scholarly journals Acquisition of plasmids conferring carbapenem and aminoglycoside resistance and loss of surface-exposed macromolecule structures as strategies for the adaptation of Acinetobacter baumannii CC104O/CC15P strains to the clinical setting

2020 ◽  
Vol 6 (9) ◽  
Author(s):  
María M. Cameranesi ◽  
Julian Paganini ◽  
Adriana S. Limansky ◽  
Jorgelina Moran-Barrio ◽  
Suzana P. Salcedo ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Clinical Setting ◽  
Type Species ◽  
Galleria Mellonella ◽  
Whole Genome Sequence ◽  
Comparative Genomic ◽  
Infection Model ◽  
Clinical Environment ◽  
Content Type ◽  
Link Type

Acinetobacter baumannii (Aba) is an emerging opportunistic pathogen associated to nosocomial infections. The rapid increase in multidrug resistance (MDR) among Aba strains underscores the urgency of understanding how this pathogen evolves in the clinical environment. We conducted here a whole-genome sequence comparative analysis of three phylogenetically and epidemiologically related MDR Aba strains from Argentinean hospitals, assigned to the CC104O/CC15P clonal complex. While the Ab244 strain was carbapenem-susceptible, Ab242 and Ab825, isolated after the introduction of carbapenem therapy, displayed resistance to these last resource β-lactams. We found a high chromosomal synteny among the three strains, but significant differences at their accessory genomes. Most importantly, carbapenem resistance in Ab242 and Ab825 was attributed to the acquisition of a Rep_3 family plasmid carrying a bla OXA-58 gene. Other differences involved a genomic island carrying resistance to toxic compounds and a Tn10 element exclusive to Ab244 and Ab825, respectively. Also remarkably, 44 insertion sequences (ISs) were uncovered in Ab825, in contrast with the 14 and 11 detected in Ab242 and Ab244, respectively. Moreover, Ab825 showed a higher killing capacity as compared to the other two strains in the Galleria mellonella infection model. A search for virulence and persistence determinants indicated the loss or IS-mediated interruption of genes encoding many surface-exposed macromolecules in Ab825, suggesting that these events are responsible for its higher relative virulence. The comparative genomic analyses of the CC104O/CC15P strains conducted here revealed the contribution of acquired mobile genetic elements such as ISs and plasmids to the adaptation of A. baumannii to the clinical setting.

scholarly journals Comparative genomic insights into Yersinia hibernica – a commonly misidentified Yersinia enterocolitica-like organism

2020 ◽  
Vol 6 (9) ◽  
Author(s):  
Scott Van Nguyen ◽  
Dechamma Mundanda Muthappa ◽  
Athmanya K. Eshwar ◽  
James F. Buckley ◽  
Brenda P. Murphy ◽  
...  
Keyword(s):  
Public Health ◽  
Yersinia Enterocolitica ◽  
Type Species ◽  
Zebrafish Embryo ◽  
Comparative Genomic ◽  
Infection Model ◽  
Content Type ◽  
Link Type ◽  
Integrative Conjugative Element ◽  
Virulence Potential

Food-associated outbreaks linked to enteropathogenic Yersinia enterocolitica are of concern to public health. Pigs and their meat are recognized risk factors for transmission of Y. enterocolitica . This study aimed to describe the comparative genomics of Y. enterocolitica along with a number of misclassified Yersinia isolates, now constituting the recently described Yersinia hibernica . The latter was originally cultured from an environmental sample taken at a pig slaughterhouse. Unique features were identified in the genome of Y. hibernica, including a novel integrative conjugative element (ICE), denoted as ICE Yh-1 contained within a 255 kbp region of plasticity. In addition, a zebrafish embryo infection model was adapted and applied to assess the virulence potential among Yersinia isolates including Y. hibernica .

