Abstract
We isolated from aerobic and anaerobic blood culture bottles from a febrile patient, a Helicobacter-like Gram negative, rod-shaped bacterium that MALDI-TOF MS failed to identify. Blood agar cultures incubated in a microaerobic atmosphere revealed a motile Gram negative rod, which was oxidase, catalase, nitrate reductase, esterase, and alkaline phosphatase positive. It grew at 42°C with no detectable urease activity. Antimicrobial susceptibility testing showed that the organism was susceptible to beta-lactams, gentamicin, erythromycin, and tetracycline but resistant to ciprofloxacin. Electronic microscopy analysis revealed a 3 × 0.5 μm curved rod bacterium harboring two sheathed amphitrichous flagella. Whole genome sequencing revealed a genome 1,708,265 base-pairs long with a GC content of 37.80% and a total of 1,697 coding sequences. The genomic analyses using the nucleotide sequences of the 16S rRNA gene, hsp60 and gyrB genes, as well as the GyrA protein sequence, and the results of Average Nucleotide Identity and in silico DNA-DNA hybridization suggest evidence for a novel Helicobacter species close to Helicobacter equorum and belonging to the group of enterohepatic Helicobacter species. As soon as the particular peptide mass fingerprint of this pathogen is added to the spectral databases, MALDI-TOF MS technology will improve its identification from clinical specimens, especially in case of “sterile infection”. We propose to associate the present strain with the Latin name of the place of isolation; Caesarodunum (Tours, France) and suggest “Helicobacter caesarodunensis” for further description of this new bacterium.
Highlights
The Helicobacter genus of the Helicobacteraceae family is composed of Gram-negative, helical-shaped rods (Euzéby, 1997), distributed into 37 different gastric and non-gastric species, called enterohepatic Helicobacters
We propose to associate the present strain with the Latin name of the place of isolation; Caesarodunum (Tours, France) and suggest “Helicobacter caesarodunensis” for further description of this new bacterium
It infects a large part of the human population and is associated with chronic gastric inflammation that can evolve toward an ulcer or gastric cancer (Mégraud et al, 2015; Floch et al, 2017)
Summary
The Helicobacter genus of the Helicobacteraceae family is composed of Gram-negative, helical-shaped rods (Euzéby, 1997), distributed into 37 different gastric and non-gastric species, called enterohepatic Helicobacters. Enterohepatic Helicobacters found in humans are usually associated with diarrheal diseases (such as Helicobacter pullorum) (Borges et al, 2015) or systemic infection in immunocompromised hosts (such as Helicobacter cinaedi) (Kawamura et al, 2014). They are urease negative and most of them produce a cytolethal distending toxin (CDT) responsible for symptoms of infection such as inflammation (Varon et al, 2014; Péré-Védrenne et al, 2016). Recent data suggest a potential role for CDT in intestinal carcinogenesis (Ge et al, 2017)
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