Towards personalized hydration assessment in patients, based on measurement of total body electrical resistance: Back to basics.

BACKGROUND & AIMS: Assessment of tissue hydration by conventional bioelectrical impedance analysis (BIA) has produced conflicting results because of flaws in the algorithms that are used to translate measurements of total body electrical resistance (TBER) into liters of body water. This type of error can be eliminated by a return to the TBER measurement itself, without attempting to convert Ohms into liters of body water. Aims of this study were to quantify tissue hydration based on TBER, to establish TBER normal values (TBERnorm), to improve the prediction of TBERnorm values in individual patients, and to evaluate this approach in patients on hemodialysis (HD). METHODS: TBERnorm values were obtained in 213 healthy controls and corrected for body height (H-TBERnorm). Inter-individual H-TBERnorm variability was reduced by correction for arm muscle cross-sectional area (AMA). Performance of this approach was evaluated in 94 patients on HD. RESULTS: H-TBERnorm was inversely related to AMA. Correction for AMA reduced the H-TBERnorm standard deviation by 31% in men and 23% in women. When applied to patients on HD, H-TBER changes within subjects were inversely related to ultrafiltration volumes, with a mean R2 of 0.95 ± 0.04 in men and 0.93 ± 0.07 in women. Clinically significant H-TBER increments occurred after volume reductions of 0.39 ± 0.25 L in men and 0.37 ± 0.18 L in women. CONCLUSIONS: TBER measurements, corrected for height and AMA, have the potential to become an objective and sensitive method to assess hydration in patients. Its clinical value remains to be shown in intervention studies.

Hippocampal volume and the course of depressive symptoms over eight years of follow-up.

OBJECTIVE: To estimate the association between hippocampal and total brain volume and the course of depressive symptoms over eight years of follow-up in patients with a history of vascular disease. METHOD: Within the SMART-Medea study, 636 participants (62 ± 10 years) had a 1.5-tesla brain MRI obtaining hippocampal and total brain volumes. Depressive symptoms were assessed with the Patient Health Questionnaire-9 biannually during eight-year follow-up. Generalized estimating equation models with robust standard errors were used to assess the associations of hippocampal and total brain volumes with depressive symptoms during follow-up adjusting for age, sex, education, and intracranial volume. An interaction term between volume and time (6-month intervals) was included to examine whether the course of depressive symptoms differed according to hippocampal and total brain volume. RESULTS: The mean PHQ-9 score was 2.8 ± 3.5. Smaller hippocampal volumes were associated with an increasing course of depressive symptom levels, while larger volumes were associated with decreasing levels (P-value interaction = 0.07). Smaller total brain volume was associated with consistently higher levels of depressive symptoms, but not with change in course of depressive symptoms (P-value interaction = 0.45). CONCLUSION: Smaller hippocampal volume but not total brain volume is associated with poorer course of depressive symptoms over eight years of follow-up.

Case-finding for cognitive impairment among people with Type 2 diabetes in primary care using the Test Your Memory and Self-Administered Gerocognitive Examination questionnaires: the Cog-ID study.

AIM: To evaluate two cognitive tests for case-finding for cognitive impairment in older patients with Type 2 diabetes. METHODS: Of 1243 invited patients with Type 2 diabetes, aged ≥70 years, 228 participated in a prospective cohort study. Exclusion criteria were: diagnosis of dementia; previous investigation at a memory clinic; and inability to write or read. Patients first filled out two self-administered cognitive tests (Test Your Memory and Self-Administered Gerocognitive Examination). Secondly, a general practitioner, blinded to Test Your Memory and Self-Administered Gerocognitive Examination scores, performed a structured evaluation using the Mini-Mental State Examination. Subsequently, patients suspected of cognitive impairment (on either the cognitive tests or general practitioner evaluation) and a random sample of 30% of patients not suspected of cognitive impairment were evaluated at a memory clinic. Diagnostic accuracy and area under the curve were determined for the Test Your Memory, Self-Administered Gerocognitive Examination and general practitioner evaluation compared with a memory clinic evaluation to detect cognitive impairment (mild cognitive impairment or dementia). RESULTS: A total of 44 participants were diagnosed with cognitive impairment. The Test Your Memory and Self-Administered Gerocognitive Examination questionnaires had negative predictive values of 81 and 85%, respectively. Positive predictive values were 39 and 40%, respectively. The general practitioner evaluation had a negative predictive value of 83% and positive predictive value of 64%. The area under the curve was ~0.70 for all tests. CONCLUSIONS: Both the tests evaluated in the present study can easily be used in case-finding strategies for cognitive impairment in patients with Type 2 diabetes in primary care. The Self-Administered Gerocognitive Examination had the best diagnostic accuracy and therefore we would have a slight preference for this test. Applying the Self-Administered Gerocognitive Examination would considerably reduce the number of patients in whom the general practitioner needs to evaluate cognitive functioning to tailor diabetes treatment.

