Broad-spectrum antibiotic their greater potential to disrupt a larger variety of normal human flora. After continued exposure to an antibiotic, bacteria may develop changes in their structure or function that make them resistant to the antibiotic. These resistant organisms will live, while the susceptible organisms will die, leaving the population of bacteria entirely resistant to a given antibiotics. For example, after the discovery of penicillin and its subsequent use to treat bacterial infections, bacteria were found to have begun producing an enzyme, penicillinase, which rendered the penicillin molecule inactive. In response to this newly-acquired resistance, newer penicillins were produced that could not
Broad-spectrum antibiotic that lists the susceptibility of community-acquired and hospital-acquired bacteria is helpful in guiding empiric therapy. Many professional organizations (for example, the Infectious Disease Society of America) publish guidelines for empiric antibiotic therapy, as do hospitals, with their choices tailored for their specific resistance patterns. Many of these guidelines also offer guidance on antibiotic dose and duration of therapy. Once a specific species has been identified and its susceptibilities determined, antibiotics can be "narrowed" to a medication which targets a more specific range of bacteria. If no specific species are identified, patients may continue on the empiric regimen. There are an