IS26 mediated antimicrobial resistance gene shuffling from the chromosome to a mosaic conjugative FII plasmid.

In the present study we report the identification of a sul3-associated class 1 integron containing the dfrA12-orfF-aadA2-cmlA1-aadA1-qacH array embedded in a Tn21-derived element that is part of a conjugative FII plasmid named pST1007-1A. The plasmid was identified in the Salmonella Typhimurium strain ST1007, a member of a clinically relevant clonal MDR lineage diffuse in Italy. ST1007 exhibited resistance to ampicillin, chloramphenicol, streptomycin, sulphamethoxazole, tetracycline and trimethoprim encoded by blaTEM-1, cmlA1, (aadA1, aadA2, strAB), (sul2, sul3), tet(B) and dfrA12 genes, respectively. Apart from pST1007-1A, ST1007 also harbours two chromosome-integrated resistance units RU1 (blaTEM-1-sul2-strAB) and RU2 (tet(B)), flanked by IS26 elements. RU1 and RU2 were able to move as translocatable units, respectively TU1 and TU2, and integrate via IS26 mediated recombination into pST1007-1A. A family of conjugative plasmids, harbouring different sets of antimicrobial resistance genes (ARG) was then generated: pST1007-1B (dfrA12-aadA2-cmlA1-aadA1-sul3- tet(B)), pST1007-1C (dfrA12-aadA2-cmlA1-aadA1-sul3-blaTEM-1-sul2-strAB), pST1007-1D (blaTEM-1-sul2-strAB), pST1007-1E (tet(B)) and pST1007-1F (dfrA12-aadA2-cmlA1-aadA1-sul3- tet(B) -blaTEM-1-sul2-strAB). pST1007-1A is also a mosaic plasmid containing two distinct DNA fragments acquired from I1 plasmids through recombination within the repA4, rfsF and repeat-3 sites. This study further highlights the role played by IS26 in intracellular ARGs shuffling. Moreover, attention has been focused on recombination hot spots that might play a key role in generating mosaic plasmids.

A novel group of IncQ1 plasmids conferring multidrug resistance.

The IncQ is a group of non-conjugative but mobilisable plasmids that are found and stably maintained in a wide range of bacteria contributing to the spread of antimicrobial resistance genes and to the insurgence of multidrug resistant bacteria. Here we report the identification, in clinical Salmonella Typhimurium strains, of an IncQ1 plasmid (pNUC) which confers resistance to sulfamethoxazole, streptomycin and tetracycline through the presence of sul2, strAB and tetA genes, respectively. pNUC was detected in five multidrug resistant S. Typhimurium strains collected in Southern Italy from various hospitals and years of isolation. Bioinformatics analyses highlighted the presence of pNUC-like plasmids in pathogenic bacteria of various Enterobacteriaceae genera or species. Taken as a whole, these plasmids constitute a novel group of IncQ1 plasmids that might have originated through recombination events between a tetR-tetA gene cluster (possibly derived from a Tn1721) and a recipient IncQ1 plasmid related to RSF1010. Our findings raise concerns regarding the possible contribution of the newly identified group of IncQ1 plasmids to the spread of tetracycline resistance.

Transcriptomic analysis of nickel exposure in Sphingobium sp. ba1 cells using RNA-seq.

Nickel acts as cofactor for a number of enzymes of many bacteria species. Its homeostasis is ensured by proteins working as ion efflux or accumulation systems. These mechanisms are also generally adopted to counteract life-threatening high extra-cellular Ni2+ concentrations. Little is known regarding nickel tolerance in the genus Sphingobium. We studied the response of the novel Sphingobium sp. ba1 strain, able to adapt to high Ni2+ concentrations. Differential gene expression in cells cultured in 10 mM Ni2+, investigated by RNA-seq analysis, identified 118 differentially expressed genes. Among the 90 up-regulated genes, a cluster including genes coding for nickel and other metal ion efflux systems (similar to either cnrCBA, nccCBA or cznABC) and for a NreB-like permease was found. Comparative analyses among thirty genomes of Sphingobium species show that this cluster is conserved only in two cases, while in the other genomes it is partially present or even absent. The differential expression of genes encoding proteins which could also work as Ni2+-accumulators (HupE/UreJ-like protein, NreA and components of TonB-associated transport and copper-homeostasis systems) was also detected. The identification of Sphingobium sp. ba1 strain adaptive mechanisms to nickel ions, can foster its possible use for biodegradation of poly-aromatic compounds in metal-rich environments.

Diversity and temporal patterns of planktonic protist assemblages at a Mediterranean Long Term Ecological Research site.

We tracked temporal changes in protist diversity at the Long Term Ecological Research (LTER) station MareChiara in the Gulf of Naples (Mediterranean Sea) on eight dates in 2011 using a metabarcoding approach. Illumina analysis of the V4 and V9 fragments of the 18S rDNA produced 869 522 and 1 410 071 sequences resulting in 6517 and 6519 OTUs, respectively. Marked compositional variations were recorded across the year, with less than 2% of OTUs shared among all samples and similar patterns for the two marker tags. Alveolata, Stramenopiles and Rhizaria were the most represented groups. A comparison with light microscopy data indicated an over-representation of Dinophyta in the sequence dataset, whereas Bacillariophyta showed comparable taxonomic patterns between sequence and light microscopy data. Shannon diversity values were stable from February to September, increasing thereafter with a peak in December. Community variance was mainly explained by seasonality (as temperature), trophic status (as chlorophyll a), and influence of coastal waters (as salinity). Overall, the background knowledge of the system provided a sound context for the result interpretation, showing that LTER sites provide an ideal setting for high-throughput sequencing (HTS) metabarcoding characterisation of protist assemblages and their relationships with environmental variations.

