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. 2021 Jan 18;11:575592. doi: 10.3389/fgene.2020.575592

Metagenomic Approaches to Analyze Antimicrobial Resistance: An Overview

Vinicius A C de Abreu 1,*, José Perdigão 1, Sintia Almeida 2,*
PMCID: PMC7848172  PMID: 33537056

Abstract

Antimicrobial resistance is a major global public health problem, which develops when pathogens acquire antimicrobial resistance genes (ARGs), primarily through genetic recombination between commensal and pathogenic microbes. The resistome is a collection of all ARGs. In microorganisms, the primary method of ARG acquisition is horizontal gene transfer (HGT). Thus, understanding and identifying HGTs, can provide insight into the mechanisms of antimicrobial resistance transmission and dissemination. The use of high-throughput sequencing technologies has made the analysis of ARG sequences feasible and accessible. In particular, the metagenomic approach has facilitated the identification of community-based antimicrobial resistance. This approach is useful, as it allows access to the genomic data in an environmental sample without the need to isolate and culture microorganisms prior to analysis. Here, we aimed to reflect on the challenges of analyzing metagenomic data in the three main approaches for studying antimicrobial resistance: (i) analysis of microbial diversity, (ii) functional gene analysis, and (iii) searching the most complete and pertinent resistome databases.

Keywords: antimicrobial resistance genes, horizontal gene transfer, metagenomic analysis, resistome, Shotgun metagenome sequencing, database

Introduction

Bacterial resistance, which is closely associated with the use of antimicrobial agents, is considered one of the most persistent global public health problems (Enne and Bennett, 2010; Giedraitienė et al., 2011). However, it is not a new phenomenon. Resistance to penicillin developed in the 1940s, immediately after the large-scale use of the antibiotic. Healthcare was the first field to face challenges created by the indiscriminate use of antibiotics. However, medicine is not alone, and the fields of agriculture, livestock farming, and aquaculture are also being affected by the increasing, continued use of antibiotics, which drives the selection of resistant bacterial populations in environments and contributes to antimicrobial resistance (Barbosa and Levy, 2000; Van Boeckel et al., 2015; von Wintersdorff et al., 2016).

Antimicrobial resistance (Table 1) develops when pathogens acquire antimicrobial resistance genes (ARGs). The acquisition of ARGs primarily occurs through genetic recombination between commensal and pathogenic microbes and is associated with the conjugation mechanism of horizontal gene transfer (HGT) (Brown and Wright, 2016; Munita and Arias, 2016). Resistance is a mechanism naturally used by bacteria, whether induced or not induced. However, the large-scale use of antibiotics drives the rapid development of highly antimicrobial-resistant strains. Antibiotic resistance spreads through genetic material exchange, primarily between bacteria of the same genus, and, at a minor frequency, between phyla (von Wintersdorff et al., 2016; Wybouw et al., 2016), resulting in the development of potentially harmful bacteria.

TABLE 1.

Resistance mechanisms, antibiotic resistance genes, and gene localization.

Chemical class Target Action Genes Gene localization Reference(s)
Sulfonamides* Folate synthesis Bacteriostatic sulI, sulII P, T Xu et al., 2018
β-Lactams Cell-wall synthesis Bactericidal ampC, blaTEM, qnrS, tetW P,C Ferro et al., 2017; Pandey and Cascella, 2020
Amphenicols Protein synthesis Bacteriostatic Bactericidal fexA, cat, cmlA, floR, cfr, fex P, T, C Rahal and Simberkoff, 1979; Kehrenberg and Schwarz, 2006; He et al., 2016
Aminoglycosides Protein synthesis Bactericidal rmtA, rmtB, armA, gar P
Tetracyclines Protein synthesis Bacteriostatic Bactericidal tet* P, T Rahal and Simberkoff, 1979; Roberts, 2005
Macrolides Protein synthesis Bacteriostatic erm*, carA, ole*, smrB, tlrC, vgaA, vgaB, lmrA, mefA, msr*, lsaA, lsaB, ereA, ereB, vgbA, vgbB, inuA, inuB, vat*, mph* P, T Kanfer et al., 1998; Roberts, 2005
Glycopeptides Cell-wall synthesis Bactericidal van* P Binda et al., 2014; Lebreton and Cattoir, 2019
Oxazolidinones Protein synthesis Bacteriostatic optrA, cfr P, C Diekema and Jones, 2001; Wang et al., 2015
Ansamycins RNA synthesis Bactericidal rpoB P Floss and Yu, 2005
Quinolones DNA synthesis Bactericidal qnr P Heeb et al., 2011; Hernández et al., 2011
Streptogramins Protein synthesis Bactericidal erm*, carA, ole*, smrB, tlrC, vgaA, vgaB, lmrA, mefA, msr*, lsaA, lsaB, ereA, ereB, vgbA, vgbB, inuA, inuB, vat*, mph* P, T Roberts, 2005
Lipopeptides Protein synthesis Bactericidal mprF, yycG, rpoB, rpoC, cls2, pgsA, agrA, prs, pnpA P, C Montero et al., 2008; Gómez Casanova et al., 2017
Lincosamides Protein synthesis Bacteriostatic erm*, carA, ole*, smrB, tlrC, vgaA, vgaB, lmrA, mefA, msr*, lsaA, lsaB, ereA, ereB, vgbA, vgbB, inuA, inuB, vat*, mph* P, T Tenson et al., 2003; Roberts, 2005
Phenicols Protein synthesis Bacteriostatic Bactericidal fexA, cat, cmlA, floR, cfr, fex P, T, C Kehrenberg and Schwarz, 2006; He et al., 2016
Pyrimidines DNA synthesis Bactericidal dfrK, dfrD, dhfrI, dhfrX P Sundstrom and Skold, 1990; Parsons et al., 1991; Charpentier and Courvalin, 1997; Petersen et al., 2000; Masters et al., 2003; Kadlec and Schwarz, 2009
Sulfonamides DNA Synthesis Bactericidal sul(1-4) P, T Connor, 1998; Razavi et al., 2017
Rifamycins RNA Synthesis Bactericidal rpoB P Floss and Yu, 2005
Lipopeptides Protein Synthesis Bactericidal mprF, yycG, rpoB, rpoC, cls2, pgsA, agrA, prs, pnpA, pmrHFIJKLM, pagP, phoP P, C Thorne and Alder, 2002; Montero et al., 2008; Gómez Casanova et al., 2017
Cationic peptides DNA synthesis, RNA synthesis, Protein synthesis, Cell-wall synthesis Bactericidal pmrHFIJKLM, pagP, phoP C Devine and Hancock, 2002; Hale and Hancock, 2007

P, plasmid; C, chromosome; T, transposon; *Tet gene family, *Erm gene family, *cat gene family, *fex gene family, *ole gene family, *msr gene family, *vat gene family, *mph gene family, *Van gene family.

