Open postdoc position
Together with Joakim Larsson‘s lab, we now have an open two-year postdoc position in bioinformatics on antibiotic resistance and biocide resistance. The development of antibiotic resistance has been driven by use of antibiotics, but antibacterial biocides also have the potential to select for antibiotic resistance. However, knowledge of which genes that contribute to biocide resistance and could be associated with antibiotic resistance is sparse. To some extent, such genes are documented in the BacMet database which we have developed, but this collection of resistance genes is only scratching the surface of all biocide resistance that exists among bacteria in the environment.
We are now looking for a postdoctoral fellow to continue the important work on bioinformatic analysis of biocide and antibiotic resistance to answer the question whether increasing biocide resistance would be a threat to human health. The postdoc will be working with the development of the BacMet database to make it more targeted towards biocidal substances and products in addition to resistance genes. The tasks include bioinformatic sequence analysis, literature studies and database and web programming. The work will also include investigations of the prevalence of the identified resistance genes in genomes and metagenomes.
The recruited person will work closely with both my group and the group of Prof. Joakim Larsson, and will participate in the JPIAMR-funded BIOCIDE project. You can apply to the postdoc position at the University of Gothenburg application portal: https://web103.reachmee.com/ext/I005/1035/job?site=7&lang=UK&validator=9b89bead79bb7258ad55c8d75228e5b7&job_id=25122
The deadline is May 4, 2022. Come work with us on this exciting topic in the intersect between two great research environments (if I may say it myself!) We look forward to your application!
Biocides and antibiotic resistance workshop
The newly formed BIOCIDE program, seeking to determine how antibacterial biocides contribute to the development of biocide resistance and spread of antibiotic resistant bacteria, is organizing a workshop on risk assessment of biocide and antibiotic resistance on the 9th of March this year. I will be giving a talk on the BacMet database and how that will be integrated in risk assessment and the research program. If you have an interest in the risk associated with biocides, or antibiotic resistance development, I strongly suggest that you take part in this exciting workshop, particularly if you are working for a regulatory authority.
The program targets biocide resistance and cross-resistance to antibiotics, guidance development for assessment of biocide resistance, the BacMet biocide resistance database, and the assessment of environmental exposure to biocides and risks for co-selection. The workshop will include speakers such as Joakim Larsson, Nabila Haddache, Marlene Ågerstrand and Frank Schreiber.
More information can be found here: https://www.gu.se/en/biocide/risk-assessment-of-biocide-and-antibiotic-resistance
Published paper: The global resistome
Late yesterday, Microbiome put online our most recent work, covering the resistomes to antibiotics, biocides and metals across a vast range of environments. In the paper (1), we perform the largest characterization of resistance genes, mobile genetic elements (MGEs) and bacterial taxonomic compositions to date, covering 864 different metagenomes from humans (350), animals (145) and external environments such as soil, water, sewage, and air (369 in total). All the investigated metagenomes were sequenced to at least 10 million reads each, using Illumina technology, making the results more comparable across environments than in previous studies (2-4).
We found that the environment types had clear differences both in terms of resistance profiles and bacterial community composition. Humans and animals hosted microbial communities with limited taxonomic diversity as well as low abundance and diversity of biocide/metal resistance genes and MGEs. On the contrary, the abundance of ARGs was relatively high in humans and animals. External environments, on the other hand, showed high taxonomic diversity and high diversity of biocide/metal resistance genes and MGEs. Water, sediment and soil generally carried low relative abundance and few varieties of known ARGs, whereas wastewater and sludge were on par with the human gut. The environments with the largest relative abundance and diversity of ARGs, including genes encoding resistance to last resort antibiotics, were those subjected to industrial antibiotic pollution and air samples from a Beijing smog event.
