Advances in uremic toxin detection and monitoring in the management of chronic kidney disease progression to end-stage renal disease

Patients with end-stage kidney disease (ESKD) rely on dialysis to remove toxins and stay alive. However, hemodialysis alone is insufficient to completely remove all/major uremic toxins, resulting in the accumulation of specific toxins over time. The complexity of uremic toxins and their varying clearance rates across different dialysis modalities poses significant challenges, and innovative approaches such as microfluidics, biomarker discovery, and point-of-care testing are being investigated. This review explores recent advances in the qualitative and quantitative analysis of uremic toxins and highlights the use of innovative methods, particularly label-mediated and label-free surface-enhanced Raman spectroscopy, primarily for qualitative detection. The ability to analyze uremic toxins can optimize hemodialysis settings for more efficient toxin removal. Integration of multiple omics disciplines will also help identify biomarkers and understand the pathogenesis of ESKD, provide deeper understanding of uremic toxin profiling, and offer insights for improving hemodialysis programs. This review also highlights the importance of early detection and improved understanding of chronic kidney disease to improve patient outcomes.

Peritoneal effluent MicroRNA profile for detection of encapsulating peritoneal sclerosis

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a catastrophic complication of peritoneal dialysis (PD) with high mortality. Our aim is to develop a novel noninvasive microRNA (miRNA) test for EPS.

METHODS

We collected 142 PD effluents (EPS: 62 and non-EPS:80). MiRNA profiles of PD effluents were examined by a high-throughput real-time polymerase chain reaction (PCR) array to first screen. Candidate miRNAs were verified by single real-time PCR. The model for EPS prediction was evaluated by multiple logistic regression and machine learning.

RESULTS

Seven candidate miRNAs were identified from the screening of PCR-array of 377 miRNAs. The top five area under the curve (AUC) values with 5 miRNA-ratios were selected using 127 samples (EPS: 56 vs non-EPS: 71) to produce a receiver operating characteristic curve. After considering clinical characteristics and 5 miRNA-ratios, the accuracies of the machine learning model of Random Forest and multiple logistic regression were boosted to AUC 0.97 and 0.99, respectively. Furthermore, the pathway analysis of miRNA associated targeting genes and miRNA-compound interaction network revealed that these five miRNAs played the roles in TGF-β signaling pathway.

CONCLUSION

The model-based miRNA expressions in PD effluents may help determine the probability of EPS and provide further therapeutic opinion for EPS.

Association between Escherichia coli with NotI-restriction resistance and urinary tract infections

BACKGROUND

Escherichia coli is the most common cause of urinary tract infections (UTIs). It is widely accepted that uropathogenic E. coli (UPEC) mainly emerge from the distal gut microbiota. Identification of bacterial characteristics that are able to differentiate UPEC from fecal commensal strains will facilitate the development of novel strategies to detect and monitor the spread of UPEC.

METHODS

Fifty fecal commensal, 83 UTI-associated and 40 biliary tract infection (BTI)-associated E. coli isolates were analyzed. The NotI restriction patterns of chromosomal DNA in the isolates were determined by pulse-field gel electrophoresis. The phylogenetic types and the presence of 9 known virulence genes of each isolate were determined by PCR analyses. Additionally, the susceptibilities of the isolates to antibiotics were revealed. Then the associations of NotI resistance with UTI-associated isolates, phylotypes, and antibiotic resistance were assessed.

RESULTS

NotI resistance was correlated with UTI-associated isolates, compared to the fecal isolates. Consistently, NotI-resistant isolates harbored a greater number of virulence factors and mainly belonged to phylotype B2. Additionally NotI resistance was correlated with chloramphenicol resistance among the bacteria. Among the fecal, UTI-associated and BTI-associated groups, the distribution of NotI-resistant group B2 isolates was correlated with UTI-associated bacteria.

CONCLUSION

NotI resistance alone is a potential marker for distinguishing fecal strains and UPEC, while the combination of NotI resistance and B2 phylogeny is a candidate marker to differentiate UPEC from fecal and other extraintestinal pathogenic E. coli. Additionally, NotI resistance may be valuable for assessing the potential of chloramphenicol resistance of E. coli.

Microfluidic Sliding Paper-Based Device for Point-of-Care Determination of Albumin-to-Creatine Ratio in Human Urine

A novel assay platform consisting of a microfluidic sliding double-track paper-based chip and a hand-held Raspberry Pi detection system is proposed for determining the albumin-to-creatine ratio (ACR) in human urine. It is a clinically important parameter and can be used for the early detection of related diseases, such as renal insufficiency. In the proposed method, the sliding layer of the microchip is applied and the sample diffuses through two parallel filtration channels to the reaction/detection areas of the microchip to complete the detection reaction, which is a simple method well suited for self-diagnosis of ACR index in human urine. The RGB (red, green, and blue) value intensity signals of the reaction complexes in these two reaction zones are analyzed by a Raspberry Pi computer to derive the ACR value (ALB and CRE concentrations). It is shown that the G + B value intensity signal is linearly related to the ALB and CRE concentrations with the correlation coefficients of R2 = 0.9919 and R2 = 0.9923, respectively. It is additionally shown that the ALB and CRE concentration results determined using the proposed method for 23 urine samples were collected from real suffering chronic kidney disease (CKD) patients are in fine agreement with those acquired operating a traditional high-reliability macroscale method. Overall, for point-of-care (POC) CKD diagnosis and monitoring in clinical applications, the results prove that the proposed method offers a convenient, real time, reliable, and low-spending solution for POC CKD diagnosis.

Assessing the quality of electronic medical records as a platform for resident education

BACKGROUND

Previous studies have assessed note quality and the use of electronic medical record (EMR) as a part of medical training. However, a generalized and user-friendly note quality assessment tool is required for quick clinical assessment. We held a medical record writing competition and developed a checklist for assessing the note quality of participants' medical records. Using the checklist, this study aims to explore note quality between residents of different specialties and offer pedagogical implications.

METHODS

The authors created an inpatient checklist that examined fundamental EMR requirements through six note types and twenty items. A total of 149 records created by residents from 32 departments/stations were randomly selected. Seven senior physicians rated the EMRs using a checklist. Medical records were grouped as general medicine, surgery, paediatric, obstetrics and gynaecology, and other departments. The overall and group performances were analysed using analysis of variance (ANOVA).

RESULTS

Overall performance was rated as fair to good. Regarding the six note types, discharge notes (0.81) gained the highest scores, followed by admission notes (0.79), problem list (0.73), overall performance (0.73), progress notes (0.71), and weekly summaries (0.66). Among the five groups, other departments (80.20) had the highest total score, followed by obstetrics and gynaecology (78.02), paediatrics (77.47), general medicine (75.58), and surgery (73.92).

CONCLUSIONS

This study suggested that duplication in medical notes and the documentation abilities of residents affect the quality of medical records in different departments. Further research is required to apply the insights obtained in this study to improve the quality of notes and, thereby, the effectiveness of resident training.

