In 1986, Bouvet and Grimont delineated two related taxa of the genus Acinetobacter termed genospecies (GS) 8 and 9. They proposed the name Acinetobacter lwoffii for GS8, which included the supposed type strain (CIP 64.10). As the authenticity of CIP 64.10 was later questioned, this study aimed at reassessing the taxonomy of these genospecies. We investigated 52 strains of GS8 or GS9, including CIP 64.10 and the genuine type strain of A. lwoffii (NCTC 5866T). All strains were subjected to the genus-wide comparative analyses of MALDI-TOF whole-cell mass spectra, rpoB gene sequences and metabolic traits while whole-genome sequences were analysed for 16 strains. The strains were classified into two distinct groups corresponding to GS8 (n=15) and GS9 (n=37). CIP 64.10 fell within GS8 whereas NCTC 5866T belonged to GS9. Intraspecies ANIb values for the genomes of GS8 (n=6) and GS9 (n=10) were ≥96.1% and ≥95.4%, respectively, whereas the ANIb values between them were 86.8-88.6%. Based on core genome phylogeny, GS8 and GS9 formed a distinct clade within the genus, with two respective, strongly supported subclades. GS8 and GS9 were similar in physiological and catabolic properties but were separable by MALDI-TOF MS. We conclude that the name A. lwoffii pertains to GS9 and not to GS8 as originally assumed and that these groups represent two species. We propose the name Acinetobacter pseudolwoffii sp. nov. for GS8, with ANC 5044T (=CCM 8638T=CCUG 67963T=CIP 111642T) as the type strain, and provide the emended description of A. lwoffii.
Together with plague, smallpox and typhus, epidemics of dysentery have been a major scourge of human populations for centuries(1). A previous genomic study concluded that Shigella dysenteriae type 1 (Sd1), the epidemic dysentery bacillus, emerged and spread worldwide after the First World War, with no clear pattern of transmission(2). This is not consistent with the massive cyclic dysentery epidemics reported in Europe during the eighteenth and nineteenth centuries(1,3,4) and the first isolation of Sd1 in Japan in 1897(5). Here, we report a whole-genome analysis of 331 Sd1 isolates from around the world, collected between 1915 and 2011, providing us with unprecedented insight into the historical spread of this pathogen. We show here that Sd1 has existed since at least the eighteenth century and that it swept the globe at the end of the nineteenth century, diversifying into distinct lineages associated with the First World War, Second World War and various conflicts or natural disasters across Africa, Asia and Central America. We also provide a unique historical perspective on the evolution of antibiotic resistance over a 100-year period, beginning decades before the antibiotic era, and identify a prevalent multiple antibiotic-resistant lineage in South Asia that was transmitted in several waves to Africa, where it caused severe outbreaks of disease.
- MeSH
- bacilární dyzentérie epidemiologie dějiny mikrobiologie MeSH
- bakteriální léková rezistence MeSH
- celosvětové zdraví MeSH
- dějiny 19. století MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- fylogeografie * MeSH
- genom bakteriální MeSH
- lidé MeSH
- molekulární epidemiologie MeSH
- molekulární evoluce * MeSH
- sekvenční analýza DNA MeSH
- séroskupina * MeSH
- Shigella dysenteriae klasifikace genetika izolace a purifikace MeSH
- Check Tag
- dějiny 19. století MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
Bacterial genomics has greatly expanded our understanding of microdiversification patterns within a species, but analyses at higher taxonomical levels are necessary to understand and predict the independent rise of pathogens in a genus. We have sampled, sequenced, and assessed the diversity of genomes of validly named and tentative species of the Acinetobacter genus, a clade including major nosocomial pathogens and biotechnologically important species. We inferred a robust global phylogeny and delimited several new putative species. The genus is very ancient and extremely diverse: Genomes of highly divergent species share more orthologs than certain strains within a species. We systematically characterized elements and mechanisms driving genome diversification, such as conjugative elements, insertion sequences, and natural transformation. We found many error-prone polymerases that may play a role in resistance to toxins, antibiotics, and in the generation of genetic variation. Surprisingly, temperate phages, poorly studied in Acinetobacter, were found to account for a significant fraction of most genomes. Accordingly, many genomes encode clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems with some of the largest CRISPR-arrays found so far in bacteria. Integrons are strongly overrepresented in Acinetobacter baumannii, which correlates with its frequent resistance to antibiotics. Our data suggest that A. baumannii arose from an ancient population bottleneck followed by population expansion under strong purifying selection. The outstanding diversification of the species occurred largely by horizontal transfer, including some allelic recombination, at specific hotspots preferentially located close to the replication terminus. Our work sets a quantitative basis to understand the diversification of Acinetobacter into emerging resistant and versatile pathogens.
