Daptomycin In Vitro Activity against Methicillin-Resistant Staphylococcus aureus Is Enhanced by d-Cycloserine in a Mechanism Associated with a Decrease in Cell Surface Charge.

The killing activity of daptomycin against an isogenic pair of daptomycin-susceptible and daptomycin-nonsusceptible (DNS) methicillin-resistant Staphylococcus aureus (MRSA) strains was enhanced by the addition of certain cell wall agents at 1× MIC. However, when high inocula of the DNS strain were used, no significant killing was observed in our experiments. Cytochrome c binding assays revealed d-cycloserine as the only agent associated with a reduction in the cell surface charge for both strains at the concentrations used.

Utility of peptide nucleic acid fluorescence in situ hybridization for rapid detection of Acinetobacter spp. and Pseudomonas aeruginosa.

The utility of peptide nucleic acid fluorescence in situ hybridization (PNA FISH) for the detection of Acinetobacter spp. and Pseudomonas aeruginosa was evaluated on broth suspensions and spiked blood cultures of ATCC strains and clinical isolates with select gram-negative rods. After testing 60 clinical isolates, PNA FISH had a sensitivity and specificity of 100% and 100%, respectively, for Acinetobacter spp. and 100% and 95%, respectively, for P. aeruginosa. PNA FISH was able to detect both pathogens simultaneously and directly from spiked blood cultures.

Functional, molecular and proteomic characterisation of bone marrow mesenchymal stem cells in rheumatoid arthritis.

OBJECTIVE: Bone marrow (BM) mesenchymal stem cells (MSCs) are being considered as potential therapeutic agents in various inflammatory autoimmune diseases for their tissue-repair and anti-inflammatory tissue-protective properties. This study investigates the reserves and function, the molecular and proteomic profile and the differentiation potential of BM MSCs in patients with active rheumatoid arthritis (RA). METHODS: We evaluated the frequency of MSCs in the BM mononuclear cell fraction using a limiting dilution assay, the proliferative/clonogenic potential and the capacity of cells to differentiate towards the osteogenic/chondrogenic/adipogenic lineages using appropriate culture conditions. We also assessed the molecular and proteomic characteristics in terms of inflammatory cytokine gene and protein expression, the relative telomere length and the survival characteristics of BM MSCs. RESULTS: MSCs from patients with RA (n = 26) and age- and sex-matched healthy individuals (n = 21) were similar in frequency, differentiation potential, survival, immunophenotypic characteristics, and protein profile. Patient MSCs, however, had impaired clonogenic and proliferative potential in association with premature telomere length loss. Transcriptome analysis revealed differential expression of genes related to cell adhesion processes and cell cycle progression beyond the G1 phase. Previous treatment with methotrexate, corticosteroids, anti-cytokine and biological agents or other disease-modifying anti-inflammatory drugs did not correlate with the clonogenic and proliferative impairment of BM MSCs. CONCLUSION: In spite of some restrictions related to the impaired clonogenic and proliferative potential, our findings support the use of autologous BM MSCs in RA and may have important implications for the ongoing efforts to repair tissue injury commonly seen in the course of the disease.

An improved method for the diagnostic approach of alpha+-thalassaemia.

An improved method for the diagnostic approach of alpha(+)-thalassaemia is described. The method is based on five common parameters: absence of iron deficiency, mild morphological abnormalities of erythrocytes, normal or slightly reduced erythrocytic indices MCV and MCH, normal chromatographic findings, and presence of haemoglobin H inclusions in erythrocytes with methyl-violet stain after, but not before, incubation with oxidant agent. We studied by DNA analysis, 58 subjects fulfilling the above mentioned diagnostic criteria and we found that 50 of them (86.2%) had a alpha-globin gene defect. In the remaining eight subjects (13.8%) no alpha-gene defect could be documented with the techniques used in the DNA analysis, which detect the six well-known alpha(+)-thalassaemic defects in the Greek population. We conclude that the improved method, we described has a high sensitivity and accuracy in the screening of alpha(+)-thalassaemia.

Changes in maternal plasma levels of VEGF, bFGF, TGF-beta1, ET-1 and sKL during uncomplicated pregnancy, hypertensive pregnancy and gestational diabetes.

