Helicobacter species infect the gastrointestinal tracts of many animals from birds through humans. Some of these have been linked to a range of human diseases including chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma, and gastric adenocarcinoma. The principal Helicobacter infection in humans is Helicobacter pylori, with infection rates in developing countries reaching 50 percent to 90 percent. Human gastric biopsy samples, however, have shown to harbour bacteria which were morphologically different from H pylori. These include Helicobacter heilmannii and Helicobacter felis which are primarily pathogens of domestic animals and were later found to infect humans as well. Gastric non-Helicobacter pylori helicobacters constitute a diverse group of bacterial species that are known to colonise the gastric mucosa of several animals. These include morphologically distinct, typically long spiral shaped bacteria originally referred to as Gastrospirillum hominis and later as H heilmannii. The latter was further subdivided in two taxa: types 1 and 2. H heilmannii type 1 are identical to H suis which colonises the stomachs of pigs. The former H heilmannii type 2 represent a group of species, known to colonise the gastric mucosa of dogs and cats and include H felis, H bizzozeronii, H salomonis, H cynogastricus, H baculiformis and a bacterium provisionally named in 2004 as ‘Candidatus H heilmannii’ because at that time, it could not be cultured in vitro. However, recently, in vitro cultures have been obtained resulting in description of H heilmannii, as a novel Helicobacter species. Sequencing of the 16S or 23S rRNA-encoding genes allows differentiation of H suis from the other gastric non-H pylori helicobacters species, but it cannot distinguish between H felis, H bizzozeronii, H salomonis, H cynogastricus, H baculiformis and Candidatus H heilmannii. For differentiation between these species, sequencing of the heat shock protein 60 or gyrase B gene is used, while sequencing of the urease A and B genes is considered to be the most suitable method since sequences of these genes are available. Dyspepsia describes a variety of symptoms, including abdominal pain, bloating, nausea, and vomiting. In these patients, endoscopy is considered to rule out gastroesophageal reflux disease, peptic or duodenal ulcer and gastric cancer. The role of H pylori infection in dyspepsia remains controversial. This study aims to identify the prevalence of H pylori and non-H pylori helicobacters, H felis and H heilmannii and to analyse the gastric pathology associated with coinfection of these organisms in patients presenting with dyspepsia.
STUDY POPULATION: Between September 2009 and February 2011, a total of 250 patients with abdominal pain or discomfort who attended the gastroenterology outpatient clinic at a tertiary care hospital in Karachi were enrolled. The mean age of these patients was 39 ± 12 years, (range 18-75) with males 162 (65 percent) and females 88 (35 percent). Of these, 136 (54 percent) were in the age group of 18-39 years, 88 (35 percent) in the group of 40-55 years and 26 (10 percent) in the group of 56-75 years. Ethical approval for the study was obtained from the Aga Khan University Ethics Review Committee. Informed consent was taken for participation in the study. A complete socio-demographic questionnaire including determination of socio-economic status, educational level, ownership of the place of residence, number of rooms in the house, number of people living in the household beside siblings, source of water supply, for example, municipal water pipeline or bore water (ground water) and type of latrine in use, was obtained from the patients. A history of exposure of enrolled patients to cats and dogs was determined and a physical examination was carried out. Inclusion criteria were ambulatory adult males and non-pregnant females; age 18 years or older; and patients with upper GI symptoms including abdominal/epigastric pain or discomfort, postprandial abdominal distension, postprandial nausea and vomiting. Exclusion criteria included receiving treatment for H pylori, concurrent or recent antibiotic use such as metronidazole, clarithromycin, amoxicillin, tetracycline, doxycycline and other cephalosporin; histamine-2 receptor blocker or proton pump inhibitor therapy and bismuth compounds in the last four weeks; patients with regular use of NSAID; patients with severe concomitant disease; and patients with upper GI surgery. A crowding index with three categories was constructed by dividing the number of individuals per household by the number of the rooms used as bedrooms. A participant’s household crowding was defined as ‘low’ if they scored an index of 0-1, ‘moderately-crowded’ were 2-4 and > 4 were ‘highly crowded’. On EGD, 242 (97 percent) were found to have endoscopic gastritis alone, while 8 (3 percent) had duodenal ulcer. Biopsy specimens from the gastric corpus and antrum were taken for rapid urease test (RUT) or histopathology for the diagnosis of H pylori and DNA extraction for polymerase chain reaction (PCR) to amplify H pylori, H felis and H heilmannii genes. Ninety patients (36 percent) out of 250 had a RUT done, while 160 (64 percent) out of 250 had histology and provided gastric biopsy specimen for the detection of Helicobacter species.
RESULTS AND DISCUSSION: Majority of the patients with H pylori infection were in the age range of 18-39 years, while H felis and H heilmannii positive patients did not show this distribution. There was no difference in the gender, ethnicity of patients, crowding index (CI) and source of water distribution among the patients with H pylori and non-H pylori infections. All patients had abdominal pain with endoscopic gastritis as the predominant finding. The false positive and false negative results obtained with RUT were 15 (36 percent) and 6 (12 percent), respectively, while with histology the false positive and false negative results obtained were 20 (30 percent) and 10 (11 percent), respectively. Univariate analysis was performed by using the independent sample t-test, Pearson’s chi-squared test or Fisher’s exact test where appropriate. A p-value of