Antimicrobial resistance is a problem because there is now less choice of effective drugs with which to treat infections. The more an antimicrobial drug is used, the more resistance develops in the germs it is used to treat. For example, only a few years after penicillin was developed, resistance to it was discovered in Staphylococcus aureus. This is a bacteria commonly found on our skin as part of our microflora ( See the 'What makes us ill' section of this site for a description of the benefits of our microflora). Some Staphylococcus aureus (See the 'Hospital acquired infection' section of this site) are now resistant to almost all antibiotics and can be very difficult to treat if they cause illness. Following years of heavy use of penicillin several species of bacteria are now resistant to this drug. Minor infections that were or are easily treated may become more serious if this trend continues as the range of effective antimicrobials is reduced.
The biggest problem facing us is the development of multi-resistant germs. This is when a germ becomes resistant to more than one antimicrobial drug. The more antimicrobials a germ is resistant to the harder it will be to treat. This is the problem with infections such as MRSA (See the Hospital Acquired Infections section of this website). When microbes are resistant the treatment may have to be with antibiotics that are less effective or have more side effects.