Rapid electrochemical-biosensor microchip platform for determination of microalbuminuria in CKD patients

An electrochemical-biosensor (EC-biosensor) microchip consisting of screen-printed electrodes and a double-layer reagent paper detection zone impregnated with amaranth is proposed for the rapid determination of microalbuminuria (MAU) in human urine samples. Under the action of an applied deposition potential, the amaranth is adsorbed on the electrode surface and the subsequent reaction between the modified surface and the MAU content in the urine sample prompts the formation of an inert layer on the electrode surface. The inert layer impedes the transfer of electrons and hence produces a drop in the response peak current, from which the MAU concentration can then be determined. The measurement results obtained for seven artificial urine samples with known MAU concentrations in the range of 0.1-40 mg/dL show that the measured response peak current is related to the MAU concentration with a determination coefficient of R² = 0.991 in the low concentration range of 0.1-10 mg/dL and R² = 0.996 in the high concentration range of 10-40 mg/dL. Furthermore, the detection results obtained for 82 actual chronic kidney disease (CKD) patients show an excellent agreement (R² = 0.988) with the hospital analysis results. Overall, the results confirm that the proposed detection platform provides a convenient and reliable approach for performing sensitive point-of-care testing (POCT) of the MAU content in human urine samples.

Escherichia coli FimH adhesins act synergistically with PapGII adhesins for enhancing establishment and maintenance of kidney infection

BACKGROUND

FimH adhesin is proposed to enhance Escherichia coli kidney infection by acting with PapGII adhesin, but genetic epidemiology study and animal study have not been widely conducted to confirm this hypothesis.

METHODS

We compared the prevalence of adhesin gene and their coexistent pattern between upper and lower urinary tract infection (UTI) strains. fimH mutant (EC114FM), papGII mutant (EC114PM) and fimH/papGII double mutant (EC114DM) were constructed from a pylonephritogenic strain (EC114). We compared among these strains for the infection ability in bladders and kidneys of female BALB/c mice challenged transurethrally with these bacteria and assessed 1, 3, and 7 days after inoculation.

RESULTS

Strains carrying fimH-only genotype were significantly more prevalent in lower UTI (P < 0.001). Strains carrying the fimH/papGII, but not papGII-only, were significantly associated with upper UTI (P = 0.001). Incidence of kidney infection increased after inoculation with EC114 on days 1 and 3, at both low and high dose, as compared with EC114DM; and the effect was greater than the sum of individual effect of EC114PM and EC114FM. Geometric means of quantitative bacterial counts in the kidneys significantly decreased when challenged with EC114FM on days 3 and 7, EC114PM on day 3 and EC114DM on day 1 after inoculation at high dose, as compared with EC114 (all P < 0.05).

CONCLUSIONS

We confirmed the advantage and synergistic action of FimH and PapGII for E. coli kidney infection and concluded that antagonists against FimH and PapGII adhesin may prevent kidney infection and enable its management.

Blood Pressure and Left Ventricular Hypertrophy in Patients on Different Peritoneal Dialysis Regimens

Objective

To examine the relation between the results of ambulatory 24-hour blood pressure monitoring (ABPM) and left ventricular mass index (LVMI), then to find the independent determinant for left ventricular hypertrophy (LVH) in peritoneal dialysis (PD) patients. Finally, to evaluate the differences in the clinical and cardiovascular characteristics between patients on continuous ambulatory PD (CAPD) and continuous cyclic PD (CCPD).

Design

An open, nonrandomized, cross-sectional study.

Setting

Divisions of nephrology and cardiology in a medical center.

Patients

Thirty-two uremic patients on maintenance PD therapy (22 patients on CAPD, and 10 on CCPD) without anatomical heart disease or history of receiving long-term hemodialysis.

Interventions

Home blood pressure (BP) and office BP were measured using the Korotkoff sound technique by sphygmomanometer. ABPM was employed for continuous measurement of BP. Echocardiography was performed for measurement of cardiac parameters and calculation of LVMI.

Main Outcome Measures

Multivariate logistic regression analysis was performed for independent determinant of LVH in PD patients. The differences in clinical and cardiovascular characteristics between CAPD and CCPD patients were compared.

Results

Simple regression analysis showed positive correlations between LVMI and the duration of hypertension, ambulatory nighttime BP/BP load/BP load > 30%, serum phosphate, calcium–phosphate product, ultrafiltration (UF) volume, and percentage of UF volume during the nighttime. A negative correlation was noted between LVMI and dipping. In multiple regression analysis, the duration of hypertension was the only variable linked to LVMI. In multivariate logistic regression analysis, only ambulatory nighttime systolic BP load > 30% had an independent association with LVH. There were correlations between office/home BP and ambulatory 24-hour BP. In addition, CCPD patients had higher LVMI, UF volume during the nighttime, and percentage of UF volume during the nighttime than those of CAPD patients.

Conclusions

In this study, ambulatory nighttime systolic BP load > 30% had an independent association with LVH. Office and home BP measurements were correlated with ABPM in PD patients. The result that CCPD patients had a higher LVMI than CAPD patients may be due to a relative volume overload during the daytime in CCPD patients.

Serum sclerostin levels are positively related to bone mineral density in peritoneal dialysis patients: a cross-sectional study

Background

Sclerostin, an antagonist of the Wingless-type mouse mammary tumor virus integration site (Wnt) pathway that regulates bone metabolism, is a potential contributor of chronic kidney disease (CKD)–mineral and bone disorder (MBD), which has various forms of presentation, from osteoporosis to vascular calcification. The positive association of sclerostin with bone mineral density (BMD) has been demonstrated in CKD and hemodialysis (HD) patients but not in peritoneal dialysis (PD) patients. This study assessed the association between sclerostin and BMD in PD patients.

Methods

Eighty-nine PD patients were enrolled; their sera were collected for measurement of sclerostin and other CKD–MBD-related markers. BMD was also assessed simultaneously. We examined the relationship between sclerostin and each parameter through Spearman correlation analysis and by comparing group data between patients with above- and below-median sclerostin levels. Univariate and multiple logistic regression models were employed to define the most predictive of sclerostin levels in the above-median category.

Results

Bivariate analysis revealed that sclerostin was correlated with spine BMD (r = 0.271, P = 0.011), spine BMD T-score (r = 0.274, P = 0.010), spine BMD Z-score (r = 0.237, P = 0.027), and intact parathyroid hormone (PTH; r = − 0.357, P < 0.001) after adjustments for age and sex. High BMD, old age, male sex, increased weight and height, diabetes, and high osteocalcin and uric acid levels were observed in patients with high serum sclerostin levels and an inverse relation was noticed between PTH and sclerostin. Univariate logistic regression analysis demonstrated that BMD is positively correlated with above-median sclerostin levels (odds ratio [OR] = 65.61, P = 0.002); the correlation was retained even after multivariate adjustment (OR = 121.5, P = 0.007).

Conclusions

For the first time, this study demonstrated a positive association between serum sclerostin levels and BMD in the PD population.

High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain

Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.

