Uncommon Salmonella Infantis Variants with Incomplete Antigenic Formula in the Poultry Food Chain, Italy.

Uncommon Salmonella Infantis variants displaying only flagellar antigens phenotypically showed identical incomplete antigenic formula but differed by molecular serotyping. Although most formed rough colonies, all shared antimicrobial resistances and the presence of usg gene with wild-type Salmonella Infantis. Moreover, they were undistinguishable wild-type Salmonella Infantis by whole-genome sequencing.

Streptococcus suis serotype 9 in Italy: genomic insights into high-risk clones with emerging resistance to penicillin.

BACKGROUND: Streptococcus suis is an important pig pathogen and an emerging zoonotic agent. In a previous study, we described a high proportion of penicillin-resistant serotype 9 S. suis (SS9) isolates on pig farms in Italy. OBJECTIVES: We hypothesized that resistance to penicillin emerged in some SS9 lineages characterized by substitutions at the PBPs, contributing to the successful spread of these lineages in the last 20 years. METHODS: Sixty-six SS9 isolates from cases of streptococcosis in pigs were investigated for susceptibility to penicillin, ceftiofur and ampicillin. The isolates were characterized for ST, virulence profile, and antimicrobial resistance genes through WGS. Multiple linear regression models were employed to investigate the associations between STs, year of isolation, substitutions at the PBPs and an increase in MIC values to ß-lactams. RESULTS: MIC values to penicillin increased by 4% each year in the study period. Higher MIC values for penicillin were also positively associated with ST123, ST1540 and ST1953 compared with ST16. The PBP sequences presented a mosaic organization of blocks. Within the same ST, substitutions at the PBPs were generally more frequent in recent isolates. Resistance to penicillin was driven by substitutions at PBP2b, including K479T, D512E and K513E, and PBP2x, including T551S, while reduced susceptibility to ceftiofur and ampicillin were largely dependent on substitutions at PBP2x. CONCLUSIONS: Here, we identify the STs and substitutions at the PBPs responsible for increased resistance of SS9 to penicillin on Italian pig farms. Our data highlight the need for monitoring the evolution of S. suis in the coming years.

Characterization of a prophage and a defective integrative conjugative element carrying the optrA gene in linezolid-resistant Streptococcus dysgalactiae subsp. equisimilis isolates from pigs, Italy.

OBJECTIVES: To investigate the optrA-carrying genetic elements and their transferability in two linezolid-resistant Streptococcus dysgalactiae subsp. equisimilis (SDSE) strains of swine origin. METHODS: SDSE strains (V220 and V1524) were phenotypically and genotypically characterized. Transferability of oxazolidinone resistance genes (filter mating), genetic elements and relatedness between isolates (WGS) were analysed. Excision of the genetic elements was assayed by inverse PCR. RESULTS: SDSE isolates were resistant to chloramphenicol, florfenicol and linezolid, but susceptible to tedizolid and both carried the optrA gene.In SDSE V220 optrA was located on a 72.9-kb ICESdyV220 inserted in the 3' end of the chromosomal rum gene. It was 94%-96% identical (coverage, from 31% to 61%) to other optrA-carrying ICEs. In-depth ICESdyV220 sequence analysis revealed that optrA was carried by an IMESdyV220 (17.9 kb), also containing the tet(O/W/32/O) gene. Inverse PCR assays excluded the ICESdyV220 mobility. In SDSE V1524, optrA was carried by the ΦSdyV1524 prophage, integrated near the 5' end of the chromosomal had gene, showing a genetic organization similar to that of other streptococcal phage. Conjugation and transduction assays failed to demonstrate the optrA transferability to streptococcal recipients. V220 and V1524 belonged to two novel sequence types (ST704 and ST634, respectively). CONCLUSIONS: To the best of our knowledge, this is the first identification of the optrA gene on a prophage and an ICE in SDSE isolates from swine brain.These findings are consistent with the current belief in the key role of bacteriophages and ICEs in the streptococcal evolution and adaptation.

S100B Affects Gut Microbiota Biodiversity.

