ABSTRACT: Malignant tumours of the stomach are common, but the incidence of stomach cancer varies from country to country, probably a result of genetic, epigenetic and environmental factors. Stomach cancer often occurs in older people whose stomachs produce only small quantities of acid. Although infection with Helicobacter pylori has been proven beyond doubt in the aetiopathogenesis of various gastric disorders, not much is known about the genotypes of H pylori infection in early-onset gastric cancer.
To ascertain the genotypes of H pylori in gastric cancer.
Ninety-two patients were separated into three groups on the basis of their endoscopic findings: group 1, gastric cancer; group 2, gastric ulcer; group 3, non-ulcer dyspepsia. Gastric biopsy specimens were obtained for culture and DNA isolation; additional specimens were taken from subjects with gastric cancer for histopathological analysis. Amplification was performed using specific oligonucleotide primers to obtain genotypic data. Four samples from each group were randomly selected for sequence analysis.
Genotypic analysis showed cagT+ve/hrgA+ve/cagA+ve/cagE+ve/vacAs1+ve to be highly prevalent in 79% of cases of H pylori infection. This genotype was found in 88% of subjects in group 1 and 78% in group 2. Intestinal-type adenocarcinoma was found in 35 subjects (83%), 32 (9%) of which harboured this genotype. Sequence analysis showed no significant strain-specific variations.
Certain genotypes of H pylori have higher predictive value for the development of intestinal-type carcinoma at an early age. Genotyping of H pylori may well be a useful tool for screening people at increased risk of developing malignancy.
Postgraduate medical journal 05/2008; 84(990):193-7. · 1.38 Impact Factor
ABSTRACT: To evaluate and develop a multiplex polymerase chain reaction (PCR) assay for diagnosing and specific identification of virulent Helicobacter pylori strains and their main virulence genes cagA, cagE, cagT, vacA and hrgA.
Genomic DNA from 82 gastric tissues was screened. A master pool of all the ingredients of multiplex reaction was prepared for amplification. Amplicons were sequenced to confirm the amplification of each target genes. Multiplex PCR assay was able to detect all the five target genes in 81.7% and deletions in one or more loci among 18.3%. Genotype cagT +ve/hrgA +ve/cagA +ve/cagE +ve/vacAs1 +ve was more predominant in this study population (67.07%). hrgA, cagT, cagE and cagA genes were present in 100%, 92.7%, 85.4% and 81.7% of the subjects, respectively. The vacAs1 subtype had higher prevalence frequency in patients with overt gastrointestinal disease (78.57%) than with GERD (gastro-esophageal reflux disease) and NUD (non-ulcer dispepsia) (50%).
The multiplex PCR assay developed herein was able to genotype H. pylori isolates based on the main virulence genes.
The ability to identify H. pylori and the majority of their virulence gene markers by multiplex PCR assay represents a considerable advancement over other PCR-based methods for genotyping H. pylori from large population, and can be explored to gain insights at the genotypic variability exhibited by this pathogen.
Journal of Applied Microbiology 01/2008; 103(6):2353-60. · 2.34 Impact Factor
ABSTRACT: In developing countries, the Helicobacter pylori (H. pylori) infection rate is high, especially in lower socioeconomic groups. The populace in developing countries lives in conditions that are highly conducive to the acquisition of microorganisms. Poor hygiene, crowded household conditions and deficient sanitation mark their day-to-day life. We aimed to find out the roles of household hygiene and water source in the prevalence and transmission of H. pylori infection among the South Indian population using polymerase chain reaction (PCR) assay.
The selected population consisted of 500 adults of varying ages ranging from 30 to 79 years, with upper gastrointestinal tract symptoms. Each participant in the study was given a questionnaire to complete. Samples to assess H. pylori infection included three gastric biopsies (two from the antrum and one from the corpus region). Infection was detected by PCR amplification of the 16S rRNA gene of H. pylori. The data was then examined statistically by univariate and multivariate analyses.