Reclassification of Parvularcula flava as Aquisalinus luteolus nom. nov. and emended description of the genus Aquisalinus

2021 ◽  
Vol 71 (10) ◽  
Author(s):  
Jun-Jie Ying ◽  
Zhi-Cheng Wu ◽  
Yuan-Chun Fang ◽  
Lin Xu ◽  
Cong Sun
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
Link Type ◽  
Type Strains

Parvularcula flava was proposed as a novel member of genus Parvularcula in 2016. Some time earlier, Aquisalinus flavus has been proposed as a novel species of a novel genus named Aquisalinus . When comparing the 16S rRNA gene sequences of type strains P. flava NH6-79T and A. flavus D11M-2T, they showed 97.9 % sequence identity, much higher than the sequence identities 92.7–94.3 % between P. flava NH6-79T and type strains in the genus Parvularcula , indicating that the later proposed novel taxon Parvularcula flava need reclassification. The phylogenetic trees based on 16S rRNA gene sequences and genome sequences both showed that P. flava NH6-79T and A. flavus D11M-2T formed a separated branch away from strains in the genera Parvularcula , Marinicaulis and Amphiplicatus . The average amino acid identity and average nucleotide identity values of P. flava NH6-79T and A. flavus D11M-2T were 87.9 and 85.0 %, respectively, much higher than the values between P. flava NH6-79T and other closely related type strains (54.3 %–58.1 % and 68.6–70.4 %, respectively). P. flava NH6-79T and A. flavus D11M-2T also contained summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) and C16 : 0 as major fatty acids, distinguishing them from other closely related taxa. Based on the results of the phylogenetic, comparative genomic and phenotypic analyses, Parvularcula flava should be reclassified as Aquisalinus luteolus nom. nov. and the description of genus Aquisalinus is emended.

scholarly journals Mutations in the two component regulator systems PmrAB and PhoPQ give rise to increased colistin resistance in Citrobacter and Enterobacter spp.

2020 ◽  
Vol 69 (4) ◽  
pp. 521-529 ◽  
Author(s):  
Matthew E. Wand ◽  
J. Mark Sutton
Keyword(s):  
Growth Rate ◽  
Type Species ◽  
Galleria Mellonella ◽  
Strain Differences ◽  
Fold Increase ◽  
Colistin Resistance ◽  
Content Type ◽  
Link Type ◽  
Carbapenem Resistant ◽  
Individual Strain

Introduction. Colistin is a last resort antibiotic for treating infections caused by carbapenem-resistant isolates. Mechanisms of resistance to colistin have been widely described in Klebsiella pneumoniae and Escherichia coli but have yet to be characterized in Citrobacter and Enterobacter species. Aim. To identify the causative mutations leading to generation of colistin resistance in Citrobacter and Enterobacter spp. Methodology. Colistin resistance was generated by culturing in increasing concentrations of colistin or by direct culture in a lethal (above MIC) concentration. Whole-genome sequencing was used to identify mutations. Fitness of resistant strains was determined by changes in growth rate, and virulence in Galleria mellonella. Results. We were able to generate colistin resistance upon exposure to sub-MIC levels of colistin, in several but not all strains of Citrobacter and Enterobacter resulting in a 16-fold increase in colistin MIC values for both species. The same individual strains also developed resistance to colistin after a single exposure at 10× MIC, with a similar increase in MIC. Genetic analysis revealed that this increased resistance was attributed to mutations in PmrB for Citrobacter and PhoP in Enterobacter , although we were not able to identify causative mutations in all strains. Colistin-resistant mutants showed little difference in growth rate, and virulence in G. mellonella, although there were strain-to-strain differences. Conclusions. Stable colistin resistance may be acquired with no loss of fitness in these species. However, only select strains were able to adapt suggesting that acquisition of colistin resistance is dependent upon individual strain characteristics.