This in vivo study in mice addresses the relationship between the biodiversity of the microbiota and the levels of S100B, a protein present in enteroglial cells, but also in foods such as milk. A positive significant correlation was observed between S100B levels and Shannon values, which was reduced after treatment with Pentamidine, an inhibitor of S100B function, indicating that the correlation was influenced by the modulation of S100B activity. Using the bootstrap average method based on the distribution of the S100B concentration, three groups were identified, exhibiting a significant difference between the microbial profiles. Operational taxonomic units, when analyzed by SIMPER analysis, showed that genera regarded to be eubiotic were mainly concentrated in the intermediate group, while genera potentially harboring pathobionts often appeared to be more concentrated in groups where the S100B amounts were very low or high. Finally, in a pilot experiment, S100B was administered orally, and the microbial profiles appeared to be modified accordingly. These data may open novel perspectives involving the possibility of S100B-mediated regulation in the intestinal microbiota.

Profiling of mitochondrial heteroplasmy in single human oocytes by next-generation sequencing.

Mitochondrial DNA (mtDNA) plays a crucial role in the development of a competent oocyte. Indeed, mtDNA alterations may predispose to chromosome nondisjunction, resulting in infertility due to a reduced vitality and quality of oocytes and embryos. In this methods paper, the multiple displacement amplification approach was applied in combination with next-generation sequencing (NGS) to amplify and sequence, in single-end, the entire mtDNA of single human oocytes to directly construct genomic NGS libraries, and subsequently, to highlight and quantify the mutations they presented. The bioinformatic workflow was carried out with a specific ad hoc developed in-house software. This approach proved to be sensitive and specific, also highlighting the mutations present in heteroplasmy, showing deletion, insertion or substitution mutations in the genes involved in the respiratory chain, even if the found variants were benign or of uncertain meaning. The analysis of mtDNA mutations in the oocyte could provide a better understanding of specific genetic abnormalities and of their possible effect on oocyte developmental competence. This study shows how this approach, based on a massive parallel sequencing of clonally amplified DNA molecules, allows to sequence the entire mitochondrial genome of single oocytes in a short time and with a single analytical run and to verify mtDNA mutations.

Legionella bononiensis sp. nov., isolated from a hotel water distribution system in northern Italy.

Legionella-like isolates, strains 27fs60, 30fs61 and 30cs62T, were isolated from a hotel water distribution system in the Emilia-Romagna region, Italy. Isolates were Gram- and Ziehl Neelsen-stain-negative, rod-shaped, with transitory flagella presence and able to grow at 32-37 °C (with an optimum at 32 °C) on buffered charcoal-yeast extract agar with l-cysteine, glycine-vancomycin-polymyxin B-cycloheximide agar and Wadowsky-Yee medium agar. The strains showed positive reactions for oxidase, hippurate and gelatinase and a weakly positive reaction for catalase. Based on the EUCAST cut-off, strain 30cs62T was resistant to ciprofloxacin (5 mg l-1). The mip and rpoB gene sequences of the three strains showed close matches to those of Legionella quateirensis ATCC 49507T with similarity values of 98.2 and 94.5 %, respectively. Whole genome sequencing of the three strains was performed, resulting in G+C contents of 39.0, 39.1 and 39.0 mol%, respectively. The identity percentage measured by average nucleotide identity between the three strains and their respective closest strains were: 91.32 % L. quateirensis NCTC 12376T, 91.45 % L. quateirensis ATCC 49507T and 91.45 % L. quateirensis ATCC 49507T, respectively. The digital DNA-DNA hybridization analysis demonstrated how the isolates were separated from the most related phylogenetic Legionella species (L. quateirensis ATCC 49507T, ≤40.10 % DNA-DNA relatedness). The concatenated phylogenetic tree based on 16S rRNA, mip, rpoB and rnpB genes, shows a close relationship with L. quateirensis ATCC 49507T. The results obtained confirm the status of an independent species. The name proposed for this species is Legionella bononiensis sp. nov. with 30cs62T (=ATCC TSD-262T=DSM 112526T) as the type strain.

Tetrodotoxin in live bivalve mollusks from Europe: Is it to be considered an emerging concern for food safety?