Characterization of CRISPR-Cas Systems in Clinical Klebsiella pneumoniae Isolates Uncovers Its Potential Association With Antibiotic Susceptibility

Prokaryotic CRISPR-Cas systems limit the acquisition of genetic elements and provide immunity against invasive bacteriophage. The characteristics of CRISPR-Cas systems in clinical Klebsiella pneumoniae isolates are still unknown. Here, 97 K. pneumoniae genomes retrieved from the Integrated Microbial Genomes & Microbiomes genome database and 176 clinical isolates obtained from patients with bloodstream (BSI, n = 87) or urinary tract infections (UTI, n = 89) in Taiwan, were used for analysis. Forty out of ninety-seven genomes (41.2%) had CRISPR-Cas systems identified by the combination of CRISPRFinder and cas1 gene sequence alignment. The phylogenetic trees revealed that CRISPR-Cas systems in K. pneumoniae were divided into two types (type I-E, 23; subtype I-E^∗, 17) based on the sequences of Cas1 and Cas3 proteins and their location in the chromosome. The distribution of type I-E and I-E^∗ CRISPR-Cas systems was associated with the multilocus sequence typing and the pulsed-field gel electrophoresis results. Importantly, no CRISPR-Cas system was identified in published genomes of clonal complex 258 isolates (ST11 and ST258), which comprise the largest multi-drug resistant K. pneumoniae clonal group worldwide. PCR with cas-specific primers showed that 30.7% (54/176) of the clinical isolates had a CRISPR-Cas system. Among clinical isolates, more type I-E CRISPR-Cas systems were found in UTI isolates (BSI, 5.7%; UTI, 11.2%), and subtype I-E^∗ CRISPR-Cas systems were dominant in BSI isolates (BSI, 28.7%; UTI, 15.7%) (p = 0.042). Isolates which had subtype I-E^∗ CRISPR-Cas system were more susceptible to ampicillin-sulbactam (p = 0.009), cefazolin (p = 0.016), cefuroxime (p = 0.039), and gentamicin (p = 0.012), compared to the CRISPR-negative isolates. The strains containing subtype I-E^∗ CRISPR-Cas systems had decreased numbers of plasmids, prophage regions, and acquired antibiotic resistance genes in their published genomes. Here, we first revealed subtype I-E^∗ CRISPR-Cas system in K. pneumoniae potentially interfering with the acquisition of phages and plasmids harboring antibiotic resistance determinants, and thus maintained these isolates susceptible to antibiotics.

Clinical and microbiological characteristics of peritoneal dialysis-related peritonitis caused by Escherichia coli in southern Taiwan

Peritonitis is a serious complication and major cause of treatment failure in patients undergoing peritoneal dialysis (PD). Escherichia coli is the major pathogen in extraintestinal Gram-negative infections, including PD-related peritonitis. The outcomes of E. coli peritonitis in PD varied from relatively favorable outcomes to a higher incidence of treatment failure. The aim of this study was to investigate the impact of bacterial virulence and host characteristics on the outcomes of PD-related peritonitis caused by E. coli. From January 2000 to June 2016, a total of 47 episodes of monomicrobial and 10 episodes of polymicrobial E. coli PD-related peritonitis, as well as 89 episodes of monomicrobial Gram-positive (56 Staphylococcus spp. and 33 Streptococcus spp.) PD-related peritonitis cases, were retrospectively enrolled. Clinical features, E. coli bacterial virulence, and outcomes were analyzed. Compared to Streptococcus spp. peritonitis, E. coli peritonitis had a higher peritoneal catheter removal rate (38 versus 12%; P = 0.0115). Compared to the monomicrobial group, patients in polymicrobial group were older and had higher peritoneal catheter removal rate (80 versus 38%; P = 0.0324). Treatment failure of E. coli peritonitis was associated with more polymicrobial peritonitis and immunocompromised comorbidity, longer duration of PD therapy, and more antimicrobial resistance. E. coli isolates with more iron-related genes had higher prevalence of phylogenetic group B2 and papG II, iha, ompT, and usp genes. This study demonstrates the important roles of clinical and bacterial characteristics in the outcomes of monomicrobial and polymicrobial E. coli PD-related peritonitis.

Subdural Hemorrhage in Patients with End-Stage Renal Disease Requiring Dialysis: A Single-Center Study

PURPOSE

Patients with end-stage renal disease (ESRD) have higher risks of subdural hemorrhage (SDH) and subsequent 30-day mortality. However, evidences regarding optimal mode of dialysis therapy during acute management are sparse. We aimed to compare the outcomes of ESRD patients who received continuous peritoneal dialysis (CPD) or extended hemodialysis (EHD) after SDH and determined factors associated with 30-day mortality.

METHODS

We retrospectively reviewed consecutive patients with SDH and ESRD in a medical center. The clinical parameters and outcomes were compared between CPD and EHD groups. Factors associated with 30-day mortality were analyzed.

RESULTS

We reviewed 32 patients, including 22 received EHD, 8 received CPD, and 2 received continuous veno-venous hemodialysis. Neurosurgery was done in 9 (28%) of them. There was no significant difference in baseline parameters and outcomes between EHD and CPD groups. The overall 30-day mortality rate was 19%. Lower Glasgow coma scale (GCS, median [interquartile range]: 10 [7-12] vs. 15 [11-15], p = 0.02) and larger changes in absolute mean arterial pressure (MAP: 26.5 [10.5-46.0] vs. 7.5 [2.0-17.8] mmHg, p = 0.01) during the first dialysis therapy were noted in patients with 30-day mortality. In multivariate analysis, consciousness disturbance at presentation was an independent risk factor for 30-day mortality.

CONCLUSION

Among ESRD patients with SDH, the 30-day mortality rates were similar between EHD and CPD groups. MAP change during dialysis might be an important modifiable risk factor for 30-day mortality, though the effect was not significant in multivariate analysis. Further prospective studies with larger sample size are warranted.

Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi2Se3/yttrium iron garnet heterostructures

Harnessing the spin–momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi₂Se₃/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi₂Se₃ film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi₂Se₃/YIG reveals signatures of the magnetic proximity effect of T_C as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices.

Understanding the effects of topological insulators on magnetization dynamics of adjacent magnetic materials is essential for novel spintronic devices. Here, Fanchiang et al. report thickness dependence of interfacial in-plane magnetic anisotropy and damping enhancement in Bi₂Se₃/yttrium iron garnet (YIG) bilayers, indicating an important role of topological surface states in the magnetization dynamics of YIG.

Incidence and outcomes of encapsulating peritoneal sclerosis (EPS) and factors associated with severe EPS

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication of long-term peritoneal dialysis (PD). However, previous studies reported large variations in its mortality rates that may associate with a different degree of EPS severity. This study reports the incidence and outcomes of EPS and identifies the risk factors associated with severe EPS.

METHODS

We retrospectively analyzed clinical data of EPS patients from 3 medical centers in Taiwan from January 1982 to September 2015, and classified patients as having mild/moderate or severe EPS. Patients with intractable intestinal obstruction/gut-related sepsis that needed surgical intervention or resulted in mortality were in severe EPS group. Follow-up for outcome was through December 31, 2015. Clinical characteristics, peritoneal dialysis (PD)-related parameters, biochemical and imaging results were analyzed and compared between groups.

