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PubMed1997

Urease-based tests for Helicobacter pylori gastritis. Accurate for diagnosis but poor correlation with disease severity.

To determine whether the urease-based CLOtest or low-dose 14C urea breath test can predict severity of gastritis or the presence of peptic ulcers, we studied 84 patients presenting for upper endoscopy. Antral biopsies were obtained for histologic analysis and CLOtesting, and urea breath testing was performed. The time to a positive CLOtest and the breath test peak values were correlated with endoscopic findings, severity of gastritis, and bacterial burden. Twenty-four patients had positive urea breath test results (22 with positive CLOtests). Patients with positive breath test results were more likely to have duodenal ulcers, higher grades of gastritis, and increased bacterial burden (p < 0.01 for all comparisons). Correlation between the time to a positive CLOtest or peak breath test values and gastritis severity or bacterial burden was poor (p > 0.05 for all comparisons). In patients with positive tests, no difference was observed between the time to a positive CLOtest or peak breath test value in patients with or without peptic ulcers (p < 0.2 for all comparisons). The low-dose 14C urea breath test and the CLOtest are both accurate for Helicobacter pylori diagnosis. However, neither test predicts the severity of the gastritis, the degree of bacterial burden, or the presence of peptic ulcers.

Adult↗

PubMed1998

Gastric urease activity is inversely associated with the success of treatment for Helicobacter pylori: effect of sofalcone.

Eradication therapy for Helicobacter pylori (H. pylori) has been established. However, the physiological factors influencing the success of treatment remain unclear. The aim of this study was to analyze these factors and to evaluate the efficacy of sofalcone on H. pylori eradication therapy. Forty-four H. pylori-infected and peptic ulcer patients were enrolled in this study. Twenty-seven patients were treated with lansoprazole (LPZ, 30 mg o.d. for 1-8 weeks) and amoxicillin (AMPC, 500 mg q.i.d, 1-2 weeks), followed by 8 weeks of treatment with famotidine (FAM, 20 mg o.d.). Moreover, sofalcone (SOF, 100 mg t.i.d) was administered to 17 patients throughout the therapeutic period. Endoscopic and serologic evaluations and the urea breath test (UBT) were performed before therapy. At the endoscopic examination, mucosal samples were biopsied and then tissue myeloperoxidase (MPO) content, an index of neutrophil infiltration was measured. Cure of H. pylori infection was determined 8 weeks after the cessation of LPZ. This eradication regimen afforded an overall cure rate of 63.0% (17/27) without SOF and 76.5% (13/17) with SOF. In the control group, treatment success was inversely associated with pre-UBT value (gastric urease activity), whereas this association was not observed in the SOF group. Furthermore, in the patients exhibiting a high preUBT value (>40%), a twofold higher eradication rate was obtained by the administration of SOF. In patients who were successfully eradicated, mucosal MPO level was slightly higher than those of unsuccessful cases, whereas there was no significant association with serum pepsinogen (PG I, PG II) concentration and its ratio (PG I/PG II). These results suggest that a low UBT value is a factor predicting treatment success. SOF administration may improve the eradication rate, especially in the high-UBT subgroup.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2000

Prolonged storage of frozen unbuffered rapid urease test.

Unbuffered rapid urease test (RUT) is an accurate, rapid, and inexpensive method of detecting Helicobacter pylori. However, it is generally recommended to prepare the reagent daily. This prospective study was undertaken to evaluate the shelf-life of our unbuffered RUT at -20 degrees C. Two sets of antral biopsies (X2) and body biopsies (X1) were taken from all patients. They were subjected to histologic examination and RUT stored at -20 degrees C. We studied 303 patients. One hundred seventy-nine (59%) were infected as defined by histologic examination. The reagent was classified according to the storage time (group I, 0-30 days [n = 109]; group II, 31-60 days [n = 63]; group III, 61-90 days [n = 80]; and group IV, tau91 days [n = 51]). There was an excellent agreement between the histologic examination and the RUT of the four groups (kappa coefficient: group I, 0.88; group III, 0.80; group III, 0.87; group IV, 0.88). The sensitivity of our RUT in groups I, II, III, and IV were 92%, 92%, 91%, and 89%, respectively. The corresponding specificity were 97%, 88%, 97%, and 100%. Our RUT remains highly sensitive and specific when it is stored at -20 degrees C for 4 months.

Biopsy↗

PubMed1997

Helicobacter rodentium sp. nov., a urease-negative Helicobacter species isolated from laboratory mice.

