D-Serine inhibits the attachment and biofilm formation of methicillin-resistant Staphylococcus aureus.

INTRODUCTION: Although therapeutic agents for methicillin-resistant Staphylococcus aureus (MRSA) are clinically available, MRSA infection is still a life-threatening disease. Bacterial attachment and biofilm formation contribute significantly to the initiation of MRSA infection. Controlling MRSA's attachment and biofilm formation might reduce the frequency of MRSA infection. According to recent data, some amino acids can reduce MRSA's attachment on plates; however, their precise inhibitory mechanisms remain unclear. Therefore, we explored the effect of the amino acids on bacterial adhesion and biofilm formation in vitro and in vivo MRSA infection models. METHODS: We tested the inhibitory effect of amino acids on MRSA and Escherichia coli (E. coli) in the attachment assay. Moreover, we evaluated the therapeutic potential of amino acids on the in vivo catheter infection model. RESULTS: Among the amino acids, D-Serine (D-Ser) was found to reduce MRSA's ability to attach on plate assay. The proliferation of MRSA was not affected by the addition of D-Ser; thus, D-Ser likely only played a role in preventing attachment and biofilm formation. Then, we analyzed the expression of genes related to attachment and biofilm formation. D-Ser was found to reduce the expressions of AgrA, SarS, IcaA, DltD, and SdrD. Moreover, the polyvinyl chloride catheters treated with D-Ser had fewer MRSA colonies. D-Ser treatment also reduced the severity of infection in the catheter-induced peritonitis model. Moreover, D-Ser reduced the attachment ability of E. coli. CONCLUSION: D-Ser inhibits the attachment and biofilm formation of MRSA by reducing the expression of the related genes. Also, the administration of D-Ser reduces the severity of catheter infection in the mouse model. Therefore, D-Ser may be a promising therapeutic option for MRSA as well as E. coli infection.

Renal prognoses by different target hemoglobin levels achieved by epoetin beta pegol dosing to chronic kidney disease patients with hyporesponsive anemia to erythropoiesis-stimulating agent: a multicenter open-label randomized controlled study.

BACKGROUND: There is no evidence regarding appropriate target hemoglobin levels in chronic kidney disease (CKD) patients with an erythropoiesis-stimulating agent (ESA)-hyporesponsiveness. Therefore, we conducted a randomized controlled study in non-dialysis dependent CKD (NDD-CKD) patients with ESA-hyporesponsiveness, comparing results of intensive versus conservative treatment to maintain hemoglobin levels. METHODS: This was a multicenter, open-label, randomized, parallel-group study conducted at 89 institutions. Among NDD-CKD patients, those with ESA-hyporesponsive renal anemia were randomly assigned to an intensive treatment group, to which epoetin beta pegol was administered with target hemoglobin level of 11 g/dL or higher, or conservative treatment group, in which the hemoglobin levels at enrollment (within ± 1 g/dL) were maintained. The primary endpoint was the time to the first kidney composite event defined as (1) transition to renal replacement therapy (dialysis or renal transplantation); (2) reduction of estimated glomerular filtration rate (eGFR) to less than 6.0 mL/min/1.73 m2; or (3) reduction of eGFR by 30% or more. Secondary endpoints were kidney function (change rate in eGFR), cardiovascular (CV) events, and safety. RESULTS: Between August 2012 and December 2015, 385 patients were registered, and 362 patients who met the eligibility criteria were enrolled. There was no significant difference in kidney survival or in CV events between the two groups. However, the incidences of the 3 types of kidney composite events tended to differ. CONCLUSIONS: In NDD-CKD patients with ESA-hyporesponsive renal anemia, the aggressive administration of ESA did not clearly extend kidney survival or result in a significant difference in the incidence of CV events.

[Trends for the etiology of infective endocarditis at our hospital these 5 years].

The aim of this study is to evaluate characteristics of infective endocarditis for 5 years at Kanazawa University Hospital. Retrospectively, we investigated 39 patients diagnosed as infective endocarditis at our hospital from 2006 to 2010 based on blood culture and/or rejected cardiac specimens. Of 39 patients with infective endocarditis, 27 were male and 12 were female. Mean age was 55.4 years and 69% patients were older than 50 years. The frequent underlying presumed diseases were cardiac diseases. Vegetation was mainly observed at mitral valve and aortic valve. Streptococcus species [14 cases (36%)] and Staphylococcus species [12 cases (31%)] were common pathogens. In Streptococcus species, the critical cause was mostly presumed to be associated with dental procedure and oral cavity. In Staphylococcus species, intravascular device and soft tissue infection were also frequently presumed. Frequency of chronic kidney disease and infection around valve were higher in Staphylococcus species than those observed in Streptococcus species [12 cases (100%) vs. 7 cases (50%); p < 0.05, 6 cases (50%) vs. 1 case (7%); p < 0.05]. Our results suggested that the etiology of patients with Staphylococcus species infection increased in number among patients suffering from infective endocarditis at our hospital.

Biocompatibility and permeability of dialyzer membranes do not affect anemia, erythropoietin dosage or mortality in japanese patients on chronic non-reuse hemodialysis: a prospective cohort study from the J-DOPPS II study.

BACKGROUND: Considerable controversy exists over the impact of the biocompatibility and flux characteristics of dialyzer membranes on anemia in chronic hemodialysis patients. METHODS: A subset of 1,207 subjects from the Japanese arm of DOPPS phase II was analyzed. RESULTS: Patient characteristics included mean age 59 years, male sex 60%, BMI 20.6, time on dialysis therapy 7.8 years, and diabetes rate 27%. Dialysis parameters were Kt/V 1.33, and normalized protein catabolic rate 1.05 g/kg/day. Initial hemoglobin level was 10.1 g/dl. 79% were treated by intravenous erythropoietin with mean weekly doses of 4,500 IU. Hemoglobin levels and erythropoietin doses during 2-year study period were not affected by dialysis membrane biocompatibility (unmodified cellulose or biocompatible) or flux (standard or high performance). The 2-year survival rate was 90.9% and was influenced by older age, presence of cardiovascular diseases and amyloidosis, lower levels of BMI and serum albumin, but not by other variables, including dialysis membranes. Use of biocompatible membranes was associated with a lower all-cause mortality (8.3 vs. 13.0% for bioincompatible, p = 0.037), but this difference was not significant in multivariate analyses (hazard ratio 0.70, p = 0.17 by Cox multivariate analysis). CONCLUSION: The biocompatibility and permeability of dialyzer membranes had no effect on anemia, erythropoietin dosage or all-cause mortality in Japanese chronic hemodialysis patients treated by non-reuse dialysis.