If a pt is on 10 mg of predisolone daily for polymyalgia and this would not impair the immune system in such a way as to undermine the effectiveness of broad spectrum antibiotics for a urinary tract infection would this still be so if dosage is 40 mg?

It should work fine: That little bit of prednisolone won't stop the neutrophils from mopping up any bacteria that escape the antibiotic.

Steroids : Steroids impair the immune system and is based on duration of therapy and dose. Long term high dose has the highest impact. The immune system will reconstitute itself once doses are reduced. Clearly in sepsis there can be an impact. Yet I deal with transplant patients who are more immunesurpessiom and we can treat them. There are options for abx and most infections can be treated. Best of luck

Maybe: Being on 40g of prednisone you would be immunosupressed and more likely to get an infection but should have no bearing on treating the infection

Excellent question: Generally speaking, taking corticosteroids can make you more susceptible to getting an infection. But I could not find reference to corticosteroids or other immunosuppressants impairing the effectiveness of antibiotics once you have an infection. The dose of antibiotics is not usually increased because the patient is immunosuppressed.

Depends: On general condition of the patient, other diseases, duration of immune suppression, dosage of steroids given, changing the dosage or the antibiotic would in the context of clinical picture and the patient's response, generally speaking if the antibiotic is the right one for the bug, and in the right dose, it won't be affected by the steroids (prednisone), wish you well