MEGARes is a hand-curated antibiotic resistance database which incorporates previously published resistance sequences for antimicrobial drugs, while also expanding to include published sequences for metal and biocide resistance determinants. In MEGARes 2.0, the nodes of the acyclic hierarchical ontology include four antimicrobial compound types, 57 classes, 220 mechanisms of resistance, and 1,345 gene groups that classify the 7,868 accessions. This works in conjunction with the AmrPlusPlus (AMR ++ version 2.0) pipeline to classify resistome sequences directly from FASTA. The database focuses on the analysis of large-scale, ecological sequence datasets with an annotation structure that allows for the development of high throughput acyclical classifiers and hierarchical statistical analysis of big data. MEGARes annotation consists of three hierarchical levels when looking at AMR genes: drug class, mechanism, and group. The MEGARes content was compiled from various other databases: Resfinder, ARG-ANNOT, Comprehensive Antibiotic Resistance Database (CARD), and the National Center for Biotechnology Information (NCBI) Lahey Clinic beta-lactamase archive. MEGARes allows users to analyze antimicrobial resistance on a population-level, similar to a microbiome analysis, from a FASTA sequence or keywords in their search bar. Furthermore, users can access AmrPlusplus, a pipeline for resistome analysis of metagenomic datasets that can be integrated with the MEGARes database. See also Antimicrobial Resistance databases References Antimicrobial resistance organizations Gene banks Metagenomics