A spiral-shaped bacterium with bipolar, single, nonsheathed flagella was isolated from the intestines of laboratory mice. The organism grew at 37 and 42 degrees C under microaerobic and anaerobic conditions, did not hydrolyze urea, was weakly positive for catalase and oxidase, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and was resistant to cephalothin and nalidixic acid. This is the first urease-negative, murine Helicobacter spp. isolated from intestines. Also, Helicobacter pullorum and this bacterium are unique among the genus Helicobacter in having nonsheathed flagella. The new bacterium appears to be part of the normal intestinal flora; although its pathogenic potential is unknown, this organism was also isolated from scid mice with diarrhea that were co-infected with Helicobacter bilis. On the basis of 16S rRNA gene sequence analysis data and biochemical and phenotypic criteria, the new organism is classified as a novel helicobacter, for which we propose the name Helicobacter rodentium. The type strain is MIT 95-1707 (= ATCC 700285).

Animals↗

PubMed1997

Corynebacterium singulare sp. nov., a new species for urease-positive strains related to Corynebacterium minutissimum.

We studied two coryneform strains from clinical specimens. These strains had type IV and corynemycolic acids in their cell walls and also had phenotypic characteristics, such as urease activity and fermentation of glucose and sucrose but not trehalose, which did not permit assignment to any previously recognized taxon. According to DNA-DNA hybridization data, these two strains are members of the same species (level of DNA similarity, 86%). Phylogenetic analysis based on comparisons of almost complete small-subunit ribosomal DNA sequences revealed that these strains are closely related to Corynebacterium minutissimum, but DNA relatedness experiments clearly showed that they constitute a distinct new species with a level of DNA relatedness to the C. minutissimum type strain of less than 40%. This new species can be differentiated from C. minutissimum strains by its enzymatic activities and carbon source utilization, and the name Corynebacterium singulare is proposed for it. The type strain is strain IBS B52218 (= CCUG 37330), which was isolated from a semen specimen.

Base Composition↗

PubMed2001

Helicobacter ganmani sp. nov., a urease-negative anaerobe isolated from the intestines of laboratory mice.

Spiral bacteria were isolated from the intestines of laboratory mice during a study examining the presence of Helicobacter species and other spiral organisms naturally infecting mice maintained at four different animal facilities in Sydney, Australia. One group of 17 isolates, cultured from mice from three of the four facilities, were found to be helicobacters but did not fall within any of the 18 currently recognized species. These isolates were unusual in that they only grew anaerobically at 37 degrees C and were incapable of growth under microaerobic conditions. Like Helicobacter rodentium, isolates possessed single, bipolar, unsheathed flagella and were urease-negative. They were positive for oxidase and reduced nitrate to nitrite but did not hydrolyse hippurate or indoxyl acetate, grew on charcoal agar and were resistant to cephalothin. 16S rDNA sequences from four strains were determined and found to be identical to one another. H. rodentium was the most closely related species in terms of 16S rDNA sequence similarity (98.2%). Numerical analysis of whole-cell proteins by SDS-PAGE for nine isolates was carried out with a comparison to all known Helicobacter species, including newly determined profiles from three H. rodentium strains. The new isolates were clearly differentiated from H. rodentium and other Helicobacter spp. On the basis of this data, including genetic, biochemical and protein analysis, it is proposed that these isolates belong to Helicobacter ganmani sp. nov. (type strain CMRI H02T = CCUG 43526T = CIP 106846T).

Anaerobiosis↗

PubMedDate not supplied

Morphometric studies of rat glial cell ultrastructure after urease-induced hyperammonaemia.

The ultrastructure of astrocytes and oligodendrocytes was investigated in hyperammonaemic rats injected daily with urease for 4 days. Glial cells were randomly photographed and magnified x28 000. Cell and nuclear sizes were estimated by planimetry and mitochondrial size and density were measured by image analysis. After 4 days of hyperammonaemia the astrocyte cytoplasmic area was increased by 46%. Mitochondrial area was increased by 20%, but after correction for cytoplasmic oedema the number and size of mitochondria were not significantly increased. The nuclear and cytoplasmic areas of oligodendrocytes were unchanged. The mitochondria of oligodendrocytes were small in the hyperammonaemic group and so was their percentage area to cytoplasmic area, but their numbers were unchanged. It was concluded that hyperammonaemia induces astrocyte oedema and increases the astrocyte mitochondrial content. These findings support the assumption that the astrocytes are the active cells in the brain metabolism of ammonia. The decrease in oligodendrocyte mitochondrial content could be considered a point against an active function of oligodendrocyte mitochondria in ammonia metabolism in hyperammonaemia.

