The invention provides novel antimicrobial chemical entities based on a nitrothiazolide backbone that exhibit antibacterial and antiparasitic action against a wide range of human pathogens. The new classes of compounds show extended action against Gram positive bacteria including MRSA drug resistant pathogens. In the Gram-positive organisms, they specifically target and functionally inhibit microbial attachment to surfaces and biofilm formation. In Gram-negative bacteria, including enteroaggregative E. coli strains, these compounds function as pilicides by inhibiting the assembly of pilin subunits into adhesive filaments. Several of these compounds show potent antimicrobial action against Gram positive bacteria, perhaps involving novel targets. Many of the benzothiophene derivatives exhibit antimicrobial activity in the low micrograms per ml range and in blocking biofilm formation in the nanomolar range; ranges considered are well within the range of utility as therapeutics.