Prevalence of Antibiotic Resistance Genes (ARGs) in a small wastewater treatment plant in Egypt

This study aimed to evaluate the occurrence and abundance of antibiotic resistance genes (ARGs) in one of the rural wastewater treatment plants (WWTP) in Egypt, namely Hawamdya.Conventional PCR and qPCR were used to detect and quantify the abundance of β-lactam (ampC and OXA-1), sulfonamide (sul1 and sul2), tetracycline (tetO and tetW), and macrolide (ermF and ermB) as well as class 1 integron (intl1).DNA was extracted from influent, activated sludge, and effluent samples.ARGs were detected and quantified in all the tested samples using specific primers for each gene, suggesting the prevalence of ARG in the wastewater entering and persisting the WWTP.The intl1 gene, a marker for integrons, was highly abundant in the influent and activated sludge, confirming that integrons play a significant role in the spread of antibiotic resistance in the Hawamdya WWTP.The highest occurrence of sul1 and ermF genes among all samples was detected in influent, suggesting the widespread use of sulfonamide and macrolide antibiotics in the located area.The activated sludge showed comparable copy numbers for most ARGs, suggesting that it serves as a reservoir of antibioticresistance genes.The effluent showed a high copy number for sul1 and sul2 genes but a lower level of intl1, indicating that the treatment process partially removes ARGs but may be less effective against integrons.The present study revealed a high abundance of ARG, especially sulfonamide resistance genes, in tested rural WWTP as a point source of ARGs in the environment and emphasized the need to control antibiotic use and develop more effective wastewater treatment strategies to minimize the spread of antibiotic resistance.