Hox genes are a hallmark of multicellular life and are not found in bacteria. Hox genes are just one type of a larger family of gene called "homeobox genes" (watch out, they sound similar!). Bacteria have genes that resemble homeobox genes (Kant et al. 2002) but they're only distantly related to those in multicellular life (Derelle, 2007), and definitely don't have Hox genes. Both plants and animals have homeobox genes, including the subset called Hox genes. The homeobox genes were first found in the fruit fly Drosophila melanogaster and have subsequently been identified in many other species, from insects to reptiles and mammals.
Homeobox genes were previously only identified in bilateria but recently cnidaria have also been found to contain homeobox domains and the "missing link" in the evolution between the two has been identified.
Homeobox genes have even been found in fungi, for example the unicellular yeasts, and in plants.
But no evidence of hox genes are found in bacteria