Meta Description: A resistance to antibacterial drugs is a classic demonstration of natural selection in microorganisms during the period of hostbacterial interaction and high intensity of antibiotic exposure. Many bacterial pathogens probably have affected humans for more than 15,000 years.
It is obvious, that the host-bacterial interaction can potentially be accompanied with microevolution of bacteria during long-term colonization protracting for lifelong persistence. Furthermore, subclinical infections are more common than apparent disease; bacteria may modulate their virulence in ways that prolong the interactions with the host to optimize transmission.
Some of the genes associated with antibacterial resistance have a long evolutionary history of diversification that began well before the antibiotic era. Environmental forces (the release of large amounts of antibacterials et cetera) might change natural ecosystem to alteration of the population dynamics of the microorganisms, including selection of resistance with consequences for human health that is difficult to predict. There is an evidence that Helicobacter pylori (H. pylori) has been colonizing humans for more than ten millions years or longer.
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