Evaluation of Prevent ID and Quantum Blue rapid tests for fecal calprotectin.

BACKGROUND: Tests for fecal calprotectin are usually either enzyme-linked immunosorbent assays (ELISA) or a time-resolved fluorimetric immunoassay (TRFIA). These time-consuming tests are performed only once every 1 or 2 weeks. Before the results of the tests are known most patients have already undergone colonoscopy. A rapid test, performed on outpatients, could minimize the number of necessary colonoscopies. To establish optimal cut-off values minimizing the necessity for colonoscopies, we compared two commercially available rapid tests with a quantitative TRFIA. METHODS: Fecal samples were collected from 85 patients with lower gastrointestinal complaints. Calprotectin was measured using quantitative TRFIA as well as using two rapid tests: Prevent ID CalDetect and Quantum Blue calprotectin. We used the TRFIA method as the golden standard with a cut-off value of 50 µg/g. The percentage correct classification, sensitivity, specificity and positive and negative predictive value were calculated for both rapid tests at various cut-off levels. RESULTS: Correlation between both of the rapid tests with TRFIA was significant. Quantum Blue calprotectin (κ 0.77) correlated better than Prevent ID CalDetect (κ 0.46). Optimal cut-off levels for Prevent ID CalDetect and Quantum Blue calprotectin rapid tests were 15 µg/g and 40 µg/g with a reduction in the number of necessary colonoscopies of 39% and 62%, respectively. CONCLUSIONS: The Quantum Blue calprotectin rapid test demonstrated better analytical performance than the Prevent ID CalDetect in reducing the number of colonoscopies. Furthermore, the former test has the advantage of using a point of care reader for quantitative measurement and for establishing an optimal cut-off level.

Evaluation of the Sysmex UF-1000i® urine flow cytometer in the diagnostic work-up of suspected urinary tract infection in a Dutch general hospital.

BACKGROUND: Automation and standardization of sediment analysis of urine samples by flow cytometry might serve as an alternative to labor-intensive laboratory methods, such as microscopic examination and culture. The Sysmex UF-1000i is a urine flow cytometer that uses two separate channels for counting blood cells and bacteria. METHODS: In this study, 358 urine samples were analyzed with the Sysmex UF-1000i in parallel with manual microscopy, Gram stain and bacterial culture, the latter considered the gold standard. RESULTS: Reproducibility for detection of white and red blood cells and bacteria was good, while detection of yeast proved unreliable. Depending on the definition of urinary tract infection (UTI) used, the negative predictive value and the percentage of false-negative results were 100% and 0% [UTI ≥ 10(5) colony forming units (CFU)/mL] and 99% and 1.3%, (UTI ≥ 10(4) CFU/mL), respectively. Pre-screening with the Sysmex UF-1000i would have resulted in a reduction of bacterial culture by 42%. Carry over of bacteria between consecutive samples due to the use of fixed sample needle was observed, but did not result in false-positive interpretation of Sysmex UF-1000i results. Because of the occurrence of carry over, samples that have been analyzed with the Sysmex UF-1000i cannot be used for subsequent urine culture. CONCLUSIONS: In conclusion, the Sysmex UF-1000i offers the possibility for screening high numbers of urine samples in a fast and standardized way, resulting in a reduction in workload and speeding the diagnostic process. It is not recommended for use in complicated patient populations, such as neutropenic patients and patients in whom yeast infection is suspected.

Assessment of hypolactasia and site-specific intestinal permeability by differential sugar absorption of raffinose, lactose, sucrose and mannitol.

The sugar absorption test is a non-invasive test for investigating intestinal permeability by simultaneous measurement of four probe sugars. In this study, we evaluated the utility of raffinose, lactose, sucrose and mannitol as probe sugars and calculated their urinary recovery as a percentage of ingested dose (mol/mol) and the recovery ratios of raffinose/mannitol, lactose/ raffinose and sucrose/raffinose. The reference ranges for these ratios, established from 39 healthy volunteers, are 0.005-0.015, 0.13-0.63 and 0.09-0.47, respectively. This sugar absorption test was performed in three patient groups. i) In 109 patients with aspecific gastrointestinal symptoms of whom intestinal histology was studied by duodenal biopsies: the urinary raffinose/mannitol recovery ratio highly correlated with gradation of duodenal damage; the sensitivity and specificity of the raffinose/mannitol ratio for detection of intestinal damage were 93% and 91%, respectively, using a cut-off level of 0.020. ii) In 70 patients in whom intestinal lactase activity was investigated by the lactose tolerance test: the urinary lactose/raffinose recovery ratio provided high diagnostic accuracy for hypolactasia (sensitivity 81% and specificity 89% at a cut-off level of 0.70). In analogy with the lactose/raffinose ratio, we suppose that the sucrose/raffinose ratio can be used as a marker of hyposucrasia. iii) In 40 patients with localized small intestinal damage, Crohn's disease of the ileum (n = 21) and celiac disease with histologically proven duodenal damage (n = 19): the raffinose/mannitol recovery ratio was increased in 100% of patients with celiac disease and in 81% of patients with Crohn's disease; increased lactose/raffinose recovery ratio (hypolactasia) and increased sucrose/raffinose (hyposucrasia) were present in 89% and 95% of celiac patients and 19% and 0% of Crohn's disease patients, respectively. The combination of the raffinose/mannitol ratio and sucrose/raffinose ratio appears to be an indication of the distribution of intestinal damage.

Assessment of intestinal permeability: enzymatic determination of urinary mannitol, raffinose, sucrose and lactose on Hitachi analyzer.

The sugar absorption test is the usual test for measurement of intestinal permeability. After intestinal absorption of probe sugars the subsequently excreted sugars are measured in urine. We have developed four enzymatic methods for the measurement of the urinary concentration of the probe sugars mannitol, raffinose, lactose and sucrose. Mannitol, lactose and sucrose are directly measured on Hitachi 917 using mannitol dehydrogenase, beta-galactosidase and invertase, respectively, as enzyme reagents. Raffinose measurement needs a three hours preincubation with alpha-galactosidase, after which the liberated sucrose is measured. The analytical performances such as within- and between-run precision, linearity, lowest detection limit, interference of other sugars and comparison with a gas chromatographic method are described for the four methods. These methods are accurate an can easily be performed in any clinical laboratory.

Quantitative determination of faecal fatty acids and triglycerides by Fourier transform infrared analysis with a sodium chloride transmission flow cell.

We studied the applicability of Fourier transform infrared (FTIR) spectroscopy to determine the amount of faecal fatty acids and triglycerides in faeces. For this, we have optimised a simple hexane extraction procedure of stool. After extraction, an aliquot of the hexane layer is directly injected into the measurement cell of the spectrophotometer and absorbance at 1714 cm(-1) and 1751 cm(-1) is read for quantitation of fatty acids and triglycerides, respectively. Comparison of the FTIR spectrophotometric method with the traditional titrimetric Van de Kamer method for faecal fat determination showed a good correlation. The advantage of our method over the previously described FTIR and near-infrared spectroscopy (NIR) methods is that it allows a combined measurement of both fatty acids and triglycerides in one run, using a simple and rapid hexane extraction procedure. Clinical validation of this method was performed by reviewing the medical records of 24 patients with steatorrhoea: patients with pancreatic steatorrhoea showed highly increased faecal triglyceride excretion, but a normal faecal fatty acid and faecal weight when compared with patients with non-pancreatic intestinal steatorrhoea.