Although numerous recent and ongoing research efforts have addressed bacterial virulence and multi-resistance mechanisms, the processes governing bacterial fitness, competition, dissemination, and adaptability remain poorly understood. Little is known about the diversity, distribution, and origin of resistance genes, especially those of most environmental bacteria that cannot be cultured under laboratory conditions (Schmieder and Edwards, 2012). The development, acquisition, and dissemination of ARGs are critical aspects of antimicrobial resistance, and the microbial community as a whole contributes to the generation of the antimicrobial resistome, rather than an individual ARG source organism (Bello-López et al., 2019; De, 2019). Therefore, understanding and identifying HGTs among pathogenic and non-pathogenic species may aid the determination of the mechanisms underlying resistance transmission and dissemination. The use of high-throughput sequencing technologies has made ARG sequence analyses feasible and accessible. Metagenomics, in particular, has facilitated the analysis of antimicrobial resistance in communities.

The term metagenomics, first used by Handelsman et al. (1998), originates from conventional microbial genomics and reflects the fact that pure cultures are not required for sequencing. The metagenomics approach is used to analyze the genomic data of environmental samples without the need to first isolate and culture microorganisms (Roh and Villatte, 2008; Cowan et al., 2015). Metagenomic analysis enables the prediction of new taxa (phyla, orders, genera, and candidate species) and genome reconstruction of organisms that cannot be cultured in vitro. The definition of community structures allows a deeper understanding of the relationships between individual components of a community and their dynamics in response to the selective pressure of a space-time parameter (Alves et al., 2018). Therefore, the metagenomic analysis of taxonomic (structural) assignment facilitates better identification of microbial communities, the discovery of new microbial metabolic capacities, and the inference of microbial functions in microbiomes where they inhabit (Simmons et al., 2014; Eloe-Fadrosh et al., 2016). Thus, sequence-based functional metagenomics is a powerful tool, widely used to discover resistance genes and identify and understand resistance mechanisms (Pehrsson et al., 2013; Xing et al., 2020). The robust structural and functional aspects of metagenomic data aid the study of antibacterial resistance.

A series of pipelines and reviews have focused on describing the best platforms for metagenomic statistical analyses and benchmarking metrics (Bengtsson-Palme et al., 2017; Quince et al., 2017; Boolchandani et al., 2019; Tamames and Puente-Sánchez, 2019; Ye et al., 2019), but this is not our goal. In this review, we have focused on the three main approaches used for metagenomic analysis of antimicrobial resistance: (i) analysis of microbial diversity, (ii) functional gene analysis, and (iii) searching the most complete and relevant resistome databases available. We will also comment on the challenges related to analyzing metagenomic data.

Metagenomic Analysis of Resistance Genes

For several years, pathogenic bacteria have been the focus of antibiotic resistance research. This line of research has facilitated the identification of critical mechanisms that mediate bacterial antibiotic resistance. Among the mechanisms of antibiotic resistance, the four most important are (McManus, 1997; Munita and Arias, 2016): (i) enzymatic modification or destruction of the antibiotic, which usually involves the overproduction of enzymes that inactivate the antibiotic (e.g., β-lactamases and aminoglycosides kinases), (ii) alteration of the antibiotic target molecule to reduce its binding capacity, (iii) modification of metabolic pathways and regulatory networks to circumvent the effect of the antibiotic, and (iv) reduction of the intracellular accumulation of the antibiotic by decreasing cellular permeability to it or activating efflux mechanisms to export the harmful molecule.

However, an increasing number of resistance studies have provided new insight into microbial pathogenicity by analyzing the ARGs of both pathogenic and non-pathogenic bacteria (Beceiro et al., 2013; Roberts, 2017). This work raised interest in the genomes of non-pathogenic organisms based on the knowledge that comparative genomic analysis might aid the elucidation of gene associations relevant to antimicrobial resistance and indicate the presence or absence of ARGs. Mass sequencing and complete genome analysis have contributed to important advances in our understanding of bacterial resistance, genes that confer this resistance, and other phenotypes of interest. Moreover, data obtained from genomic analyses have revealed the remarkable genetic plasticity of bacteria, which enables them to respond to a wide variety of threats, including antibiotics. However, to understand the functioning of sets of genes that can acquire antibiotic resistance in resistomes, metagenomic methods are increasingly being used (Ghosh et al., 2013; Costa et al., 2015; Wang et al., 2020; Zhao et al., 2020). Metagenomic approaches can be function- or sequence-based (Schloss and Handelsman, 2003). In sequence-based methods, multiple sequence reads are generated and analyzed using sequence analysis software.

The most comprehensive approach for metagenome sequencing is complete genome sequencing; this approach allows the study of the structural and functional diversities of a microbial community by identifying genes and metabolic pathways and reconstructing almost complete bacterial genomes (Chen and Pachter, 2005; De, 2019). The main advantage of this approach is its sensitivity, as it allows the detection of a greater abundance of species and identification of potential ARGs.

Complete metagenomic sequencing, since it was implemented, has had a tremendous impact on the study of structural and functional microbial diversities in environmental and clinical samples and has been an alternative to rRNA sequencing (Escobar-Zepeda et al., 2018). Alternatively, functional metagenomics employ different approaches to study genes of interest, including gene cloning and sequencing and biochemical analysis (Ngara and Zhang, 2018; Tamames et al., 2019). Functional metagenomics are mostly used for the identification of resistance genes.

However, some challenges affect the quality of metagenomic analysis, with the first being low sensitivity in detecting minority populations that harbor resistance genes, which has proved to be an obstacle at the time of analysis (Lynch and Neufeld, 2015). The second is the low specificity in identifying allelic variants, which can have substantial impact, as different variants can impart different phenotypic susceptibilities (Forslund et al., 2013). To overcome these challenges, metagenomic analyses must employ both sequence- and function-based approaches, including functional gene annotation (Chistoserdovai, 2010; Lam et al., 2015) in the analysis pipeline, and heterologous expression of identified genes (Tripathi and Nailwal, 2020).

Taxonomic Assignment

Horizontal gene transfer is a common method of genetic transfer between species of the same genus or with similar characteristics (Soucy et al., 2015). Thus, studying taxonomic assignments of resistome elements is fundamental for identifying bacteria that shape a resistome. Indeed, the microbial community composition or relative abundance of sampled organisms can be inferred through the taxonomic assignment analysis of resistome elements (Ruppé et al., 2019; Rice et al., 2020). Identifying the bacterial community composition can be accomplished via two distinct approaches: (i) direct measurement of raw data, which does not require the assembly of contigs and (ii) the assembly of contigs for subsequent composition inference. Both strategies have weaknesses and strengths (Mathe, 2002).

Taxonomic classification without the assembly of contigs is a faster approach, with a lower computational cost and no assembly problems (Rodríguez-Brazzarola et al., 2018). However, the quality and length of sequences are important during taxonomic assignment analysis, and poor-quality or short sequences, which are common in the non-assembly based approach, tend to generate matches with low statistical significance (Breitwieser et al., 2019; Ye et al., 2019).

