Bacteria is a band of musicians from All That that look and perform songs that are titled for "bacteria"-themed substances. They are meant to be a mixed parody of punk, grunge, and heavy metal bands. The band consists of Maggot (played by Josh Server) on lead guitar and lead vocals, Rash (played by Alisa Reyes) on guitar, and Spew (played by Kenan Thompson) on drums.
In one sketch taking place at Dullmont Junior High School, Maggot mentioned that Bacteria got its name when Spew hadn't bathed in 3 1/2 years, before the rest of the info was cut off by Miss Fingerly before Maggot could go into further details.
In Season 4, Maggot and Spew would hold an audition for a replacement member after Rash "quit the band" (Alisa Reyes had left the show after Season 3). After various failed auditions, eventually a young man named Bwah (played by Danny Tamberelli) would be welcomed into the band.