Epidemiology and control of vancomycin-resistant enterococci (VRE) in a renal unit.

This study reports an outbreak of infection and colonization caused by vancomycin-resistant enterococci (VRE) in the renal service of a large teaching hospital. The polymerase chain reaction and pulsed-field gel electrophoresis were used to study the epidemiology of 26/34 strains of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium from the outbreak in comparison with five strains from other hospitals in Edinburgh and the Borders, and three from other wards in the Royal Infirmary. The study revealed a heterogeneous population of vancomycin-resistant E. faecalis. Over 60% of E. faecium isolates had matching pulsed-field gel electrophoresis patterns and all of these were of VanA phenotype. These results suggest that clonal spread of VanA phenotype E. faecium within and possibly between hospitals is the major vancomycin-resistant enterococcal problem in Edinburgh. Screening of patients and isolation of colonized and infected patients appear to have been successful in controlling the spread of VRE.

Change in nutritional status of patients on peritoneal dialysis.

OBJECTIVE: To document the prevalence of undernutrition/overnutrition in patients on peritoneal dialysis (PD) and to examine whether nutritional status (NS) changes with time on this form of dialysis. DESIGN: Retrospective observational study. Patients had been on PD >2 years. Data included age, gender, diagnosis, peritonitis rate, anthropometry and biochemistry. A classification system for NS was devised using BMI, TSF, MAMC and serum albumin. SETTING: Regional Peritoneal Dialysis Programme, University Teaching Hospital. PATIENTS: 82 patients were on PD on March 1994. A cohort of 28 patients remained on PD after 2 years and complete nutritional data was available for 23 of these patients (9 male, 14 female: mean age 58yrs). RESULTS: 65% of patients were classified as having an acceptable NS at the start of PD and 56% were classified as acceptable at the latest assessment. The prevalence of mild/moderate undernutrition both at the start of PD and at the latest assessment was 26% (different patients at each assessment). No patients were classified as severely undernourished. The prevalence of overnutrition at the start of PD was 9% and at the latest assessment was 17%. There was no statistically significant difference in NS between diabetics and non-diabetics nor between male and female patients although undernutrition was more frequently observed in males. Overnutrition increased with time in both genders but this did not reach statistical significance. There was no difference in initial NS between those who remained on PD and those who died. Change in NS was not related to peritonitis rate. CONCLUSION: Whereas this study has insufficient statistical power to avoid a Type II error it supports our clinical observation that NS does not substantially change with time in this population. There are, however, a small number of individuals who exhibit changes in NS. Given the difficulty in predicting change in NS with time, regular nutritional assessment is important to identify those who require more intensive dietetic intervention.

Recombinant erythropoietin improves cognitive function in patients maintained on chronic ambulatory peritoneal dialysis.

Psychometric performance was studied in 17 patients maintained on CAPD. Nine patients treated with rHuEpo performed a battery of psychometric tests before treatment (haemoglobin mean (SD) 6.8 (0.8) g/dl) and after partial correction of anaemia (haemoglobin 9.0 (1.0) g/dl). The same battery of psychometric tests was administered to eight patients (haemoglobin 7.7 (0.7) g/dl), matched with the treatment group for age, duration of dialysis and social class, who did not receive rHuEpo. The National Adult Reading Test was used in all patients to estimate the premorbid IQ (the peak cognitive level attained before any cognitive deterioration). In the rHuEpo-treated group current IQ, measured by a short form of the Wechsler Adult Intelligence Scale--Revised, improved by a mean of 7.2 points (P < 0.01) and approached estimated premorbid levels, while in the control group an improvement by 0.3 points was not significant. Concentration and speed of information processing were assessed by the Paced Auditory Serial Addition Task and also improved in the treatment group (P < 0.05). Memory, assessed by the Rey Auditory Verbal Learning Test, tended to improve in the treatment group with amelioration of anaemia, although only the improvement in delayed recall was significant. No overall change was seen in either group in the time taken to complete the Trail Making Test (part A). These results are consistent with our earlier findings in haemodialysis patients, indicating that anaemia makes a reversible contribution to uraemic cognitive dysfunction.

Furosemide disposition in patients on CAPD.