Soluble intercellular adhesion molecule-1 in serum and cerebrospinal fluid of clinically active relapsing-remitting multiple sclerosis: correlation with Gd-DTPA magnetic resonance imaging-enhancement and cerebrospinal fluid findings.

We measured soluble intercellular adhesion molecule-1 (sICAM-1) in the serum and cerebrospinal fluid (CSF) of 35 clinically active relapsing-remitting (RR) multiple sclerosis (MS) patients who underwent both lumbar puncture and gadopentetate dimeglumine (Gd-DTPA)-enhanced MRI within an interval of 1 week, and of 30 neurological controls of whom 17 had noninflammatory neurologic diseases (NIND), 8 bacterial meningitis (BM), and 5 AIDS dementia complex (ADC). Thirteen of the MS patients assumed corticosteroids at the time of the study. While sICAM-1 serum levels were highest in the BM group (p < 0.005), untreated MS patients showed levels higher (p < 0.05) than treated MS and NIND, but similar to ADC. Moreover, the untreated MS group had CSF/serum sICAM-1:CSF/serum albumin (sICAM-1 index) values higher than the treated group (p < 0.01), NIND (p < 0.005), and BM (p < 0.05); high sICAM-1 index was found also in ADC. Untreated MS patients with one or more Gd-DTPA-enhancing MRI lesions (Gd-positive) had higher mean values of CSF/serum albumin ratio (QAlbumin) and CSF mononuclear cells compared to patients without such lesions (Gd-negative). In the untreated Gd-negative patients, sICAM-1 serum levels were higher (p < 0.05) than those in Gd-positive patients. In the latter group, there were positive correlations between the number of CSF mononuclear cells and both IgG (p < 0.01) and sICAM-1 indices (p < 0.05), between QAlbumin and QsICAM-1 (p < 0.005) and between Qalbumin and the Expanded Disability Status Scale score (p = 0.05). There were no significant correlations in the Gd-negative group. These results suggest that sICAM-1 index can be a better marker of intrathecal sICAM-1 synthesis than CSF levels and provide additional insights, in vivo, into the blood-brain barrier mechanisms underlying MRI Gd-enhancement in clinically active RR MS.

Blood-brain barrier changes in multiple sclerosis.

We review the salient published data suggesting blood-brain barrier (BBB) damage in multiple sclerosis (MS). We focus attention specifically on: 1) the cerebral microvessel involvement in demyelination plaques, 2) the presence of dynamic changes in BBB permeability depending on the phase of the disease course, 3) the primary role of cerebral endothelial cells in the development of the intracerebral immune response.

[Usefulness of a standardized method for collecting anamnestic data in multiple sclerosis (MS)]. / Utilità di un metodo standardizzato per la raccolta dei dati anamnestici nella sclerosi multipla (SM).

In order to improve the collection of historical data and the evaluation of the clinical course of the disease in MS patients, a standard questionnaire was structured using precise criteria for definition of the disease phase, type of course and symptoms, respectively. A preliminary validation resulted in significant inter- and intra-observer agreement on all collected historical data and definition of lesion localization. Such structured interviews, included in day-to-day clinical care as well as in computerized databases for MS, could improve the possibility of collecting data shareable between different studies and centers.

Multivariate analysis of predictive factors of multiple sclerosis course with a validated method to assess clinical events.

The clinical data of 309 patients with definite multiple sclerosis were recorded in the European data base for multiple sclerosis (EDMUS) to determine the prognostic significance of several demographic and clinical variables. An interview with closed questions structured according to standardised criteria of disease phases and courses was used to assess the clinical course. The reliability was evaluated by four trained neurologists in a sample of 33 patients with multiple sclerosis. Both the within and between rater agreement on data collection was fair to high for the historical variables (K = 0.33-1). Between rater agreement was more variable for the evaluation of 12 different EDMUS event categories (K = 0.3-0.95). The predictive model for the time to reach a secondary progression showed that an age at onset older than 25 (p = 0.006) and an event at onset followed by disability > or = 3 on the Kurtzke expanded disability status scale (EDSS; p = 0.004) were the most unfavourable clinical variables in 249 patients with relapsing remitting (180) or relapsing progressive (69) courses. In the 69 patients with relapsing progressive disease, the time to reach severe disability (EDSS > or = 6) was negatively influenced by a first interval between attacks shorter than one year, a number of bouts with EDSS > 2 in the first two years of the disease, and involvement of the pyramidal system at onset (p < 0.05). In 60 patients with chronic progressive disease this outcome was negatively influenced by pyramidal, brainstem, and sensory involvement at onset (p < 0.01).