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
Quinolone antibiotic with urinary catheters. In community-acquired infections, they are recommended only when risk factors for multidrug resistance are present or after other antibiotic regimens have failed. However, for serious acute cases of pyelonephritis or bacterial prostatitis where the person may need to be hospitalised, fluoroquinolones are recommended as first-line therapy. Due to people with sickle-cell disease being at increased risk for developing osteomyelitis from the "Salmonella", fluoroquinolones are the "drugs of choice" due to their ability to enter bone tissue without chelating it, as tetracyclines are known to do. Fluoroquinolones are featured prominently in guidelines for the treatment of hospital-acquired pneumonia.