RESULTS

Fifty-eight of 3202 patients undergoing PD during the study period had EPS (prevalence 1.8%). The incidence of EPS increased for patients on PD for >6-8 years (≤6 yrs. vs. >6-8 yrs., 0.0% vs. 1.8%, p = 0.001). Relative to those on PD for >6-8 years, the risk of EPS significantly increased with PD duration longer than 10 years (>10-12 years vs. >6-8 years: OR: 5.5, 95% CI: 1.7-17.1, p < 0.01). Twenty-three patients fulfilled the criteria for severe EPS. The overall mortality rate of EPS was 35% (20/58), and was 74% (17/23) in the severe EPS group. The average serum levels of C-reactive protein (CRP) and intact-parathyroid hormone (i-PTH), which were checked every 3~6 months within one year before diagnosis of EPS, were higher in severe EPS group than in mild/moderate group (p = 0.02, p = 0.08, respectively). Multivariate analysis revealed severe EPS was independently associated with bowel tethering (based on CT), presentation with bloody ascites, diagnosis of EPS after withdrawal from PD, and i-PTH ≥ 384 pg/mL. Receiver operating characteristic analysis indicated that presentation with 2 or more of the 5 risk factors (EPS diagnosis after PD withdrawal, bloody ascites, bowel tethering, CRP ≥ 29 mg/L, and i-PTH ≥ 384 pg/mL) had a good accuracy (AUC = 0.80, p = 0.001) for prediction of severe EPS.

CONCLUSIONS

The incidence of EPS increases with PD duration. Severe EPS has high mortality rate and is associated with bowel tethering, presentation of bloody ascites, diagnosis after PD withdrawal, and higher serum levels of i-PTH before EPS diagnosis. Having 2 or more of the 5 risk factors can provide a good accuracy for prediction of severe EPS.

Parathyroidectomy Associates with Reduced Mortality in Taiwanese Dialysis Patients with Hyperparathyroidism: Evidence for the Controversy of Current Guidelines

Parathyroidectomy is recommended by the clinical guidelines for dialysis patients with unremitting secondary hyperparathyroidism (SHPT). However, the survival advantage of parathyroidectomy is debated because of the selection bias in previous studies. To minimize potential bias in the present nationwide cohort study, we enrolled only dialysis patients who had undergone radionuclide parathyroid scanning to ensure all patients had severe SHPT. The parathyroidectomized patients were matched with the controls based on propensity score for parathyroidectomy. Mortality hazard was estimated using multivariate Cox proportional hazard models adjusting for comorbidities before scanning (model 1) or over the whole study period (model 2). Our results showed that among the 2786 enrolled patients, 1707 underwent parathyroidectomy, and the other 1079 were controls. The crude mortality rates were lower in the parathyroidectomized patients than in the controls. In adjusted analyses for the population matched on propensity score, parathyroidectomy was associated with a significant 20% to 25% lower risk for all-cause mortality (model 1: hazard ratio 0.76, 95% confidence interval 0.61 to 0.94; model 2: hazard ratio 0.80, 95% confidence internal 0.64 to 0.98). We concluded that parathyroidectomy was associated with a reduced long-term mortality risk in dialysis patients with severe SHPT.

Compliance Index, a Marker of Peripheral Arterial Stiffness, may Predict Renal Function Decline in Patients with Chronic Kidney Disease

BACKGROUND

Compliance index derived from digital volume pulse (CI-DVP), measuring the relationship between volume and pressure changes in fingertip, is a surrogate marker of peripheral arterial stiffness. This study investigated if CI-DVP can predict renal function deterioration, cardiovascular events and mortality in patients with chronic kidney disease (CKD).

METHODS

In this prospective observational study, 149 CKD patients were included for final analysis. CI-DVP and brachial-ankle pulse wave velocity (baPWV) were measured, decline in renal function was assessed by the estimated glomerular filtration rate (eGFR) slope. Composite renal and cardiovascular outcomes were evaluated, including ≥50% eGFR decline, start of renal replacement therapy, and major adverse events.

RESULTS

Patients in CKD stages 3b to 5 had higher baPWV and lower CI-DVP values than those in patients with CKD stages 1 to 3a. Stepwise multivariate linear regression analysis showed that lower CI-DVP (p =0.0001) and greater proteinuria (p =0.0023) were independent determinants of higher eGFR decline rate. Multivariate Cox regression analysis revealed that CI-DVP (HR 0.68, 95% CI 0.46-1.00), baseline eGFR (HR 0.96, 95% CI 0.94-0.98) and serum albumin (HR 0.17, 95% CI 0.07-0.42) were independent predictors for composite renal and cardiovascular outcomes.

CONCLUSIONS

Compliance index, CI-DVP, was significantly associated with renal function decline in patients with CKD. A higher CI-DVP may have independent prognostic value in slower renal function decline and better composite renal and cardiovascular outcomes in CKD patients.

The prognostic value of left ventricular global peak systolic longitudinal strain in chronic peritoneal dialysis patients

Background

Although left ventricular (LV) global systolic longitudinal strain (GLS) reliably and accurately assesses LV systolic function and is also a powerful prognostic predictor, the importance and prognostic value of GLS in end-stage renal disease patients receiving maintenance peritoneal dialysis (PD) remain unclear. This study sought to determine the prognostic value of GLS in chronic PD patients.

Methods

This prospective study collected clinical and echocardiographic data from 106 stable PD patients (50.0 ± 13.9 years, 45% male) in a dialysis unit of a university hospital. These patients were enrolled from April 2010 to June 2010 and followed until August 2013 (follow-up duration 30.3 ± 14.3 months). The primary outcomes were the presence of major adverse events (MAEs), defined as all-cause mortality, and major adverse cardiovascular cerebral events (MACCEs), i.e. cardiovascular death, cardiac hospitalization, and stroke.

Results

Twenty-nine patients (27%) reported a primary outcome. Patients with MAEs had worse LV systolic function (MAEs vs. no MAEs, − 14.8 ± 2.8 vs. − 17.1 ± 2.5%, p = 0.003). Using multivariate Cox regression analyses, being male, having a history of heart failure, diabetes mellitus, an increased pulse pressure (≥ 60 mm Hg), and GLS ≥ − 15% were independent predictors of MAEs. The independent risk factors of MACCEs were a history of diabetes mellitus, an increased pulse pressure, and GLS ≥ − 15%. After comparison of the overall log likelihood χ² of the predictive power, GLS was found to add prognostic information to a model based on traditional risk factors.

Conclusion

GLS ≥ − 15% provided additional prognostic information that allowed for the early identification of high-risk PD patients.

