**5. Bioaccumulation and bacteria resistance genes**

Antibiotics like amoxicillin are used not only for treating human health issues; they are also wide used in livestock farming and fish farming for treating diseases. The improper admin‐ istration of theses pharmaceutical compounds may lead to the occurrence of these drugs in food supplies [4, 78, 94]. Over the last decades, the occurrence of antibiotics in tissues of aquatic organisms has raised the interest of different organisations around the globe, particularly the FDA in USA. It has been reported that continuous exposure to these pharmaceutical com‐ pounds may result in accumulation of the parent compound, their metabolites or both in tissues of aquatic organisms [95].

Due to the risk associated with direct and indirect effects on human health due to both passive and active consumption of antibiotics has lead to set regulations on the use of some antibiotics and the establishment of maximum residue limits. The US official limit tolerance for amoxi‐ cillin residues is 0.01ppm (10 ppb o 10ng/g) in milk and uncooked cattle tissue; however, no tolerance has been established for amoxicillin residues in fish tissues at the present time [78, 95, 96].

It is important to remark that the presence of these drugs in animal tissues can have undesirable effects on consumer health such as allergies; however, the main problem related with the presence of this antimicrobial compounds in fish tissues is the non-controlled ingestion of antibiotics, possibly inducing resistance in bacterial strains [4, 66, 94, 95].

It has been recently shown an exchange of genes for resistance to antibiotics between bacteria in the aquaculture environment and bacteria in the terrestrial environment, including bacteria of animals and human pathogens [4, 97–99]. Therefore, the presence of antibiotics in the aquatic environment can result in the appearances of resistance among human pathogens forming part of its microbiota [4, 100–102].

To sum up the unrestricted use of antibiotics like amoxicillin for any purpose in any country has the potential to affect human and animal health on a global scale; hence, this problem should be dealt through unified local and global preventive approaches [4, 103, 104].