Major depressive episodes over the course of 7 years and hippocampal subfield volumes at 7 tesla MRI: the PREDICT-MR study.

INTRODUCTION: Smaller hippocampal volumes have been associated with major depressive disorder (MDD). The hippocampus consists of several subfields that may be differentially related to MDD. We investigated the association of occurrence of major depressive episodes (MDEs), assessed five times over seven years, with hippocampal subfield and entorhinal cortex volumes at 7 tesla MRI. METHODS: In this prospective study of randomly selected general practice attendees, MDEs according to DSM-IV-R criteria were assessed at baseline and after 6, 12, 39 and 84 months follow-up. At the last follow-up, a T2 (0.7 mm(3)) 7 tesla MRI scan was obtained in 47 participants (60±10 years). The subiculum, cornu ammonis (CA) 1 to 3, dentate gyrus&CA4 and entorhinal cortex volumes were manually segmented according a published protocol. RESULTS: Of the 47 participants, 13 had one MDE and 5 had multiple MDEs. ANCOVAs, adjusted for age, sex, education and intracranial volume, revealed no significant differences in hippocampal subfield or entorhinal cortex volumes between participants with and without an MDE in the preceding 84 months. Multiple episodes were associated with smaller subiculum volumes (B=-0.03 mL/episode; 95% CI -0.06; -0.003), but not with the other hippocampal subfield volumes, entorhinal cortex, or total hippocampal volume. LIMITATIONS: A limitation of this study is the small sample size which makes replication necessary. CONCLUSIONS: In this exploratory study, we found that an increasing number of major depressive episodes was associated with smaller subiculum volumes in middle-aged and older persons, but not with smaller volumes in other hippocampal subfields or the entorhinal cortex.

Cognitive performance and the course of depressive symptoms over 7 years of follow-up: the SMART-MR study.

BACKGROUND: Depressive symptoms and cognitive impairment often co-occur, but their interactive relationship is complex and the direction of causation is still a topic of research. We examined the influence of cognitive performance on the course of depressive symptoms during 7 years of follow-up in patients with vascular disease. METHOD: Within the SMART-MR study, 736 patients (mean age 62 ± 10 years) had neuropsychological assessment on four cognitive domains at baseline [memory (MEM), working memory (WMEM), executive functioning (EXEC), and information processing speed (SPEED)]. Depressive symptoms were assessed with the Patient Health Questionnaire-9 (PHQ-9) at baseline and every 6 months during 7 years of follow-up. Generalized Estimating Equation (GEE) models were used to assess the association between cognitive performance with depressive symptoms at multiple time points during follow-up. Interaction terms between the respective cognitive domains and time was included to examine if the course of depressive symptoms differed according to baseline cognitive performance. RESULTS: The GEE analyses showed no significant interactions between the respective cognitive domains and time indicating no different course of depressive symptoms according to baseline cognitive performance. Lower MEM, EXEC or SPEED, but not WMEM performance, was significantly associated with more depressive symptoms during follow-up per z score decrease: MEM [B = 0.70, 95% confidence interval (CI) 0.35-1.05]; EXEC (B = 0.88, 95% CI 0.41-1.36), and SPEED (B = 0.57, 95% CI 0.21-0.92). CONCLUSIONS: Poorer cognitive performance on the domains MEM, EXEC and SPEED, but not WMEM, was associated with higher levels of depressive symptoms over 7 years of follow-up, but not with a different course of depressive symptoms over time.

Physical activity, structural brain changes and cognitive decline. The SMART-MR study.