The complex interplay among bacterial motility and virulence factors in different Escherichia coli infections

Motility mediated by the flagella of Escherichia coli is important for the bacteria to move toward host cells. Here, we present the relationship among bacterial motility, virulence factors, antimicrobial susceptibility, and types of infection. A total of 231 clinical E. coli isolates from different infections were collected and analyzed. Higher-motility strains (motility diameter ≥6.6 mm) were more common in spontaneous bacterial peritonitis (SBP) (SBP 59 %, colonization 32 %, urinary tract infection 16 %, urosepsis 34 %, and biliary tract infection 29 %; p < 0.0001). Compared with the higher-motility group, there was a higher prevalence of afa and ompT genes (p = 0.0160 and p = 0.0497, respectively) in E. coli strains with lower motility. E. coli isolates with higher and lower motility were in different phylogenetic groups (p = 0.018), with a lower prevalence of A and B1 subgroups in higher-motility strains. Also, the patterns of virulence factors and antibiotic susceptibility of E. coli isolates derived from various infections were significantly different. This study demonstrates that the prevalence of higher-motility strains was greater in E. coli isolates from SBP compared to other types of infection. Various types of E. coli infection were associated with differences in bacterial motility, virulence factors, and antibiotic susceptibility. More bacterial virulence factors may be necessary for the development of extraintestinal infections caused by E. coli isolates with lower motility.

Clinical and microbiological characteristics of Klebsiella pneumoniae from community-acquired recurrent urinary tract infections

Understanding the pathogenesis of recurrent urinary tract infection (RUTI) and whether it is attributable to reinfection with a new strain or relapse with the primary infecting strain is of considerable importance. Because previous studies regarding community-acquired Klebsiella pneumoniae RUTI are inconclusive, we undertook this study to evaluate the characteristics of the host and the bacterial agent K. pneumoniae in RUTI. A prospective study was designed, using consecutive patients diagnosed with community-acquired K. pneumoniae-related UTI from January 2007 to December 2009. Of the total 468 consecutive episodes, we found 7 patients with RUTI. All the patients with RUTI were elderly (median, 74 years), with diabetes (100 %, 7 out of 7). Clinical K. pneumoniae isolates derived from the same patients with RUTI revealed identical genomic fingerprints, indicating that K. pneumoniae UTI relapsed despite appropriate antibiotic therapy. The antimicrobial resistance, growth curve and biofilm formation of the recurrent isolates did not change. K. pneumoniae strains causing RUTI had more adhesion and invasiveness than the colonization strains (p < 0.01). When we compared the recurrent strains with the community-acquired UTI strains, the prevalence of diabetes mellitus was significant (100 % vs 53.7 %, p = 0.03) in the RUTI group. Our data suggest that K. pneumoniae strains might be able to persist within the urinary tract despite appropriate antibiotic treatment, and the greater adhesion and invasiveness in the recurrent strains may play an important role in recurrent infections.

Early identification of microorganisms in blood culture prior to the detection of a positive signal in the BACTEC FX system using matrix-assisted laser desorption/ionization-time of flight mass spectrometry

BACKGROUND

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a valuable method for rapid identification of blood stream infection (BSI) pathogens. Integration of MALDI-TOF MS and blood culture system can speed the identification of causative BSI microorganisms.

MATERIALS AND METHODS

We investigated the minimal microorganism concentrations of common BSI pathogens required for positive blood culture using BACTEC FX and for positive identification using MALDI-TOF MS. The time to detection with positive BACTEC FX and minimal incubation time with positive MALDI-TOF MS identification were determined for earlier identification of common BSI pathogens.

RESULTS

The minimal microorganism concentrations required for positive blood culture using BACTEC FX were >10(7)-10(8) colony forming units/mL for most of the BSI pathogens. The minimal microorganism concentrations required for identification using MALDI-TOF MS were > 10(7) colony forming units/mL. Using simulated BSI models, one can obtain enough bacterial concentration from blood culture bottles for successful identification of five common Gram-positive and Gram-negative bacteria using MALDI-TOF MS 1.7-2.3 hours earlier than the usual time to detection in blood culture systems.

CONCLUSION

This study provides an approach to earlier identification of BSI pathogens prior to the detection of a positive signal in the blood culture system using MALDI-TOF MS, compared to current methods. It can speed the time for identification of BSI pathogens and may have benefits of earlier therapy choice and on patient outcome.

Clinical and microbiological characteristics of peritoneal dialysis-related peritonitis caused by Klebsiella pneumoniae in southern Taiwan

BACKGROUND/PURPOSE(S)

Gram-negative peritonitis is a frequent and serious complication of peritoneal dialysis (PD). No previous reports have focused on Klebsiella pneumoniae infection. The aim of this study was to investigate the host and bacterial factors associated with K. pneumoniae PD-related peritonitis.

METHODS

We retrospectively studied K. pneumoniae PD-peritonitis cases treated at a university hospital in southern Taiwan during 1990-2011, and analyzed the clinical features and outcomes and bacterial characteristics of serotypes, hypermucoviscosity (HV), and virulence-associated genes such as wabG, uge, and rmpA in K. pneumoniae PD-related peritonitis. Fifty-four isolates of K. pneumoniae-related community-acquired urinary tract infection (UTI) and 76 morphologically different nonpathogenic K. pneumoniae isolates from healthy adults were used as controls.

RESULTS

K. pneumoniae was the second most common monomicrobial pathogen causing Gram-negative PD-related peritonitis (n = 13, 2.7%), and the most common pathogen involved in polymicrobial peritonitis (16/43, 37.2%) and associated with high catheter removal rate (7/16, 43.8%). Compared with Escherichia coli peritonitis cases, patients with monomicrobial K. pneumoniae peritonitis also had insignificantly higher incidence of sepsis/bacteremia [n = 5 (38%), p = 0.11] and a higher mortality rate [n = 3 (23%), p = 0.36]. The prevalence of K1/K2 (n = 1, 7.7%) serotypes was low, but there was a higher prevalence of serotype K20 (n = 3, 23.1%) in K. pneumoniae isolates derived from monomicrobial PD-related peritonitis compared with control groups. HV phenotype (p < 0.001) and rmpA genotype (p = 0.007) were absent in the peritonitis group.

CONCLUSION

This is the first study focused on clinical and microbiological characteristics of K. pneumoniae PD-related peritonitis. K. pneumoniae was a common Gram-negative pathogen causing monomicrobial and polymicrobial PD-related peritonitis in southern Taiwan. The bacterial characteristics with low percentage of capsular serotype K1/K2, no significant HV, and absence of rmpA suggest a different pathogenesis in K. pneumoniae PD-related peritonitis compared with that in UTI and liver abscess.

