The presence of antibiotics, antibiotic resistance genes, and antibiotic resistant bacteria in the environment (i.e., outside of clinical settings, such as antibiotic-treated patients or antibiotic-impregnated locations, such as hospitals) is a cause of growing worldwide concern, as it reveals the extensive impact of antibiotic abuse and other human-related pressures upon microbes. Also, the potential clinical and environmental impact of the presence of antibiotic resistance outside the obvious clinical settings is mostly unknown, but could be unexpectedly large, as resistance in clinical conditions can be seen as a very small "tip of the iceberg". The field of detecting and measuring resistance in the environment has rapidly evolved from mostly anecdotal reports at the end of the 1990s, to a systematic search of organisms and genes in a wide variety of settings, from ancient permafrost to migratory birds. This book will review the available evidence and hypotheses on where this resistance is coming from and for how long it has been there; what are the selective and maintenance pressures involved, and how is resistance spreading; what are the known and possible traits that are being selected and spread along with antibiotic resistance ones; what are the laboratory and in-silico strategies to look into this issue, and their advantages and disadvantages.

The presence of antibiotics, antibiotic resistance genes, and antibiotic resistant bacteria in the environment (i.e., outside of clinical settings, such as antibiotic-treated patients or antibiotic-impregnated locations, such as hospitals) is a cause of growing worldwide concern, as it reveals the extensive impact of antibiotic abuse and other human-related pressures upon microbes. Also, the potential clinical and environmental impact of the presence of antibiotic resistance outside the obvious clinical settings is mostly unknown, but could be unexpectedly large, as resistance in clinical conditions can be seen as a very small "tip of the iceberg". The field of detecting and measuring resistance in the environment has rapidly evolved from mostly anecdotal reports at the end of the 1990s, to a systematic search of organisms and genes in a wide variety of settings, from ancient permafrost to migratory birds. This book will review the available evidence and hypotheses on where this resistance is coming from and for how long it has been there; what are the selective and maintenance pressures involved, and how is resistance spreading; what are the known and possible traits that are being selected and spread along with antibiotic resistance ones; what are the laboratory and in-silico strategies to look into this issue, and their advantages and disadvantages.

Avoiding infection has always been expensive. Some human populations escaped tropical infections by migrating into cold climates but then had to procure fuel, warm clothing, durable housing, and crops from a short growing season. Waterborne infections were averted by owning your own well or supporting a community reservoir. Everyone got vaccines in rich countries, while people in others got them later if at all. Antimicrobial agents seemed at first to be an exception. They did not need to be delivered through a cold chain and to everyone, as vaccines did. They had to be given only to infected patients and often then as relatively cheap injectables or pills off a shelf for only a few days to get astonishing cures. Antimicrobials not only were better than most other innovations but also reached more of the world's people sooner. The problem appeared later. After each new antimicrobial became widely used, genes expressing resistance to it began to emerge and spread through bacterial populations. Patients infected with bacteria expressing such resistance genes then failed treatment and remained infected or died. Growing resistance to antimicrobial agents began to take away more and more of the cures that the agents had brought.

Avoiding infection has always been expensive. Some human populations escaped tropical infections by migrating into cold climates but then had to procure fuel, warm clothing, durable housing, and crops from a short growing season. Waterborne infections were averted by owning your own well or supporting a community reservoir. Everyone got vaccines in rich countries, while people in others got them later if at all. Antimicrobial agents seemed at first to be an exception. They did not need to be delivered through a cold chain and to everyone, as vaccines did. They had to be given only to infected patients and often then as relatively cheap injectables or pills off a shelf for only a few days to get astonishing cures. Antimicrobials not only were better than most other innovations but also reached more of the world's people sooner. The problem appeared later. After each new antimicrobial became widely used, genes expressing resistance to it began to emerge and spread through bacterial populations. Patients infected with bacteria expressing such resistance genes then failed treatment and remained infected or died. Growing resistance to antimicrobial agents began to take away more and more of the cures that the agents had brought.