OBJECTIVE: We aimed to examine the cross-sectional and prospective relationship between leisure time physical activity, brain MRI abnormalities and cognitive performance in patients with vascular disease. METHODS: Within the SMART-MR study, 1.5 T MRI of the brain and neuropsychological examinations were performed at baseline (n = 1232) and after 3.9 ± 0.4 years follow-up (n = 663). Automatic brain segmentation was used to quantify intracranial (ICV), total brain, ventricular, and white matter lesion (WML) volumes. Brain infarcts were rated visually. Level of physical activity was expressed in metabolic equivalents (MET) hours p/week. With linear regression analysis we examined associations of level of physical activity with brain MRI measures and with cognitive performance, adjusted for potential confounders. For the association with brain infarcts relative risks (RR) were calculated with Poisson regression. RESULTS: At baseline, an increase in physical activity of one SD (39.7 METh/w) was significantly associated with larger total brain volume (B = 0.20% of ICV; 95% CI 0.06; 0.33%). A trend was found for the association of physical activity with smaller ventricular volume (B = -0.04% of ICV; 95% CI -0.09; 0.02%) and with a decreased risk for brain infarcts (RR = 0.91, 95% CI: 0.82-1.02). No association was found with smaller WML volume (B = -0.02% of ICV; 95% CI -0.07; 0.04%). No associations with change in brain structures over time were observed. Also, no associations between physical activity and cognitive performance or cognitive decline were found. CONCLUSION: These data suggest that leisure time physical activity does not have a significant contribution in preventing or slowing down brain abnormalities and cognitive decline in this cohort of middle-aged individuals already burdened with vascular disease.

Detection of diarrhoea-causing protozoa in general practice patients in The Netherlands by multiplex real-time PCR.

The diagnostic value of a multiplex real-time PCR for the detection of Entamoeba histolytica, Giardia lamblia and Cryptosporidium parvum/Cryptosporidium hominis was evaluated by comparing the PCR results obtained with those of routinely performed microscopy of faecal samples from patients consulting their general practitioner (GP) because of gastrointestinal complaints. Analysis of 722 faecal DNA samples revealed that the prevalence of G. lamblia was 9.3% according to PCR, as compared to 5.7% by microscopy. The number of infections detected was more than double in children of school age. Furthermore, G. lamblia infection was detected in 15 (6.6%) of 228 faecal samples submitted to the laboratory for bacterial culture only. C. parvum/C. hominis infections were not diagnosed by routine procedures, but DNA from these organisms was detected in 4.3% of 950 DNA samples. A strong association with age was noted, with Cryptosporidium being detected in 21.8% of 110 children aged <5 years. C. hominis was the most prevalent species. E. histolytica was not detected in this study population. Analysis of microscopy data revealed that the number of additional parasites missed by PCR was small. Overall, the study demonstrated that a multiplex real-time PCR approach is a feasible diagnostic alternative in the clinical laboratory for the detection of parasitic infections in patients consulting GPs because of gastrointestinal symptoms.

Effect of short daily home haemodialysis on quality of life, cognitive functioning and the electroencephalogram.

BACKGROUND: End-stage renal disease patients have a poor quality of life (QoL), suffer from impaired cognitive functioning, and their electroencephalogram (EEG) shows abnormalities. Conventional haemodialysis (CHD) only partially restores these disorders. Short daily haemodialysis (SDHD) has been reported to improve QoL, but effects on cognitive functioning and EEG have yet to be described. METHODS: Of the 13 patients (11 male, 2 female, age 45.5 +/- 8.1 years), 11 completed the Kidney Disease Quality of Life and Affect Balance Scale questionnaires, 10 underwent neuropsychological testing, and all 13 underwent EEG examination. For the neuropsychological assessments, nine patients (six male, three female, age 45.4 +/- 12.6) who remained on the CHD schedule, served as controls. The dialysis schedule of thrice-a-week for 4 h was changed in the experimental group to six times a week for 2 h (SDHD) over a period of 6 months and back to thrice a week for 4 h. RESULTS: When on SDHD, patients rated several dimensions of health-related QoL as being improved. After resuming CHD, one of these dimensions again decreased and several others worsened even lower than baseline. Cognitive functioning did not change when compared with control data. On the EEG, alpha peak frequency increased slightly when on SDHD but decreased significantly after resuming CHD. CONCLUSIONS: SDHD improves health-related QoL, but has no clear effects on cognitive functioning and EEG. Resumption of CHD after SDHD decreases aspects of QoL and EEG alpha peak frequency but has no effect on cognitive functioning.