Long-term efficacy of miglustat in paediatric patients with Niemann-Pick disease type C

Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease characterized by progressive neurological manifestations. Oral miglustat was first approved for the treatment of children and adults with NP-C in Europe in 2009. There are still relatively few published data on the long-term efficacy and safety of miglustat in patients with NP-C in clinical practice. We report the effects of up to 6 years of treatment with miglustat 100 mg t.i.d. in five children. Overall, 3/5 patients displayed progressive dysphagia before starting miglustat, and 4/5 showed marked cognitive and/or motor impairment. The mean age at treatment start was 11.6 years, and the median (range) duration of therapy so far is 4 (4.1 to 6.1) years. No treatment dose alterations were required, but therapy was interrupted for 1-3 months at least once in all patients due to supply issues. Swallowing function was stabilised during miglustat therapy, with no significant increase in Han dysphagia scale or aspiration-penetration index scores among four evaluable patients (p > 0.05). Scores on the mini-mental state examination indicated an improvement in cognitive function during the first 3-6 months of miglustat therapy, followed by stabilisation up to 5 years. Ambulatory function remained stable for at least the first 2 years of treatment in most patients, but there was a trend towards deterioration thereafter, possibly related to treatment interruptions. The safety/tolerability profile of miglustat was similar to previous clinical studies, although reports of gastrointestinal disturbances were rare. Overall, miglustat appeared to stabilise key parameters of neurological disease progression.

Nonprotein calorie supplement improves adherence to low-protein diet and exerts beneficial responses on renal function in chronic kidney disease

OBJECTIVE

Malnutrition is common in patients with chronic kidney disease (CKD) who are on low-protein diets and is a powerful predictor of morbidity and mortality in CKD. Studies have shown that patients on low-protein diets often have difficulty meeting nutritional energy requirements. Our study evaluated the effects of a nonprotein calorie (NPC) supplement on renal function and nutritional status in patients on a low-protein diet.

DESIGN

This was a prospective, randomized, open-label, controlled clinical trial.

SUBJECTS

A total of 109 patients with CKD (men, 67%; mean age, 54.5 ± 13 years) with stage 3 to 4 disease were randomly assigned to the intervention group (n = 55) or the control group (n = 54).

INTERVENTION

All participants received individualized dietary counseling aimed at achieving a daily protein intake of 0.6 to 0.8 g and a daily energy intake of 30 to 35 kcal/kg. The intervention group consumed a 200-kcal NPC supplement daily. The control group received dietary counseling only.

MAIN OUTCOME MEASURE

The estimated glomerular filtration rate (eGFR) was calculated using the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation. Urine protein excretion, dietary protein and energy intake, and serum levels of creatinine, urea nitrogen, cholesterol, triglycerides, and albumin were assessed at baseline, at 12 weeks, and at 24 weeks.

RESULTS

Dietary protein intake and urine protein excretion levels decreased significantly in the intervention group and were significantly lower than those of the control group. In addition, serum levels of creatinine and urea nitrogen decreased significantly, and eGFR increased significantly in the intervention group compared with baseline assessments. No significant differences were observed in the control group.

CONCLUSIONS

The NPC supplement improved patient adherence to the low-protein diet and reduced urine protein excretion in patients with CKD.

Role of K1 capsule antigen in cirrhotic patients with Escherichia coli spontaneous bacterial peritonitis in southern Taiwan

Spontaneous bacterial peritonitis (SBP) is one of the most serious complications in patients with cirrhosis. This study aimed to investigate the prevalence of SBP caused by Escherichia coli isolates with or without the K1 capsule antigen in cirrhotic patients and the outcome. From January 2004 to January 2012, a total of 54 and 41 E. coli strains derived from patients with SBP and intestinal perforation (IP), respectively, were included for comparison in this study. Bacterial characteristics including phylogenetic groups, K1 capsule antigen, and 14 virulence factor genetic determinants, as well as data regarding patient characteristics, clinical manifestations, and in-hospital deaths, were collected and analyzed. The prevalence of the K1 capsule antigen gene neuA was more common in SBP isolates compared to IP isolates (28 % vs. 10 %, p = 0.0385). Phylogenetic groups B2 and group D were dominant in E. coli isolates with and without the K1 capsule antigen, respectively. The prevalence of virulence factors genes papG II, ompT, and usp was higher in E. coli K1 strains. There were 26 deaths (48 %) during hospitalization. Presence of the K1 capsule antigen in E. coli isolates was significantly associated with in-hospital death in cirrhotic patients with SBP (42 % vs. 14 %, p = 0.0331). This study demonstrates a higher prevalence of the K1 capsule antigen in E. coli SBP compared to E. coli peritonitis caused by IP. There were significant associations between the K1 capsule antigen and in-hospital mortality and bacterial virulence in cirrhotic patients with E. coli SBP.

Bacterial characteristics and glycemic control in diabetic patients with Escherichia coli urinary tract infection

BACKGROUND

Patients with diabetes mellitus have an increased risk of infection. The roles of bacterial characteristics and glycemic control in diabetic patients with Escherichia coli infection have not been well investigated. The aims of this study were to examine the bacterial characteristics and glycemic control in diabetic patients with E. coli infections arising in the urinary tract.

METHODS

A total of 271 E. coli isolates were collected from urine and bloodstream. Phylogenetic groups, the presence of virulence genes, and antimicrobial susceptibility of E. coli isolates were determined.

RESULTS

There were few differences in E. coli bacterial characteristics between 190 diabetic and 81 nondiabetic patients. In diabetic patients with urosepsis, there was a higher hemoglobin A(1C) level, and the related E. coli strains had more neuA, papG II, afa and hlyA genes, and a lower prevalence of antimicrobial resistance to cephalosporins and fluoroquinolones than those with asymptomatic bacteriuria and urinary tract infection. Multivariate logistic regression analysis revealed that increased hemoglobin A(1C) and presence of papG II and afa genes were independent factors associated with development of urosepsis in diabetic patients.

CONCLUSION

This study demonstrated that more virulent E. coli isolates, especially with papG II and afa genes, and poorer glycemic control were important determinants for development of urosepsis in diabetic patients.

Urine analysis in microfluidic devices

Microfluidics has attracted considerable attention since its early development in the 1980s and has experienced rapid growth in the past three decades due to advantages associated with miniaturization, integration and automation. Urine analysis is a common, fast and inexpensive clinical diagnostic tool in health care. In this article, we will be reviewing recent works starting from 2005 to the present for urine analysis using microfluidic devices or systems and to provide in-depth commentary about these techniques. Moreover, commercial strips that are often treated as chips and their readers for urine analysis will also be briefly discussed. We start with an introduction to the physiological significance of various components or measurement standards in urine analysis, followed by a brief introduction to enabling microfluidic technologies. Then, microfluidic devices or systems for sample pretreatments and for sensing urinary macromolecules, micromolecules, as well as multiplexed analysis are reviewed, in this sequence. Moreover, a microfluidic chip for urinary proteome profiling is also discussed, followed by a section discussing commercial products. Finally, the authors' perspectives on microfluidic-based urine analysis are provided. These advancements in microfluidic techniques for urine analysis may improve current routine clinical practices, particularly for point-of-care (POC) applications.

Comparative outcomes between hemo- and peritoneal dialysis patients with acute intracerebral hemorrhage

BACKGROUND/AIMS

The optimal mode of dialysis for end-stage renal disease (ESRD) patients with spontaneous intracerebral hemorrhage (ICH) remains controversial. We compared the outcomes of ESRD patients who received continuous peritoneal dialysis (CPD) or extended hemodialysis (EHD) after ICH, and investigated the factors determining prognosis.

