Helicobacter kumamotonensis sp. nov., isolated from human clinical specimens.
Abstract: A Gram-stain-negative, spiral bacterium (PAGU 1991T) was isolated from the blood of a patient with diffuse large B-cell lymphoma. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate was very closely related to Helicobacter equorum LMG 23362T (99.1 % similarity), originally isolated from a faecal sample from a healthy horse. PAGU 1991T was also very closely related to PAGU 1750 in our strain library (=CCUG 41437) with 99.7 % similarity. Additional phylogenetic analyses based on the 23S rRNA gene sequence and GyrA amino acid sequence further supported the close relationship between the two human isolates (PAGU 1991T and PAGU 1750) and the horse strain. However, a phylogenetic analysis based on 16S rRNA showed that the two human isolates formed a lineage that was distinct from the horse strain (less than 99.2 % similarity). In silico whole-genome comparisons based on digital DNA-DNA hybridization, average nucleotide identity based on blast and orthologous average nucleotide identity using usearch between the two human isolates and the type strain of H. equorum showed values of less than 52.40, 93.47, and 93.50 %, respectively, whereas those between the two human isolates were 75.8, 97.2, and 97.2 %, respectively. These data clearly demonstrated that the two human isolates formed a single species, distinct from H. equorum. Morphologically, the human isolates could be distinguished by the type of flagella; the human isolates showed a bipolar sheathed flagellum, whereas that of H. equorum was monopolar. Biochemically, the human isolate was characterized by growth at 42 °C under microaerobic conditions and nitrate reduction unability. We conclude that the two human isolates, obtained from geographically and temporally distinct sources, were a novel species, for which we propose the name Helicobacter kumamotonensis sp. nov., with the type strain PAGU 1991T (=GTC 16810T=CCUG 75774T).
Publication Date: 2023-03-16 PubMed ID: 36920987DOI: 10.1099/ijsem.0.005732Google Scholar: Lookup
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Summary
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The abstract describes the identification of a new species of Helicobacter bacterium, called Helicobacter kumamotonensis, found in the blood of a human patient with diffuse large B-cell lymphoma.
Isolation and Identification
- The researchers first identified the new species when they discovered a Gram-negative, spiral bacterium in the blood sample of a patient suffering from diffuse large B-cell lymphoma. This bacterium was given the temporary label PAGU 1991.
- They found the bacterium to be closely related to another strain of bacteria, LMG 23362. This strain, which has a 99.1% genetic similarity with PAGU 1991, was originally found in a horse’s fecal sample.
- PAGU 1991 also showed a striking genetic resemblance to another bacteria strain, PAGU 1750, from their strain library, having a 99.7% genetic similarity.
Phylogenetic Analysis and Comparisons
- Additional analysis using 23S rRNA gene sequence and GyrA amino acid sequence revealed a close relationship between the two human isolates (PAGU 1991 and PAGU 1750) and the horse strain, confirming the shared ancestry of these strains.
- However, an examination based on 16S rRNA gene indicated that the two human isolates form a separate lineage from the horse strain, given that they have less than 99.2% similarity.
- Whole-genome comparisons using techniques such as digital DNA-DNA hybridization, average nucleotide identity based on blast, and orthologous average nucleotide identity using usearch further established that the two human isolates form a distinct species from the horse strain.
Morphological and Biochemical Characteristics
- The human isolates could be differentiated from the horse strain by their differing flagellar types. The new human isolate has a bipolar sheathed flagellum, while the horse strain has a monopolar flagellum.
- From a biochemical perspective, the human isolate differed from the horse strain in its ability to grow at 42 degrees Celsius under microaerobic conditions and its inability to reduce nitrate.
- Given these differences, the researchers named the new bacteria species found in humans as Helicobacter kumamotonensis, with the strain PAGU 1991 serving as the type strain.
Cite This Article
APA
Kawamura Y, Fujimoto Y, Kutsuna R, Tomida J, Yamamoto KI, Miyoshi-Akiyama T, Okuno M, Ogura Y, Matsuoka M, Kawaguchi T, Tsutsuki H, Sawa T.
(2023).
Helicobacter kumamotonensis sp. nov., isolated from human clinical specimens.
Int J Syst Evol Microbiol, 73(3).
https://doi.org/10.1099/ijsem.0.005732 Publication
Researcher Affiliations
- Department of Microbiology, Aichi Gakuin University, School of Pharmacy,, 1-100 Kusumoto-cho, Nagoya, Aichi 464-8650, Japan.
- Department of Microbiology, Aichi Gakuin University, School of Pharmacy,, 1-100 Kusumoto-cho, Nagoya, Aichi 464-8650, Japan.
- Department of Microbiology, Aichi Gakuin University, School of Pharmacy,, 1-100 Kusumoto-cho, Nagoya, Aichi 464-8650, Japan.
- Department of Microbiology, Aichi Gakuin University, School of Pharmacy,, 1-100 Kusumoto-cho, Nagoya, Aichi 464-8650, Japan.
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjou, Kumamoto, Kumamoto 860-8556, Japan.
- Pathogenic Microbe laboratory, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan.
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan.
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan.
- Department of Hematology, Rheumatology and Infectious Disease, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjou, Kumamoto, Kumamoto 860-8556, Japan.
- Department of Medical Technology, Faculty of Health Science, Kumamoto Health Science University, 325 Izumi-machi, Kita-ku, Kumamoto, 861-5598, Japan.
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjou, Kumamoto, Kumamoto 860-8556, Japan.
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjou, Kumamoto, Kumamoto 860-8556, Japan.
MeSH Terms
- Humans
- Animals
- Horses
- Bacterial Typing Techniques
- Phylogeny
- RNA, Ribosomal, 16S / genetics
- Sequence Analysis, DNA
- Fatty Acids / chemistry
- DNA, Bacterial / genetics
- Base Composition
- Helicobacter
- Nucleic Acid Hybridization
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