Pathogens that are antibiotic or antimicrobial resistant produce diseases and infections that cannot be treated with standard antibiotics. These microbes have changed and mutated in ways that greatly reduce or eliminate the effectiveness of antibiotic drugs in curing or preventing infections. For example, methicillin-resistant Staphylococcus aureus (also called MRSA or golden staph) that can cause urinary tract infections and bacterial pneumonia and multidrug-resistant Mycobacterium tuberculosis (called MDR-TB), are bacteria that are not affected by antibiotics. Most doctors agree that avoiding unnecessary prescription of antibiotics can reduce these resistant bacteria.