Ammonia↗

PubMed1997

Clinical assessment of the bacterial load of Helicobacter pylori on gastric mucosa by a new multi-scaled rapid urease test.

The present study tests the efficacy of the multi-scaled urease test (MUT) in detecting Helicobacter pylori infection and determines whether the MUT can predict the bacterial density on histology. A total of 111 sets of gastric specimens were obtained from patients with dyspepsia but without recent bleeding. Two biopsies were taken as closely as possible in each set. One sample was used for the MUT (Hp fast; GI Supply, Camp Hill, PA, USA), while the other was used to determine the histological density of H. pylori by modified Giemsa stain (grade 0-5). The results of MUT were interpreted as negative if the colour was yellow or bright green (reaction score 0) and positive if the colour was green, light blue, or blue (reaction score 1, 2 and 3, respectively). The reaction scores of MUT were recorded sequentially at 15 and 30 min and 1, 4 and 24 h. On the basis of histological confirmation, MUT had a sensitivity of 89.6%, a specificity of 88.2%, a positive predictive value of 94.5% and a negative predictive value of 78.9%. Focusing on specimens with the presence of bacteria under histology, 77 specimens were divided into five subgroups by grades of density of H. pylori (HPD1-5). The reaction scores had become sequentially elevated from 30 min through to 24 h in each subgroup. For subgroups HPD4 and 5, the positive rates of MUT were 70.6 and 66.6%, respectively, as early as 30 min and progressed to 100% within 4 h. In contrast, the positive rate for the HPD1 subgroup was 16.6% at 4 h and increased to only 62.5% at 24 h. In subgroups HPD 2 and 3, the positive rates were less than 30% at 30 min, but became more than 66.6% at 4 h and were 100% at 24 h. The early (i.e. mean value of reaction scores before 4 h) and late (24 h) mean reaction scores disclosed two elevated trends as the density of H. pylori increased (early: 0.2, 0.7, 0.8, 1.5, 1.2; late: 1.4, 2.3, 2.6, 3.0, 3.0; P < 0.05). In conclusion, MUT is a reliable method for the diagnosis of H. pylori infection. It can also indirectly predict the density of H. pylori on histology.

Biopsy↗

PubMed1997

Shelf life of unbuffered rapid urease test.

BACKGROUND: Unbuffered rapid urease test (RUT) is an accurate and inexpensive method to detect Helicobacter pylori. However, the test is not always readily available because the reagents must be mixed freshly or stored at -20 degrees C after mixing. From our experience, storage at 4 degrees C for less than 6 days seemed to have no effect on the test's accuracy. This prospective study was undertaken to evaluate the shelf life of our unbuffered RUT. MATERIAL AND METHODS: Forty-five patients were studied. From all patients, two sets of antral biopsy (X2) and body biopsy (X1) were taken. One set was subjected to histological examination; the other set was placed into a single capped Eppendorff tube for RUT. The tube was examined for any color change at 1 and 5 minutes. RESULTS: Twenty-six patients (58%) were infected as defined by histological examination. The reagent was classified according to the storage time (group 1, < or = 5 days; group 2, > 5 days). The mean storage times of group 1 (n = 24) and group 2 (n = 21) were 3.1 (1.7 SD) days and 7.7 (1.2 SD) days, respectively. At 1 and 5 minutes, the sensitivity of group 1 was consistently higher than that of group 2 (1 minute, 61% versus 38%; 5 minutes, 92% versus 62%), and no false-positive result was observed in either group. CONCLUSION: RUT remains highly sensitive and specific when it was stored at 4 degrees C for up to 5 days but should be discarded after that period.

Bacteriological Techniques↗

PubMed1979

A new method of urea removal using urease and expanded polytetrafluoroethylene membrane.

A new method for urea removal using a gas membrane is introduced along with some preliminary results. The membrane used was expanded polytetrafluoroethylene (E-PTFE) which is highly permeable to gaseous substances, while at the same time it is highly resistant to water permeation. In in vitro experiments using 10 mmol/L ammonia solution it was revealed that the single-pass reduction rate was approximately 95% at 30 degrees C at a flow rate of 200 ml/min. In animal experiments using four dogs, the extraction rate of urea was 40.4 +/- 4.4% after four hours of dialysis using 5 L dialysate. However, elevation of blood ammonia was observed in all dogs tested. Removal of ammonia by means of a gas membrane is considered to be feasible and has the possibility of being used for maintenance hemodialysis in combination with urease and charcoal.