METHODS

We incorporated our ICH patients with ESRD, requiring dialysis from January 2005 to December 2009. Patients were allocated to the CPD or EHD group according to the dialysis mode after ICH. We compared the 30-day mortality rate and modified Rankin Scale (mRS) of the two groups and analyzed the factors associated with mortality.

RESULTS

There were 40 patients with 16 episodes in CPD and 27 episodes in EHD group, without significant differences in baseline demographic data. The 30-day mortality rate and mRS were not different between the two groups. The patients who died within 30 days had higher ICH scores (4 +/- 1 vs. 1 +/- 1, p < 0.001) and outcome scores (5 +/- 2 vs. 1 +/- 1, p < 0.001). Dialysis-related complications occurred more frequently in the PD group (p = 0.07), but were unrelated to mortality.

CONCLUSION

Among ESRD patients with ICH, EHD had a similar 30-day mortality rate and 30-day mRS to those receiving CPD. The mortality was significantly related to the severity of ICH.

PapG II adhesin in the establishment and persistence of Escherichia coli infection in mouse kidneys

Most human pyelonephritogenic Escherichia coli express the PapG II adhesin. However, the role of the PapG II adhesin in enhancing the establishment and persistence of E. coli infection in the kidney is controversial. A pyelonephritogenic strain, EC114, which possesses one copy of the papG II gene, but without other virulence factors (such as S/F1C-fimbriae, hemolysin, and cytotoxic necrotizing factor 1) was selected for the construction of a papG II mutant. The resulting papG II mutant was confirmed by polymerase chain reaction, Southern hybridization, and agglutination assay, and designated as MEC114. We compared MEC114 with the parental strain (EC114) for colonization ability in the bladder and kidney of female BALB/c mice, which were challenged transurethrally with 50 microl of a low (5x10(4) CFU (colony-forming unit)) or high (5x10(8) CFU) dose of EC114 or MEC114 and assessed 1, 3, and 7 days after inoculation. Geometric means of quantitative bacterial counts in the kidney were significantly decreased when challenged with MEC114 on day 3 after inoculation, at both low and high dose (P<0.05), as compared with EC114. On the seventh day, both strains were mainly cleared from the kidney. Renal biopsy showed a similar degree of inflammatory response to both strains 1, 3, and 7 days after inoculation. In brief, the PapG II adhesin can enhance the early establishment of E. coli infection in the kidney, but the bacteria do not maintain infection owing to the host immune response.

Host and bacterial virulence factors predisposing to emphysematous pyelonephritis

BACKGROUND

Emphysematous pyelonephritis (EPN) is a rare, severe, gas-forming infection of the kidney, and its precise pathogenesis remains obscure.

METHODS

To investigate the roles of host and bacterial virulence factors in the pathogenesis of EPN, we compared: (1) host factors in patients with EPN (n = 47) with those in patients with acute renal infections without gas formation (non-EPN; n = 79), (2) the prevalence of virulence gene in causative Escherichia coli strains from 16 of the 47 EPN cases with all 79 non-EPN cases by means of polymerase chain reaction analysis, and (3) gas volumes produced by EPN and non-EPN strains cultured in broths at 3 glucose concentrations (100, 180, and 250 mg/dL [5.6, 10.0, and 13.9 mmol/L]).

RESULTS

Diabetes mellitus (DM) with poor glycemic control (ie, hemoglobin A1c level > 11%) and urinary tract obstruction were more prevalent in the EPN group. However, DM with poor glycemic control was the only host factor independently associated with EPN (odds ratio, 4.9; P = 0.018). EPN strains had a greater prevalence of the uropathogenic-specific protein (usp) genes. Multivariate analyses also showed the association between usp and EPN with borderline significance (odds ratio, 8.4; P = 0.057). There was no significant difference in gas production by E coli isolated from patients with or without EPN.

CONCLUSION

DM with poor glycemic control and urinary tract obstruction are host factors predisposing to EPN. There was no difference in gas production between EPN and non-EPN E coli strains. The distribution of E coli virulence genes was remarkably similar between the 2 groups. However, the PapG II adhesin (papG II) gene is significantly decreased and the usp gene is increased with borderline significance in EPN E coli strains.

A novel application of an anaerobic membrane process in wastewater treatment

The applications of membrane processes in anaerobic biological wastewater treatment still have some limitations due to severe membrane scaling and fouling, although they have been proven to achieve superior COD removal and biomass retention. An innovative anaerobic membrane process for wastewater treatment was conducted to control the membrane scaling problems. The process comprises an anaerobic reactor, an aerobic reactor, and a membrane separation tank. Anaerobic sludge from a full-scale UASB reactor treating food wastewater was inoculated to anaerobic and aerobic reactor to purify synthetic wastewater consisting of glucose and sodium acetate. The anaerobic reactor was operated in a sludge bed type without three-phase separator. The aerobic reactor can eliminate residual organics from the anaerobic reactor effluent using facultative microorganisms. To provide solid-liquid separation, hollow fiber ultrafiltration module was submerged in the separation tank. The results clearly show that the anaerobic membrane process combined methanogenic and aerobic COD reduction is a stable system. No fatal scaling was found after two months of operation even without chemical cleaning for the membrane. It was also found that inorganic precipitates formed in the aerobic reactor were reduced due to CO2 stripping in aerobic reactor. Another important finding was that the inorganic precipitates were entrapped into facultative aerobes floc. The ash/SS ratio of aerobes floc increased from 0.17 to 0.55 after 50 days of operation, which confirms this phenomenon. Based on our investigation, the new process can control scaling effectively to extend the membrane application in anaerobic treatment.

The role of bacterial virulence and host factors in patients with Escherichia coli bacteremia who have acute cholangitis or upper urinary tract infection

We studied the pathogenic role of host and Escherichia coli virulence factors in the development of E. coli bacteremia in patients with acute cholangitis (AC) or upper urinary tract infection (UTI). Isolates recovered from 75 adult patients consecutively admitted to the hospital with E. coli bacteremia caused by AC (n=24) or upper UTI (n=51) were evaluated, as were 30 fecal strains isolated from healthy control individuals. Virulence genes of E. coli were detected by polymerase chain reaction analysis, including papG genes (classes I-III), sfa/foc, fimH, afa, hlyA, cnf1, and iutA. Our results show that biliary tract obstruction and urinary tract obstruction are important host factors for the development of E. coli bacteremia in patients with AC and upper UTI, respectively. With regard to E. coli virulence factors, the papG class II gene might play a more important role in the development of E. coli bacteremia in patients with upper UTI than in those with AC.