Contrarily, the length of contigs is an advantage for taxonomic classification using contig assembly. Thus, this approach predominantly makes use of databases (Rodríguez-Brazzarola et al., 2018). Moreover, in some cases, contig assembly may enable partial genome reconstruction of a previously unknown organism. However, chimeric contig formation is possible owing to sample heterogeneity, which can be related to sample origin, and sample and sequence quality. All these features are closely linked to assembly quality, which influences classification quality.

In ARG analyses, genome assembly can help differentiate between bacteria in terms of conserved regions like ribosomes, possible HGT regions, and several classes of transposable elements. This is because the reduced size of gene sequences directly impacts gene annotation transfer and studies of biological mechanisms associated with resistance. Thus, taxonomic assignment by contig assembly tends to better facilitate the identification and understanding of resistance mechanisms, such as the understanding of microbiota structural relationship roles in resistome studies. However, it is important to emphasize that researchers must be aware of the type of sample being worked with, if the sample is too heterogeneous and if there is sufficient computational power to analyze the amount of data collected. Even for good-quality, long sequences, taxonomic classification without assembly could be a more appropriate approach from a computational point of view, depending on the dataset and the computational power available (Rodríguez-Brazzarola et al., 2018).

Notably, studying the taxonomic assignments of resistome elements using high-throughput sequencing goes beyond identifying ARGs in host-pathogen relations and can be used to study resistomes in environmental samples, such as those from water reservoirs (Ekwanzala et al., 2020; Yu et al., 2020), hospitals (MetaSUB Consortium et al., 2020), livestock wastewater and feces (Jia S. et al., 2017), human feces (Karkman et al., 2019), soil (Chen et al., 2017), air (Yang et al., 2018; Li et al., 2021), and biogeographical and biogeochemical processes (Quinn et al., 2014; Kuang et al., 2016; Roose-Amsaleg and Laverman, 2016; Liu et al., 2018).

Functional Characterization and Databases

Studying taxonomic signatures enables a better understanding of the relationships between the members of a microbial community. Alternatively, functional metagenomic approach aims to identify functions within the community via the discovery of new enzymes, groups of biosynthetic genes, and ARGs. The functional annotation of a metagenome is similar to its genomic annotation, such that predicted gene sequences are compared to existing sequences in annotated databases (Dong and Strous, 2019). Thus, the high-throughput sequencing of microbial community genomes is a powerful tool to generate information about gene functions, metabolic pathways, and microbial genome evolution (Zhang et al., 2011).

There is a wide range of databases and tools to classify the taxonomic profile of a community and performing functional analyses; thus, the choice of reference database can have important implications for the quality of information obtained. There are three important points regarding sequence- and function-based analyses. First, functional analysis provides an opportunity to perform various sub-analyses, depending on the sequencing depth, including functional category, protein family, gene ontology, protein–protein interaction, pathway, and subsystem analysis. Second, for both types of analysis methods, researchers can work with assembled or non-assembled data. Finally, there are tools, usually open source tools, such as QIIME (Caporaso et al., 2010), Mothur (Schloss et al., 2009), and MEGAN (Huson et al., 2007), that perform both types of analysis.

Genomic annotation employs sequence comparison with similarity-based search tools, such as BLAST+, which was developed by the National Center for Biotechnology Information (NCBI) (Altschul et al., 1997). DIAMOND (Buchfink et al., 2015) performs pairwise sequence alignment for protein and translated DNA searches, which are designed for the high performance analysis of large sequence data; it has the advantage of being fast and is, therefore, attractive for the annotation of huge volumes of metagenomic data. USEARCH (Edgar, 2010) offers search and grouping algorithms that are faster than BLAST. RAPSearch2 (Zhao et al., 2012) is similar to BLAST, in that it uses flexible-length seeds on a reduced amino acid alphabet of ten symbols with the differential. Tools, such as BLAST, offer their own dataset (NR and RefSeq are most used), whereas others offer only alignment options, requiring the use of a third-party dataset (nr/nt, RefSeq, Env_NR, and UniProt). In both cases, it is necessary to download datasets separately or create one’s own local dataset. These tools use their databases for annotation or allow the user to employ a third-party database.

Although there are good database options and tools for comprehensive metagenomic analyses, continuous improvement for the detection and characterization of genetic elements is necessary, as it is important for understanding resistance acquisition over time and evolutionary dynamics. Thus, resistome databases must be constantly updated to include newly identified variant sequences, inserts, and deletions to improve our understanding of these variations in context of resistance (Danko et al., 2019). Moreover, the use of a non-specific or generalist database could generate inherent database bias for the target niche or organism. The choice of an appropriate database for sequence annotation is essential. This choice should be based on the type of data and ecosystem studied. We have highlighted below, the most frequently cited specialist databases for ARGs that allow metagenomic data input (Table 2), including ResFinder, Comprehensive Antibiotic Resistance Database (CARD), MEGARes, ARG-database, and Resfams.

TABLE 2.

Bioinformatic resources for studying ARGs identified using targeted metagenomics.

ARG, Antimicrobial resistance gene; DC, Discontinued.

ResFinder is one of the oldest databases that keeps its sequences up to date. It extracts information from other databases, such as the Lahey1 database and ARDB (both now defunct). ResFinder also sources information from published literature, including reviews (Zankari et al., 2013). It uses the BLAST algorithm to assess sequence similarity. Fully- or draft-assembled sequences from different platforms, genomes or metagenomes, and long or short reads can be used as inputs for ResFinder.

Comprehensive Antibiotic Resistance Database is based on the core components of antimicrobial resistance, including genes and proteins, and utilizes published literature and controlled terminology to robustly investigate data. It is the most commonly used database in metagenomic projects. In addition to having a curated database (Jia B. et al., 2017), it includes resistome data that were computationally predicted in continuation of the ARDB project, which is now defunct.

MEGARes, a database of approximately 8,000 manually curated resistance genes with hierarchical statistical analysis, was published in 2016 and updated in 2019 (Doster et al., 2019). It relies on a specific Galaxy pipeline, although it offers the alternative option of downloading the entire database for integration with custom pipelines. The MEGARes dataset comprises several sources, including the curated CARD database (Doster et al., 2019).

Antimicrobial resistance gene-database is hierarchically structured (ARG type-subtype-reference sequence). Its first version integrated ARGs from ARDB and CARD, and redundant sequences were removed. When it was updated in 2018 (Yin et al., 2018), proteins from the NCBI-NR database were added, thereby tripling the number of sequences in the first version. Based on a specific Galaxy pipeline, the latest version also offers the option to download the database, allowing the integration of the available data with a custom analysis pipeline.