BACKGROUND: Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factor-beta1 (TGF-beta1), endothelin-1 (ET-1) and soluble c-kit ligand (sKL) are cytokines involved in embryogenesis. MATERIALS AND METHODS: Maternal plasma cytokines were measured with ELISA during the three trimesters of gestation and on the day of delivery in 93 pregnant women and 18 age-matched non-pregnant control women. RESULTS: The VEGF and bFGF levels increased during the first trimester and declined thereafter, but they remained above the controls' values until delivery. The TGF-beta1 levels increased during the first trimester and remained unchanged thereafter. On the contrary, the ET-1 levels decreased and remained low until delivery. VEGF, bFGF, TGF-beta1 and ET-1 were increased in hypertensive pregnancy. Except for ET-1, these cytokines were also increased in gestational diabetes. No changes in plasma sKL were documented. CONCLUSION: All the aforementioned cytokines play a role in uncomplicated pregnancy, whereas hypertensive pregnancy is causatively-related with increased ET-1.

Antimicrobial agents for treatment of serious infections caused by resistant Staphylococcus aureus and enterococci.

As clinicians increasingly contend with infections due to staphylococci or enterococci resistant to, or failing treatment with, traditional antimicrobial agents, understanding the potential roles of older as well as more recently introduced antimicrobial agents becomes important. Older agents, such as clindamycin and trimethoprim-sulfamethoxazole, have been used to treat infections due to community-acquired methicillin-resistant Staphylococcus aureus. Among the licensed agents, quinupristin-dalfopristin, linezolid, daptomycin, and tigecycline are active in vitro against most strains of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium, but these agents differ in their approved clinical indications. New agents currently under investigation may further expand treatment options.

Normal bone marrow hematopoietic stem cell reserves and normal stromal cell function support the use of autologous stem cell transplantation in patients with multiple sclerosis.

Bone marrow (BM) stem cell reserves and function and stromal cell hematopoiesis supporting capacity were evaluated in 15 patients with multiple sclerosis (MS) and 61 normal controls using flow cytometry, clonogenic assays, long-term BM cultures (LTBMCs) and enzyme-linked immunosorbent assays. MS patients displayed normal CD34+ cell numbers but a low frequency of colony-forming cells (CFCs) in both BM mononuclear and purified CD34+ cell fractions, compared to controls. Patients had increased proportions of activated BM CD3+/HLA-DR+ and CD3+/CD38+ T cells that correlated inversely with CFC numbers. Patient BM CD3+ T cells inhibited colony formation by normal CD34+ cells and patient CFC numbers increased significantly following immunomagnetic removal of T cells from BMMCs, suggesting that activated T cells may be involved in the defective clonogenic potential of hematopoietic progenitors. Patient BM stromal cells displayed normal hematopoiesis supporting capacity indicated by the CFC number in the nonadherent cell fraction of LTBMCs recharged with normal CD34+ cells. Culture supernatants displayed normal stromal derived factor-1 and stem cell factor/kit ligand but increased flt-3 ligand levels. These findings provide support for the use of autologous stem cell transplantation in MS patients. The low clonogenic potential of BM hematopoietic progenitors probably reflects the presence of activated T cells rather than an intrinsic defect.

In vitro activity of an oral streptogramin antimicrobial, XRP2868, against gram-positive bacteria.

The comparative in vitro potency of XRP2868, a new oral semisynthetic streptogramin antibiotic, was evaluated against gram-positive bacteria. XRP2868 inhibited all staphylococci at < or = 1 microg/ml and all non-pneumococcal streptococci at < or = 0.25 microg/ml and was fourfold more potent than quinupristin-dalfopristin against Staphylococcus aureus and Enterococcus faecium.

Activated T-lymphocytes with myelosuppressive properties in patients with chronic idiopathic neutropenia.

To characterize the cellular components responsible for the impaired granulopoiesis in chronic idiopathic neutropenia (CIN), we investigated the origin of the proapoptotic cytokine producing cells in the bone marrow (BM) microenvironment of CIN patients. We found that the interferon gamma (IFN gamma) and/or Fas-ligand expressing cells in patient BM mononuclear cells and long-term BM culture stroma cells were the CD3(+) T-lymphocytes but not the CD14(+) monocytes/macrophages. The percentage of activated T-lymphocytes was increased in patients' BM as indicated by the proportions of human leucocyte antigen (HLA)-DR(+), CD25(+), CD38(+), CD69(+) and Fas(+) cells within the CD3(+) fraction. Intracellular IFN gamma expression was higher in the BM than peripheral blood of the patients and was associated with increased BM T-lymphocyte numbers. In crossover experiments, patient CD3(+) T-lymphocytes conferred autologous and allogeneic haemopoietic progenitor cell colony inhibition. Patients' T-cell receptor repertoire and polymerase chain reaction analysis did not reveal any clonal T-lymphocyte expansion, suggesting the absence of a direct, antigen-driven recognition of CD34(+) myeloid progenitor cells by patient T-lymphocytes. We conclude that CIN patients have increased number of activated T-lymphocytes in the BM, probably in the setting of a localized polyclonal immune reaction and that these cells confer an inhibitory effect on myelopoiesis through myelosuppressive cytokines including Fas-ligand and IFN gamma.

