"Micro" is a modifier of "evolution", not of "bacteria". "Micro" refers to the degree of evolutionary change, not to the size of the organism. Bacteria can experience a macroevolutionary degree of change.
A simple Google search of "bacteria macroevolution" returns 148,000 results, and of "bacteria speciation" returns 740,000 results. Perhaps you had a typo when you tried it?
Sorry, no typos. Here is another example which illustrates my point that even articles discussing macroevolution in bacteria are unsure about the definition and indicate that it might just aswell be called microevolution.