Emergence of a plasmid-borne tigecycline resistance in Klebsiella pneumoniae in Vietnam

2021 ◽  
Author(s):  
Aki Hirabayashi ◽  
Van Thi Thu Ha ◽  
An Van Nguyen ◽  
Son Thai Nguyen ◽  
Keigo Shibayama ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Gene Cluster ◽  
Type Species ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Whole Genome Sequence ◽  
High Sequence Identity ◽  
Pump System ◽  
Content Type ◽  
Link Type

Tigecycline is a last-resort antimicrobial used to treat multidrug-resistant Gram-negative bacterial infections. One of the common antimicrobial resistance mechanisms is the efflux pump system composed of membrane protein complexes to excrete xenobiotic substrates. Recently, a novel gene cluster, tmexCD1-toprJ1, encoding the resistance–nodulation–cell division (RND) efflux pump was identified on plasmids in Klebsiella pneumoniae isolates in China. TMexCD1-TOprJ1 was found to be capable of excreting multiple antimicrobials, including tigecycline, which contributed to the strain's resistance. In this study, we identified K. pneumoniae isolates harbouring the tmexCD1-toprJ1 genes outside of China for the first time. Two tigecycline-resistant K. pneumoniae isolates belonging to ST273 by multilocus sequence typing were collected from different patients in a medical institution in Hanoi, Vietnam, in 2015. Whole-genome sequence analysis revealed that these isolates harboured a 288.0 kb tmexCD1-toprJ1–carrying plasmid with IncFIB and IncHI1B replicons. The tmexCD1-toprJ1 gene cluster was surrounded by several mobile gene elements, including IS26, and the plasmids had high sequence identity with that of K. pneumoniae isolated in China. Our finding suggests that the horizontal spread of tigecycline resistance mediated by tmexCD1-toprJ1–carrying plasmids has occurred in Vietnam and other countries, and raises concern about the further global dissemination.

scholarly journals Investigation of Novel pmrB and eptA Mutations in Isogenic Acinetobacter baumannii Isolates Associated with Colistin Resistance and Increased Virulence In Vivo

2019 ◽  
Vol 63 (3) ◽  
Author(s):  
Stefanie Gerson ◽  
Jonathan W. Betts ◽  
Kai Lucaßen ◽  
Carolina Silva Nodari ◽  
Julia Wille ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Lipid A ◽  
Galleria Mellonella ◽  
Resistance Mechanism ◽  
Resistant Isolate ◽  
Infection Model ◽  
Colistin Resistance ◽  
Strain Specificity ◽  
Content Type

ABSTRACT Colistin resistance in Acinetobacter baumannii is of great concern and is a threat to human health. In this study, we investigate the mechanisms of colistin resistance in four isogenic pairs of A. baumannii isolates displaying an increase in colistin MICs. A mutation in pmrB was detected in each colistin-resistant isolate, three of which were novel (A28V, I232T, and ΔL9-G12). Increased expression of pmrC was shown by semi-quantitative reverse transcription-PCR (qRT-PCR) for three colistin-resistant isolates, and the addition of phosphoethanolamine (PEtN) to lipid A by PmrC was revealed by mass spectrometry. Interestingly, PEtN addition was also observed in some colistin-susceptible isolates, indicating that this resistance mechanism might be strain specific and that other factors could contribute to colistin resistance. Furthermore, the introduction of pmrAB carrying the short amino acid deletion ΔL9-G12 into a pmrAB knockout strain resulted in increased pmrC expression and lipid A modification, but colistin MICs remained unchanged, further supporting the strain specificity of this colistin resistance mechanism. Of note, a mutation in the pmrC homologue eptA and a point mutation in ISAba1 upstream of eptA were associated with colistin resistance and increased eptA expression, which is a hitherto undescribed resistance mechanism. Moreover, no cost of fitness was observed for colistin-resistant isolates, while the virulence of these isolates was increased in a Galleria mellonella infection model. Although the mutations in pmrB were associated with colistin resistance, PEtN addition appears not to be the sole factor leading to colistin resistance, indicating that the mechanism of colistin resistance is far more complex than previously suspected and is potentially strain specific.

scholarly journals Proposal to rename Carnobacterium inhibens as Carnobacterium inhibens subsp. inhibens subsp. nov. and description of Carnobacterium inhibens subsp. gilichinskyi subsp. nov., a psychrotolerant bacterium isolated from Siberian permafrost