The overall prevalence of H. pylori was detected to be 80 percent. Prevalence increased with an increase in age and it was found to be 90 percent in the 70-79 year age group (p-value is less than 0.01). The prevalence of infection among people who drank water from wells was 92 percent compared with 74.8 percent of those who drank tap water (p-value is less than 0.001). H. pylori infection prevalence was found to be higher in people with low clean water index (CWI) (88.2 percent) than in those with higher CWI (33.3 percent) (p-value is less than 0.001). While the prevalence of H. pylori in the subjects with lower socioeconomic status was 86.1 percent, in higher groups, it was 70 percent (p-value is less than 0.001). The prevalence of H. pylori was also found to be higher in subjects who lived in overcrowded houses. It was 83.7 percent with high crowding index, 76.6 percent with medium crowding index, and 71.3 percent with low crowding index (p-value is less than 0.05).
The results of the present study suggest that the risk of acquisition and transmission of H. pylori can be prevented to a large extent by following improved household hygienic practices, proper waste disposal measures as well as the regular use of boiling water for drinking purposes.
Singapore medical journal 07/2007; 48(6):543-9. · 0.73 Impact Factor
ABSTRACT: Since the discovery of Helicobacter pylori (H. pylori), much progress has been made worldwide in the field of its epidemiology. In spite of these advancements, many aspects of epidemiology still remain unclear, particularly among populations with low socio-economic status. The present study was designed to elucidate the different routes of transmission of H. pylori in the Hyderabad (South India) population and to investigate the impact of certain factors, such as age, gender, and lifestyle.
Samples used for the study included saliva and biopsy samples of 400 symptomatic subjects from Hyderabad, India. The patients were retrospectively grouped, based on histopathology of the biopsy and 16S rRNA amplification of both saliva and biopsy as H. pylori positive and negative.
This study showed that the prevalence of H. pylori in both saliva and biopsy samples increased with age. In addition, the H. pylori infection was found more commonly in the saliva and biopsy samples among males (64 percent and 60 percent, respectively) than females (53.3 percent and 64 percent, respectively). Similarly, 71.6 percent and 73.5 percent of those who consumed municipal water acquired H. pylori (which were respectively found in their saliva and biopsy samples) compared to a lesser proportion (12.6 percent and 12.6 percent, respectively) of those who consumed boiled or filtered water. The study also found that subjects who preferred home-cooked food (57.1 percent and 57.7 percent) showed a lower prevalence of H. pylori in saliva and biopsy samples, respectively, compared to those (80 percent and 88 percent) who frequently ate out.
The results of the present study suggest that besides the oral-oral route, the transmission of H. pylori also takes place through the consumption of food prepared under unhygienic conditions. Consumption of municipal tap water also has a high impact in the transmission of H. pylori.
Singapore medical journal 05/2006; 47(4):291-6. · 0.73 Impact Factor
ABSTRACT: Current guidelines that recommend Helicobacter pylori eradication treatment without endoscopy in selected patients underscore the importance of non-invasive testing. The accuracy of saliva as a non-invasive specimen was compared with that of invasive tests in pretreatment diagnosis of H. pylori infection.
One hundred patients undergoing gastroscopy were grouped into 80 symptomatic and 20 asymptomatic subjects and were investigated for the presence of H. pylori in saliva and stomach. Samples tested comprised saliva and gastric biopsies collected from each patient. Exclusion criteria were history of peptic ulcer, bleeding ulcer, cancer or recent use of antibiotics, proton pump inhibitors and non-steroidal anti-inflammatory drugs. Two sets of primers homologous to 534 bp fragment of H. pylori DNA, which have been shown previously to be highly specific and sensitive, were used for the polymerase chain reaction (PCR) amplification.
72 (90 percent) of the symptomatic group and 10 asymptomatic subjects were infected with H. pylori in the stomach as determined by histology and direct PCR amplification of biopsy DNA obtained from each subject. H. pylori DNA was identified in the saliva of 70 (87.5 percent) symptomatic subjects and 12 (60 percent) asymptomatic control subjects.
High rates of detection using saliva as a specimen indicate that saliva of the infected person could serve as a reliable non-invasive alternative to detect the presence of H. pylori infection in comparison to the currently available standard diagnostic tests.
Singapore medical journal 06/2005; 46(5):224-8. · 0.73 Impact Factor