16S–23S rRNA Gene Intergenic Spacer Region Variability Helps Resolve Closely Related Sphingomonads

Sphingomonads comprise a physiologically versatile group many of which appear to be adapted to oligotrophic environments, but several also had features in their genomes indicative of host associations. In this study, the extent variability of the 16S-23S rDNA intergenic spacer (ITS) sequences of 14 ATCC reference sphingomonad strains and 23 isolates recovered from drinking water was investigated through PCR amplification and sequencing. Sequencing analysis of the 16S-23S rRNA gene ITS region revealed that the ITS sizes for all studied isolates varied between 415 to 849 bp, while their G+C content was 42.2 mol% to 57.9 mol%. Five distinct ITS types were identified: ITSnone (without tRNA genes), ITSAla(TGC), ITSAla (TGC)+Ile (GAT), ITSIle (GAT)+Ala (TGC) and ITS Ile (GAT)+Pseudo. All of the identified tRNAAla (TGC) molecules consisted of 73 bases, and all of the tRNAIle (GAT) molecules consisted of 74 bases. We also detected striking variability in the size of the ITS region among the various examined isolates. Highest variability was detected within the ITS-2

Expanded genome-wide comparisons give novel insights into population structure and genetic heterogeneity of Leishmania tropica complex

Leishmania tropica is one of the main causative agents of cutaneous leishmaniasis (CL). Population structures of L. tropica appear to be genetically highly diverse. However, the relationship between L. tropica strains genomic diversity, protein coding gene evolution and biogeography are still poorly understood. In this study, we sequenced the genomes of three new clinical L. tropica isolates, two derived from a recent outbreak of CL in camps hosting Syrian refugees in Lebanon and one historical isolate from Azerbaijan to further refine comparative genome analyses. In silico multilocus microsatellite typing (MLMT) was performed to integrate the current diversity of genome sequence data in the wider available MLMT genetic population framework. Single nucleotide polymorphism (SNPs), gene copy number variations (CNVs) and chromosome ploidy were investigated across the available 18 L. tropica genomes with a main focus on protein coding genes. MLMT divided the strains in three populations that broadly correlated with their geographical distribution but not populations defined by SNPs. Unique SNPs profiles divided the 18 strains into five populations based on principal component analysis. Gene ontology enrichment analysis of the protein coding genes with population specific SNPs profiles revealed various biological processes, including iron acquisition, sterols synthesis and drug resistance. This study further highlights the complex links between L. tropica important genomic heterogeneity and the parasite broad geographic distribution. Unique sequence features in protein coding genes identified in distinct populations reveal potential novel markers that could be exploited for the development of more accurate typing schemes to further improve our knowledge of the evolution and epidemiology of the parasite as well as highlighting protein variants of potential functional importance underlying L. tropica specific biology

Origin and Evolution of European Community-Acquired Methicillin- Resistant Staphylococcus aureus

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized in Europe and worldwide in the late 1990s. Within a decade, several genetically and geographically distinct CA-MRSA lineages carrying the small SCCmec type IV and V genetic elements and the Panton-Valentine leukocidin (PVL) emerged around the world. In Europe, the predominant CA-MRSA strain belongs to clonal complex 80 (CC80) and is resistant to kanamycin/amikacin and fusidic acid. CC80 was first reported in 1993 but was relatively rare until the late 1990s. It has since been identified throughout North Africa, the Middle East, and Europe, with recent sporadic reports in sub-Saharan Africa. While strongly associated with skin and soft tissue infections, it is rarely found among asymptomatic carriers. Methicillin-sensitive S. aureus (MSSA) CC80 strains are extremely rare except in sub-Saharan Africa. In the current study, we applied whole-genome sequencing to a global collection of both MSSA and MRSA CC80 isolates. Phylogenetic analyses strongly suggest that the European epidemic CA-MRSA lineage is derived from a PVL-positive MSSA ancestor from sub-Saharan Africa. Moreover, the tree topology suggests a single acquisition of both the SCCmec element and a plasmid encoding the fusidic acid resistance determinant. Four canonical SNPs distinguish the derived CA-MRSA lineage and include a nonsynonymous mutation in accessory gene regulator C (agrC). These changes were associated with a star-like expansion into Europe, the Middle East, and North Africa in the early 1990s, including multiple cases of cross-continent imports likely driven by human migrations. IMPORTANCE With increasing levels of CA-MRSA reported from most parts of the Western world, there is a great interest in understanding the origin and factors associated with the emergence of these epidemic lineages. To trace the origin, evolution, and dissemination pattern of the European CA-MRSA clone (CC80), we sequenced a global collection of strains of the S. aureus CC80 lineage. Our study determined that a single descendant of a PVL-positive methicillin-sensitive ancestor circulating in sub-Saharan Africa rose to become the dominant CA-MRSA clone in Europe, the Middle East, and North Africa. In the transition from a methicillin-susceptible lineage to a successful CA-MRSA clone, it simultaneously became resistant to fusidic acid, a widely used antibiotic for skin and soft tissue infections, thus demonstrating the importance of antibiotic selection in the success of this clone. This finding furthermore highlights the significance of horizontal gene acquisitions and underscores the combined importance of these factors for the success of CA-MRSA

Tracking the international spread of SARS-CoV-2 lineages B.1.1.7 and B.1.351/501Y-V2

Publisher Copyright: © 2021 O'Toole Á et al.Late in 2020, two genetically-distinct clusters of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with mutations of biological concern were reported, one in the United Kingdom and one in South Africa. Using a combination of data from routine surveillance, genomic sequencing and international travel we track the international dispersal of lineages B.1.1.7 and B.1.351 (variant 501Y-V2). We account for potential biases in genomic surveillance efforts by including passenger volumes from location of where the lineage was first reported, London and South Africa respectively. Using the software tool grinch (global report investigating novel coronavirus haplotypes), we track the international spread of lineages of concern with automated daily reports, Further, we have built a custom tracking website (cov-lineages.org/global_report.html) which hosts this daily report and will continue to include novel SARS-CoV-2 lineages of concern as they are detected.Peer reviewe