2015 ◽  
Vol 65 (Pt_2) ◽  
pp. 556-561 ◽  
Author(s):  
Wayne L. Nicholson ◽  
Kateryna Zhalnina ◽  
Rafael R. de Oliveira ◽  
Eric W. Triplett
Keyword(s):  
Sequence Analysis ◽  
Type Species ◽  
Fatty Acid Content ◽  
Optimal Growth ◽  
Whole Genome Sequence ◽  
Rrna Gene ◽  
Positive Staining ◽  
The Novel ◽  
Content Type ◽  
Link Type

A novel, psychrotolerant facultative anaerobe, strain WN1359T, was isolated from a permafrost borehole sample collected at the right bank of the Kolyma River in Siberia, Russia. Gram-positive-staining, non-motile, rod-shaped cells were observed with sizes of 1–2 µm long and 0.4–0.5 µm wide. Growth occurred in the range of pH 5.8–9.0 with optimal growth at pH 7.8–8.6 (pH optimum 8.2). The novel isolate grew at temperatures from 0–37 °C and optimal growth occurred at 25 °C. The novel isolate does not require NaCl; growth was observed between 0 and 8.8 % (1.5 M) NaCl with optimal growth at 0.5 % (w/v) NaCl. The isolate was a catalase-negative, facultatively anaerobic chemo-organoheterotroph that used sugars but not several single amino acids or dipeptides as substrates. The major metabolic end-product was lactic acid in the ratio of 86 % l-lactate : 14 % d-lactate. Strain WN1359T was sensitive to ampicillin, chloramphenicol, fusidic acid, lincomycin, monocycline, rifampicin, rifamycin SV, spectinomycin, streptomycin, troleandomycin and vancomycin, and resistant to nalidixic acid and aztreonam. The fatty acid content was predominantly unsaturated (70.2 %), branched-chain unsaturated (11.7 %) and saturated (12.5 %). The DNA G+C content was 35.3 mol% by whole genome sequence analysis. 16S rRNA gene sequence analysis showed 98.7 % sequence identity between strain WN1359T and Carnobacterium inhibens . Genome relatedness was computed using both Genome-to-Genome Distance Analysis (GGDA) and Average Nucleotide Identity (ANI), which both strongly supported strain WN1359T belonging to the species C. inhibens . On the basis of these results, the permafrost isolate WN1359T represents a novel subspecies of C. inhibens , for which the name Carnobacterium inhibens subsp. gilichinskyi subsp. nov. is proposed. The type strain is WN1359T ( = ATCC BAA-2557T = DSM 27470T). The subspecies Carnobacterium inhibens subsp. inhibens subsp. nov. is created automatically. An emended description of C. inhibens is also provided.

scholarly journals Genome sequence analyses show that Neisseria oralis is the same species as ‘ Neisseria mucosa var. heidelbergensis’

2013 ◽  
Vol 63 (Pt_10) ◽  
pp. 3920-3926 ◽  
Author(s):  
Julia S. Bennett ◽  
Keith A. Jolley ◽  
Martin C. J. Maiden
Keyword(s):  
Genome Sequence ◽  
Type Species ◽  
Whole Genome Sequence ◽  
23S Rrna ◽  
Rrna Gene ◽  
Whole Genome ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Neisseria Mucosa

