Bacterial removal depends on the size of the filter. Microfilters remove many bacteria, including Campylobacter, Salmonella, Shigella, and E. coli.

Ultrafilters do most bacteria (and many viruses).

See https://www.cdc.gov/healthywater/drinking/home-water-treatme...

Lifestraw, for example, does 99.9999% of bacteria. See http://www.lifestraw.com/faqs/

Typical portable water filters do remove bacteria, but not viruses.

that's why you put iodine tablets in and/or cook water.

Source? The LifeStraw claims to filter out 99.9999% of bacteria, which makes sense, since bacteria are large and thereby easily filtered relative to other contaminants like viruses and dissolved metals.