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Species Bacteroides fragilis
Name: Bacteroides fragilis (Veillon and Zuber 1898) Castellani and Chalmers 1919 (Approved Lists 1980)
Basonym: "Bacillus fragilis" Veillon and Zuber 1898
Etymology: fra’gi.lis. L. masc. adj. fragilis, easily broken, brittle, fragile (relating to the brittle colonies that may form under some culture conditions)
Type strain: ATCC 25285; CCUG 4856; CIP 77.16; DSM 2151; DSM 29413; JCM 11019; LMG 10263; NBIMCC 8847; NCTC 9343
Conduct genome-based taxonomy at
16S rRNA gene:
KP326374
Analyse
FASTA
Effective publication: Castellani A, Chalmers AJ. Manual of Tropical Medicine, 3rd ed. Williams Wood and Co., New York, 1919.
IJSEM list:
Skerman VBD, McGowan V, Sneath PHA. Approved lists of bacterial names. Int J Syst Bacteriol 1980; 30:225-420. 
Nomenclatural status: validly published under the ICNP
Taxonomic status: correct name (and explicitly recommended for medical use)
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Synonyms:
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Name Kind Bacteroides hominis Liu et al. 2022 heterotypic synonym, validly published under the ICNP "Bacteroides hominis" Afrizal et al. 2022 heterotypic synonym, not validly published "Bacillus fragilis" Veillon and Zuber 1898 homotypic synonym, not validly published, basonym of name in Approved Lists
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Emendations:
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Hahnke et al. 2016
Hahnke RL, Meier-Kolthoff JP, Garcia-Lopez M, Mukherjee S, Huntemann M, Ivanova NN, Woyke T, Kyrpides NC, Klenk HP, Goker M. Genome-Based Taxonomic Classification of Bacteroidetes. Front Microbiol 2016; 7:2003.
Oren A, Garrity GM. List of changes in taxonomic opinion no. 26. Notification of changes in taxonomic opinion previously published outside the IJSEM. Int J Syst Evol Microbiol 2017; 67:2081-2086.
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Hahnke et al. 2016
Hahnke RL, Meier-Kolthoff JP, Garcia-Lopez M, Mukherjee S, Huntemann M, Ivanova NN, Woyke T, Kyrpides NC, Klenk HP, Goker M. Genome-Based Taxonomic Classification of Bacteroidetes. Front Microbiol 2016; 7:2003.
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Notes:
- 🥇 Nomenclatural type of the genus Bacteroides Castellani and Chalmers 1919 (Approved Lists 1980). Publication: Castellani A, Chalmers AJ. Manual of Tropical Medicine, 3rd ed. Williams Wood and Co., New York, 1919.
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⏰ According to Committee (2025), this species is an earlier heterotypic synonym of "Bacteroides hominis" Afrizal et al. 2022.
Publication:
Committee AH. Mitigating changes in prokaryotic nomenclature: Definitions and Workflow. Zenodo 2025; 2025:15320329.
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⏰ According to Committee (2025), this species is an earlier heterotypic synonym of Bacteroides hominis Liu et al. 2022.
Publication:
Committee AH. Mitigating changes in prokaryotic nomenclature: Definitions and Workflow. Zenodo 2025; 2025:15320329.
- 😷 The risk group for Belgium has been imported on 2024-02-05. The full classification is: risk group = 2, note = "human and animal pathogen - biological class of risk animal: 2". — The risk group for Canada has been imported on 2024-02-27. The full classification is: risk group = 2, note = "Animal classification RG: 2 - Security sensitive biological agent: No - Terrestrial animal pathogen under Canadian Food Inspection Agency authority: No - Containment level: Containment Level 2". — The risk group for Swiss Confederation has been imported on 2024-02-01. The full classification is: risk group = 2, note = "TA". — The risk group for Germany has been imported on 2023-10-29. The full classification is: risk group = 2. — The risk group for France has been imported on 2024-08-30. The full classification is: risk group = 2. — The risk group for Sweden has been imported on 2024-02-05. The full classification is: risk group = 2. — The risk group for Taiwan has been imported on 2024-11-03. The full classification is: risk group = 2, note = "P650 = v". — The risk group for United Kingdom has been imported on 2024-01-31. The full classification is: risk group = 2. — If in doubt, use the risk group given in the regulations for your country and, if these are not available, use the risk group given in the catalogue of the culture collection from which you have obtained or intend to obtain the strain.
- 🎓 Name mentioned 5572 times in PubMed until 2025-06-04.
- 🙆 This name is on the List of Recommended Names for bacteria of medical importance (LoRN) as the name to be applied to this species. The name is on LoRN because of the recorded risk group of the species itself.
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⚠ This name is retained (and recommended for medical use. This will change in the future) instead of Bacteroides hominis Liu et al. 2022.
Publication:
Liu C, Du MX, Abuduaini R, Yu HY, Li DH, Wang YJ, Zhou N, Jiang MZ, Niu PX, Han SS, et al. Enlightening the taxonomy darkness of human gut microbiomes with a cultured biobank. Microbiome 2021; 9:119.
Oren A, Garrity GM. Validation list no. 205. List of new names and new combinations previously effectively, but not validly, published. Int J Syst Evol Microbiol 2022; 72:5331.
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🧍 According to Bartlett et al. (2022), this species is an established human pathogen.
Publication:
Bartlett A, Padfield D, Lear L, Bendall R, Vos M. A comprehensive list of bacterial pathogens infecting humans. Microbiology 2022; 168:0.
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🧍 The phylogenetic position of this species was determined in a genome-scale analysis by García-López et al. (2019).
Publication:
Garcia-Lopez M, Meier-Kolthoff JP, Tindall BJ, Gronow S, Woyke T, Kyrpides NC, Hahnke RL, Goker M. Analysis of 1,000 Type-Strain Genomes Improves Taxonomic Classification of Bacteroidetes. Front Microbiol 2019; 10:2083.
Number of child taxa with a validly published and correct name: 0
Number of child taxa with a validly published name, including synonyms: 0
Total number of child taxa: 2
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Child taxa:
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Name Nomenclatural status Taxonomic status "Bacteroides fragilis subsp. distasonis" Falkler and Burger 1981 not validly published preferred name "Bacteroides fragilis subsp. thetaiotaomicron" (Distaso 1912) Holdeman and Moore 1970 not validly published synonym
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Parent taxon: Bacteroides Castellani and Chalmers 1919 (Approved Lists 1980)
Assigned by: Castellani A, Chalmers AJ. Manual of Tropical Medicine, 3rd ed. Williams Wood and Co., New York, 1919.
Linking: To permanently link to this page, use https://lpsn.dsmz.de/species/bacteroides-fragilisLink copied to clipboard
Record number: 773945
This LPSN page was printed on 2025-06-16 10:17:09