Antibiotic Resistance Trends of Escherichia coli in Sewage Treatment Plant Raw Influent, Primary Effluent, Secondary Effluent, and Final Effluent

Changes in antibiotic resistance of Escherichia coli as they go thorough the different stages of conventional activated sludge processes were investigated. The main objective of the study was to determine if the domestic wastewater treatment process caused any significant changes in the antibiotic resistance of E. coli. Throughout a two-year sampling program, over 3,500 E. coli isolates from four stages of the wastewater treatment process were tested for resistance to six different antibiotics. Results show that the percent of resistant bacteria in any of the stages can be highly variable in different samples. A one-way ANOVA test showed that there was no statistically significant difference in the overall percentage of resistant E. coli from the four different stages.