Single doses of oral and intravenous furosemide were given to 8 healthy male volunteers (40 mg) and 11 patients with renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD) (80 mg). In the volunteers, absorption was variable. Only one half of the intravenous dose and one third of the oral dose was available for renal pharmacological action as judged by the urinary recovery. In the patients, absorption was also variable and was markedly delayed (tmax 128 vs 90 min) but more complete (bioavailability 70.1 vs 53.6%). The differences between the two groups were not significant, however (95% C.I.: -90 to 30 and -40.4 to 7.5 respectively). The mean elimination half-life was significantly longer in the patients following both the oral (228 vs 65.1 min) and intravenous dose (195 vs 60.3 min). The total body clearance of furosemide in the volunteers was 138 ml x min(-1) and this was much lower in the CAPD patients (61.9 ml x min(-1)) in whom the renal clearance was negligible. Although there were trends indicating differences in absorption between the two groups, the significant differences in furosemide disposition observed in CAPD patients were due to renal failure.

The disposition of paracetamol and its conjugates during multiple dosing in patients with end-stage renal failure maintained on haemodialysis.

The disposition of oral paracetamol (1.0 g 3 times daily for 10 days) was studied in 6 patients with end-stage renal failure (creatinine clearance < 5 ml x min-1) maintained on haemodialysis 2 or 3 times per week. Blood was sampled daily for 10 days. The time of sampling depended on whether the patients were dialysed in the morning or afternoon but was always within 5 h of the last dose of paracetamol. On dialysis days samples were taken at the start of the session. The mean plasma concentration of paracetamol was 6.8 mg x l-1 after the first 24 h and subsequently varied little throughout the 10 days. Apparent steady-state plasma concentrations of 60.0 mg x l-1 and 54.5 mg x l-1 were reached for the glucuronide and sulphate conjugate of paracetamol respectively by the 2nd day of treatment with little variation throughout the remainder of the study. These steady-state concentrations of paracetamol glucuronide and sulphate were much lower than predicted. The steady-state plasma concentrations of the retained cysteine and mercapturate conjugates of paracetamol were low (5.7 and 3.7 mg x l-1, respectively) and there was no evidence of accumulation of these potentially toxic metabolites. It is not clear why regular dosing with paracetamol in haemodialysis patients did not cause the accumulation of paracetamol glucuronide or sulphate as predicted. There may be enterohepatic elimination of retained paracetamol conjugates or depletion of substrates such as inorganic sulphate during chronic dosing.

Alpha-1-proteinase inhibitor and pulmonary haemorrhage in systemic vasculitis.

Alpha-1-proteinase inhibitor phenotypes and levels were examined in 40 antineutrophil cytoplasmic antibody positive cases of systemic vasculitis. An excess of PiZ and PiS alleles were associated with the development of pulmonary haemorrhage and alpha-1-proteinase inhibitor levels were lower in the subgroup with pulmonary haemorrhage. However, this allelic imbalance and reduced alpha-1-proteinase inhibitor level was not confined to antiproteinase 3 positive patients and did not appear to be associated with other organ involvement or disease severity.

Conventional 15 G needle technique for renal biopsy compared with ultrasound-guided spring-loaded 18 G needle biopsy.

Two techniques for percutaneous renal biopsy were retrospectively reviewed to assess their relative safety and efficacy. Ultrasound localization of the kidney by a radiologists, with subsequent biopsy performed by a renal physician using a hand-held 15 G cutting needle (Tru-Cut), was compared with biopsy performed by a radiologist using an 18 G cutting needle with a spring-loaded biopsy device (Biopty) and real-time ultrasound guidance. The smaller needle with real-time ultrasound is more reliable at retrieving an adequate specimen for histological examination (93%) than the "conventional" technique (79%). Fewer complications occurred in the Biopty group although the difference did not reach statistical significance. The average length of stay in hospital was significantly shorter for elective biopsies with the Biopty device (1.80 compared with 2.93 nights, p less than 0.01). We recommend the use of the Biopty device with an 18 G needle and real-time ultrasound guidance as the method of choice for percutaneous renal biopsy.

Errors in fluid balance with pump control of continuous hemodialysis.

