibiotic resistant strain of E. coli plays a big factor in your UTI problem, and that would be true with or without the Remicade. But, the Remicade will lower your own defenses, so that does complicate things. Another problem with Remicade is that it is long acting, so it takes a long time (4-12 weeks) to metabolize and be out of your system.
Yes, a double edged sword indeed, since they provide a lot of good, but with pitfalls too. Remember though, not all immune suppressants are not equal. Prednisone and other steroids are probably the worst in regard to side effects, as they can destroy many parts of your body, and that is why drugs like methotrexate and anti-TNF drugs are used to get you off them.
In regard to IV drugs and side effects; yes it is true that side effects tend to be worse with IV than oral. That is because they are delivered to your system in full force immediately, without passing through the liver first, or being slowly absorbed as they are in the gut. So, if you have an allergy, IV will produce a faster and more dangerous reaction than oral. However, with oral dosing, the reaction can drag out much longer, after you stop taking it.
Hopefully, they find the antibiotic your E.coli strain is sensitive to and you can get back to normal!
Jan