Tetrodotoxins (TTXs) are a group of potent neurotoxins named after the Tetraodontidae fish family (pufferfish). TTXs have been reported in several animal taxa, both terrestrial and marine. The ingestion of TTX-contaminated flesh can cause serious neurotoxic symptomatology and can eventually lead to death. Traditionally, TTXs have been associated with Asian countries, in particular with pufferfish consumption. However, they have also been reported in bivalve mollusks farmed in the Pacific area and, recently, in European seas. In Europe, different countries have reported TTXs, especially those bordering the Mediterranean Sea. As a consequence, in 2017 the European Food Safety Authority (EFSA) released an opinion with reference to TTX present in marine gastropods and bivalves, proposing a safety limit of 44 µg/kg TTXs in shellfish meat, below which no adverse effects should be observed in humans. Nevertheless, this limit has been exceeded on many occasions in European shellfish and, while for bivalves there have been no registered human intoxications, that is not the case for marine gastropods. However, TTXs have not yet been included in the list of marine biotoxins officially monitored in live bivalve mollusks within the European Union (EU). Thus, the aims of this manuscript are to discuss the increasing occurrence of TTXs in live bivalve mollusks from European sea waters, to acknowledge the still ongoing knowledge gaps that should be covered and to stimulate constructive debate on the eventuality of adopting a shared regulatory context, at least in the EU, for monitoring and managing this potential threat to food safety.

Identification and characterization of a spreadable IncI1 plasmid harbouring a blaCTX-M-15 gene in an Italian human isolate of Salmonella serovar Napoli.

Salmonella enterica subsp. enterica serovar Napoli (S. Napoli) ranks among the top serovars causing human infections in Italy, although not common in other European countries. Isolates are generally pan-susceptible or resistant to aminoglycosides only, however data on antimicrobial resistance genes in strains of S. Napoli are limited. Recently an isolate encoding resistance to third generation cephalosporins was reported. This study aimed to characterize plasmid-encoded cephalosporin resistance due to the blaCTX-M-15 gene in a human S. Napoli isolate in Italy, and to investigate plasmid stability over time. S. Napoli 16/174478 was confirmed to be ESBL-producing. The blaCTX-M-15 gene was shown to be located on an IncI1α plasmid of 90,272 bp (50.03 GC%) encoding for 107 coding sequences (CDS). The plasmid was successfully transferred by conjugation to an E. coli 1816 recipient strain (conjugation frequency 3.9 × 10-2 transconjugants per donor). Transconjugants were confirmed to carry the IncI1α plasmid, and to be ESBL-producing strains as well. Moreover, transconjugant colonies maintained the plasmid for up to 10 passages. The identification of S. Napoli isolates able to produce ESBLs is of great concern, as this pathogen is frequently associated with invasive infections and a higher risk of bacteraemia, and its reservoir has not yet been clearly identified.

Comparative genomic analysis reveals high intra-serovar plasticity within Salmonella Napoli isolated in 2005-2017.

BACKGROUND: Salmonella enterica subsp. enterica serovar Napoli (S. Napoli) is among the top serovars causing human infections in Italy, although it is relatively uncommon in other European countries; it is mainly isolated from humans and the environment, but neither the reservoir nor its route of infection are clearly defined. This serovar is characterized by high genomic diversity, and molecular evidences revealed important similarities with typhoidal serovars. RESULTS: 179 S. Napoli genomes as well as 239 genomes of typhoidal and non-typhoidal serovars were analyzed in a comparative genomic study. Phylogenetic analysis and draft genome characterization in terms of Multi Locus Sequence Typing (MLST), plasmid replicons, Salmonella Pathogenicity Islands (SPIs), antimicrobial resistance genes (ARGs), phages, biocide and metal-tolerance genes confirm the high genetic variability of S. Napoli, also revealing a within-serovar phylogenetic structure more complex than previously known. Our work also confirms genomic similarity of S. Napoli to typhoidal serovars (S. Typhi and S. Paratyphi A), with S. Napoli samples clustering primarily according to ST, each being characterized by specific genomic traits. Moreover, two major subclades of S. Napoli can be clearly identified, with ST-474 being biphyletic. All STs span among isolation sources and years of isolation, highlighting the challenge this serovar poses to define its epidemiology and evolution. Altogether, S. Napoli strains carry less SPIs and less ARGs than other non-typhoidal serovars and seldom acquire plasmids. However, we here report the second case of an extended-spectrum ß-lactamases (ESBLs) producing S. Napoli strain and the first cases of multidrug resistant (MDR) S. Napoli strains, all isolated from humans. CONCLUSIONS: Our results provide evidence of genomic plasticity of S. Napoli, highlighting genomic similarity with typhoidal serovars and genomic features typical of non-typhoidal serovars, supporting the possibility of survival in different niches, both enteric and non-enteric. Presence of horizontally acquired ARGs and MDR profiles rises concerns regarding possible selective pressure exerted by human environment on this pathogen.

