Emerging Infectious Diseases Probable Causes of Emerging Infectious Diseases Antimicrobial Resistance Medical science has been successful in fighting infectious diseases for more than 54 years. Yet, disease bacteria and microbes have been evolving for about 3.5 billion years.
Bacteria survive by developing a natural resistance to their enemies.
Due to resistance, drugs that once worked against certain bacteria are now not always effective against those same bacteria. Once bacteria evolve, the resistance characteristic is passed on to future generations and sometimes to other bacterial species.