Renal cell carcinoma complicated by emphysematous pyelonephritis in a non-diabetic patient with renal failure

A 72-year-old non-diabetic uremic woman underwent right nephrectomy for urolithiasis at the age of 50. Because pyuria, fever, chilliness and left flank pain developed during preparing for arteriovenous fistula, she was admitted to National Cheng Kung University Hospital. Renal cell carcinoma (RCC) complicated with emphysematous pyelonephritis (EPN) was diagnosed and immediately treated with antibiotics and CT-guided percutaneous catheter drainage. Cultures of pus and blood yielded Escherichia coli. She received left radical nephrectomy later for the control of persistent sepsis and removal of left renal tumor. The pathology of the tumor was composed of a glandular arrangement of granular cells with the occasional atypism, and renal parenchyma had been totally replaced by RCC. The non-tumor part of the kidney showed chronic pyelonephritis. Five months later, multiple metastases developed. We reported this first uremic case with EPN and RCC, but without diabetes mellitus and urinary tract obstruction. The gas formation may be due to large RCC, which caused impaired tissue perfusion and E. coli infection.

Roles of host and bacterial virulence factors in the development of upper urinary tract infection caused by Escherichia coli

Aims of this study are to identify host and Escherichia coli virulence factors associated with upper urinary tract infection (UTI) by comparing them with those for lower UTI and determining the association between major predisposing host factors for upper UTI and urovirulence genes for E coli. Host factors and urovirulence genes of E coli associated with bacteremia in patients with upper UTI and their interactions also were studied. One hundred thirty-nine adult patients who fulfilled clinical diagnostic criteria for upper (n = 81) or lower UTI (n = 58) caused by E coli between January 1997 and December 1999 were retrospectively enrolled into this study. Old age (> or =60 years), male sex, diabetes with poor blood glucose control (ie, glycosylated hemoglobin A1C > or = 8.1%), immunosuppression, and urinary tract obstruction were more frequently associated host factors for patients with upper UTI than for those with lower UTI. Using polymerase chain reaction, the papG class II allele was detected more frequently for E coli strains isolated from patients with upper UTI than for those from patients with lower UTI (85% versus 52%; P < 0.0001). Multivariate analysis showed that diabetes with poor blood glucose control, immunosuppression, urinary tract obstruction, and papG class II allele were independently associated with upper UTI. For patients without these three predisposing host factors, the prevalence of papG class II allele was significantly greater in those with upper UTI than those with lower UTI. However, the papG class II allele was less prevalent in strains isolated from patients with upper UTI with urinary tract obstruction or with two of the three predisposing host factors. In addition, both univariate and multivariate analyses showed that old age and papG class II allele were risk factors for the development of E coli bacteremia in patients with upper UTI. In conclusion, both host and E coli virulence factors contribute to the development of upper UTI, and less virulent strains can cause upper UTI in hosts with predisposing factors.

Glycopeptide antibiotic biosynthesis: enzymatic assembly of the dedicated amino acid monomer (S)-3,5-dihydroxyphenylglycine

Four proteins, DpgA-D, required for the biosynthesis by actinomycetes of the nonproteinogenic amino acid monomer (S)-3,5-dihydroxyphenylglycine (Dpg), that is a crosslinking site in the maturation of vancomycin and teicoplanin antibiotic scaffolds, were expressed in Escherichia coli, purified in soluble form, and assayed for enzymatic activity. DpgA is a type III polyketide synthase, converting four molecules of malonyl-CoA to 3,5-dihydroxyphenylacetyl-CoA (DPA-CoA) and three free coenzyme A (CoASH) products. Almost no turnover was observed for DpgA until DpgB was added, producing a net k(cat) of 1-2 min(-1) at a 3:1 ratio of DpgB:DpgA. Addition of DpgD gave a further 2-fold rate increase. DpgC had the unusual catalytic capacity to convert DPA-CoA to 3,5-dihydroxyphenylglyoxylate, which is a transamination away from Dpg. DpgC performed a net CH(2) to C=O four-electron oxidation on the Calpha of DPA-CoA and hydrolyzed the thioester linkage with a k(cat) of 10 min(-1). Phenylacetyl-CoA was also processed, to phenylglyoxylate, but with about 500-fold lower k(cat)/K(M). DpgC showed no activity in anaerobic incubations, suggesting an oxygenase function, but had no detectable bound organic cofactors or metals. A weak enoyl-CoA hydratase activity was detected for both DpgB and DpgD.

Decreased predominance of papG class II allele in Escherichia coli strains isolated from adults with acute pyelonephritis and urinary tract abnormalities

PURPOSE

We compared the genotypes of fimbriae or adhesions of Escherichia coli causing acute pyelonephritis in adults with and without urinary tract abnormalities.

MATERIALS AND METHODS

We studied a total of 92 E. coli strains isolated from 54 patients with acute pyelonephritis and a normal urinary tract, and 38 with urinary tract abnormalities. Of those with urinary tract abnormalities 13 with moderate to severe hydronephrosis were also considered a separate group for the purpose of analysis. The genes of 7 known fimbriae or adhesins of E. coli were detected by the polymerase chain reaction, including the papG class I to III alleles (PapG adhesins of P-fimbriae), sfa/foc (S-/F1C-fimbriae), fimH (type 1 fimbriae), and afa (afimbrial adhesin). Virulence genes associated with APN were identified by comparing the prevalence of each of these 7 genes in E. coli strains from 54 patients with acute pyelonephritis with a normal urinary tract to the prevalence in the strains from 37 patients with acute cystitis using univariate and multivariate analysis. Differences in the prevalence of the genes associated with acute pyelonephritis and the incidence of underlying illness were then compared in the 3 acute pyelonephritis groups.

RESULTS

On univariate and multivariate analysis the papG class II allele was the only virulence gene associated with acute pyelonephritis (p <0.0001 and 0.001, respectively). No significant difference was noted in the prevalence of underlying medical disease in the 3 acute pyelonephritis groups. The papG class II allele was significantly less predominant in E. coli strains isolated from acute pyelonephritis cases with versus without urinary tract abnormalities (76% versus 93%, p = 0.03). The incidence of the papG class II allele in patients with urinary tract abnormalities and moderate to severe hydronephrosis was less than in those without urinary tract abnormalities (69% versus 93%, p = 0.04).

CONCLUSIONS

Our results imply that the papG class II allele has an important role in E. coli infection in patients with acute pyelonephritis and a normal urinary tract, while urinary tract abnormalities and/or obstruction may permit ascending infection of E. coli strains with lower adhesive ability.

Real-time PCR for rapid genotyping of angiotensin-converting enzyme insertion/deletion polymorphism

OBJECTIVE

To develop a real-time PCR technique for detection of the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene.

DESIGN AND METHODS

Three primers were designed for performing real-time PCR in the presence of SYBR Green I as flurochrome followed by melting curve analysis. Forty human genomic DNA that have been genotyped by two-rounds of conventional PCR were used for evaluation of this technique.

RESULTS

Melting curve analysis indicated the melting peak at 73.9 degrees C and 76.2 degrees C corresponding to the presence of I and D alleles, respectively. Comparable genotyping results were obtained by both conventional and real-time PCR. Besides, the mistyping of ID allele individuals by the first run of conventional PCR were accurately genotyped by single-tube real time PCR.

CONCLUSIONS

The real-time PCR method presented in this study provides a rapid and sensitive way for genotyping of ACE gene that may be suitable for large-scale clinical and epidemiologic study.