Long-term blood pressure monitoring and echocardiographic findings in patients with end-stage renal disease: reverse epidemiology explained?

BACKGROUND: In patients with end-stage renal disease (ESRD) hypertension is common and often leads to left ventricular (LV) hypertrophy and diastolic dysfunction, but hypotension at the onset of dialysis is associated with increased mortality. We studied blood pressure data over longer periods of time in patients on haemodialysis and related them to echocardiographic outcome, in order to elucidate these contradictory findings. METHODS: In 50 haemodialysis patients mean arterial pressure (MAP) and pulse pressure (PP) were calculated in the first three months of haemodialysis, the complete period from the start of haemodialysis until echocardiography and the last three months of haemodialysis before echocardiography. Hypertension load, pulse pressure and interdialytic weight gain were quantified and related to echocardiography. RESULTS: LV mass index was associated with MAP in all three periods, and also with the hypertension load, PP and PP load. In patients with LV dilatation, MAP and PP averaged over the complete period of dialysis were 5 to 7 mmHg higher than in patients without LV dilatation. Blood pressure parameters were the same in patients with or without LV diastolic dysfunction or systolic dysfunction. Systolic dysfunction was more frequent in patients undergoing long-term haemodialysis treatment. Interdialytic weight gain was not associated with any of the echocardiographic variables. CONCLUSION: When long-term blood pressure values are considered, hypertension is associated with parameters of early cardiac damage such as increased LV mass index and not with parameters of advanced heart failure such as systolic dysfunction. This supports the hypothesis that the presence of advanced heart failure reciprocally influences blood pressure in a negative way, thereby explaining the 'reverse epidemiology' of blood pressure and mortality in ESRD.

[Nephrogenic fibrosing dermopathy]. / Nefrogene fibroserende dermopathie.

A 58-year-old man with renal insufficiency, who was being treated by haemodialysis, developed progressive skin lesions. He had thickening and hardening of the skin at the extremities and swelling of the toes and fingers with flexion contractures. His face was not affected. Laboratory evaluation was unremarkable and a skin biopsy [table: see text] showed an increase of collagen and mucin, without an inflammatory infiltrate. These clinical features resemble a recently reported new disorder: nephrogenic fibrosing dermopathy. This disorder manifests as scleromyxedema-like cutaneous skin lesions without associated paraproteinemia, occurring in the setting of renal disease. The histopathologic features of nephrogenic fibrosing dermopathy, i.e. thickened collagen and mucin deposition, are unique. The incidence, prevalence and cause of the disease are unknown and there is currently no effective treatment. The Centers for Disease Control and Prevention (CDC) in the USA are calling on physicians who have encountered patients suffering from this type of lesions to contact the CDC for an intended control study.

Ferric saccharate induces oxygen radical stress and endothelial dysfunction in vivo.

BACKGROUND: Intravenous iron supplementation is used widely in haemodialysis patients. However, nontransferrin-bound iron (NTBI), which increases after intravenous supplementation of ferric saccharate, has been suggested to act as a catalytic agent in oxygen radical formation in vitro and may thus contribute to endothelial impairment in vivo. MATERIALS AND METHODS: In 20 healthy volunteers the effect of 100 mg ferric saccharate infusion was investigated. Vascular ultrasound was used to assess endothelium-dependent vasodilatation at baseline, and 10 and 240 min after ferric saccharate infusion. Whole blood was collected to measure NTBI and in vivo radical formation was assessed by electron spin resonance. A time-control study was performed using saline infusion. RESULTS: Infusion of ferric saccharate induces a greater than fourfold increase in NTBI, as well as a transient, significant (P < 0.01) reduction of flow-mediated dilatation 10 min after infusion of ferric saccharate, when compared with saline. The generation of superoxide in whole blood increased significantly 10 and 240 min after infusion of ferric saccharate by, respectively, 70 and 53%. CONCLUSIONS: Iron infusion at a currently used therapeutic dose for intravenous iron supplementation leads to increased oxygen radical stress and acute endothelial dysfunction.

Nontransferrin-bound iron in the plasma of haemodialysis patients after intravenous iron saccharate infusion.