Resfams is organized by ontology with a curated database of protein families and associated profile hidden Markov models (HMMs) and protein sequences from the CARD database, the Lactamase Engineering Database, and Jacoby and Bush’s collection of curated beta-lactamase proteins. It was designed to quantitatively understand the relationship between human and environmental resistomes, with an analysis of over 6000 microbial genomes. It was last updated in 2018 (Gibson et al., 2015).

Although the databases fully complement one another and are often redundant, they continue to be cited as having individual specificities for particular datasets, which hinders recommendations. Given the importance of studies on microbial resistance and the quality of data obtained, it is essential that a platform-independent dataset be available for the antibiotic resistance research community. In one sequence database (DNA/Protein/raw data sequences), INSDC (International Nucleotide Sequence Database), initiatives for the unification and integration have already been implemented. INSDC is a standardization and unification initiative among the main sequence databases (DDBJ, EMBL-EBI, and NCBI), making the data of these databases effectively interchangeable (Karsch-Mizrachi et al., 2018). This type of integration initiative eliminates developer and researcher concerns regarding the “best” dataset for a sample and focuses on the importance and applicability of the analyses and outputs.

Conclusion

Metagenomics is a promising tool for identifying and understanding antibiotic resistance mechanisms, using sequence- and function-based approaches. Notably, however, various analyses of antimicrobial resistance are strongly related to other aspects of the research being carried out, such as mutations, pathogens, metabolic pathways, and gene expression. Reviews analyzing antimicrobial resistance addressing these aspects are strongly recommended.

The most important considerations in a metagenomic resistome study are understanding the nature of the dataset being analyzed and the support that is available for its analysis. If one takes into account the large quantity of data and the complexity of the biological mechanisms involved in antibiotic resistance, it may be preferable to adopt reductionist approaches to decrease bias and increase the objectivity of analyses. It is important to emphasize that the costs of algorithms, computers, and analytical tools are decreasing; in silico predictions based on machine learning are thus becoming more common and have the potential to predict resistance outside databases. This will allow for the development of high-throughput data analysis approaches and the answering more complex questions regarding antimicrobial resistance.

Author Contributions

SA and VA wrote the manuscript, as well as guided and reviewed the work. JP revised the writing and formulated the tables. All authors contributed to the article and approved the submitted version.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

We wish to thank the Paraense Amazon Foundation for Research Support (FAPESPA) and Pós-graduação em Ciência da Informação for the intermediation of financial support.

Funding. This work was supported by the Pró-Reitoria de Pesquisa da Universidade Federal do Para – PROPESP/UFPA. JP received grant-aided support by the Brazilian Federal Agency for the scientific research fellowship from FAPESPA.

