During the last decade, many investigators have studied matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of mycobacteria. Diverse and contradictory results indicated that optimal level for routine testing has not been reached yet. This work aimed to assess Vitek MS through two distinct versions, Saramis v4.12 RUO and the IVD v3.0, under conditions close to routine laboratory practice. Overall, 111 mycobacterial isolates were subjected to protein extraction and same spectra were matched against both databases. The IVD v3.0 database proved to be superior to Saramis v4.12 and its identification rates remarkably increased, from 67% to 94% for isolates grown on Middlebrook 7H10 solid medium and from 62% to 91% for isolates grown on mycobacterial growth indicator tube (MGIT) liquid medium. With this new version, IVD v3.0, MALDI-TOF MS might be integrated into routine clinical diagnostics, although molecular techniques remain mandatory in some cases.
Toxoplasmosis, caused by the apicomplexan parasite Toxoplasma gondii, is one of the most common infections in the world due to the lifelong persistence of this parasite in a latent stage. This parasite hijacks host signaling pathways through epigenetic mechanisms which converge on key nuclear proteins. Here, we report a new parasite persistence strategy involving T. gondii rhoptry protein ROP16 secreted early during invasion, which targets the transcription factor UHRF1 (ubiquitinlike containing PHD and RING fingers domain 1), and leads to host cell cycle arrest. This is mediated by DNMT activity and chromatin remodeling at the cyclin B1 gene promoter through recruitment of phosphorylated UHRF1 associated with a repressive multienzymatic protein complex. This leads to deacetylation and methylation of histone H3 surrounding the cyclin B1 promoter to epigenetically silence its transcriptional activity. Moreover, T. gondii infection causes DNA hypermethylation in its host cell, by upregulation of DNMTs. ROP16 is already known to activate and phosphorylate protective immunity transcription factors such as STAT 3/6/5 and modulate host signaling pathways in a strain-dependent manner. Like in the case of STAT6, the strain-dependent effects of ROP16 on UHRF1 are dependent on a single amino-acid polymorphism in ROP16. This study demonstrates that Toxoplasma hijacks a new epigenetic initiator, UHRF1, through an early event initiated by the ROP16 parasite kinase.Keywords Toxoplasma gondii · UHFR1 · ROP16 · Cyclin B1 · DNMT · Epigenetic regulation Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Introduction. Rickettsia sibirica mongolitimonae was recently reported as a common rickettsiosis in France. Current serological evidence suggests the presence of scrub typhus and spotted fever group rickettsiosis in Sri Lanka. We detected a human case of R. sibirica mongolitimonae in Sri Lanka. Methodology. A skin biopsy of the eschar was tested for the presence of Rickettsia spp. using qPCR assay targeting a 109-bp fragment of a hypothetical protein and by PCR amplification and sequencing targeting the ompA gene. Results. A 30-year-old woman who had just returned from travel to a jungle in Sri Lanka was evaluated as an outpatient for fever. Examination revealed an enlarged axillary lymph node, a maculopapular rash and an eschar at her left flank and a skin biopsy of the eschar was performed. The skin biopsy was positive for the presence of Rickettsia spp. by qPCR and PCR amplification and sequencing targeting the ompA gene revealed R. sibirica mongolitimonae. Immunofluorescence assay on an acute serum sample for spotted fever group rickettsial antigens (Rickettsia conorii conorii, R. sibirica mongolitimonae, Rickettsia felis) and typhus group rickettsiae (Rickettsia typhi) was negative. The patient was treated by oral doxycycline (200 mg/day) for one week. Conclusions. R. sibirica mongolitimonae should be considered in the differential diagnosis of patients with suspected rickettsiosis in, or returning from, Sri Lanka.
Polyphasic taxonomic analysis was performed on a novel bacterium, designated UR159 T , isolated in 2016 from human blood of a septic patient hospitalized in France. Preliminary 16S rRNA gene sequence-based phylogenetic analysis indicated that strain UR159 T belonged to the family Flavobacteriaceae, forming a distinct phyletic line distantly related (<94% sequence similarity) to known species of the family. Further phenotypic, chemotaxonomic and genomic analyses were performed. Cells were non-motile, oxidase-negative, catalase-positive Gram-negative rod. It was strictly aerobic yielding yellow-pigmented colonies, and was metabolically rather inert. Major fatty acids were iso-branched fatty acids, predominantly iso-C 15:0 (55.5%) and iso-C 17:1 ω9c (8.8%). Whole genome sequencing revealed a 2.3-Mbp genome encoding a total of 2,262 putative genes with a genomic DNA G+C content at 37.6 mol%. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strain UR159 T and the most closely related members of the Flavobacteriaceae were <75% and <39%, respectively, much below the established cutoffs for ANI (<95-96%) and isDDH (<70%) for species and genus delineation. Average Amino Acid Identity (AAI) percentages were also estimated and were lower than 65% (cut-off proposed for genus delineation for uncultivated prokaryotes) in all cases, except for F. marinum that was just at the limit (65.1%). Based on these findings, we propose it as a new genus and species, Avrilella dinanensis gen. nov., sp.
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