Helicobacter kumamotonensis sp. nov., isolated from human clinical specimens.

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).

Evolutionary analysis of gyrA gene from Neisseria meningitidis bacterial strains of clonal complex 4821 collected in China between 1978 and 2016.

BACKGROUND: Neisseria meningitidis (N.meningitidis) bacteria belonging to clonal complex 4821 (CC4821) have been mainly reported in China and have been characterized by a high resistance rate to ciprofloxacin (CIP). The aim of this study was to assess the evolution of the DNA gyrase A (gyrA) gene from N.meningitidis CC4821 strains collected in China between 1978 and 2016. The complete sequence of gyrA gene from 77 strains are reported in this study and analyzed in the context of publicly available sequences from N. meningitidis of other CCs as well as other Neisseria species. RESULTS: The phylogenetic analysis of CC4821 gyrA gene reveals at least 5 distinct genetic clusters. These clusters are not CC4821-specific showing that gyrA evolution is independent of CC4821 evolution. Some clusters contain sequences from other Neisseria species. Recombination within N.meningitidis strains and between Neisseria species was identified in SimPlot analysis. Finally, amino acid substitutions within GyrA protein were analyzed. Only one position, 91 (83 in E.coli gyrA gene), was linked to CIP resistance. Thirty-one additional putative resistance markers were identified, as amino acid substitutions were only found in resistant strains. CONCLUSIONS: The evolution of gyrA gene of CC4821 N.meningitidis strains is not dependent on CC4821 evolution or on CIP resistance phenotype. Only amino acid 91 is linked to CIP resistance phenotype. Finally, recombination inter- and intra-species is likely to result in the acquisition of various resistance markers, 31 of them being putatively mapped in the present study. Analyzing the evolution of gyrA gene within CC4821 strains is critical to monitor the CIP resistance phenotype and the acquisition of new resistance markers. Such studies are necessary for the control of the meningococcal disease and the development of new drugs targeting DNA gyrase.

Synthesis, biological evaluation and docking studies of 4-aryloxymethyl coumarins derived from substructures and degradation products of vancomycin.

Two series of 4-aryloxymethyl coumarins derived from the reaction of 4-bromomethyl coumarins with ethyl gallate and ethyl ester of N-Benzoyl tyrosine have been synthesized. Gallate ethers 3a-3g and tyrosine derivatives 4e-4j were most effective against Entercoccus faecalis. They were also found to be effective against Aspergillus niger and Candida albicans. Comparative docking studies with novobiocin have indicated better binding ability and higher 'C' score values than novobiocin.