References

  1. Altschul S. F., Madden T. L., Schäffer A. A., Zhang J., Zhang Z., Miller W., et al. (1997). Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Res. 25 3389–3402. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Alves L. de F., Westmann C. A., Lovate G. L., de Siqueira G. M. V., Borelli T. C., Guazzaroni M.-E. (2018). Metagenomic Approaches for Understanding New Concepts in Microbial Science. Int. J. Genom. 2018:e2312987. 10.1155/2018/2312987 [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Barbosa T. M., Levy S. B. (2000). The impact of antibiotic use on resistance development and persistence. Drug Resist. Updates 3 303–311. 10.1054/drup.2000.0167 [DOI] [PubMed] [Google Scholar]
  4. Beceiro A., Tomas M., Bou G. (2013). Antimicrobial Resistance and Virulence: a Successful or Deleterious Association in the Bacterial World? Clin. Microbiol. Rev. 26 185–230. 10.1128/CMR.00059-12 [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bello-López J. M., Cabrero-Martínez O. A., Ibáñez-Cervantes G., Hernández-Cortez C., Pelcastre-Rodríguez L. I., Gonzalez-Avila L. U., et al. (2019). Horizontal Gene Transfer and Its Association with Antibiotic Resistance in the Genus Aeromonas spp. Microorganisms 7:363. 10.3390/microorganisms7090363 [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bengtsson-Palme J., Larsson D. G. J., Kristiansson E. (2017). Using metagenomics to investigate human and environmental resistomes. J. Antimicrob. Chemother. 72 2690–2703. 10.1093/jac/dkx199 [DOI] [PubMed] [Google Scholar]
  7. Binda E., Marinelli F., Marcone G. (2014). Old and New Glycopeptide Antibiotics: Action and Resistance. Antibiotics 3 572–594. 10.3390/antibiotics3040572 [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Boolchandani M., D’Souza A. W., Dantas G. (2019). Sequencing-based methods and resources to study antimicrobial resistance. Nat. Rev. Genet. 20 356–370. 10.1038/s41576-019-0108-4 [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Breitwieser F. P., Lu J., Salzberg S. L. (2019). A review of methods and databases for metagenomic classification and assembly. Brief. Bioinform. 20 1125–1136. 10.1093/bib/bbx120 [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Brown E. D., Wright G. D. (2016). Antibacterial drug discovery in the resistance era. Nature 529 336–343. 10.1038/nature17042 [DOI] [PubMed] [Google Scholar]
  11. Buchfink B., Xie C., Huson D. H. (2015). Fast and sensitive protein alignment using DIAMOND. Nat. Methods 12 59–60. 10.1038/nmeth.3176 [DOI] [PubMed] [Google Scholar]
  12. Caporaso J. G., Kuczynski J., Stombaugh J., Bittinger K., Bushman F. D., Costello E. K., et al. (2010). QIIME allows analysis of high-throughput community sequencing data. Nat. Methods 7 335–336. 10.1038/nmeth.f.303 [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Charpentier E., Courvalin P. (1997). Emergence of the trimethoprim resistance gene dfrD in Listeria monocytogenes BM4293. Antimicr. Agents Chemother. 41 1134–1136. 10.1128/AAC.41.5.1134 [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Chen K., Pachter L. (2005). Bioinformatics for Whole-Genome Shotgun Sequencing of Microbial Communities. PLoS Comp. Biol. 1:e24. 10.1371/journal.pcbi.0010024 [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Chen Q.-L., An X.-L., Zhu Y.-G., Su J.-Q., Gillings M. R., Ye Z.-L., et al. (2017). Application of Struvite Alters the Antibiotic Resistome in Soil, Rhizosphere, and Phyllosphere. Environ. Sci. Technol. 51 8149–8157. 10.1021/acs.est.7b01420 [DOI] [PubMed] [Google Scholar]
  16. Chistoserdovai L. (2010). Functional metagenomics: recent advances and future challenges. Biotechnol. Genet. Eng. Rev. 26 335–352. [PubMed] [Google Scholar]
  17. Connor E. E. (1998). Sulfonamide antibiotics. Prim. Care Update OB/GYNS 5 32–35. 10.1016/S1068-607X(97)00121-2 [DOI] [Google Scholar]
  18. Costa P. S., Reis M. P., Ávila M. P., Leite L. R., de Araújo F. M. G., Salim A. C. M., et al. (2015). Metagenome of a Microbial Community Inhabiting a Metal-Rich Tropical Stream Sediment. PLoS One 10:e0119465. 10.1371/journal.pone.0119465 [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Cowan D., Ramond J.-B., Makhalanyane T., De Maayer P. (2015). Metagenomics of extreme environments. Curr. Opin. Microbiol. 25 97–102. 10.1016/j.mib.2015.05.005 [DOI] [PubMed] [Google Scholar]
  20. Danko D., Bezdan D., Afshinnekoo E., Ahsanuddin S., Bhattacharya C., Butler D. J., et al. (2019). Global Genetic Cartography of Urban Metagenomes and Anti-Microbial Resistance. Microbiology 2019:526 10.1101/724526 [DOI] [Google Scholar]
  21. De R. (2019). Metagenomics: aid to combat antimicrobial resistance in diarrhea. Gut. Pathog. 11 47. 10.1186/s13099-019-0331-8 [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Devine D., Hancock R. (2002). Cationic Peptides: Distribution and Mechanisms of Resistance. Curr. Pharmaceut. Design 8 703–714. 10.2174/1381612023395501 [DOI] [PubMed] [Google Scholar]
  23. Diekema D. J., Jones R. N. (2001). Oxazolidinone antibiotics. Lancet 358 1975–1982. 10.1016/S0140-6736(01)06964-1 [DOI] [PubMed] [Google Scholar]
  24. Dong X., Strous M. (2019). An Integrated Pipeline for Annotation and Visualization of Metagenomic Contigs. Front. Genet. 10:999. 10.3389/fgene.2019.00999 [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Doster E., Lakin S. M., Dean C. J., Wolfe C., Young J. G., Boucher C., et al. (2019). MEGARes 2.0: a database for classification of antimicrobial drug, biocide and metal resistance determinants in metagenomic sequence data. Nucleic Acids Res. 48 D561–D569. 10.1093/nar/gkz1010 [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Edgar R. C. (2010). Search and clustering orders of magnitude faster than BLAST. Bioinformatics 26 2460–2461. 10.1093/bioinformatics/btq461 [DOI] [PubMed] [Google Scholar]
  27. Ekwanzala M. D., Dewar J. B., Momba M. N. B. (2020). Environmental resistome risks of wastewaters and aquatic environments deciphered by shotgun metagenomic assembly. Ecotoxicol. Environ. Safety 197:110612. 10.1016/j.ecoenv.2020.110612 [DOI] [PubMed] [Google Scholar]
  28. Eloe-Fadrosh E. A., Ivanova N. N., Woyke T., Kyrpides N. C. (2016). Metagenomics uncovers gaps in amplicon-based detection of microbial diversity. Nat. Microbiol. 1 1–4. 10.1038/nmicrobiol.2015.32 [DOI] [PubMed] [Google Scholar]
  29. Enne V. I., Bennett P. M. (2010). “Methods to Determine Antibiotic Resistance Gene Silencing,” in Antibiotic Resistance Protocols, eds Gillespie S. H., McHugh T. D. (Totowa, NJ: Humana Press; ), 29–44. 10.1007/978-1-60327-279-7_3 [DOI] [PubMed] [Google Scholar]
