A global perspective on microbial risk factors in effluents of wastewater treatment plants

Effective monitoring and management of microbial risk factors in wastewater treatment plants (WWTPs) effluents require a comprehensive investigation of these risks. A global survey on microbial risk factors in WWTP effluents could reveal important insights into their risk features. This study aims to explore the abundance and types of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), the vector of ARG/VFG, and dominant pathogens in global WWTP effluents. We collected 113 metagenomes of WWTP effluents from the Sequence Read Archive of the National Center for Biotechnology Information and characterized the microbial risk factors. Our results showed that multidrug resistance was the dominant ARG type, while offensive virulence factors were the most abundant type of VFGs. The most dominant types of ARGs in the vector of plasmid and phage were both aminoglycoside resistance, which is concerning as aminoglycosides are often a last resort for treating multi-resistant infections. Acinetobacter baumannii was the most dominant pathogen, rather than Escherichia coli, and a weak negative correlation between Escherichia coli and two other dominant pathogens (Acinetobacter baumannii and Bacteroides uniformis) suggests that using Escherichia coli as a biological indicator for all pathogens in WWTP effluents may not be appropriate. The Getah virus was the most dominant virus found in global WWTP effluents. Our study presents a comprehensive global-scale investigation of microbial risk factors in WWTP effluents, providing valuable insights into the potential risks associated with WWTP effluents and contributing to the monitoring and control of these risks.