Proteomic analysis of Brucella melitensis and Brucella ovis for identification of virulence factor using bioinformatics approachs.

The genus Brucella includes several genetically monomorphic species but with different phenotypic and virulence characteristics. In this study, proteins of two Brucella species, B. melitensis type strain 16 M and B. ovis REO198 were compared by proteomics approach, in order to explain the phenotypic and pathophysiological differences among Brucella species and correlate them with virulence factors. Protein extracts from the two Brucella species were separated by SDS-PAGE and 5 areas, which resulted qualitatively and quantitatively different, were analyzed by nLC-MS/MS. A total of 880 proteins (274 proteins of B. melitensis and 606 proteins of B. ovis) were identified; their functional and structural features were analyzed by bioinformatics tools. Four unique peptides belonging to 3 proteins for B. ovis and 10 peptides derived from 7 proteins for B. melitensis were chosen for the high amount of predicted B-cell epitopes exposed to the solvent. Among these proteins, outer-membrane immunogenic protein (N8LTS7) and 25 kDa outer-membrane immunogenic protein (Q45321), respectively of B. ovis and B. melitensis, could be interesting candidates for improving diagnostics tests and vaccines. Moreover, 8 and 13 outer and periplasmic non homologue proteins of B. ovis and B. melitensis were identified to screen the phenotypic differences between the two Brucella strains. These proteins will be used to unravel pathogenesis and ameliorate current diagnostic assays.

Crimean-Congo Hemorrhagic Fever Virus Genome in Tick from Migratory Bird, Italy.

We detected Crimean-Congo hemorrhagic fever virus in a Hyalomma rufipes nymph collected from a whinchat (Saxicola rubetra) on the island of Ventotene in April 2017. Partial genome sequences suggest the virus originated in Africa. Detection of the genome of this virus in Italy confirms its potential dispersion through migratory birds.

Metagenomic analysis of bacterial community in a travertine depositing hot spring.

Several factors influence bacteria biodiversity in hot springs. The impact of biotic and abiotic pathways on travertine deposition plays a key role in microbial ecology and in the final composition of the waterborne microbiota. The metabolism of some bacterial groups such as photoautotrophs or lithoautotrophs influences water chemistry, favoring carbonate precipitation processes. The role of microbial mats in mineral precipitation processes is not fully clarified. For the first time, a comprehensive metagenomic analysis has been undertaken in the historical Bullicame hot spring. Bacterial biodiversity was characterized and biomineralization activities were assigned to different genera. A higher biodiversity in mat samples compared to water samples was observed: Shannon index of 3.34 and 0.86, respectively. Based on the functional assignment of each Operational Taxonomic Unit, the bacteria involved in biologically- induced mineralization are prevalent in mat and released in the water. According to the principle that each geothermal water specimen has distinctive physic-chemical characteristics, our results suggest new interacting bio-actions within these ecosystems. The saturation index and the chemical composition, as the high concentration of sulfur species and HCO3, can be linked to create a selective environment where pioneer communities are able to live and shape the ecosystem.

Outbreak of unusual Salmonella enterica serovar Typhimurium monophasic variant 1,4 [5],12:i:-, Italy, June 2013 to September 2014.

