Experimentally induced resistance to nalidixic acid in Bacillus subtillis does not lead to resistance to other antibiotics Introduction: In the environment, bacteria often encounter various antibiotics and, through various mechanisms, evolve to become resistant to these antibiotics. Some of these mechanisms sometimes involve beneficial mutations in a bacterium that allow it to survive antibiotics, but more frequently they involve a transfer of genes from other bacteria, even bacteria of different species. Through the transfer of genes from other bacteria, a bacterium can acquire resistance against different antibiotics (Levy 2002). Nalidixic acid is commonly used to treat urinary tract infections (Nalidixic Acid (Systematic) 1999), and is therefore found in concentrated amounts in the urine. . When a person urinates, any excess nalidixic acid can easily reach the soil, where Bacillus subtilis is naturally found. Since nalidixic acid would be diluted to subtherapeutic concentrations, all nalidixic acid would do is select for resistant strains of any bacteria (e.g. B. subtilis) encountered (Levy 2002). Since bacteria can transmit resistance factors to other currently non-resistant bacteria, the harmless B. subtilis harboring resistance factors against nalidixic acid can potentially transmit the resistance factors to harmful bacteria. Bacteria, however, often develop resistance not just to one antibiotic but to several antibiotics, and can transmit resistance factors for all of these antibiotics to other bacteria. This study will attempt to produce nalidixic acid-resistant B. subtillis and determine whether these nalidixic acid-resistant B. subtillis are also resistant to other antibiotics, especially those of the same class… half of the article. .....important so as not to lose its effectiveness due to antibiotic resistance.References:Ciprofloxacin (oral) [Internet]. Medline Plus Health Information, US National Library of Medicine, National Institutes of Health; [updated April 3, 2003; cited 5 April 2003]. Available from: http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a688016.htmlLevy, S.B. 2002. The antibiotic paradox: How the misuse of antibiotics destroys their healing powers. Perseus Publishing, MA.Hardy, SP 2002. Human Microbiology. Taylor and Francis, NY. Nalidixic acid (systematic) [Internet]. Medline Plus Health Information, US National Library of Medicine, National Institutes of Health; [updated June 14, 1999; cited March 6, 2003]. Available from: http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202387.htmlVoyles, B.A. 2003. Personal communication. Antimicrobial susceptibility testing.