Staphylococcus Aureus

I am working with staphylococcus aureus in the lab.
I have cloned a target gene with a HA epitope tag and analysed the secretion of this target protein in the supernatant by western blotting using an anti-HA antibody. I also western blotted empty vectors, which didn’t have my target gene and so no HA epitope tag. But when I western blotted the samples, I seen bands around the 47kDa, which I thought were due to my target protein but they were also present in the empty vectors.
After doing some research I found that there is a Surface Protein A, which must be binding to the anti-HA antibody.
How do I stop these bands from appearing and being able to differentiate my target protein from Protein A? Both proteins are off similar size.