Read the passage carefully and answer the question given below.<br><br>Diagnosing disease and prompting treatment options is one thing, but can artificial intelligence really design new drugs to tackle the source of antimicrobial resistance? Apparently it can, right down to the atom.<br><br>Massachusetts Institute of Technology (MIT) has used generative A.I. to structure two new antibiotics that have shown much promise in mice models, killing super bugs that cause drug resistance and MSRA, a bacterial infection many antibiotics fail to cure.<br><br>Antimicrobial resistance has become a global public health threat. In 2019, it led to around 5 million deaths, according to World Health Organisation estimates. Excessive use of antibiotics has made bacteria mutate to resist the drug, but very few new antibiotics have been launched over the decades. The MIT study, published in the journal 'cell', aims to bridge the gap.<br><br>According to the passage, what is the cause of bacterial mutation to resist the drug?