Christopher A. Gulvik

Evolutionary dynamics and genomic features of the Elizabethkingia anophelis 2015 to 2016 Wisconsin outbreak strain

An atypically large outbreak of Elizabethkingia anophelis infections occurred in Wisconsin. Here we show that it was caused by a single strain with thirteen characteristic genomic regions. Strikingly, the outbreak isolates show an accelerated evolutionary rate and an atypical mutational spectrum. Six phylogenetic sub-clusters with distinctive temporal and geographic dynamics are revealed, and their last common ancestor existed approximately one year before the first recognized human infection. Unlike other E. anophelis, the outbreak strain had a disrupted DNA repair mutY gene caused by insertion of an integrative and conjugative element. This genomic change probably contributed to the high evolutionary rate of the outbreak strain and may have increased its adaptability, as many mutations in protein-coding genes occurred during the outbreak. This unique discovery of an outbreak caused by a naturally occurring mutator bacterial pathogen provides a dramatic example of the potential impact of pathogen evolutionary dynamics on infectious disease epidemiology.

Complete Genome Sequences of Four Strains from the 2015-2016 Elizabethkingia anophelis Outbreak

ABSTRACT The complete circularized genome sequences of selected specimens from the largest known Elizabethkingia anophelis outbreak to date are described here. Genomic rearrangements observed among the outbreak strains are discussed.

Phylogeography of Burkholderia pseudomallei Isolates, Western Hemisphere

The bacterium Burkholderia pseudomallei causes melioidosis, which is mainly associated with tropical areas. We analyzed single-nucleotide polymorphisms (SNPs) among genome sequences from isolates of B. pseudomallei that originated in the Western Hemisphere by comparing them with genome sequences of isolates that originated in the Eastern Hemisphere. Analysis indicated that isolates from the Western Hemisphere form a distinct clade, which supports the hypothesis that these isolates were derived from a constricted seeding event from Africa. Subclades have been resolved that are associated with specific regions within the Western Hemisphere and suggest that isolates might be correlated geographically with cases of melioidosis. One isolate associated with a former World War II prisoner of war was believed to represent illness 62 years after exposure in Southeast Asia. However, analysis suggested the isolate originated in Central or South America.

Enterococcus crotali sp. nov., isolated from faecal material of a timber rattlesnake

A facultatively anaerobic, Gram-stain-positive bacterium, designated ETRF1T, was found in faecal material of a timber rattlesnake (Crotalus horridus). Based on a comparative 16S rRNA gene sequence analysis, the isolate was assigned to the genus Enterococcus. The 16S rRNA gene sequence of strain ETRF1T showed >97 % similarity to that of the type strains of Enterococcus rotai, E. caccae, E. silesiacus, E haemoperoxidus, E. ureasiticus, E. moraviensis, E. plantarum, E. quebecensis, E. ureilyticus, E. termitis, E. rivorum and E. faecalis. The organism could be distinguished from these 12 phylogenetically related enterococci using conventional biochemical testing, the Rapid ID32 Strep system, comparative pheS and rpoA gene sequence analysis, and comparative whole genome sequence analysis. The estimated in silico DNA-DNA hybridization values were <70 %, and average nucleotide identity values were <96 %, when compared to these 12 species, further validating that ETRF1T represents a unique species within the genus Enterococcus. On the basis of these analyses, strain ETRF1T (=CCUG 65857T=LMG 28312T) is proposed as the type strain of a novel species, Enterococcus crotali sp. nov.

Genomic Characterization and Copy Number Variation of Bacillus anthracis Plasmids pXO1 and pXO2 in a Historical Collection of 412 Strains