  30. Escobar-Zepeda A., Godoy-Lozano E. E., Raggi L., Segovia L., Merino E., Gutiérrez-Rios R. M., et al. (2018). Analysis of sequencing strategies and tools for taxonomic annotation: Defining standards for progressive metagenomics. Sci. Rep. 8:12034. 10.1038/s41598-018-30515-5 [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Ferro G., Guarino F., Cicatelli A., Rizzo L. (2017). β-lactams resistance gene quantification in an antibiotic resistant Escherichia coli water suspension treated by advanced oxidation with UV/H2O2. J. Hazard. Mater. 323 426–433. 10.1016/j.jhazmat.2016.03.014 [DOI] [PubMed] [Google Scholar]
  32. Floss H. G., Yu T.-W. (2005). RifamycinMode of Action, Resistance, and Biosynthesis. Chem. Rev. 105 621–632. 10.1021/cr030112j [DOI] [PubMed] [Google Scholar]
  33. Forslund K., Sunagawa S., Kultima J. R., Mende D. R., Arumugam M., Typas A., et al. (2013). Country-specific antibiotic use practices impact the human gut resistome. Genome Res. 23 1163–1169. 10.1101/gr.155465.113 [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Ghosh T. S., Gupta S. S., Nair G. B., Mande S. S. (2013). In Silico Analysis of Antibiotic Resistance Genes in the Gut Microflora of Individuals from Diverse Geographies and Age-Groups. PLoS One 8:e83823. 10.1371/journal.pone.0083823 [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Gibson M. K., Forsberg K. J., Dantas G. (2015). Improved annotation of antibiotic resistance determinants reveals microbial resistomes cluster by ecology. ISME J. 9 207–216. 10.1038/ismej.2014.106 [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Giedraitienė A., Vitkauskienė A., Naginienė R., Pavilonis A. (2011). Antibiotic Resistance Mechanisms of Clinically Important Bacteria. Medicina 47:19 10.3390/medicina47030019 [DOI] [PubMed] [Google Scholar]
  37. Gómez Casanova N., Siller Ruiz M., Muñoz Bellido J. L. (2017). Mechanisms of resistance to daptomycin in Staphylococcus aureus. Rev. Esp. Quimioter. 30 391–396. [PubMed] [Google Scholar]
  38. Hale J. D., Hancock R. E. (2007). Alternative mechanisms of action of cationic antimicrobial peptides on bacteria. Expert. Rev. Anti. Infective Ther. 5 951–959. 10.1586/14787210.5.6.951 [DOI] [PubMed] [Google Scholar]
  39. Handelsman J., Rondon M. R., Brady S. F., Clardy J., Goodman R. M. (1998). Molecular biological access to the chemistry of unknown soil microbes: a new frontier for natural products. Chem. Biol. 5 R245–R249. 10.1016/S1074-5521(98)90108-9 [DOI] [PubMed] [Google Scholar]
  40. He T., Shen Y., Schwarz S., Cai J., Lv Y., Li J., et al. (2016). Genetic environment of the transferable oxazolidinone/phenicol resistance gene optrA in Enterococcus faecalis isolates of human and animal origin. J. Antimicrob. Chemother. 71 1466–1473. 10.1093/jac/dkw016 [DOI] [PubMed] [Google Scholar]
  41. Heeb S., Fletcher M. P., Chhabra S. R., Diggle S. P., Williams P., Cámara M. (2011). Quinolones: from antibiotics to autoinducers. FEMS Microbiol. Rev. 35 247–274. 10.1111/j.1574-6976.2010.00247.x [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Hernández A., Sánchez M. B., Martínez J. L. (2011). Quinolone Resistance: Much More than Predicted. Front. Microbiol. 2:22. 10.3389/fmicb.2011.00022 [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Huson D. H., Auch A. F., Qi J., Schuster S. C. (2007). MEGAN analysis of metagenomic data. Genome Res. 17 377–386. 10.1101/gr.5969107 [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Jia B., Raphenya A. R., Alcock B., Waglechner N., Guo P., Tsang K. K., et al. (2017). CARD 2017: expansion and model-centric curation of the comprehensive antibiotic resistance database. Nucleic Acids Res. 45 D566–D573. 10.1093/nar/gkw1004 [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Jia S., Zhang X.-X., Miao Y., Zhao Y., Ye L., Li B., et al. (2017). Fate of antibiotic resistance genes and their associations with bacterial community in livestock breeding wastewater and its receiving river water. Water Res. 124 259–268. 10.1016/j.watres.2017.07.061 [DOI] [PubMed] [Google Scholar]
  46. Kadlec K., Schwarz S. (2009). Identification of a Novel Trimethoprim Resistance Gene, dfrK, in a Methicillin-Resistant Staphylococcus aureus ST398 Strain and Its Physical Linkage to the Tetracycline Resistance Gene tet(L). Antimicr. Agents Chemother. 53 776–778. 10.1128/AAC.01128-08 [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Kanfer I., Skinner M. F., Walker R. B. (1998). Analysis of macrolide antibiotics. J. Chromatogr. A 812 255–286. 10.1016/S0021-9673(98)00276-3 [DOI] [PubMed] [Google Scholar]
  48. Karkman A., Pärnänen K., Larsson D. G. J. (2019). Fecal pollution can explain antibiotic resistance gene abundances in anthropogenically impacted environments. Nat. Commun. 10:80. 10.1038/s41467-018-07992-3 [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Karsch-Mizrachi I., Takagi T., Cochrane G. (2018). The international nucleotide sequence database collaboration. Nucleic Acids Res. 46 D48–D51. 10.1093/nar/gkx1097 [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Kehrenberg C., Schwarz S. (2006). Distribution of Florfenicol Resistance Genes fexA and cfr among Chloramphenicol-Resistant Staphylococcus Isolates. Antimicrob. Agents Chemother. 50 1156–1163. 10.1128/AAC.50.4.1156-1163.2006 [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Kuang J., Huang L., He Z., Chen L., Hua Z., Jia P., et al. (2016). Predicting taxonomic and functional structure of microbial communities in acid mine drainage. ISME J. 10 1527–1539. 10.1038/ismej.2015.201 [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Lam K. N., Cheng J., Engel K., Neufeld J. D., Charles T. C. (2015). Current and future resources for functional metagenomics. Front. Microbiol. 6:1196. 10.3389/fmicb.2015.01196 [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Lebreton F., Cattoir V. (2019). “Resistance to Glycopeptide Antibiotics,” in Bacterial Resistance to Antibiotics – From Molecules to Man, eds Bonev B. B., Brown N. M. (New York: Wiley; ), 51–80. 10.1002/9781119593522.ch3 [DOI] [Google Scholar]
  54. Li X., Wu Z., Dang C., Zhang M., Zhao B., Cheng Z., et al. (2021). A metagenomic-based method to study hospital air dust resistome. Chem. Engin. J. 406:126854. 10.1016/j.cej.2020.126854 [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Liu B., Pop M. (2009). ARDB–Antibiotic Resistance Genes Database. Nucleic Acids Res. 37 D443–D447. 10.1093/nar/gkn656 [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Liu L., Su J.-Q., Guo Y., Wilkinson D. M., Liu Z., Zhu Y.-G., et al. (2018). Large-scale biogeographical patterns of bacterial antibiotic resistome in the waterbodies of China. Environ. Int. 117 292–299. 10.1016/j.envint.2018.05.023 [DOI] [PubMed] [Google Scholar]
  57. Lynch M. D. J., Neufeld J. D. (2015). Ecology and exploration of the rare biosphere. Nat. Rev. Microbiol. 13 217–229. 10.1038/nrmicro3400 [DOI] [PubMed] [Google Scholar]