Ammonia↗

PubMed1999

Successful recovery of H. pylori from rapid urease tests (CLO tests).

OBJECTIVE: Culture of Helicobacter pylori (H. pylori) and the determination of its antibiotic susceptibility is of increasing importance with the rise in numbers of antibiotic-resistant strains. The aim of this study was to determine whether H. pylori could be successfully isolated from antral biopsies used in Rapid Urease Tests (CLOtests) in clinical practice. METHODS: Antral biopsies from patients undergoing endoscopy were inserted into the gel of CLOtests to determine the H. pylori status of the patients. If the CLOtest was positive at the end of the endoscopy session, it was kept at ambient temperature until processed. In the laboratory, biopsies were removed from the gel and cultured on selective and nonselective media. In an attempt to enhance the recovery rate of H. pylori, a subset of positive CLOtests were kept at 4 degrees C from the time that the color change was noted until the removal of the biopsy. RESULTS: One hundred and forty-one positive CLOtests were studied at times between 1 h and 6 h postendoscopy. Culture success was 93% in the 1st hour but fell off sharply after 2 h (p < 0.001). Isolation was also improved if positive CLOtests were stored at 4 degrees C and plated out within 4 h (p < 0.001). CONCLUSIONS: H. pylori can be successfully cultured from biopsies in CLOtests kept at room temperature within 2 h or within 4 h if kept at 4 degrees C. Thus the antral biopsy in the CLOtest can be usefully retrieved when, in the light of the CLOtest result, the physician wishes to obtain both culture and antibiotic sensitivity results.

Biopsy↗

PubMed2000

Rapid urease tests lack sensitivity in Helicobacter pylori diagnosis when peptic ulcer disease presents with bleeding.

OBJECTIVE: The eradication of Helicobacter pylori (H. pylori) in patients with bleeding peptic ulcer disease (PUD) decreases the rate of ulcer rebleeding. Although all methods for H. pylori diagnosis have been extensively evaluated in uncomplicated PUD the efficacy of the commonly used rapid urease test (RUT) has not been established in patients with bleeding peptic ulcer disease. The aim of this study was to evaluate the efficacy of the RUT (CLOtest) in patients with bleeding duodenal ulcers (DUs). METHODS: Consecutive patients with symptoms of upper GI tract hemorrhage and a DU at the time of endoscopy were evaluated. The presence of H. pylori infection was determined by RUT, microbiology, and histology. Consecutive patients with uncomplicated DUs were similarly evaluated. The prevalence of H. pylori as determined by the RUT alone was compared to that determined by a combination of all tests in both patient groups. RESULTS: Fifty-five patients with bleeding DUs and 69 with nonbleeding DUs were evaluated. The prevalence of H. pylori in patients presenting with bleeding was 72.7% (95% confidence interval [CI] 61.0-84.5%) and lower than the prevalence rate of 92.8% (95% CI 86.6-98.8%) in patients with uncomplicated PUD (p < 0.05). The prevalence of H. pylori in the bleeding DU group as determined by RUT alone (54.5%) was less than that determined by a combination of all tests (73%) with a false-negative rate of 10 of 40 (25%; 95% CI 11.6-38.4%) (p < 0.05). This false-negative rate was significantly greater than that observed in the group presenting with dyspepsia (1 of 64 [1.6%; 95% CI 0-4.6%]) (p < 0.01). CONCLUSIONS: The prevalence of H. pylori is lower in patients with bleeding DUs when compared to patients with uncomplicated DUs. In addition, the sensitivity and negative predictive value of the RUT is lower in patients presenting with bleeding, and other methods of H. pylori diagnosis should be used in this patient group.

Adult↗

PubMed1999

13C-urea breath test results in pigs challenged with Helicobacter pylori or other urease producing bacteria.

The gastric bacterial flora and its influence on the 13C-urea breath test (UBT) for detection of Helicobacter pylori infection was studied in a pig model. Seven SPF minipigs were used. H. pylori or a mix of other urease positive bacteria were administered orally. UBT, serum and biopsies for histology and culture were collected. Our results show that UBT is not specific for H. pylori in pigs as the gastric bacterial flora is responsible for the high UBT values observed. Furthermore, the Ellegaard Göttingen SPF minipigs are not useful in an animal model for H. pylori studies.