Monophasic variant of Salmonella enterica subspecies enterica serovar Typhimurium (monophasic S. Typhimurium), with antigenic structure 1,4,[5],12:i:-, appears to be of increasing importance in Europe. In Italy, monophasic S. Typhimurium represented the third most frequent Salmonella serovar isolated from human cases between 2004 and 2008. From June 2013 to October 2014, a total of 206 human cases of salmonellosis were identified in Abruzzo region (Central Italy). Obtained clinical isolates characterised showed S. Typhimurium 1,4,[5],12:i:- with sole resistance to nalidixic acid, which had never been observed in Italy in monophasic S. Typhimurium, neither in humans nor in animals or foods. Epidemiological, microbiological and environmental investigations were conducted to try to identify the outbreak source. Cases were interviewed using a standardised questionnaire and microbiological tests were performed on human as well as environmental samples, including samples from fruit and vegetables, pigs, and surface water. Investigation results did not identify the final vehicle of human infection, although a link between the human cases and the contamination of irrigation water channels was suggested.

Rat mir-155 generated from the lncRNA Bic is 'hidden' in the alternate genomic assembly and reveals the existence of novel mammalian miRNAs and clusters.

MicroRNAs (miRNAs) are a class of small noncoding RNAs acting as post-transcriptional gene expression regulators in many physiological and pathological conditions. During the last few years, many novel mammalian miRNAs have been predicted experimentally with bioinformatics approaches and validated by next-generation sequencing. Although these strategies have prompted the discovery of several miRNAs, the total number of these genes still seems larger. Here, by exploiting the species conservation of human, mouse, and rat hairpin miRNAs, we discovered a novel rat microRNA, mir-155. We found that mature miR-155 is overexpressed in rat spleen myeloid cells treated with LPS, similarly to humans and mice. Rat mir-155 is annotated only on the alternate genome, suggesting the presence of other "hidden" miRNAs on this assembly. Therefore, we comprehensively extended the homology search also to mice and humans, finally validating 34 novel mammalian miRNAs (two in humans, five in mice, and up to 27 in rats). Surprisingly, 15 of these novel miRNAs (one for mice and 14 for rats) were found only on the alternate and not on the reference genomic assembly. To date, our findings indicate that the choice of genomic assembly, when mapping small RNA reads, is an important option that should be carefully considered, at least for these animal models. Finally, the discovery of these novel mammalian miRNA genes may contribute to a better understanding of already acquired experimental data, thereby paving the way to still unexplored investigations and to unraveling the function of miRNAs in disease models.

Orione, a web-based framework for NGS analysis in microbiology.

UNLABELLED: End-to-end next-generation sequencing microbiology data analysis requires a diversity of tools covering bacterial resequencing, de novo assembly, scaffolding, bacterial RNA-Seq, gene annotation and metagenomics. However, the construction of computational pipelines that use different software packages is difficult owing to a lack of interoperability, reproducibility and transparency. To overcome these limitations we present Orione, a Galaxy-based framework consisting of publicly available research software and specifically designed pipelines to build complex, reproducible workflows for next-generation sequencing microbiology data analysis. Enabling microbiology researchers to conduct their own custom analysis and data manipulation without software installation or programming, Orione provides new opportunities for data-intensive computational analyses in microbiology and metagenomics. AVAILABILITY AND IMPLEMENTATION: Orione is available online at http://orione.crs4.it.

Characterization of a Novel Species of Legionella Isolated from a Healthcare Facility: Legionella resiliens sp. nov.

Two Legionella-like isolates, 8cVS16T and 9fVS26, were isolated from a water distribution system (WDS) in a healthcare facility. Cells were Gram- and Ziehl Neelsen-stain-negative, rod-shaped, motile, and exhibited a blue-white fluorescence under Wood's lamp at 365 nm. The strains grew in a range of 32-37 °C on BCYE with L-cysteine (Cys+), GVPC, and MWY agar medium, with a positive reaction for oxidase, catalase, and gelatinase. The dominant fatty acids were summed features 3 (C16:1ω7c/C16:1ω6c) (27.7%), C16:0 iso (17.5%), and C16:0 (16.3%), and Q13 as the major ubiquinone. The mip and rpoB gene sequences showed a similarity of 96.7% and 92.4%, with L. anisa (ATCC 35292T). The whole genomes sequencing (WGS) performed displayed a GC content of 38.21 mol% for both. The digital DNA-DNA hybridization (dDDH) analysis demonstrated the separation of the two strains from the phylogenetically most related L. anisa (ATCC 35292T), with ≤43% DNA-DNA relatedness. The Average Nucleotide Identity (ANI) between the two strains and L. anisa (ATCC 35292T) was 90.74%, confirming that the two isolates represent a novel species of the genus Legionella. The name proposed for this species is Legionella resiliens sp. nov., with 8cVS16T (=DSM 114356T = CCUG 76627T) as the type strain.