  58. Masters P. A., O’Bryan T. A., Zurlo J., Miller D. Q., Joshi N. (2003). Trimethoprim-Sulfamethoxazole Revisited. Arch. Int. Med. 163:402. 10.1001/archinte.163.4.402 [DOI] [PubMed] [Google Scholar]
  59. Mathe C. (2002). Current methods of gene prediction, their strengths and weaknesses. Nucleic Acids Res. 30 4103–4117. 10.1093/nar/gkf543 [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. McArthur A. G., Waglechner N., Nizam F., Yan A., Azad M. A., Baylay A. J., et al. (2013). The Comprehensive Antibiotic Resistance Database. Antimicrob. Agents Chemother. 57 3348–3357. 10.1128/AAC.00419-13 [DOI] [PMC free article] [PubMed] [Google Scholar]
  61. McManus M. C. (1997). Mechanisms of bacterial resistance to antimicrobial agents. Am. J. Health Syst. Pharm. 54 1420–1433. 10.1093/ajhp/54.12.1420 [DOI] [PubMed] [Google Scholar]
  62. MetaSUB Consortium, Chng K. R., Li C., Bertrand D., Ng A. H. Q., Kwah J. S., et al. (2020). Cartography of opportunistic pathogens and antibiotic resistance genes in a tertiary hospital environment. Nat. Med. 26 941–951. 10.1038/s41591-020-0894-4 [DOI] [PMC free article] [PubMed] [Google Scholar]
  63. Montero C. I., Stock F., Murray P. R. (2008). Mechanisms of Resistance to Daptomycin in Enterococcus faecium. Antimicrob. Agents Chemother. 52 1167–1170. 10.1128/AAC.00774-07 [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Munita J. M., Arias C. A. (2016). Mechanisms of Antibiotic Resistance. Microbiol. Spectr. 4:15. 10.1128/microbiolspec.VMBF-0016-2015 [DOI] [PMC free article] [PubMed] [Google Scholar]
  65. Ngara T. R., Zhang H. (2018). Recent Advances in Function-based Metagenomic Screening. Genom. Proteom. Bioinform. 16 405–415. 10.1016/j.gpb.2018.01.002 [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Pandey N., Cascella M. (2020). Beta Lactam Antibiotics. Treasure Island, FL: StatPearls Publishing; Available online at: http://www.ncbi.nlm.nih.gov/books/NBK545311/ (accessed on June 23, 2020). [PubMed] [Google Scholar]
  67. Parsons Y., Hall R. M., Stokes H. W. (1991). A new trimethoprim resistance gene, dhfrX, in the In7 integron of plasmid pDGO100. Antimicrob. Agents Chemother. 35 2436–2439. 10.1128/AAC.35.11.2436 [DOI] [PMC free article] [PubMed] [Google Scholar]
  68. Pehrsson E. C., Forsberg K. J., Gibson M. K., Ahmadi S., Dantas G. (2013). Novel resistance functions uncovered using functional metagenomic investigations of resistance reservoirs. Front. Microbiol. 7:145. 10.3389/fmicb.2013.00145 [DOI] [PMC free article] [PubMed] [Google Scholar]
  69. Petersen A., Guardabassi L., Dalsgaard A., Olsen J. E. (2000). Class I integrons containing a dhfrI trimethoprim resistance gene cassette in aquatic Acinetobacter spp. FEMS Microbiol. Lett. 182 73–76. 10.1111/j.1574-6968.2000.tb08876.x [DOI] [PubMed] [Google Scholar]
  70. Quince C., Walker A. W., Simpson J. T., Loman N. J., Segata N. (2017). Shotgun metagenomics, from sampling to analysis. Nat. Biotechnol. 35 833–844. 10.1038/nbt.3935 [DOI] [PubMed] [Google Scholar]
  71. Quinn R. A., Lim Y. W., Maughan H., Conrad D., Rohwer F., Whiteson K. L. (2014). Biogeochemical Forces Shape the Composition and Physiology of Polymicrobial Communities in the Cystic Fibrosis Lung. mBio 5 e00956–13. 10.1128/mBio.00956-13 [DOI] [PMC free article] [PubMed] [Google Scholar]
  72. Rahal J. J., Simberkoff M. S. (1979). Bactericidal and Bacteriostatic Action of Chloramphenicol Against Meningeal Pathogens. Antimicrob. Agents Chemother. 16 13–18. 10.1128/AAC.16.1.13 [DOI] [PMC free article] [PubMed] [Google Scholar]
  73. Razavi M., Marathe N. P., Gillings M. R., Flach C.-F., Kristiansson E., Joakim Larsson D. G. (2017). Discovery of the fourth mobile sulfonamide resistance gene. Microbiome 5:160. 10.1186/s40168-017-0379-y [DOI] [PMC free article] [PubMed] [Google Scholar]
  74. Rice E. W., Wang P., Smith A. L., Stadler L. B. (2020). Determining Hosts of Antibiotic Resistance Genes: A Review of Methodological Advances. Environ. Sci. Technol. Lett. 7 282–291. 10.1021/acs.estlett.0c00202 [DOI] [Google Scholar]
  75. Roberts M. C. (2005). Update on acquired tetracycline resistance genes. FEMS Microbiol. Lett. 245 195–203. 10.1016/j.femsle.2005.02.034 [DOI] [PubMed] [Google Scholar]
  76. Roberts M. C. (2017). “Antibiotic-Resistant Environmental Bacteria and Their Role as Reservoirs in Disease,” in Modeling the Transmission and Prevention of Infectious Disease, ed. Hurst C. J. (Cham: Springer International Publishing; ), 187–212. 10.1007/978-3-319-60616-3_7 [DOI] [Google Scholar]
  77. Rodríguez-Brazzarola P., Pérez-Wohlfeil E., Díaz-del-Pino S., Holthausen R., Trelles O. (2018). “Analyzing the Differences Between Reads and Contigs When Performing a Taxonomic Assignment Comparison in Metagenomics,” in Bioinformatics and Biomedical Engineering Lecture Notes in Computer Science eds Rojas I., Ortuño F. (Cham: Springer International Publishing; ), 450–460. 10.1007/978-3-319-78723-7_39 [DOI] [Google Scholar]
  78. Roh C., Villatte F. (2008). Isolation of a low-temperature adapted lipolytic enzyme from uncultivated micro-organism. J. Appl. Microbiol. 105 116–123. 10.1111/j.1365-2672.2007.03717.x [DOI] [PubMed] [Google Scholar]
  79. Roose-Amsaleg C., Laverman A. M. (2016). Do antibiotics have environmental side-effects? Impact of synthetic antibiotics on biogeochemical processes. Environ. Sci. Pollut. Res. 23 4000–4012. 10.1007/s11356-015-4943-3 [DOI] [PubMed] [Google Scholar]
  80. Ruppé E., Ghozlane A., Tap J., Pons N., Alvarez A.-S., Maziers N., et al. (2019). Prediction of the intestinal resistome by a three-dimensional structure-based method. Nat. Microbiol. 4 112–123. 10.1038/s41564-018-0292-6 [DOI] [PubMed] [Google Scholar]
  81. Schloss P. D., Handelsman J. (2003). Biotechnological prospects from metagenomics. Curr. Opin. Biotechnol. 14 303–310. 10.1016/S0958-1669(03)00067-3 [DOI] [PubMed] [Google Scholar]
  82. Schloss P. D., Westcott S. L., Ryabin T., Hall J. R., Hartmann M., Hollister E. B., et al. (2009). Introducing mothur: Open-Source, Platform-Independent, Community-Supported Software for Describing and Comparing Microbial Communities. AEM 75 7537–7541. 10.1128/AEM.01541-09 [DOI] [PMC free article] [PubMed] [Google Scholar]
  83. Schmieder R., Edwards R. (2012). Insights into antibiotic resistance through metagenomic approaches. Fut. Microbiol. 7 73–89. 10.2217/fmb.11.135 [DOI] [PubMed] [Google Scholar]
  84. Simmons C. W., Reddy A. P., D’haeseleer P., Khudyakov J., Billis K., Pati A., et al. (2014). Metatranscriptomic analysis of lignocellulolytic microbial communities involved in high-solids decomposition of rice straw. Biotechnol. Biof. 7:495. 10.1186/s13068-014-0180-0 [DOI] [PMC free article] [PubMed] [Google Scholar]
