Identification of antibiotic resistance genes and their bacterial hosts in samples collected from wastewater treatment plants in Palestine

ABSTRACT Wastewater treatment plants are considered disseminators of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs). In the West Bank, Palestine, there are four working wastewater treatment plants (WWTPs) located in Jenin, Tulkarem, Ramallah (Al-Terah), and Al-Bierh. Most of which have secondary treatment facilities that depend on the activated sludge process. In this study, Illumina high-throughput sequence analysis was used to determine the profile of ARB and ARGs in Al-Bierh and Al-Terah WWTPs. Raw wastewater sample (influent) and secondary treated water sample (effluent) were collected over two seasons, summer and winter. The results showed a higher number of ARB and a wider diversity of ARGs in the winter samples than in the summer samples. The most abundant species found in both seasons and across the samples were Acinetobacter baumannii in the Al-Bireh sample, and Pasteurella multocida in the Al-Terah sample. Moreover, 138 different ARGs conferring resistance to 12 antibiotic classes were detected. The most abundant ARG was the one resistant to macrolides and tetracyclines. The removal efficiency of the 10 most prevalent ARB and ARGs was high, ranging from 85% to 100% in both treatment plants. In conclusion, the unfiltered antibiotics and ARGs can be taken up by plants and crops and thus pose a public health problem. The abundance of ARGs and their bacterial hosts was found to be higher in winter. Therefore, improving the sanitation and efficiency of treatment systems should be a priority for policymakers to limit the burden of ARB and ARGs in treated wastewater in Palestine. IMPORTANCE Untreated wastewater plays a key role in spreading antibiotic-resistant bacteria (ARB) containing antibiotic-resistant genes (ARG) in the environment. The current study characterized the ARB and ARG in two wastewater treatment plants (WWTP) in Jenin and Ramallah, Palestine, in summer and winter in both pre-treated and post-treated water. In winter, ARB were more abundant, and ARGs were highly diverse in both plants alike. Acinetobacter baumannii , an extremely drug-resistant bacterium, was found as a dominant bacterium. The study revealed 12 ARG groups based on the antibiotic class in the two WWTPs, with β-lactamases showing the highest number of resistant genes. The efficiency of removal of bacteria in both plants ranged from 85% to 100%.