This may be possible considering the recent development in bacterial genomics and availability of bacterial chromosomal and extrachromosomal sequences, where metabolic differences may be revealed and accordingly biochemical screening test can be developed?

I don't know if there is a general method, but maybe an approach you could try is to investigate some enzymes that are related to the infection process of the host?

I think you should search about pathogenic island by molecular methods.because all of pathogenic bacteria have pathogenic island in specific parts of their chromosome

You are right and I have already heard of such pathogenicity islands with some phytopathogenic bacteria, but I am not sure if this is true with all of them? and if there are other pathogenicity islands findable in animal and human pathogenic bacteria? And if there are general primers in order to dicriminate such bacterial loads in food and other materials, for example, for quarantine purposes, or for fast screenings of non-hazardous bacteria.

Thank You very much and I will be glad to read more on this topic. Best Wishes