A paper investigating this vast amount of data is of course hard to describe in a blog post, so I strongly suggest the interested reader to head over to Microbiome’s page and read the full paper (1). However, here’s a ver short summary of the findings:
- The median relative abundance of ARGs across all environments was 0.035 copies per bacterial 16S rRNA
- Antibiotic-polluted environments have (by far) the highest abundances of ARGs
- Urban air samples carried high abundance and diversity of ARGs
- Human microbiota has high abundance and diversity of known ARGs, but low taxonomic diversity compared to the external environment
- The human and animal resistomes are dominated by tetracycline resistance genes
- Over half of the ARGs were only detected in external environments, while 20.5 % were found in human, animal and at least one of the external environments
- Biocide and metal resistance genes are more common in external environments than in the human microbiota
- Human microbiota carries low abundance and richness of MGEs compared to most external environments
Importantly, less than 1.5 % of all detected ARGs were found exclusively in the human microbiome. At the same time, 57.5 % of the known ARGs were only detected in metagenomes from environmental samples, despite that the majority of the investigated ARGs were initially encountered in pathogens. Still, our analysis suggests that most of these genes are relatively rare in the human microbiota. Environmental samples generally contained a wider distribution of resistance genes to a more diverse set of antibiotics classes. For example, the relative abundance of beta-lactam resistance genes was much larger in external environments than in human and animal microbiomes. This suggests that the external environment harbours many more varieties of resistance genes than the ones currently known from the clinic. Indeed, functional metagenomics has resulted in the discovery of many novel ARGs in external environments (e.g. 5). This all fits well with an overall much higher taxonomic diversity of environmental microbial communities. In terms of consequences associated with the potential transfer of ARGs to human pathogens, we argue that unknown resistance genes are of greater concern than those already known to circulate among human-associated bacteria (6).
This study describes the potential for many external environments, including those subjected to pharmaceutical pollution, air and wastewater/sludge, to serve as hotspots for resistance development and/or transmission of ARGs. In addition, our results indicate that these environments may play important roles in the mobilization of yet unknown ARGs and their further transmission to human pathogens. To provide guidance for risk-reducing actions we – based on this study – suggest strict regulatory measures of waste discharges from pharmaceutical industries and encourage more attention to air in the transmission of antibiotic resistance (1).
- Pal C, Bengtsson-Palme J, Kristiansson E, Larsson DGJ: The structure and diversity of human, animal and environmental resistomes. Microbiome, 4, 54 (2016). doi: 10.1186/s40168-016-0199-5
- Durso LM, Miller DN, Wienhold BJ. Distribution and quantification of antibiotic resistant genes and bacteria across agricultural and non-agricultural metagenomes. PLoS One. 2012;7:e48325.
- Nesme J, Delmont TO, Monier J, Vogel TM. Large-scale metagenomic-based study of antibiotic resistance in the environment. Curr Biol. 2014;24:1096–100.
- Fitzpatrick D, Walsh F. Antibiotic resistance genes across a wide variety of metagenomes. FEMS Microbiol Ecol. 2016. doi:10.1093/femsec/fiv168.
- Allen HK, Moe LA, Rodbumrer J, Gaarder A, Handelsman J. Functional metagenomics reveals diverse β-lactamases in a remote Alaskan soil. ISME J. 2009;3:243–51.
- Bengtsson-Palme J, Larsson DGJ: Antibiotic resistance genes in the environment: prioritizing risks. Nature Reviews Microbiology, 13, 369 (2015). doi: 10.1038/nrmicro3399-c1
Presentation on biocide and metal conference
I have been asked to give a short talk on the metals and biocides and antibiotic resistance co-selection conference I mentioned in February. My presentation will take place late Tuesday afternoon, and is entitled “Elucidating biocide and metal co-selection for antibiotic resistance in sewage treatment plants using metagenomics“. I hope to see you there!
Conference on antibiotic co-selection by biocides and metals
The Royal Swedish Academy of Sciences (KVA) is, together with Joakim Larsson, arranging a conference on the mechanisms and evidence for the involvement of metals and biocides in selection of antibiotic resistant bacteria. Several experts from around Europe will attend and give talks, including for example Dan Andersson, Kristian Brandt, Teresa Coque, Will Gaze, Åsa Melhus and Chris Rensing. The symposium is open to everyone and is free of charge (although registration is binding).
The conference take place between 15th and 16th of March, at The Royal Swedish Academy of Sciences’ facilities at Lilla Frescativägen in Stockholm. And you should join us; register here!
