Proposal of Helicobacter higonensis sp. nov. isolated from a human clinical specimen, and emended description of Helicobacter valdiviensis Collado, 2014

We have previously isolated a gram-negative microaerophilic strain, PAGU2000T from a patient presenting with a fever in Kumamoto Prefecture, Japan. The present study aimed to comprehensively analyze the taxonomy of the isolated strain using a polyphasic approach. The 16S rRNA gene sequence analysis indicated that the strain was a member of enterohepatic Helicobacter. The strain PAGU2000T shared a 97.5% 16S rRNA gene nucleotide identity with Helicobacter valdiviensis, and this taxonomic position was confirmed by phylogenetic analysis of the GyrA amino acid sequences. The proposed strain PAGU2000T has a 1.482 Mbp chromosome with a DNA G + C content of 31.3 mol% and encodes 1520 predicted coding sequences. The average nucleotide identity between the strain PAGU2000T and type strain of H. valdiviensis was 70.3%, which was lower than the recommended threshold of 95% for species delineation. The strain PAGU2000T was a motile, non-spore-forming, and spiral-shaped bacterium, exhibiting catalase and oxidase activities but not urease and nitrate reduction. This study demonstrates that the isolate represents a novel species within enterohepatic Helicobacter, for which the name Helicobacter higonensis is proposed (type strain: PAGU2000T = GTC 16811T = LMG 33095T). In this study, we describe the phenotypic and morphological features of this strain and propose an emended description of some biochemical traits of H. valdiviensis.

Molecular surveillance of Helicobacter species with high prevalence from two streams with various wastewater pollution in Taiwan

Helicobacter species are potential zoonotic pathogens classified as either enterohepatic or gastric. Helicobacter infection can be transmitted through wastewater from households and livestock and through water from irrigation and streams. In this study, the distribution and source of Helicobacter species in the Donggang and Yenshui rivers, two natural water bodies with different characteristics, were analyzed. A total of 44 water samples were collected over the four seasons. The samples were subjected to Helicobacter 16 s rRNA gene PCR, followed by sequencing and comparison for identification and analysis. The detection rate of Helicobacter species in both rivers was 79.55%, with H. kayseriensis (10/35, 28.57%) being the most common species. Analysis of the environment around the sampling sites showed a high detection rate in the livestock-rich area, and the results of BLAST for species identification and comparison indicated feces as the contamination source. The area around the Donggang River was developed for animal husbandry, led to a high detection rate of Helicobacter species. Many Helicobacter species were identified to have a risk of zoonotic transmission, especially if the stream is used as a source of drinking, agricultural, or even aquacultural water. The high presence of Helicobacter species in natural water bodies suggests that wastewater treatment is an effective strategy to control pathogen spread. Therefore, investigation and monitoring of pathogens in wastewater are highly important. However, methods for the isolation and culture of Helicobacter species in natural waters have yet to be developed. Hence, future research should focus on developing such methods.

An update on novel taxa and revised taxonomic status of bacteria isolated from non-domestic animals described in 2022

Numbers of new and revised microbial taxa are continuously expanding, and the rapid accumulation of novel bacterial species is challenging to keep up with in the best of circumstances. With that in mind, following the template of reports on prokaryotic species isolated from humans, this is now the second publication summarizing new and revised taxa in non-domestic animal species in the Journal of Clinical Microbiology. The majority of new taxa were obtained as part of programs to identify bacteria from mucosal surfaces and the gastrointestinal tract from healthy wildlife. A few notable bacteria included new Erysipelothrix spp. from mammalian and aquatic sources and a novel Bartonella spp. isolated from a rodent, both of which could be considered members of emerging and re-emerging genera with pathogenic potential in humans and animals.

Helicobacter ibis sp. nov., isolated from faecal droppings of black-faced ibis (Theristicus melanopis)

As part of a larger study on Epsilonproteobacteria carried by wild birds in the city of Valdivia (southern Chile), two curved rod-shaped Gram-stain-negative strains (A82T and WB-40) were recovered from faecal samples and subjected to a taxonomic study. Results of a genus-specific PCR showed that these isolates belonged to the genus Helicobacter. Further identification by 16S rRNA and hsp60 (60 kDa heat-shock protein) gene sequence analysis revealed that they formed a separate phylogenetic clade, different from other known Helicobacter species with 'Helicobacter burdigaliensis' CNRCH 2005/566HT and Helicobacter valdiviensis WBE14T being the most closely related species. This was confirmed by core-genome phylogeny as well as digital DNA-DNA hybridization and average nucleotide identity analyses between the genomes of strains A82T and WB-40 and all other Helicobacter species. The draft genome sequences of A82T and WB-40, obtained by Illumina NextSeq 2000 sequencing, consisted of 1.6 Mb with a G+C content of 31.9-32.0 mol%. The results obtained from the phylogenetic and genomic characterization, together with their different morphological and biochemical features, revealed that these two strains represent a novel species, for which we propose the name Helicobacter ibis sp. nov. with A82T (=LMG 32718T=CCCT 22.04T) as the type strain.