Relative abundance of intI1, the clinical class 1 integron-integrase gene, has been previously suggested as a suitable proxy for anthropogenic pollution . This has been attributed to its association to a diverse number of genes that confer resistance to AAs, metals and disinfectants, plus it can be found in a number of bacteria (pathogenic and non-pathogenic). The abundance of this gene can also change rapidly due to changes in the environment, as host cells have rapid generation time and adapt to selective pressures of the environment. Recent work has also proposed that clinical intI1 could be used to indicate the abundance of ARGs and to monitor the removal of ARGs in the wastewater treatment process .