In addition to drugs being specific to a certain kind of organism (bacteria, fungi, etc.), some drugs are specific to a certain genus or species of organism, and will not work on other organisms. Because of this specificity, medical microbiologists must consider the effectiveness of certain antimicrobial drugs when making recommendations. Additionally, strains of an organism may be resistant to a certain drug or class of drug, even when it is typically effective against the species. These strains, termed resistant strains, present a serious public health concern of growing importance to the medical industry as the spread of antibiotic resistance worsens. Antimicrobial resistance is an increasingly problematic issue that leads to millions of deaths every year.