IDENTIFICATION OF HELICOBACTER PYLORI INFECTION IN PATIENTS WITH UPPER GASTROINTESTINAL DISEASES, AND ITS ANTIMICROBIAL SENSITIVITY

H.pylori is the cause of duodenal ulcer, and a lot of other gastrointestinal diseases, the aim of this study was to see the extent of this microorganism in our patients and to study its antimicrobial sensitivity. The study included 283 patients(148 males and 135 females) with upper gastrointestinal complaints including dyspepsia, heartburn, bleeding, and malabsorption to evaluate the presence of Helicobacter pylori (H.pylori) infection using rapid urease test (RUT) and culture to see there sensitivity to different antibiotics. The study revealed that 199 patients (70.3%) have positive RUT compared to 218 patients (77.0%) showed positive culture results. The positive culture results were confirmed by positive results of biochemical tests (oxidase, catalase and urease). Antibiotic sensitivity testing was performed in 28 cultures of H. pylori, and the results showed that 26 cultures ( 92.9%) were sensitive to amoxycillin, followed by clarithromycin, rifampicin and cephalexin with figures of 23 (82.1%), 22 (78.6%) and 21 (75.0%) respectively. Whereas, 16 cultures (57.1%) were resistant to metronidazole, 15 (53.4%) to erythromycin and 9 (32.1%) to both cephalothin and tetracycline. It is concluded that, H.pylori infection is a predominant etiological factor of upper gastrointestinal diseases, Also, RUT represent simple, convenient and reliable mean for the rapid diagnosis of H.Pylori infection. Antibiotic sensitivity was the highest with amoxycillin and clarithromycin while the most resistant antibiotic strains were encountered with metronidazole. Introduction he discovery of Helicobacter pylori (H.pylori) infection as infective causative agent of peptic ulcer disease twenty years ago 1 , has revolutionized the etiology, pathogenesis and treatment of that disease. Now, and beyond any doubt, H.pylori infection represent the principal etiological factor of peptic ulcer 2, 3 and even gastric cancer 3 . The pathogenecity of H.pylori infection depends on the presence of virulence factors and the host response. The microorganisms resist gastric acidity and local host defense mechanisms 4 . H.pylori is able to live in the acidic medium of the stomach due to its ability to produce the enzyme "Urease" which hydrolyzes urea into one molecule of carbon dioxide and two molecules of ammonia which converted into ammonium hydroxide, which in turn, raises the pH of the surrounding medium 5 . H.pylori is the most common urease producing microorganism, next to Ureaplasma urelyticum. The toxic effect of urease to the host is related to the production of ammonium hydroxide resulting from urea hydrolysis. Ammonium hydroxide is toxic to the gastric cells, where the cellular viability is reduced with increasing ammonia concentrations generated from urea catabolism. The cellular viability T Identification of Helicobacter pylori Infection Saad Sh, Hammadi Bas J Surg, September, 11 2005 restored with addition of urease inhibitor, acetahydroxamic acid, which reduces the enzyme activity, and there by, the number of ammonia molecules generated 6 . There is a widely accepted evidence that H. pylori is sensitive to a broad spectrum of antimicrobial agents including amoxycillin, metronidazole and clarithromycin.It is resistant to low number of antimicrobials such as sulphonamides, nalidixic acid and vancomycin 7,8 . The aim of this study was to determine the prevalence of H.pylori infection among patients with upper gastrontestinal complaints, using rapid urease test (RUT) and microbiological identification, and its antibiotic sensitivity. Patients and Methods This is a prospective study carried out from July, 2000 throughout December, 2002, and included 283 patients with various upper gastrointestinal complaints including dyspepsia, heartburn, bleeding, and malabsorption. They were 148(52.4%) males and 135(47.6%) females. The age range 1870 years of age. Patients were subjected to upper gastrointestinal endoscopy at Al-Sadder Teaching Hospital, and then two biopsies from the gastric antrum were taken. The first one was used for the RUT while the second was retained to culture H. pylori in a microphilic conditions depending on a native gas pack which was qualified in culturing this bacterium 9 . RUT was done by dissolving 10 g of urea in 100 ml of distilled water, then 0.02g of phenol red indicator is added.20 ML of the solution is placed in plastic container, and the biopsy specimen is immersed in that container and the color change from yellow to pink is observed for an hour 10 . H. pylori are identified by several means, including Gram stain 11 , biochemical