Douglas Harper's Etymology Dictionary
1850s, "resembling a sieve," from Latin colum "strainer;" meaning "resembling a bacillus of the coli group" is from 1906, from coli + form.
Wiktionary
a. Of or pertaining to the bacteria that inhabit the intestines (especially the colon) of mammals n. Such a bacterium
Wikipedia
Usage examples of "coliform".
Fecal coliform is at levels of 100,000 to 5 million colonies per milliliter at the border checkpoint, far above the treaty limit of 240 colonies.
I do not understand the current frenzy, since point-source discharges from the floodplain's seventeen small towns produce in one calendar year twelve times the amount of chemically contaminated stormwater runoff, groundwater leaching, and coliform discharge into surface waters than the combined discharge of all farms in the floodplain for the past decade.