BACKGROUND: Many haemodialysis patients treated with recombinant human erythropoietin (r-HuEPO) receive intravenous iron supplementation on a regular basis. It has been shown previously that this may result in a transient "oversaturation" of transferrin. METHODS: Ten stable haemodialysis patients on r-HuEPO treatment received 100 mg iron saccharate in 60 min, and 1 week later 100 mg in 6 min. Conventional iron metabolism parameters and nontransferrin-bond iron, detected with HPLC after addition of nitrilotriacetate and pretreatment with cobalt, were measured. Also, iron was measured in dialysate. RESULTS: Serum iron increased from 9.6 +/- 6.2 to 213.7 +/- 49.4 micromol L(-1) (P < 0.001) when iron was given in 60 min, and from 11.1 +/- 4.7 to 219.3 +/- 43.7 micromol L(-1) (P < 0.001) when iron was given in 6 min. Transferrin saturation increased from 0.22 +/- 0.18 to 4.75 +/- 1.35 in protocol 1 and 0.26 +/- 0.16 to 4.91 +/- 1.38 in protocol 2. Nontransferrin-bound iron increased from 0.74 +/- 0.69 to 3.79 +/- 1.41 micromol L(-1) in protocol 1, and from 0.90 +/- 0.92 to 2.90 +/- 0.96 micromol L(-1) in protocol 2. No significant iron concentrations were found in dialysate before or during the iron saccharate infusion. CONCLUSION: Nontransferrin-bound iron exists in plasma of dialysis patients after infusion of iron saccharate. There was no difference when 100 mg iron was given in 60 min or in 6 min. Before iron infusion, appreciable concentrations of nontransferrin-bound iron could already be detected. The clinical significance is not clear, but the findings may be important since nontransferrin-bound iron can act as a catalytic agent in the formation of hydroxyl radicals, thus potentially inducing cell damage and atherosclerosis.

Clinical outcome of daily dialysis.

Dialysis patients are prone to malnutrition, which may be counteracted by daily home hemodialysis (DHHD, 6 times a week) due to improved clinical outcome and quality of life. Eleven patients were treated with DHHD during 18 months, after a run-in period with three dialysis sessions a week. The total weekly dialysis dose was kept constant during the first 6 months of DHHD, whereupon it was allowed to increase. KT/V was 3.1 +/- 0.5 at baseline, 3.2 +/- 0.5 after 6 months and 4.0 +/- 0.8 at 18 months. Blood pressure decreased from 142 +/- 19/83 +/- 8 to 130 +/- 25/79 +/- 9 mmHg with a more than 50% reduction in antihypertensive medication. Potassium did not change, but potassium binding resins could be stopped almost completely. Bicarbonate increased from 20.6 +/- 3.3 to 23.1 +/- 2.6 mEq/L after 18 months. Patients with a protein intake of less than 1.0 g/kg/d showed a greater increase in body weight (62.3 +/- 6.0 to 65.5 +/- 3.7, P: < 0.05) and normalized protein catabolic rate (nPCR) (0.87 +/- 0.08 to 1.25 +/- 0.36, ns) than patients with acceptable protein intake (>/=1.0 g/kg/d). Phosphate decreased, though not significantly, especially in the latter group. Erythropoietin dose could be reduced from 6400 +/- 5400 U/L at baseline to 5100 +/- 4000 U/L at 18 months. Quality of life improved significantly, especially with to respect to physical condition and mental health. The DHHD markedly improves hemodynamic control and quality of life. Overall nutritional parameters did not change, except cholesterol. Patients with a low protein intake, however, showed a significant increase in body weight, and a greater rise in nPCR.

Daily home haemodialysis in The Netherlands: effects on metabolic control, haemodynamics, and quality of life.