tests including oxidase 12 , catalase 12 and urease 7 tests. Antibiotic sensitivity testing was performed in 28 cultures of H. pylori, according to the availability of antibiotic discs 13 . Results Table I resents the diagnosis at endoscopy, where 46.3% of patients have gastritis, followed by duodenal ulcer (13.8%), gastritis and duodenal ulcer (11.3%), duodenitis (6.4%) and gastritis and duodenitis (6.4%). Normal endoscopy was confirmed in 9.2% of patients. As shown in TableII, RUT revealed that 199 patients (70.3%) were infected with H.pylori compared to 218 patients (77.0%) confirmed by microbiological means. Table III present findings biochemical tests in positive cultures (N = 218), where all showed positive tests of oxidase, catalase and urease. As presented Table IV amoxycillin showed the highest sensitivity rates, where 26 cultures (92.9%) were sensitive to it, followed by clarithromycin, rifampicin and cephalexin with figures of 23 (82.1%), 22 (78.6%) and 21 (75.0%) respectively. On the other hand, 16 cultures (57.1%) were resistant to metronidazole, 15 (53.4%) to erythromycin and 9 (32.1%) to both cephalothin and tetracycline. Discussion The diagnosis of H.pylori infection as a cause of peptic ulcer disease, focused the attention of researchers toward ulcer therapy and the use of antimicrobials for the eradication of infection, as it promotes the healing of ulcer and reduces the rate of it's recurrence 4 . The study revealed that 77.0% of patients have positive culture results. This finding is in agreement with other studies 14,15 . The positive results of Identification of Helicobacter pylori Infection Saad Sh, Hammadi Bas J Surg, September, 11 2005 cultures of H.pylori are supported by results of biochemical tests which showed positive tests in all cultures. This is similar to the observation of others 7,9,12 . The result of cultures in this study is satisfactory, as there is no ideal culture medium for cultivation of H.pylori, but it differs from one medium to another 12 . Urease production by H.pylori represent an essential step for its colonization in the gastric mucosa, as it provide alkaline environment surrounding the microorganism suitable for its survival through urea breakdown 4 . Also, the gastric juice in H.pylori infected patients contains high ammonia concentrations more than urea concentrations compared to noninfected subjects 16 . The RUT result was positive in 70.3% of patient, which is comparable to other results 17-20 .The urease present in the stomach of patients with gastrointestinal diseases is of infective origin, because its activity is abolished with antibiotic treatment 21 . However, negative result of RUT, in the presence of H.pylori infection, may be encountered in some cases due to low bacterial count in the biopsy specimen leading to false negative result 22 . The benefit of RUT arises from its convenience and feasibility, as it can be done in the endoscopy room, and the result can be obtained within one hour compared to 3-4 days of the culture results. The study revealed very high sensitivity rate of H. pylori to amoxycillin, which is in agreement with several studies published elsewhere in the world 23,24 , indicating a low resistance rate of H. pylori to this antibiotic. The sensitivity rate of H. pylori to clarithromycin was also high, and it is comparable to that of Realdi et al 25 , while it is different from other reports 12,26 . In western countries the resistance rate of H.pylori to clarithromycin reached to 60% due to the prolonged use of this somewhat expensive drug 26 , while it is a little bit new drug in our country. On the other hand, the widely used drug in the combination treatment for the eradication of H.pylori infection, metronidazole, showed the highest resistance rate among the tested antibiotics(57.1%), a result comparable to that of Bindyna 27 and Xiao et al 28 , while it is distinctly higher than that of Magraud 29 . This result can be explained by the irrational use of the drug as well as it's abuse in gastrointestinal complaints. This, in turn, necessitates further studies to clarify the effectiveness of metronidazole in the eradication strategy of H. pylori infection. In conclusion, H.pylori is the principal infective agent causing upper gastrointestinal disease. The RUT represent simple, rapid as well as satisfactory diagnostic tool of H.pylori infection. The highest antibiotic sensitivity rates were encountered with amoxycillin and clarithromycin, while the highest antibiotic resistance rates were encountered with metronidazole. Identification of Helicobacter pylori Infection Saad Sh, Hammadi Bas J Surg, September, 11 2005 Table I. Endoscopical diagnosis of the studied Patients