Animals↗

PubMed1980

Capillary size, density and ultrastructure in brain of rats with urease-induced hyperammonaemia.

The capillary diameter, the capillary area as percentage of brain area, the minimal intercapillary distance, the harmonic mean basement membrane thickness and the mitochondrial content of capillary endothelium were estimated in the striatum of normal rats and after 4 days' urease-induced hyperammonaemia. Electronic image analysis, planimetry and classification with a ruler were the methods used. The capillary diameter was increased after 4 days' hyperammonaemia. The mitochondrial content of capillary endothelium was decreased after hyperammonaemia, while all other parameters were unchanged. Using an inverse logarithmic transformation, the distribution of the basement membrane intercepts was approximately normal. The increased capillary diameter could be a result of vascular paralysis induced by hyperammonaemia. The metabolic working capability is decreased in hyperammonaemia but the diffusion properties across the basement membrane and in the brain parenchyma appear from a morphological point of view to be unchanged.

Ammonia↗

PubMed2006

Verification, characterization and tissue-specific expression of UreG, a urease accessory protein gene, from the amphioxus Branchiostoma belcheri.

UreG genes have been found in bacteria, fungi and plants but have not yet identified in animals, although a putative UreG-like gene has been documented in sea urchin. In the course of a large-scale sequencing of amphioxus gut cDNA library, we have identified a cDNA with high similarity to UreG genes. Both reverse transcription-polymerase chain reaction and nested polymerase chain reaction, as well as in situ hybridization histochemistry, verified that the cDNA represented an amphioxus UreG gene (AmphiUreG) rather than a microbial contaminant of the cDNA library. This is further supported by the presence of urease activity in amphioxus gut, gill and ovary. AmphiUreG encodes a deduced protein of 200 amino acid residues including a highly conserved P-loop, bearing approximately 46%-49%, 44%-48%, and 29%-37% similarity to fungal, plant and bacterial UreG proteins, respectively. It shows a tissue-specific expression pattern in amphioxus, and is especially abundant in the digestive system. This is the first UreG gene identified in animal species.

Amino Acid Sequence↗

PubMed1966

Urease activity in blue-green algae.

The apparent enzymatic hydrolysis of urea has been detected in whole blue-green algae and in cell extracts. Urease is present as an intracellullar component in cultures in which no bacterial contaminants are found. The activity in the cells was recovered from the extracts.

Ammonia↗

PubMed1991

In vitro measurement of the adherence of Staphylococcus epidermidis to plastic by using cellular urease as a marker.

A rapid and sensitive in vitro assay was developed to quantitatively assess the adherence of Staphylococcus epidermidis to a hydrophobic plastic surface. The assay is based upon the detection of cell-associated urease activity as a marker of bacteria remaining adherent to the polystyrene microwells of flat-bottomed, 96-well tissue culture plates. Using ATCC 35984, a slime-producing strain of S. epidermidis, the assay could detect as few as 3 x 10(3) bacteria and was linear to 3.5 x 10(7) bacteria. The adherence of both slime-positive and slime-negative coagulase-negative staphylococci could be evaluated by using this method. This assay could be used to examine factors which influence the adherence of individual S. epidermidis strains to hydrophobic surfaces and to develop agents or coating materials which suppress the adherence of coagulase-negative staphylococci to biomedical implants.

Bacterial Adhesion↗

PubMed2003

Characterization of urease-positive thermophilic Campylobacter subspecies by multilocus enzyme electrophoresis typing.

Thirty-one urease-positive thermophilic Campylobacter (UPTC) isolates, including three reference strains (NCTC12892, NCTC12895 and NCTC12896), and three Campylobacter lari isolates, which were isolated from several countries and sources, were compared genotypically by using multilocus enzyme electrophoresis (MLEE). We examined allelic variation around seven enzyme loci, including the adenylate kinase, alkaline phosphatase, catalase, fumarase, malic enzyme, malate dehydrogenase, and L-phenylalanyl-L-leucine peptidase loci. MLEE typing revealed the presence of 23 different electrophoretic types (ETs) among the 31 UPTC isolates, and 14 isolates shared six electrophoretic profiles. Three different ETs were identified for the three C. lari isolates examined, and no ETs were shared by UPTC and C. lari isolates. Quantitative analyses were subsequently performed by using allelic variation data, and the results demonstrated that the mean genetic diversity was 0.655. In conclusion, MLEE demonstrated that the UPTC isolates examined are genetically hypervariable and form a cluster separate from the C. lari cluster.

Bacterial Typing Techniques↗