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Keim P, Grunow R, Vipond R, Grass G, Hoffmaster A, Birdsell DN, Klee SR, Pullan S, Antwerpen M, Bayer BN, Latham J, Wiggins K, Hepp C, Pearson T, Brooks T, Sahl J, Wagner DM. Whole Genome Analysis of Injectional Anthrax Identifies Two Disease Clusters Spanning More Than 13 Years. EBioMedicine 2015; 2:1613-8. [PMID: 26870786 PMCID: PMC4740342 DOI: 10.1016/j.ebiom.2015.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/24/2015] [Accepted: 10/02/2015] [Indexed: 12/30/2022] Open
Abstract
Background Anthrax is a rare disease in humans but elicits great public fear because of its past use as an agent of bioterrorism. Injectional anthrax has been occurring sporadically for more than ten years in heroin consumers across multiple European countries and this outbreak has been difficult to trace back to a source. Methods We took a molecular epidemiological approach in understanding this disease outbreak, including whole genome sequencing of Bacillus anthracis isolates from the anthrax victims. We also screened two large strain repositories for closely related strains to provide context to the outbreak. Findings Analyzing 60 Bacillus anthracis isolates associated with injectional anthrax cases and closely related reference strains, we identified 1071 Single Nucleotide Polymorphisms (SNPs). The synapomorphic SNPs (350) were used to reconstruct phylogenetic relationships, infer likely epidemiological sources and explore the dynamics of evolving pathogen populations. Injectional anthrax genomes separated into two tight clusters: one group was exclusively associated with the 2009–10 outbreak and located primarily in Scotland, whereas the second comprised more recent (2012–13) cases but also a single Norwegian case from 2000. Interpretation Genome-based differentiation of injectional anthrax isolates argues for at least two separate disease events spanning > 12 years. The genomic similarity of the two clusters makes it likely that they are caused by separate contamination events originating from the same geographic region and perhaps the same site of drug manufacturing or processing. Pathogen diversity within single patients challenges assumptions concerning population dynamics of infecting B. anthracis and host defensive barriers for injectional anthrax. Funding This work was supported by the United States Department of Homeland Security grant no. HSHQDC-10-C-00,139 and via a binational cooperative agreement between the United States Government and the Government of Germany. This work was supported by funds from the German Ministry of Defense (Sonderforschungsprojekt 25Z1-S-431,214). Support for sequencing was also obtained from Illumina, Inc. These sources had no role in the data generation or interpretation, and had not role in the manuscript preparation. Panel 1: Research in Context Systematic Review We searched PubMed for any article published before Jun. 17, 2015, with the terms “Bacillus anthracis” and “heroin”, or “injectional anthrax”. Other than our previously published work (Price et al., 2012), we found no other relevant studies on elucidating the global phylogenetic relationships of B. anthracis strains associated with injectional anthrax caused by recreational heroin consumption of spore-contaminated drug. There were, however, publically available genome sequences of two strains involved (Price et al., 2012, Grunow et al., 2013) and the draft genome sequence of Bacillus anthracis UR-1, isolated from a German heroin user (Ruckert et al., 2012) with only limited information on the genotyping of closely related strains (Price et al., 2012, Grunow et al., 2013). Lay Person Interpretation Injectional anthrax has been plaguing heroin drug users across Europe for more than 10 years. In order to better understand this outbreak, we assessed genomic relationships of all available injectional anthrax strains from four countries spanning a > 12 year period. Very few differences were identified using genome-based analysis, but these differentiated the isolates into two distinct clusters. This strongly supports a hypothesis of at least two separate anthrax spore contamination events perhaps during the drug production processes. Identification of two events would not have been possible from standard epidemiological analysis. These comprehensive data will be invaluable for classifying future injectional anthrax isolates and for future geographic attribution. Whole genome sequences of injectional anthrax B. anthracis isolates fall in two tight but distinct genomic clusters. The distinct genomic clusters are consistent with two or more disease events that overlap in time and space. Defining pathogen clusters will lead to better public health responses to difficult to track disease outbreaks.
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Affiliation(s)
- Paul Keim
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA; The Pathogen Genomics Division, The Translational Genomics Research Institute, 3051 W. Shamrell Blvd, Suite 106, Flagstaff, AZ 86001 USA
| | | | - Richard Vipond
- Public Health England, Porton Down, Wiltshire SP4 0JG, United Kingdom; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool L69 7BE, United Kingdom
| | - Gregor Grass
- Bundeswehr Institute of Microbiology, Munich, Germany
| | - Alex Hoffmaster
- The Center for Disease Control and Prevention, Atlanta, GA, USA
| | - Dawn N Birdsell
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | | | - Steven Pullan
- Public Health England, Porton Down, Wiltshire SP4 0JG, United Kingdom; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool L69 7BE, United Kingdom
| | - Markus Antwerpen
- Public Health England, Porton Down, Wiltshire SP4 0JG, United Kingdom
| | - Brittany N Bayer
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | - Jennie Latham
- Public Health England, Porton Down, Wiltshire SP4 0JG, United Kingdom
| | - Kristin Wiggins
- The Pathogen Genomics Division, The Translational Genomics Research Institute, 3051 W. Shamrell Blvd, Suite 106, Flagstaff, AZ 86001 USA
| | - Crystal Hepp
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | - Talima Pearson
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | - Tim Brooks
- Public Health England, Porton Down, Wiltshire SP4 0JG, United Kingdom; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool L69 7BE, United Kingdom
| | - Jason Sahl
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA; The Pathogen Genomics Division, The Translational Genomics Research Institute, 3051 W. Shamrell Blvd, Suite 106, Flagstaff, AZ 86001 USA
| | - David M Wagner
- The Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
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