Bacteria are a highly adaptable single-celled lifeform. They are prokaryotic organisms that lack a membrane-bound nucleus or membrane-bound organelles.
Bacteria can be stopped with antibiotics. (DS9: "Afterimage")
The Crystalline Entity left no trace of life behind on Melona IV, not even soil bacteria. (TNG: "Silicon Avatar")
Doctor Beverly Crusher first assumed that a bacterial infection was responsible for some VISOR malfunctions Geordi La Forge experienced in 2368. She later realized that tampering by solanogen-based lifeforms was responsible as she couldn't find any matching beacterial stem in the medical database. (TNG: "Schisms")
Upon his arrival in a village on Bajor in 2369, Julian Bashir ran a scan for bacteria in the water. (DS9: "The Storyteller")
The bio-neural gel packs of the USS Voyager were once infected with bacteria from cheese by Neelix. (VOY: "Learning Curve")
In late 2372, Dr. Bashir told Odo that an illness that made it difficult for him to hold his shape could be a bacterial infection. (DS9: "Broken Link")
Classes and types of bacteria