Residues of antimicrobial drugs and their metabolites, antibiotic resistance genes (ARGs), and antibiotic resistant bacteria (ARBs), are continuously introduced into the aquatic environment from hospital wastewater discharges and municipal wastewater treatment plant (WWTP) effluents. However, current literature lacks an understanding of the role of antibiotic resistance (AR) elements from the environment on the proliferation and dissemination of AR in a human population that is directly impacted by these wastewater-contaminated waters.
Ingestion of AR elements could change an individual’s intestinal microbiota, resulting in prolonged intestinal carriage of ARBs that can be asymptomatic, but may precede personal infection with an AR pathogen and contribute to the dissemination and maintenance of AR within the community. Therefore, the central focus of this research is to examine the spatio-temporal dynamics of AR element diffusion from potential sources (hospital discharges and WWTP effluents) to locations downstream (e.g., naturally-occurring riverine tributaries), including tube wells that are used as sources for domestic purposes (e.g., drinking, cooking). In Bangladesh, there is a high risk of AR dissemination in the human population because of the general availability and unregulated use of broad-spectrum antibiotics, and poor access to safe water and basic sanitation. These conditions are common in many other developing countries where ARB infections are widespread.
This project employs a spatial sampling procedure using geographic information systems to assess the spatial and temporal dynamics of AR elements in water environments and their relationship to intestinal ARB carriage in humans that consume water from the affected environment. Project team leads will determine the occurrence of several classes of antimicrobials such as fluoroquinolines, cephalosporins, and beta-lactams in water using highly sensitive liquid chromatography/mass spectrometry methods. In addition, we will analyze specific ARGs, such as NDM-1, blaTEM, and blaCTX-M, by quantitative polymerase chain reaction. We will collect stool specimens from healthy individuals living in the surrounding communities where water samples have been collected, and will test samples by conventional microbiologic and advanced molecular techniques for the prevalence of Third-Generation Cephalosporin Resistant, Extended-Spectrum Beta-Lactamase-Producing, and Carbapenem-resistant Enterobacteriaceae.
Results from this study will provide quantitative information on the relationship between the amounts and types of antimicrobial residues and ARGs in water with human intestinal carriage of ARBs. Results will also provide knowledge on the seasonal variations at which antimicrobial residues and ARGs from hospital and urban wastewaters contribute to the prevalence and spread of ARBs in affected communities. Our team will use the data produced as the basis for a planned R01 proposal that will examine how the environmental AR gene pool is modulated by natural and human factors (climate change, waste), and the interrelationship of environmental and human resistomes.
Dhaka, Bangladesh, where AMR to multiple drugs is commonly identified among pathogens of public health significance.
To investigate the role of wastewater discharges from health facilities via hospital wastewater outlet pipes and from municipal wastewater treatment on the dissemination of ARGs and ARBs in the environment and to study how antimicrobials in water contribute to the prevalence of intestinal carriage of ARBs in developing countries where untreated hospital and urban wastewater effluents are commonly discharged into rivers and streams.
Shamim Islam, Jared Aldstadt, and Diana Aga. Global antimicrobial resistance: a complex and dire threat with few definite answers. Tropical Medicine and International Health. Volume 00 No 00. 2019