Safety and efficacy of glycopeptide antibiotics.

It would be difficult to envision the practice of infectious diseases over the past 20 years without the availability of the glycopeptide antibiotics. The two agents currently in clinical use, vancomycin and teicoplanin, have proven remarkably versatile in many common applications. Several attributes of these agents account for this favourable profile: (i) their broad spectrum of activity against Gram-positive bacteria, including strains resistant to many other antimicrobials; (ii) their favourable pharmacokinetic properties that allow the once- or twice-daily dosing regimens that have made out-of-hospital therapy possible; and (iii) their generally good safety profiles which, along with their structural dissimilarity to beta-lactam and other antimicrobials, permits their use in many patients who are intolerant of other antibiotic regimens. It is not entirely surprising, therefore, that despite more than 40 years of clinical use and the interim appearance of bacterial strains resistant to this drug class, there remains continued interest in the development of newer members of the glycopeptide antibiotic class. This paper is intended to provide a global overview of the efficacy and safety of glycopeptide antibiotics currently in use, as background to understanding the need for and potential roles of new agents of this class.

Acute myeloid/NK precursor cell leukemia with trisomy 4 and a novel point mutation in the extracellular domain of the G-CSF receptor in a patient with chronic idiopathic neutropenia.

Chronic idiopathic neutropenia (CIN) has been well recognized as a granulocytic disorder not associated with increased risk to malignant transformation. Four cases, however, of acute myeloid leukemia have been recently reported in patients with CIN. In the current paper, we report on a CIN patient who developed acute myeloid/natural killer (NK) precursor cell leukemia 11 years after diagnosis and 4 months after initiation of treatment with recombinant human granulocyte colony-stimulating factor (rhG-CSF). Leukemic cells had trisomy 4 as the sole cytogenetic abnormality and, also, a novel point mutation in the extracellular domain of the G-CSF receptor (G-CSFR) leading to truncated protein with a loss of 36 amino acids. There was no evidence that this receptor transmitted signals even in the presence of high doses of rhG-CSF in the cultures. We consider that CIN may be a preleukemic condition, at least in a subset of patients, and that rhG-CSF administration is unlikely to be involved in the leukemic transformation in this patient, although such a possibility could not be completely ruled out.

Increased cell apoptosis in bone marrow trephine biopsies and immunomagnetically isolated myeloid progenitor cells in patients with chronic idiopathic neutropenia.

The frequency of apoptotic cells in bone marrow trephine biopsies and cytospins of immunomagnetically isolated myeloid progenitor cells was determined in 39 patients with chronic idiopathic neutropenia (CIN) and 12 hematologically normal individuals using the in situ end-labeling (ISEL) apoptosis detection method. We found that 66.7% of the patients but none of the normal controls displayed apoptotic cells equal to or higher than 5% of the total mononuclear cells in bone marrow biopsies (p<0.01). In the double stain, we also found that the proportion of apoptotic CD15(+) myeloid precursor cells did not differ significantly between patients and control subjects, while the proportion of apoptotic CD34(+) hemopoietic cells could not be estimated with accuracy because of the presence of CD34(+) endothelial cells. Significantly increased apoptosis was noted in cytospins of immunomagnetically isolated patient CD34(+) and CD34(+)/CD33(+) cells but not CD34(-)/CD33(+) cells, compared to the controls ( p<0.001, p<0.02 and p>0.05, respectively). These findings confirm and extend our previous observations in flow-cytometric studies of apoptosis in CIN, indicating that increased apoptosis in CIN bone marrow concerns mainly the CD34(+) and CD34(+)/CD33(+) progenitor cell compartments. We conclude that the accelerated apoptosis in these compartments may account for the impaired neutrophil production in CIN patients.

Complete regression of primary gastric plasmacytoma following Helicobacter pylori eradication.

We describe the first case of a primary gastric plasmacytoma stage I completely regressed following Helicobacter pylori (H.pylori) eradication. The patient, a 61-year-old man, had a long history of chronic gastritis and gastric ulcers with recurrent gastrointestinal hemorrhage. Diagnosis of H.pylori infection was based on the positive urease breath test, the elevated titers of serum anti- H.pylori antibodies, and the detection of the bacterium in gastric mucosa biopsy specimens. Diagnosis of gastric plasmacytoma was based on the findings of histopathology, immunocytochemistry and in situ hybridization. Eradication of H.pylori with antibiotics was followed by disappearance of endoscopic and histopathologic features of the gastric tumor 3 months after the completion of the treatment. No relapse has been documented 20 months after the initial diagnosis of plasmacytoma. A possible causal relationship between the tumor and the underlying H.pylori infection is discussed.

