Learn the basic differences.<span> There are key differences between bacteria and viruses in size, origins, and effects on the body.</span>[1]<span>Viruses are the smallest and simplest life form; they are 10 to 100 times smaller than bacteria.<span>Bacteria are single-celled organisms that can live either inside or outside other cells. They can survive without a cellular host.[2] Viruses, on the other hand, are only intracellular organisms, meaning that they infiltrate the host cell and live inside the cell. Viruses change the host cell's genetic material from its normal function to producing the virus itself.</span><span>Antibiotics cannot kill viruses, but can kill most bacteria, with the exception of bacteria that have become resistant to the antibiotic.[3] Misuse and overuse of antibiotics have led to antibiotic resistance. Antibiotics are becoming less effective against potentially harmful bacteria. [4] Gram-negative bacteria are highly resistant to treatment with antibiotics, but can be killed by some.<span>[5]</span></span></span>
