Situational status of antibiotic resistance of E. coli in the Escalerilla WWTP, Arequipa, Peru

During the COVID-19 pandemic in Peru, a notable increase in self-medication with antibiotics has been observed, raising concerns about the increase in bacterial resistance. In this context, we evaluated the situation in wastewater treatment plants (WWTPs) using biochemical methods and sensitivity tests, such as the Kirby-Bauer assay. The results of our study show a high sensitivity to antibiotics in most of the strains analyzed, particularly towards β-lactams. However, this sensitivity appears to be influenced by seasonal patterns of medication consumption, supported by studies indicating that its contribution to the total flow is minimal. We analyzed 49 strains of Escherichia coli, 27% of which showed no resistance to any antibiotic, while the highest resistance was observed against tetracycline (63%). High levels of resistance to fluoroquinolones, such as ciprofloxacin and levofloxacin, were also recorded. In contrast, amikacin and piperacillin-tazobactam showed minimal resistance, with only one strain resistant to each. Multiresistance, defined as resistance to at least two antibiotics, was identified in 35% of the strains, with two of them showing resistance to 8 and 10 antibiotics, respectively.