Bacteria are mostly free living organisms with all the necessary components to grow and reproduce. Some bacteria can form spores which are a dormant form of the organism. Spores are exceptionally resistant to heat, disinfectants and radiation.
Viruses are not living organisms. The best way to look at viruses is to think of them as tiny machines. They cannot reproduce on their own. They must hijack a host cell and use the hosts own reproduction components to produce more viruses. While viruses are not living they are composed of biological materials and therefore can be destroyed easily while outside the host.
Controlling Bacteria and Viruses
Outside the body, bacteria and viruses are relatively easy to kill using disinfectants. Disinfectants can cause physical damage to the microorganism (e.g. alcohols and QUATS) or chemical damage (e.g. chlorine, bromine). Resistance to disinfectants is extremely rare.
Once inside the body, a bacterial infection can be controlled using antibiotics. Antibiotics kill bacteria by targeting a particular enzyme unique to the bacteria – this is why antibiotics can kill the infection with minimal side effects to the patient. Viruses however are unaffected by antibiotics and the best form of protection from a viral infection is vaccination. Vaccination prepares the body’s own immune system to kill the viral infection.
Some bacteria develop resistance to antibiotics (e.g. MRSA) making them more difficult to treat when they have infected a person. However antibiotic resistant bacteria are just as easily killed by disinfectants as are “normal” bacteria. Therefore, it is easier to reduce the risk of infection by eliminating microorganisms from the healthcare environment before they infect a patient.