The use of pumps both proximal and distal to the dialyzer during continuous hemodialysis provides control of dialysate and ultrafiltration flow rates, thereby reducing nursing time. However, we had noted unexpected severe extracellular fluid depletion suggesting that errors in pump delivery may be responsible. We measured in vitro the operation of various pumps under conditions similar to continuous hemodialysis. Fluid delivery of peristaltic and roller pumps varied with how the tubing set was inserted in the pump. Piston and peristaltic pumps with dedicated pump segments were more accurate. Pumps should be calibrated and tested under conditions simulating continuous hemodialysis prior to in vivo use.

Recombinant erythropoietin improves cognitive function in chronic haemodialysis patients.

Psychometric performance was studied on two occasions in 18 chronic haemodialysis patients. Nine patients treated with rHuEpo performed a battery of psychometric tests before treatment, haemoglobin [mean (SD)] 5.8 (0.6) g/dl and after partial correction of anaemia, haemoglobin 9.3 (1.28) g/dl. The same battery of psychometric tests was administered on two occasions to nine patients (haemoglobin 7.3 (1.2) g/dl) matched with the treatment group for age, educational status and social class, who did not receive rHuEpo. In the rHuEpo-treated group, IQ, measured by the Wechsler Adult Intelligence Scale-Revised, improved by a mean of 8.7 points (P less than 0.01), while in the control group an improvement by a mean of 2.5 points was not significant. Comparison between the groups of the change in IQ score was significant (P = 0.04). There was no change in the mean scores obtained in either group for the other psychometric tests administered including the Paced Auditory Serial Addition Test, Rey auditory verbal learning, and Borkowski verbal fluency test. These results indicate that anaemia makes a reversible contribution to uraemic cognitive dysfunction.

Effect of treatment mode on the natural history of acquired cystic disease of the kidney in patients on renal replacement therapy.

The natural history of acquired cystic disease of the kidney has been investigated in a long-term follow-up study of patients on renal replacement therapy. A cohort of 145 end-stage renal failure patients was initially investigated with ultrasonography to determine the degree of cystic change. Seventy-three patients were available for follow up a minimum of 3 years later. The grade of cystic disease progressed in dialysis patients and progression was more marked in haemodialysis patients than patients maintained on CAPD. Patients with functioning renal transplants did not show progression of cystic change and in two patients regression was seen. Nine patients maintained on chronic dialysis at the time of initial ultrasound subsequently received renal grafts, and three of these patients had evidence of regression of cystic change on follow-up scanning. After 3 years follow-up a single haemodialysis patient had evidence of a solid lesion in a cystic kidney and this has not progressed during a further 12 months of follow-up. Acquired cystic disease of the kidney is a progressive disease in chronic dialysis patients. However, over a follow-up period of 3 years, patients with functioning renal grafts do not show similar progression. The incidence of solid renal tumours has been shown to be low.

Multiple forms of alkaline phosphatase in plasma of hemodialysis patients.

We used quantitative assays to measure the activity of the bone, liver, and intestinal forms of alkaline phosphatase in plasma in 75 patients with endstage chronic renal failure undergoing hemodialysis. The results were correlated with radiological and other biochemical indices of bone disease and with biochemical indices of liver disease. The total activity of alkaline phosphatase in plasma increased in 28 patients. In 10 of these patients, nine of whom had increased activity of gamma-glutamyltransferase in plasma, the increase in total activity of alkaline phosphatase was from the liver isoenzyme alone (nine patients) or from the liver and bone isoenzymes together (one patient). Intestinal alkaline phosphatase in plasma, although greater than 23 U/L in eight patients, was solely responsible for the increase in total alkaline phosphatase in one patient (who had normal gamma-glutamyltransferase). Bone alkaline phosphatase in plasma was increased in 25 patients, seven of whom had normal total alkaline phosphatase, and was closely correlated (r = 0.78) with osteocalcin concentration in plasma, which was increased in a much greater proportion of patients (99%). Both total and bone alkaline phosphatase were correlated with parathyrin in plasma (r = 0.46 and 0.50, respectively) and with osteocalcin (r = 0.60 and 0.78, respectively). Osteocalcin and bone alkaline phosphatase, but not parathyrin, decreased with age, implying that the skeletal response to parathyrin may be age dependent. In patients with increased total alkaline phosphatase undergoing hemodialysis, the concurrent measurement of gamma-glutamyltransferase may help identify whether the enzyme increase originates from the liver or bone, but this approach wrongly identified the source of the increase in three of 28 patients. Therefore, we recommend a separate measurement of the bone isoenzyme of alkaline phosphatase.