Antibiotics not working for e coli infection 10^6 cfu/ml. i've tried 5 different antibiotics. i'm 28 weeks pregnant and told it can cause prematurity ?

Unusual: That does meet criteria for treatment as long as you are having symptoms along with it. The culture should also include antibiotic sensitivity testing to target your specific strain of e.coli. This will guide a correct antibiotic choice which should work if taken exactly as prescribed for the full duration of therapy. For highly resistant strains, a urologist may perform bladder irrigation.