Published paper: Co-occurences of resistance genes across bacteria
Yesterday, a paper I co-authored with my colleagues Chandan Pal, Erik Kristiansson and Joakim Larsson on the co-occurences of resistance genes against antibiotics, biocides and metals in bacterial genomes and plasmids became published in BMC Genomics. In this paper (1) we utilize the publicly available, fully sequenced, genomes and plasmids in GenBank to investigate the co-occurence network of resistance genes, to better understand risks for co-selection for resistance against different types of compounds. In short, the findings of the paper are that:
- ARGs are associated with BMRG-carrying bacteria and the co-selection potential of biocides and metals is specific towards certain antibiotics
- Clinically important genera host the largest numbers of ARGs and BMRGs and those also have the highest co-selection potential
- Bacteria isolated from human and domestic animal origins have the highest co-selection potential
- Plasmids with co-selection potential tend to be conjugative and carry toxin-antitoxin systems
- Mercury and QACs are potential co-selectors of ARGs on plasmids, however BMRGs are common on chromosomes and could still have indirect co-selection potential
- 14 percent of bacteria and more than 70% of the plasmids completely lacked resistance genes
This analysis was possible thanks to the BacMet database of antibacterial biocide and metal resistance genes, published about two years ago (2). The visualization of the plasmid co-occurence network we ended up with can be seen below. Note the strong connection between the mercury resistance mer operon and the antibiotic resistance genes to the right.
On a side note, it is interesting to note that the underrepresentation of detoxification systems in marine environments we noted last year (3) still seems to hold for genomes (and particularly plasmids), supporting the genome streamlining hypothesis (4).
- Pal C, Bengtsson-Palme J, Kristiansson E, Larsson DGJ: Co-occurrence of resistance genes to antibiotics, biocides and metals reveals novel insights into their co-selection potential. BMC Genomics, 16, 964 (2015). doi: 10.1186/s12864-015-2153-5 [Paper link]
- Pal C, Bengtsson-Palme J, Rensing C, Kristiansson E, Larsson DGJ: BacMet: Antibacterial Biocide and Metal Resistance Genes Database. Nucleic Acids Research, 42, D1, D737-D743 (2014). doi: 10.1093/nar/gkt1252 [Paper link]
- Bengtsson-Palme J, Alm Rosenblad M, Molin M, Blomberg A: Metagenomics reveals that detoxification systems are underrepresented in marine bacterial communities. BMC Genomics, 15, 749 (2014). doi: 10.1186/1471-2164-15-749 [Paper link]
- Giovannoni SJ, Cameron TJ, Temperton B: Implications of streamlining theory for microbial ecology. ISME Journal, 8, 1553-1565 (2014).
Published paper: BacMet Database
It seems like our paper on the recently launched database on resistance genes against antibacterial biocides and metals (BacMet) has gone online as an advance access paper in Nucleic Acids Research today. Chandan Pal – the first author of the paper, and one of my close colleagues as well as my roommate at work – has made a tremendous job taking the database from a list of genes and references, to a full-fledged browsable and searchable database with a really nice interface. I have contributed along the process, and wrote the lion’s share of the code for the BacMet-Scan tool that can be downloaded along with the database files.
BacMet is a curated source of bacterial resistance genes against antibacterial biocides and metals. All gene entries included have at least one experimentally confirmed resistance gene with references in scientific literature. However, we have also made a homology-based prediction of genes that are likely to share the same resistance function (the BacMet predicted dataset). We believe that the BacMet database will make it possible to better understand co- and cross-resistance of biocides and metals to antibiotics within bacterial genomes and in complex microbial communities from different environments.
The database can be easily accessed here: http://bacmet.biomedicine.gu.se, and use of the database in scientific work can cite the following paper, which recently appeared in Nucleic Acids Research:
Pal C, Bengtsson-Palme J, Rensing C, Kristiansson E, Larsson DGJ: BacMet: Antibacterial Biocide and Metal Resistance Genes Database. Nucleic Acids Research. Database issue, advance access. doi: 10.1093/nar/gkt1252 [Paper link]