That's a fungus, not a bacteria.
True, my bad. While talking about bacteria I interchangeably used the wrong type of microorganism, in the right context - effect of antibiotics and probiotics on gut microflora.
Speaking of which - Vitamin B3 also seems to be a powerful antifungal that is being used or considered in conjunction with treatments of resistant Candida overgrowth.
Vitamin B3 as a Novel Approach to Treat Fungal Infections - Science Daily, 2010 August 10
Led by IRIC Principal Investigators Martine Raymond, Alain Verreault and Pierre Thibault, in collaboration with Alaka Mullick, from the Biotechnology Research Institute of the National Research Council Canada, the study is the subject of a recent article in Nature Medicine. Infections by the yeast Candida albicans represent a significant public health problem and a common complication in immunodeficient individuals such as AIDS patients, cancer patients undergoing chemotherapy and recipients of organ transplants. While some treatments are available, their efficacy can be compromised by the emergence of drug-resistant strains. The current study shows that a C. albicans enzyme, known as Hst3, is essential to the growth and survival of the yeast. Researchers found that genetic or pharmacological inhibition of Hst3 with nicotinamide, a form of vitamin B3, strongly reduced C. albicans virulence in a mouse model. Both normal and drug-resistant strains of C. albicans were susceptible to nicotinamide. In addition, nicotinamide prevented the growth of other pathogenic Candida species and Aspergillus fumigatus (another human pathogen), thus demonstrating the broad antifungal properties of nicotinamide. ..... < snip > A team of scientists from the Institute for Research in Immunology and Cancer (IRIC) of the University of Montreal have identified vitamin B3 as a potential antifungal treatment.
That's a fungus, not a bacteria.
In other words, then, there's a fungus among us.
Cheers!