  85. Soucy S. M., Huang J., Gogarten J. P. (2015). Horizontal gene transfer: building the web of life. Nat. Rev. Genet. 16 472–482. 10.1038/nrg3962 [DOI] [PubMed] [Google Scholar]
  86. Sundstrom L., Skold O. (1990). The dhfrI trimethoprim resistance gene of Tn7 can be found at specific sites in other genetic surroundings. Antimicrob. Agents Chemother. 34 642–650. 10.1128/AAC.34.4.642 [DOI] [PMC free article] [PubMed] [Google Scholar]
  87. Tamames J., Puente-Sánchez F. (2019). SqueezeMeta, A Highly Portable, Fully Automatic Metagenomic Analysis Pipeline. Front. Microbiol. 9:3349. 10.3389/fmicb.2018.03349 [DOI] [PMC free article] [PubMed] [Google Scholar]
  88. Tamames J., Cobo-Simón M., Puente-Sánchez F. (2019). Assessing the performance of different approaches for functional and taxonomic annotation of metagenomes. BMC Genom. 20:960. 10.1186/s12864-019-6289-6 [DOI] [PMC free article] [PubMed] [Google Scholar]
  89. Tenson T., Lovmar M., Ehrenberg M. (2003). The Mechanism of Action of Macrolides, Lincosamides and Streptogramin B Reveals the Nascent Peptide Exit Path in the Ribosome. J. Mole. Biol. 330 1005–1014. 10.1016/S0022-2836(03)00662-4 [DOI] [PubMed] [Google Scholar]
  90. Thorne G. M., Alder J. (2002). Daptomycin: a novel lipopeptide antibiotic. Clin. Microbiol. Newslett. 24 33–40. 10.1016/S0196-4399(02)80007-1 [DOI] [Google Scholar]
  91. Tripathi L. K., Nailwal T. K. (2020). Metagenomics: Applications of functional and structural approaches and meta-omics. Rec. Adv. Microbial. Div. 4 471–505. 10.1016/B978-0-12-821265-3.00020-7 [DOI] [Google Scholar]
  92. Tsafnat G., Copty J., Partridge S. R. (2011). RAC: Repository of Antibiotic resistance Cassettes. Database 2011 bar054–bar054. 10.1093/database/bar054 [DOI] [PMC free article] [PubMed] [Google Scholar]
  93. Van Boeckel T. P., Brower C., Gilbert M., Grenfell B. T., Levin S. A., Robinson T. P., et al. (2015). Global trends in antimicrobial use in food animals. Proc. Natl. Acad. Sci. U. S. A. 112 5649–5654. 10.1073/pnas.1503141112 [DOI] [PMC free article] [PubMed] [Google Scholar]
  94. von Wintersdorff C. J. H., Penders J., van Niekerk J. M., Mills N. D., Majumder S., van Alphen L. B., et al. (2016). Dissemination of Antimicrobial Resistance in Microbial Ecosystems through Horizontal Gene Transfer. Front. Microbiol. 7:173. 10.3389/fmicb.2016.00173 [DOI] [PMC free article] [PubMed] [Google Scholar]
  95. Wang S., Yan Z., Wang P., Zheng X., Fan J. (2020). Comparative metagenomics reveals the microbial diversity and metabolic potentials in the sediments and surrounding seawaters of Qinhuangdao mariculture area. PLoS One 15:e0234128. 10.1371/journal.pone.0234128 [DOI] [PMC free article] [PubMed] [Google Scholar]
  96. Wang Y., Lv Y., Cai J., Schwarz S., Cui L., Hu Z., et al. (2015). A novel gene, optrA, that confers transferable resistance to oxazolidinones and phenicols and its presence in Enterococcus faecalis and Enterococcus faecium of human and animal origin. J. Antimicr. Chemother. 70 2182–2190. 10.1093/jac/dkv116 [DOI] [PubMed] [Google Scholar]
  97. Wybouw N., Pauchet Y., Heckel D. G., Van Leeuwen T. (2016). Horizontal Gene Transfer Contributes to the Evolution of Arthropod Herbivory. Genome Biol. Evol. 8 1785–1801. 10.1093/gbe/evw119 [DOI] [PMC free article] [PubMed] [Google Scholar]
  98. Xing C., Chen J., Zheng X., Chen L., Chen M., Wang L., et al. (2020). Functional metagenomic exploration identifies novel prokaryotic copper resistance genes from the soil microbiome. Metallomics 12 387–395. 10.1039/C9MT00273A [DOI] [PubMed] [Google Scholar]
  99. Xu R., Yang Z.-H., Wang Q.-P., Bai Y., Liu J.-B., Zheng Y., et al. (2018). Rapid startup of thermophilic anaerobic digester to remove tetracycline and sulfonamides resistance genes from sewage sludge. Sci. Tot. Environ. 612 788–798. 10.1016/j.scitotenv.2017.08.295 [DOI] [PubMed] [Google Scholar]
  100. Yang Y., Jiang X., Chai B., Ma L., Li B., Zhang A., et al. (2016). ARGs-OAP: online analysis pipeline for antibiotic resistance genes detection from metagenomic data using an integrated structured ARG-database. Bioinformatics 32 2346–2351. 10.1093/bioinformatics/btw136 [DOI] [PubMed] [Google Scholar]
  101. Yang Y., Zhou R., Chen B., Zhang T., Hu L., Zou S. (2018). Characterization of airborne antibiotic resistance genes from typical bioaerosol emission sources in the urban environment using metagenomic approach. Chemosphere 213 463–471. 10.1016/j.chemosphere.2018.09.066 [DOI] [PubMed] [Google Scholar]
  102. Ye S. H., Siddle K. J., Park D. J., Sabeti P. C. (2019). Benchmarking Metagenomics Tools for Taxonomic Classification. Cell 178 779–794. 10.1016/j.cell.2019.07.010 [DOI] [PMC free article] [PubMed] [Google Scholar]
  103. Yin X., Jiang X.-T., Chai B., Li L., Yang Y., Cole J. R., et al. (2018). ARGs-OAP v2.0 with an expanded SARG database and Hidden Markov Models for enhancement characterization and quantification of antibiotic resistance genes in environmental metagenomes. Bioinformatics 34 2263–2270. 10.1093/bioinformatics/bty053 [DOI] [PubMed] [Google Scholar]
  104. Yu K., Li P., Chen Y., Zhang B., Huang Y., Huang F.-Y., et al. (2020). Antibiotic resistome associated with microbial communities in an integrated wastewater reclamation system. Water Res. 173:115541. 10.1016/j.watres.2020.115541 [DOI] [PubMed] [Google Scholar]
  105. Zankari E., Hasman H., Kaas R. S., Seyfarth A. M., Agerso Y., Lund O., et al. (2013). Genotyping using whole-genome sequencing is a realistic alternative to surveillance based on phenotypic antimicrobial susceptibility testing. J. Antimicrob. Chemother. 68 771–777. 10.1093/jac/dks496 [DOI] [PubMed] [Google Scholar]
  106. Zhang T., Zhang X.-X., Ye L. (2011). Plasmid metagenome reveals high levels of antibiotic resistance genes and mobile genetic elements in activated sludge. PLoS One 6:e26041. 10.1371/journal.pone.0026041 [DOI] [PMC free article] [PubMed] [Google Scholar]
  107. Zhao R., Yu K., Zhang J., Zhang G., Huang J., Ma L., et al. (2020). Deciphering the mobility and bacterial hosts of antibiotic resistance genes under antibiotic selection pressure by metagenomic assembly and binning approaches. Water Res. 186:116318. 10.1016/j.watres.2020.116318 [DOI] [PubMed] [Google Scholar]
  108. Zhao Y., Tang H., Ye Y. (2012). RAPSearch2: a fast and memory-efficient protein similarity search tool for next-generation sequencing data. Bioinformatics 28 125–126. 10.1093/bioinformatics/btr595 [DOI] [PMC free article] [PubMed] [Google Scholar]
  109. Zhou C. E., Smith J., Lam M., Zemla A., Dyer M. D., Slezak T. (2007). MvirDB–a microbial database of protein toxins, virulence factors and antibiotic resistance genes for bio-defence applications. Nucleic Acids Res. 35 D391–D394. 10.1093/nar/gkl791 [DOI] [PMC free article] [PubMed] [Google Scholar]

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