**5. Environmental source of carbapenem-resistant strains**

#### **5.1. General considerations**

Extensive studies are devoted to the ecotoxicity of industrial compounds or of pharmaceutical wastes [45]. Even though existing tools permit measurement of the concentration of any chemical in a certain geographic area, it is almost impossible to accurately estimate the influence of external factors that, no doubt, interfere with the spread or chemical transformation of any substance—like antibiotics. When biology occurs, the problems become more complicated. Nowadays, a different approach in follow-up to the intricate relationships of abundant microorganisms from a specific environment is needed. Antibiotics, like any other chemicals, do not differ in the way of spreading, accumulation, and changing certain environmental characteristics. It is not an exaggeration to state that multidrugresistant microorganisms from hospital facilities are the nightmare of health practitioners. Analyzing bacterial species one by one provides certain information, but the big picture contains much more. Before starting to accumulate new data, there are huge unexplored resources, like public databases. Our concern was related to the magnitude of change on environmental microbiome by medical activities, especially the use of carbapenems. We extensively searched carbapenemases, or similar beta-lactamases, in protein databases available, and we compared their similitudes depending on their isolation source. The goal of searching similitudes between carbapenemase of clinical samples and their counterpart of environmental origin was to assess the influence of medical activities in changing soil and water microbiota.