BACKGROUND: More frequent dialysis has been claimed to improve clinical outcome and quality of life. METHODS: Clinical status was optimized in 13 haemodialysis patients during a run-in period of 2 months with three dialysis sessions a week. Thereafter, daily home haemodialysis (DHHD, 6 sessions per week) was initiated. The total weekly dialysis dose (Kt/V) was kept constant. RESULTS: Weekly Kt/V was 3.2+/-0.13 (M+/-SEM) before, and 3.2+/-0.15 after 6 months of DHHD (NS), time-averaged concentration of urea (TACu) was 21.2+/-1.6 mmol/l and 20.1+/-0.9 mmol/l (NS). Urea reduction was 0.56+/-0.05 before DHHD, and 0.41+/-0.06 during DHHD (P<0.0001). Serum K remained unchanged, but significantly less exchange resins were used (P<0.02). Also, the dose of phosphate-binding agents could be decreased. Values for Na, K, Cl, bicarbonate, Ca, PTH, albumin, and Hb remained unchanged. Iron deficiency developed in some patients. Twenty-four-hour blood pressure monitoring showed a decrease of systolic blood pressure (141.1+/-17.2 mmHg before, and 130.9+/-19.2 mmHg during DHHD, P<0.001). Diastolic blood pressure remained constant (82.8+/-7.2 and 76.9+/-10.1 mmHg, NS). Mean arterial pressure decreased from 102.2+/-9.5 to 94.9+/-1.4 mmHg (P<0.02). Blood pressure decreased mainly in previously hypertensive patients. Mean target weight increased 0.8 kg. The amount of antihypertensive drugs used decreased from 1.88+/-0.35 to 0.75+/-0.17 (P<0.005, n=7). Dialysis sessions were much more stable, also in patients with cardiac insufficiency. Quality of life questionnaires (Rand 36, Nottingham Health Profile, Uraemic Symptoms Profile) showed a significant improvement of physical condition and fewer uraemic symptoms. CONCLUSION: DHHD compared to conventional thrice-weekly haemodialysis with similar weekly Kt/V results in an improved haemodynamic control and quality of life, but has lesser impact on metabolic regulation.

The absorption of iron is disturbed in recombinant human erythropoietin-treated peritoneal dialysis patients.

BACKGROUND: Intravenous iron supplementation is often necessary in recombinant human erythropoietin (r-HuEPO)-treated haemodialysis (HD) patients, but rarely in r-HuEPO-treated peritoneal dialysis (PD) patients. This may be due to differences in iron absorption or blood loss. METHOD: Iron absorption (whole-body counting after ingestion of a radiolabelled iron test dose) and iron metabolism were compared in eight iron-replete rHuEPO-treated PD patients (serum ferritin 100-500 microg/l) and 68 healthy iron-replete controls (sufficient iron in bone marrow specimen). RESULTS: Mucosal uptake (13.4+/-9.8%), mucosal transfer (0.34+/-0.18) and iron retention (4.9+/-4.0) in PD patients was significantly lower than in controls (42.9+/-18.8%, P < 0.0001, 0.63+/-0.18, P < 0.0001, and 28.0+/-16.7%, P<0.0001). CONCLUSION: Iron absorption is impaired in PD patients, as we have shown previously for HD patients. One reason for higher iron needs in HD patients may be higher blood losses due to the dialysis procedure and blood sampling for laboratory tests.

Assessment of resolution and intercenter reproducibility of results of genotyping Staphylococcus aureus by pulsed-field gel electrophoresis of SmaI macrorestriction fragments: a multicenter study.

Twenty well-characterized isolates of methicillin-resistant Staphylococcus aureus were used to study the optimal resolution and interlaboratory reproducibility of pulsed-field gel electrophoresis (PFGE) of DNA macrorestriction fragments. Five identical isolates (one PFGE type), 5 isolates that produced related PFGE subtypes, and 10 isolates with unique PFGE patterns were analyzed blindly in 12 different laboratories by in-house protocols. In several laboratories a standardized PFGE protocol with a commercial kit was applied successfully as well. Eight of the centers correctly identified the genetic homogeneity of the identical isolates by both the in-house and standard protocols. Four of 12 laboratories failed to produce interpretable data by the standardized protocol, due to technical problems (primarily plug preparation). With the five related isolates, five of eight participants identified the same subtype interrelationships with both in-house and standard protocols. However, two participants identified multiple strain types in this group or classified some of the isolates as unrelated isolates rather than as subtypes. The remaining laboratory failed to distinguish differences between some of the related isolates by utilizing both the in-house and standardized protocols. There were large differences in the relative genome lengths of the isolates as calculated on the basis of the gel pictures. By visual inspection, the numbers of restriction fragments and overall banding pattern similarity in the three groups of isolates showed interlaboratory concordance, but centralized computer analysis of data from four laboratories yielded percent similarity values of only 85% for the group of identical isolates. The differences between the data sets obtained with in-house and standardized protocols could be the experimental parameters which differed with respect to the brand of equipment used, imaging software, running time (20 to 48 h), and pulsing conditions. In conclusion, it appears that the standardization of PFGE depends on controlling a variety of experimental intricacies, as is the case with other bacterial typing procedures.