Biophysical characterization of the cetacean morbillivirus haemagglutinin glycoprotein.

Cetacean morbillivirus (CeMV) is an enveloped, non-segmented, negative-stranded RNA virus that infects marine mammals, spreading across species and causing lethal disease outbreaks worldwide. Among the eight proteins encoded by the CeMV genome, the haemagglutinin (H) glycoprotein is responsible for the virus attachment to host cell receptors. CeMV H represents an attractive target for antiviral and diagnostic research, yet the elucidation of the molecular mechanisms underlying its role in infection and inter-species transmission was hampered thus far due to the unavailability of recombinant versions of the protein. Here we present the cloning, expression and purification of a recombinant CeMV H ectodomain (rH-ecto), providing an initial characterization of its biophysical and structural properties. Sodium dodecyl sulphate - polyacrylamide gel electrophoresis (PAGE) combined to Western blot analysis and periodic acid Schiff assay showed that CeMV rH-ecto is purifiable at homogeneity from insect cells as a secreted, soluble and glycosylated protein. Miniaturized differential scanning fluorimetry, Blue Native PAGE and size exclusion chromatography coupled to multiangle light scattering revealed that CeMV rH-ecto is globularly folded, thermally stable and exists in solution in the oligomeric states of dimer and multiple of dimers. Furthermore, negative stain electron microscopy single particle analysis allowed us to delineate a low-resolution molecular architecture of the CeMV rH-ecto dimer, which recapitulates native assemblies from other morbilliviral H proteins, such as those from measles virus and canine distemper virus. This set of experiments by orthogonal techniques validates the CeMV rH-ecto as an experimental model for future biochemical studies on its structure and functions.

Phenotypic and genotypic antimicrobial resistance correlation and plasmid characterization in Salmonella spp. isolates from Italy reveal high heterogeneity among serovars.

Introduction: The spread of antimicrobial resistance among zoonotic pathogens such as Salmonella is a serious health threat, and mobile genetic elements (MGEs) carrying antimicrobial resistance genes favor this phenomenon. In this work, phenotypic antimicrobial resistance to commonly used antimicrobials was studied, and the antimicrobial resistance genes (ARGs) and plasmid replicons associated with the resistances were determined. Methods: Eighty-eight Italian Salmonella enterica strains (n = 88), from human, animal and food sources, isolated between 2009 and 2019, were selected to represent serovars with different frequency of isolation in human cases of salmonellosis. The presence of plasmid replicons was also investigated. Results and discussion: Resistances to sulphonamides (23.9%), ciprofloxacin (27.3%), ampicillin (29.5%), and tetracycline (32.9%) were the most found phenotypes. ARGs identified in the genomes correlated with the phenotypical results, with blaTEM-1B, sul1, sul2, tetA and tetB genes being frequently identified. Point mutations in gyrA and parC genes were also detected, in addition to many different aminoglycoside-modifying genes, which, however, did not cause phenotypic resistance to aminoglycosides. Many genomes presented plasmid replicons, however, only a limited number of ARGs were predicted to be located on the contigs carrying these replicons. As an expectation of this, multiple ARGs were identified on contigs with IncQ1 plasmid replicon in strains belonging to the monophasic variant of Salmonella Typhimurium. In general, high variability in ARGs and plasmid replicons content was observed among isolates, highlighting a high level of heterogeneity in Salmonella enterica. Irrespective of the serovar., many of the ARGs, especially those associated with critically and highly important antimicrobials for human medicine were located together with plasmid replicons, thus favoring their successful dissemination.