National survey of the occurrence of antimicrobial agents in Australian wastewater and their socioeconomic correlates

A critical approach to combatting antimicrobial resistance involves monitoring the usage of antimicrobial agents (antimicrobials). Despite the increasing per capita use of antimicrobials in Australia, surveys remain limited. Here we investigated the occurrence and use of 102 antimicrobials and their transformation products in raw wastewater collected from 50 wastewater treatment plants across Australia, encompassing ~50% of the national population. The wastewater data were subsequently correlated with catchment-matched Census data to identify population-level socioeconomic factors associated with antimicrobial use. The results showed the detection of 41 antimicrobials and 15 transformation products, covering most of the common antimicrobial groups, with 30 analytes detected at a frequency >50%. Amoxicilloic acid and cephalexin occurred at the highest concentrations and population-normalized mass loads. Correlation analysis revealed a significant association between the consumption of antimicrobials and various socioeconomic statuses, including income, education, occupation, housing, race, health condition and transport. Our study offers comprehensive insight into the patterns of antimicrobial use at the population level in Australia and highlights potential socioeconomic drivers of its use.