Bacillus anthracis microorganisms are of historical and epidemiological importance and are among the most homogenous bacterial groups known, even though the B. anthracis genome is rich in mobile elements. Mobile elements can trigger the diversification of lineages; therefore, characterizing the extent of genomic variation in a large collection of strains is critical for a complete understanding of the diversity and evolution of the species. Here, we sequenced a large collection of B. anthracis strains (>400) that were recovered from human, animal, and environmental sources around the world. Our results confirmed the remarkable stability of gene content and synteny of the anthrax plasmids and revealed no signal of plasmid exchange between B. anthracis and pathogenic B. cereus isolates but rather predominantly vertical descent. These findings advance our understanding of the biology and pathogenomic evolution of B. anthracis and its plasmids. ABSTRACT Bacillus anthracis plasmids pXO1 and pXO2 carry the main virulence factors responsible for anthrax. However, the extent of copy number variation within the species and how the plasmids are related to pXO1/pXO2-like plasmids in other species of the Bacillus cereus sensu lato group remain unclear. To gain new insights into these issues, we sequenced 412 B. anthracis strains representing the total phylogenetic and ecological diversity of the species. Our results revealed that B. anthracis genomes carried, on average, 3.86 and 2.29 copies of pXO1 and pXO2, respectively, and also revealed a positive linear correlation between the copy numbers of pXO1 and pXO2. No correlation between the plasmid copy number and the phylogenetic relatedness of the strains was observed. However, genomes of strains isolated from animal tissues generally maintained a higher plasmid copy number than genomes of strains from environmental sources (P < 0.05 [Welch two-sample t test]). Comparisons against B. cereus genomes carrying complete or partial pXO1-like and pXO2-like plasmids showed that the plasmid-based phylogeny recapitulated that of the main chromosome, indicating limited plasmid horizontal transfer between or within these species. Comparisons of gene content revealed a closed pXO1 and pXO2 pangenome; e.g., plasmids encode <8 unique genes, on average, and a single large fragment deletion of pXO1 in one B. anthracis strain (2000031682) was detected. Collectively, our results provide a more complete view of the genomic diversity of B. anthracis plasmids, their copy number variation, and the virulence potential of other Bacillus species carrying pXO1/pXO2-like plasmids. IMPORTANCE Bacillus anthracis microorganisms are of historical and epidemiological importance and are among the most homogenous bacterial groups known, even though the B. anthracis genome is rich in mobile elements. Mobile elements can trigger the diversification of lineages; therefore, characterizing the extent of genomic variation in a large collection of strains is critical for a complete understanding of the diversity and evolution of the species. Here, we sequenced a large collection of B. anthracis strains (>400) that were recovered from human, animal, and environmental sources around the world. Our results confirmed the remarkable stability of gene content and synteny of the anthrax plasmids and revealed no signal of plasmid exchange between B. anthracis and pathogenic B. cereus isolates but rather predominantly vertical descent. These findings advance our understanding of the biology and pathogenomic evolution of B. anthracis and its plasmids.

Draft Reference Genome Sequence of Corynebacterium mastitidis 16-1433, Isolated from a Mouse

ABSTRACT We report here a nearly complete draft genome sequence for a Corynebacterium mastitidis isolate from a mouse. The total read coverage is 198×, and the genome size is 2,264,319 bp with a 69.04% GC content. This genome complements the only other genome available for C. mastitidis, which was obtained from a sheep.

Burkholderia thailandensis Isolated from Infected Wound, Arkansas, USA

The bacterium Burkholderia thailandensis, a member of the Burkholderia pseudomallei complex, is generally considered nonpathogenic; however, on rare occasions, B. thailandensis infections have been reported. We describe a clinical isolate of B. thailandensis, BtAR2017, recovered from a patient with an infected wound in Arkansas, USA, in 2017.

Necrotizing Pneumonia Caused by Chromobacterium violaceum: Report of a Rare Human Pathogen Causing Disease in an Immunodeficient Child

Chromobacterium violaceum is a rare, potentially serious pathogen. Most clinicians have no experience with its clinical appearance or treatment. We describe a case of a child presenting with necrotizing pneumonia caused by C. violaceum. We describe case complexities, including the need for a multidisciplinary approach to diagnosis and treatment.

Streptococcus azizii sp. nov., isolated from naïve weanling mice

Three isolates of a previously reported novel catalase-negative, Gram-stain-positive, coccoid, alpha-haemolytic, Streptococcus species that were associated with meningoencephalitis in naïve weanling mice were further evaluated to confirm their taxonomic status and to determine additional phenotypic and molecular characteristics. Comparative 16S rRNA gene sequence analysis showed nearly identical intra-species sequence similarity (≥99.9 %), and revealed the closest phylogenetically related species, Streptococcus acidominimus and Streptococcuscuniculi, with 97.0 and 97.5 % sequence similarity, respectively. The rpoB, sodA and recN genes were identical for the three isolates and were 87.6, 85.7 and 82.5 % similar to S. acidominimus and 89.7, 86.2 and 80.7 % similar to S. cuniculi, respectively. In silico DNA-DNA hybridization analyses of mouse isolate 12-5202T against S. acidominimus CCUG 27296T and S. cuniculi CCUG 65085T produced estimated values of 26.4 and 25.7 % relatedness, and the calculated average nucleotide identity values were 81.9 and 81.7, respectively. These data confirm the taxonomic status of 12-5202T as a distinct Streptococcus species, and we formally propose the type strain, Streptococcusazizii 12-5202T (=CCUG 69378T=DSM 103678T). The genome of Streptococcus azizii sp. nov. 12-5202T contains 2062 total genes with a size of 2.34 Mbp, and an average G+C content of 42.76 mol%.