Low colonization prevalence of Staphylococcus aureus with reduced vancomycin susceptibility among patients undergoing hemodialysis in the San Francisco Bay area.

BACKGROUND: Staphylococcus aureus exhibits varying degrees of reduced vancomycin susceptibility, and strains with intermediate levels of resistance are thought to emerge by antibiotic selection of subpopulations in heterogeneously resistant precursor strains exposed to this antibiotic. We sought to determine the prevalence of and risk factors for carriage of potential heterogeneous vancomycin-intermediate S. aureus (hVISA). METHODS: We prospectively observed a cohort of 211 patients undergoing hemodialysis and performed quarterly surveillance cultures for up to 2 years. We screened for reduced vancomycin susceptibility using brain-heart infusion agar with 4 microg/mL vancomycin. RESULTS: We identified 10 colonizing potential hVISA isolates recovered from 7 patients among both methicillin-susceptible and methicillin-resistant S. aureus strains. No confirmed hVISA isolates were identified; we can be 95% certain that the prevalence of confirmed hVISA carriage does not exceed 1.4%. When compared with noncolonized hemodialysis patients, neither vancomycin exposure, duration of hospitalization, nor any baseline clinical or demographic factor was found to predict colonization with potential hVISA on univariate analyses; increased number of months receiving hemodialysis was associated with potential hVISA colonization on multivariate analysis. CONCLUSIONS: Despite numerous published reports of S. aureus with reduced vancomycin susceptibility, carriage of these isolates remains a rare phenomenon. Given the unclear clinical significance of potential hVISA, it is not clear whether clinical laboratories should identify such strains, or how they should do so.

Association of dietary protein intake and microalbuminuria in healthy adults: Third National Health and Nutrition Examination Survey.

BACKGROUND: The relationship between dietary protein intake (DPI) and microalbuminuria (MA) is unclear. We investigated whether DPI was associated with urinary albumin level in a population sample of persons with normal kidney function. METHODS: We addressed this question in adults aged 20 to 80 years from the Third National Health and Nutrition Examination Survey (n = 12,422). DPI was assessed from a 24-hour dietary recall and quantified as percentage of total energy intake. MA is defined as urinary albumin-creatinine ratio 30 mg/g (3 mg/mmol) or greater. RESULTS: In multivariable logistic regression models adjusted for sociodemographic characteristics and coronary heart disease risk factors, DPI was not associated with MA in normotensive or nondiabetic persons. In crude models, odds ratios (ORs) for MA were 1.9 (95% confidence interval, 1.2 to 3.0) in persons with hypertension (n = 3,433) and 2.4 (95% confidence interval, 1.1 to 5.2) in those with diabetes (n = 1,165) in the highest (>19%) versus lowest (<11.7%) quintile of DPI. However, in models adjusted for the concurrent prevalence of diabetes or hypertension, this association attenuated to nonsignificance. Persons in the highest quintile of DPI who had both hypertension and diabetes (n = 634) had a significantly elevated OR for MA (3.3; 95% confidence interval, 1.4 to 7.8) compared with those in the lowest quintile. CONCLUSION: DPI is not associated with MA in healthy persons or those with isolated hypertension or diabetes. However, in persons with both conditions, high DPI is associated with increased prevalence of MA. These findings suggest the need for further research on weight-loss strategies for high-risk persons.

A comparison of dual dialyzers in parallel and series to improve urea clearance in large hemodialysis patients.

BACKGROUND: Dialysis adequacy targets frequently are difficult to achieve in large hemodialysis patients. Dual dialyzers can be used to improve clearance. It is unknown whether series or parallel configurations are superior. METHODS: Eighteen large hemodialysis patients (mean weight, 92.4 kg) were enrolled in a randomized, crossover trial to directly compare dual dialyzers in parallel and series configurations. Treatment times, blood flow rates, and dialysate flow rates were kept constant. RESULTS: Compared with a single dialyzer, parallel dual dialyzers increased the single-pool Kt/V (spKt/V) from 1.25 +/- 0.22 to 1.43 +/- 0.29 (P < 0.003). Series dual dialyzers improved urea clearance measured by spKt/V (spKt/V(urea)) to 1.46 +/- 0.26 (P < 0.0003 compared with a single dialyzer). Kt/V and urea reduction ratio of dual dialyzers in parallel were not significantly different from those of dual dialyzers in series. Half the subjects failed to meet the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative recommended adequacy target for spKt/V(urea) of 1.2 or less using a single dialyzer. With the use of dual dialyzers, 83% of subjects achieved this adequacy target. Serum levels of a middle molecule, beta2-microglobulin, were reduced 34% after 2 months of dual-dialyzer therapy. Cost analysis estimates annual net savings of 1,260 dollars with dual-dialyzer therapy, primarily from projected savings in inpatient expenses. CONCLUSION: In large hemodialysis patients, our study shows that dual dialyzers in parallel and series are equally effective at improving urea clearance without prolonging dialysis treatment times.

