Why Does Evolution Matter Now?

Describe the non-TB antibiotic resistant bacteria evolution (from your second article).

One antibiotic resistant bacteria that has evolved over the years is methicillin-resistant staphylococcus aureus, which is also known as MRSA. This bacteria staphylococcus aureus was first discovered in the 1880s was known to cause painful skin and soft tissue conditions. In 1943 penicillin became a widely used antibiotic by doctors. By 1945 more than 20% of of the S. aureus strains seen in hospitals were already resistant to penicillin.

In the year 1959 doctors starting using the powerful antibiotic methicillin to treat the S. aureus strains. But, unfortunately within two years methicillin-resistant strains of S. aureus (MRSA) appeared. Meticillin works by deactivating a protein that bacteria use to synthesize their cell walls. But, some individuals were able to synthesis their walls using a different protein that was not affected by methicillin. The ones that survived reproduced quickly and became increasingly common, leading to the spread of MRSA.

Initially, methicillin-resistant S. aureus could be treated by antibiotics that worked differently from methicillin. But over the years it has became more difficult to treat because more MRSA strains are resistant to multiple antibiotics.

How does the misuse of antibiotics affect the evolution of disease causing bacteria?

The misuse of antibiotics affects evolution of disease causing bacteria in many ways. Doctors start fighting a bacteria with a certain antibiotic. Sometimes the antibiotic does not kill all of the bacteria. The bacteria that is not killed with the antibiotic reproduces very quickly and passes on their resistance. Bacteria can exchange genes with members of their own and other species which also helps explain how other present-day multidrug-resistant bacterias have evolved.

For example the MRSA drug-resistant bacteria has evolved after the use of many antibiotics over the last century. It first became...