Phylogenies generated from whole genome sequence (WGS) data provide definitive means of bacterial isolate characterization for typing and taxonomy. The species status of strains recently defined with conventional taxonomic approaches as representing Neisseria oralis was examined by the analysis of sequences derived from WGS data, specifically: (i) 53 Neisseria ribosomal protein subunit (rps) genes (ribosomal multi-locus sequence typing, rMLST); and (ii) 246 Neisseria core genes (core genome MLST, cgMLST). These data were compared with phylogenies derived from 16S and 23S rRNA gene sequences, demonstrating that the N. oralis strains were monophyletic with strains described previously as representing ‘ Neisseria mucosa var. heidelbergensis’ and that this group was of equivalent taxonomic status to other well-described species of the genus Neisseria . Phylogenetic analyses also indicated that Neisseria sicca and Neisseria macacae should be considered the same species as Neisseria mucosa and that Neisseria flavescens should be considered the same species as Neisseria subflava . Analyses using rMLST showed that some strains currently defined as belonging to the genus Neisseria were more closely related to species belonging to other genera within the family; however, whole genome analysis of a more comprehensive selection of strains from within the family Neisseriaceae would be necessary to confirm this. We suggest that strains previously identified as representing ‘ N. mucosa var. heidelbergensis’ and deposited in culture collections should be renamed N. oralis . Finally, one of the strains of N. oralis was able to ferment lactose, due to the presence of β-galactosidase and lactose permease genes, a characteristic previously thought to be unique to Neisseria lactamica , which therefore cannot be thought of as diagnostic for this species; however, the rMLST and cgMLST analyses confirm that N. oralis is most closely related to N. mucosa .

scholarly journals Treponema phagedenis (ex Noguchi 1912) Brumpt 1922 sp. nov., nom. rev., isolated from bovine digital dermatitis

2020 ◽  
Vol 70 (3) ◽  
pp. 2115-2123 ◽  
Author(s):  
Peter Kuhnert ◽  
Isabelle Brodard ◽  
Maher Alsaaod ◽  
Adrian Steiner ◽  
Michael H. Stoffel ◽  
...  
Keyword(s):  
Type Strain ◽  
Type Species ◽  
Sequence Data ◽  
Whole Genome Sequence ◽  
Valid Species ◽  
Species Identity ◽  
Digital Dermatitis ◽  
Content Type ◽  
Link Type ◽  
Specific Pcr

‘ Treponema phagedenis ’ was originally described in 1912 by Noguchi but the name was not validly published and no type strain was designated. The taxon was not included in the Approved Lists of Bacterial Names and hence has no standing in nomenclature. Six Treponema strains positive in a ‘ T. phagedenis ’ phylogroup-specific PCR test were isolated from digital dermatitis (DD) lesions of cattle and further characterized and compared with the human strain ‘ T. phagedenis ’ ATCC 27087. Results of phenotypic and genotypic analyses including API ZYM, VITEK2, MALDI-TOF and electron microscopy, as well as whole genome sequence data, respectively, showed that they form a cluster of species identity. Moreover, this species identity was shared with ‘ T. phagedenis ’-like strains reported in the literature to be regularly isolated from bovine DD. High average nucleotide identity values between the genomes of bovine and human ‘ T. phagedenis ’ were observed. Slight genomic as well as phenotypic variations allowed us to differentiate bovine from human isolates, indicating host adaptation. Based on the fact that this species is regularly isolated from bovine DD and that the name is well dispersed in the literature, we propose the species Treponema phagedenis sp. nov., nom. rev. The species can phenotypically and genetically be identified and is clearly separated from other Treponema species. The valid species designation will allow to further explore its role in bovine DD. The type strain for Treponema phagedenis sp. nov., nom. rev. is B43.1T (=DSM 110455T=NCTC 14362T) isolated from a bovine DD lesion in Switzerland.

scholarly journals Teredinibacter haidensis sp. nov., Teredinibacter purpureus sp. nov. and Teredinibacter franksiae sp. nov., marine, cellulolytic endosymbiotic bacteria isolated from the gills of the wood-boring mollusc Bankia setacea (Bivalvia: Teredinidae) and emended description of the genus Teredinibacter

2021 ◽  
Author(s):  
Marvin A. Altamia ◽  
J. Reuben Shipway ◽  
David Stein ◽  
Meghan A. Betcher ◽  
Jennifer M. Fung ◽  
...  
Keyword(s):  
Type Strain ◽  
Type Species ◽  
Sequence Data ◽  
Amino Acid Identity ◽  
Whole Genome Sequence ◽  
Phenotypic Characterization ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Content Type ◽  
Link Type