Associations of serologic markers of infection and inflammation with vascular disease events and mortality in American dialysis patients.

BACKGROUND: Inflammatory markers predict cardiovascular risk and mortality in endstage renal disease. The relationship of chronic infections to inflammation and vascular disease events has not been reported among American dialysis patients. METHODS: We performed a cross-sectional and prospective study of a multiracial cohort of 97 chronic hemodialysis patients in California. Anti-Chlamydia pneumoniae IgA and IgG antibodies (Cp-IgA and Cp-IgG), anti-Helicobacter pylori antibodies (Hp-IgG), and highly sensitive C-reactive protein (hsCRP) levels were measured at enrollment. We ascertained the prevalence of atherosclerotic vascular (coronary artery, cerebrovascular, and peripheral vascular) disease (AVD) events, and observed participants for at least 1 year for incident events and mortality. We defined statistical significance as P < 0.01. RESULTS: Elevated hsCRP levels (77%) and seropositivity to C. pneumoniae were common (Cp-IgA, 49%; Cp-IgG, 64%), whereas the seroprevalence of Hp-IgG was relatively low (25%). The hsCRP levels did not vary with infection status. In bivariate analysis, Cp-IgA and Cp-IgG were each associated with approximately fourfold higher odds of prevalent AVD (P < 0.01). Although anti-chlamydial antibodies maintained nearly significant associations with AVD after covariate adjustment (P < 0.05), antibodies did not predict outcomes over the period of observation. However, hsCRP was a nearly significant independent predictor of prevalent AVD (P = 0.02) and of mortality during follow-up (P = 0.01). We did not detect an association of Hp-IgG with any study outcome. CONCLUSIONS: Our findings generalize a possible link between C. pneumoniae and prevalent atherosclerosis in American hemodialysis patients and confirm the importance of hsCRP as a prognostic indicator. Our work does not support H. pylori as an important mediator of cardiovascular risk in dialysis patients.

New insights into protein intake and progression of renal disease.

PURPOSE OF REVIEW: For several decades, dietary protein restriction has been considered as a strategy to slow renal disease progression. Recently, a National Kidney Foundation advisory board incorporated recommendations for supervised low-protein diets into guidelines for the care of non-dialyzed patients with chronic kidney failure. Despite this consensus statement, the clinical utility of dietary modification remains controversial. This article reviews new investigations of protein intake as a mediator of renal function and physiology published since 1 October 2002. RECENT FINDINGS: Population-level data indicate graded risk for progressive renal functional decline with increasing protein intake among women with mild renal insufficiency, and support a possible association of higher protein consumption with the risk of microalbuminuria in people with concomitant diabetes and hypertension. A link between the quantity of protein intake and the rate of renal deterioration is suggested by preliminary prospective studies among incident peritoneal dialysis patients, renal transplant recipients, and animal models of kidney disease. Varied renal consequences based on protein composition were reported in population-based studies, animal-model experiments, and animal studies of in-utero protein exposure. Clinical trial experience raises concern for the feasibility of dietary interventions in practice. SUMMARY: New research supports the view that high-protein diets accelerate renal disease progression, suggests differential consequences based on protein source, and explores risk among defined sub-populations. Topics for future exploration include the renal impact of high-protein weight-loss regimens, implications of dietary protein quantity and type across the stages of chronic kidney disease, and translation of animal studies of prenatal nutrition to humans.

Randomized trial of folic acid for prevention of cardiovascular events in end-stage renal disease.

High serum total homocysteine (tHcy) is gaining scrutiny as a risk factor for cardiovascular disease in the general population. The relationship between tHcy and mortality and cardiovascular events in patients with end-stage renal disease (ESRD) is unsettled. This randomized trial evaluates the efficacy of high-dose folic acid in preventing events in ESRD. A total of 510 patients on chronic dialysis were randomized to 1, 5, or 15 mg of folic acid contained in a renal multivitamin with a median follow-up of 24 mo. Mortality, cardiovascular events, and homocysteine levels were assessed. There were 189 deaths, and 121 patients experienced at least one cardiovascular event. Composite rates of mortality and cardiovascular events among the folic acid groups did not differ (at 24 mo: 43.7% in 1 mg group, 38.6% in 5 mg group, 47.1% in 15 mg group; log-rank P = 0.47). Unexpectedly, high baseline tHcy was associated with lower event rates. From lowest to highest quartile, event rates at 24 mo were 54.5% for Q1, 41.8% for Q2, 41.2% for Q3, and 34.7% for Q4 (log-rank P = 0.033). In contrast to some studies describing tHcy as a risk factor for mortality and cardiovascular events, this study found a reverse relationship between tHcy and events in ESRD patients. Administration of high-dose folic acid did not affect event rates.