Polymerase chain reaction in the detection of Helicobacter pylori infection.

OBJECTIVE: To determine the presence of Helicobacter pylori (H. pylori) infection, in patients suffering from gastritis and peptic ulcer disease by polymerase chain reaction (PCR) and correlate the results with the histological diagnosis. DESIGN: Analytical, comparative study. PLACE AND DURATION OF STUDY: Section of Gastroenterology, Department of Medicine and Pathology, Aga Khan University Hospital and School of Life Sciences and Chemical Technology, Ngee Ann Polytechnic, Singapore from November, 2001 to December, 2002. PATIENTS AND METHODS: Gastric antral biopsies were obtained from 64 patients attending the Gastroenterology Section of Aga Khan University Hospital. Patients on nonsteroidal-anti-inflammatory drugs (NSAIDS) were excluded. Gastric biopsies were sent for histopathology and used for DNA extraction and PCR amplification of H. pylori 16S ribosomal RNA (rRNA) gene. Results were compared and statistically analyzed. RESULTS: H. pylori were not visible by histology in 57.6 % (34/59) and could be seen in 42.4 % (25/59). PCR test was negative for H. pylori DNA in 44.1 % (26/59) and positive in 55.9 % (33/59) with p<0.001. CONCLUSION: PCR H. pylori DNA is a sensitive method for the diagnosis of H. pylori infection and its use as a diagnostic tool along with histology increases the detection rate of H. pylori infection. Two different staining methods for the organism should be used to avoid missing diagnosis of H. pylori infection.

Irritable bowel syndrome: in search of an etiology: role of Blastocystis hominis.

This study was designed to examine stool specimens of irritable bowel syndrome (IBS) patients for Blastocystis hominis, a common intestinal parasite. One hundred fifty patients were enrolled, 95 IBS cases and 55 controls. These patients provided a medical history, and underwent physical and laboratory evaluations that included stool microscopy and culture for B. hominis and colonoscopy. The 95 cases (51 males and 44 females) had a mean +/- SD age of 37.8 +/- 13.2 years. Stool microscopy was positive for B. hominis in 32% (30 of 95) of the cases and 7% (4 of 55) of the controls (P = 0.001). Stool culture was positive in 46% (44 of 95) of the cases and 7% (4 of 55) of the controls (P < 0.001). Stool culture for B. hominis in IBS was more sensitive than microscopy (P < 0.001). Blastocystis hominis was frequently demonstrated in the stool samples of IBS patients; however, its significance in IBS still needs to be investigated. Stool culture has a higher positive yield for B. hominis than stool microscopy.

Polymerase chain reaction-based genotype classification among human Blastocystis hominis populations isolated from different countries.

Since the genotype of human Blastocystis hominis isolates is highly polymorphic, PCR-based genotype classification using known sequenced-tagged site (STS) primers would allow the identification or classification of different genotypes. Five populations of human B. hominis isolates obtained from Japan, Pakistan, Bangladesh, Germany, and Thailand were subjected to genotype analysis by using seven kinds of STS primers. Ninety-nine out of 102 isolates were identified as one of the known genotypes, while one isolate from Thailand showed two distinct genotypes and two isolates from Japan were negative with all the STS primers. The most dominant genotype among four populations, except for all four isolates from Thailand, was subtype 3 and it varied from 41.7% to 92.3%. The second most common genotype among four populations was either subtype 1 (7.7-25.0%) or subtype 4 (10.0-22.9%). Subtype 2, subtype 5, and/or subtype 7 were only rarely detected among the isolates from Japan and Germany, while subtype 6 was not detected. The phylogenetic position of the two isolates which were negative with all STS primers, was inferred from the small subunit rRNA (SSU rRNA) genes with the known sequence data of 20 Blastocystis isolates. Since the two isolates were positioned in an additional clade in the phylogenetic tree, this suggested they were a new genotype. These results demonstrated that PCR-based genotype classification is a powerful tool with which to analyse genotypes of Blastocystis isolates obtained from clinical samples. In addition, two groups of the isolates from 15 symptomatic and 11 asymptomatic patients in Bangladesh were compared with the PCR-based subtype classification. Since both groups were only classified into two distinct genotypes of subtype 1 or subtype 3 and no statistically significant difference was observed between the two groups, in this study it could not be shown that the specific genotype correlated with the pathogenic potential of B. hominis.

The presence of antiamoebic constituents in psyllium husk.

The crude extract of psyllium husk (ispaghula) and its active constituent (petroleum fraction) caused varying degrees of growth inhibition in three different species of Entamoeba, i.e. Entamoeba histolytica, E. invadens and E. dispar. The inhibitory effect of the crude extract was in the dose range of 1-10 mg/mL, whereas a similar inhibitory effect was obtained with the petroleum fraction at a much lower dose (0.1-1.0 mg/mL), indicating that the active chemical(s) is/are concentrated in the petroleum fraction. These data support the traditional use of psyllium husk in amoebic dysentery.

Atlas color de parasitología clínica

Trata amebas infecciosas para el hombre,flagelados intestinales y genitales, Balantidium coli, parásitos del paludismo, toxoplasma gondii, sarcocystis e isospora, cestodes, trematodes, nematodes, etc