Here, we describe three endosymbiotic bacterial strains isolated from the gills of the shipworm, Bankia setacea (Teredinidae: Bivalvia). These strains, designated as Bs08T, Bs12T and Bsc2T, are Gram-stain-negative, microaerobic, gammaproteobacteria that grow on cellulose and a variety of substrates derived from lignocellulose. Phenotypic characterization, phylogeny based on 16S rRNA gene and whole genome sequence data, amino acid identity and percentage of conserved proteins analyses, show that these strains are novel and may be assigned to the genus Teredinibacter . The three strains may be differentiated and distinguished from other previously described Teredinibacter species based on a combination of four characteristics: colony colour (Bs12T, purple; others beige to brown), marine salt requirement (Bs12T, Bsc2T and Teredinibacter turnerae strains), the capacity for nitrogen fixation (Bs08T and T. turnerae strains) and the ability to respire nitrate (Bs08T). Based on these findings, we propose the names Teredinibacter haidensis sp. nov. (type strain Bs08T=ATCC TSD-121T=KCTC 62964T), Teredinibacter purpureus sp. nov. (type strain Bs12T=ATCC TSD-122T=KCTC 62965T) and Teredinibacter franksiae sp. nov. (type strain Bsc2T=ATCC TSD-123T=KCTC 62966T).

scholarly journals Robust demarcation of 17 distinct Bacillus species clades, proposed as novel Bacillaceae genera, by phylogenomics and comparative genomic analyses: description of Robertmurraya kyonggiensis sp. nov. and proposal for an emended genus Bacillus limiting it only to the members of the Subtilis and Cereus clades of species

2020 ◽  
Vol 70 (11) ◽  
pp. 5753-5798 ◽  
Author(s):  
Radhey S. Gupta ◽  
Sudip Patel ◽  
Navneet Saini ◽  
Shu Chen
Keyword(s):  
Type Species ◽  
Phylogenetic Trees ◽  
Bacillus Species ◽  
Comparative Genomic ◽  
Molecular Evidence ◽  
Content Type ◽  
Link Type ◽  
Conserved Signature Indels ◽  
Genomic Scale

To clarify the evolutionary relationships and classification of Bacillus species, comprehensive phylogenomic and comparative analyses were performed on >300 Bacillus/Bacillaceae genomes. Multiple genomic-scale phylogenetic trees were initially reconstructed to identify different monophyletic clades of Bacillus species. In parallel, detailed analyses were performed on protein sequences of genomes to identify conserved signature indels (CSIs) that are specific for each of the identified clades. We show that in different reconstructed trees, most of the Bacillus species, in addition to the Subtilis and Cereus clades, consistently formed 17 novel distinct clades. Additionally, some Bacillus species reliably grouped with the genera Alkalicoccus, Caldalkalibacillus, Caldibacillus, Salibacterium and Salisediminibacterium . The distinctness of identified Bacillus species clades is independently strongly supported by 128 identified CSIs which are unique characteristics of these clades, providing reliable means for their demarcation. Based on the strong phylogenetic and molecular evidence, we are proposing that these 17 Bacillus species clades should be recognized as novel genera, with the names Alteribacter gen. nov., Ectobacillus gen. nov., Evansella gen. nov., Ferdinandcohnia gen. nov., Gottfriedia gen. nov., Heyndrickxia gen. nov., Lederbergia gen. nov., Litchfieldia gen. nov., Margalitia gen. nov., Niallia gen. nov., Priestia gen. nov., Robertmurraya gen. nov., Rossellomorea gen. nov., Schinkia gen. nov., Siminovitchia gen. nov., Sutcliffiella gen. nov. and Weizmannia gen. nov. We also propose to transfer ‘ Bacillus kyonggiensi s’ to Robertmurraya kyonggiensis sp. nov. (type strain: NB22=JCM 17569T=DSM 26768). Additionally, we report 31 CSIs that are unique characteristics of either the members of the Subtilis clade (containing the type species B. subtilis ) or the Cereus clade (containing B. anthracis and B. cereus ). As most Bacillus species which are not part of these two clades can now be assigned to other genera, we are proposing an emended description of the genus Bacillus to restrict it to only the members of the Subtilis and Cereus clades.

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