Non-Hodgkin's lymphoma in patients with systemic lupus erythematosus.

Two cases of non-Hodgkin's lymphoma (NHL) associated with systemic lupus erythematosus (SLE) are described. Patient-1 was a 65-year-old woman in whom SLE and diffuse large B-cell lymphoma were concurrently diagnosed. The patient presented with low-grade fever, butterfly rash, arthritis and generalized lymphadenopathy without splenomegaly or bone marrow involvement. Complete remission of NHL and SLE was achieved with cyclophosphamide, adriamycin, vincristine and prednisone. Patient-2 was a 56-year-old woman in whom SLE had been diagnosed 14 years earlier. The patient presented with low-grade fever, bulky splenomegaly without lymphadenopathy, IgMA paraproteinemia, and expansion of a monoclonal CD19+/CD22+ lambda-type B-cell population in both bone marrow and peripheral blood. Diagnosis of a lympho-plasmacytoid lymphoma was established histologically after splenectomy. A partial remission of the neoplasm was achieved with cyclophosphamide, vincristine and prednisone. We suggest that the development of NHLs in patients with SLE may not be coincidental and we recommend the search for NHL in cases of SLE with prominent lymphadenopathy, massive splenomegaly or expansion of a monoclonal CD19+/CD22+ B-cell population.

In vitro activity of the new oxazolidinone AZD2563 against Enterococci.

The activity of a new oxazolidinone antimicrobial, AZD2563, was assessed against >500 clinical isolates of enterococci representing six species. All isolates, including those resistant to other antibiotic classes, were inhibited by AZD2563 at concentrations

Prevalence of the fsr locus in Enterococcus faecalis infections.

The fsr locus of Enterococcus faecalis confers virulence in animal models. A retrospective analysis of fsr prevalence in diverse E. faecalis clinical isolates demonstrated fsr in all endocarditis isolates versus 53% of stool isolates (P = 0.005). This supports a role for fsr-mediated virulence in the pathogenesis of enterococcal infections in humans.

Antimicrobial activity of quinupristin-dalfopristin combined with other antibiotics against vancomycin-resistant enterococci.

Interactions between quinupristin-dalfopristin and six other antimicrobials were examined by checkerboard arrays against 50 clinical isolates of vancomycin-resistant Enterococcus faecium selected to represent a range of susceptibilities to individual agents. Unequivocal synergistic or antagonistic interactions at clinically relevant concentrations were infrequently encountered when the streptogramin was combined with chloramphenicol, ampicillin, imipenem, vancomycin, or teicoplanin. Combinations with doxycycline resulted in synergistic inhibition in 36% of checkerboards. Against 10 strains of Enterococcus faecalis, synergistic interactions were found when quinupristin-dalfopristin was combined with doxycycline (four strains), either glycopeptide (three strains), or ampicillin (two strains). Combination with quinupristin-dalfopristin increased the ampicillin MIC from 1 to 4 microg/ml for one strain. For 10 strains of E. faecium, interactions were also assessed by time-kill methods using concentrations of the agents attainable in human serum. Most of these antimicrobials augmented killing by quinupristin-dalfopristin to a minor degree. Against 2 of the 12 strains in this collection that were not highly resistant to gentamicin, the combination of quinupristin-dalfopristin (2 microg/ml) plus gentamicin (5 microg/ml) resulted in killing approaching 3 log(10) CFU/ml. With the exception of doxycycline, inhibitory interactions between quinupristin-dalfopristin and other agents tested against vancomycin-resistant strains of E. faecium were uncommon at clinically relevant concentrations.

Molecular characterization of vancomycin-resistant Enterococci repopulating the gastrointestinal tract following treatment with a novel glycolipodepsipeptide, ramoplanin.

We characterized baseline and repopulating stool isolates recovered during a phase II trial of ramoplanin for the treatment of patients with stool carriage of vancomycin-resistant enterococci (VRE). Repopulation with a strain with a related genotype was found in 74, 60, and 53% of individuals in groups treated with placebo, 100 mg of ramoplanin, and 400 mg of ramoplanin, respectively. All ramoplanin-treated patients with a culture positive for VRE at day 7 had a relapse caused by a genotypically related isolate. In ramoplanin-treated patients, antibiotics with activities against anaerobic organisms were associated with positive cultures on day 7 (relative risk [RR] = 8.8; P = 0.004), and the avoidance of such antibiotics was significantly associated with culture negativity through day 21 (RR = 0.16; P = 0.02).