Increase in resistance rates of H. pylori isolates to metronidazole and tetracycline-comparison of three 3-year studies

Antimicrobials have been useful in the treatment of H.pylori-related dyspeptic diseases. However, emergence of resistant strains often decreases the eradication rates of H.pylori infections. Large-scale use of antimicrobials will lead to the diminishment of susceptible strains while allowing resistant survivors to outgrow and spread resistance genes. The aim of this study was to assess the change in antimicrobial resistance rate of H.pylori isolates from 2005 to 2008 and indicate the consequences of indiscriminate and widespread use of antimicrobials against H. pylori-and non-H.pylori-related infections. A total of 110 H. pylori strains were isolated from dyspeptic patients during 2005 to 2008 and tested for their susceptibility to antimicrobials using the disk diffusion method. MICs were determined for metronidazole [8 micro g/mL], tetracycline [0.5 micro g/mL], clarithromycin [2 micro g/mL], amoxicillin [1 micro g/mL] and furazolidone [0.5 micro g/mL]. Since the rates of resistance to metronidazole and tetracycline were remarkably high, another 50 isolates were tested for their susceptibility to metronidazole at the same MIC [8 micro g/mL] and tetracycline at MICs of 0.5, 1 and 2 micro g/mL. Resistance rates were compared to those obtained in our two previous studies between 1997-2000 and 2001-2004. The resistance rates of 110 H.pylori isolates to clarithromycin, amoxicillin and furazolidone were 7.3%, 7.3%, and 4.5%, respectively. Among 160 H.pylori isolates, 55.6% exhibited resistance to metronidazole and 38.1% to tetracycline. Compared to our two previous studies, the resistance rates of H.pylori isolates to current antimicrobials has changed over time. The change in resistance rates of clarithromycin, amoxicillin and furazolidone was not statistically significant. However, resistance to metronidazole and tetracycline showed a considerable increase from 33-36.3% to 55.6% and 0-0.7% to 38.1%, respectively. Emergence of resistance due to the intensive use of antibiotics has become a global public health problem. It appears that plasmid-carried genes are involved in the spread of resistance traits among bacteria. Results obtained in this study indicate that the increase in resistance rates of H.pylori isolates to metronidazole and tetracycline could be the indication of indiscriminate and frequent use of antibiotics in Iran

Detection of Helicobacter pylori infection by imported IgG ELISA kits in comparison with Iranian home made kit

Helicobacter pylori [Hp] is a gram negative, spiral shaped bacterium which colonizes the gastric mucosa and induces gastroduodenal complications varying from mild gastritis with no clinical complications to peptic ulcer diseases and even gastric malignancies. The rate of Hp infection is 30-50% in developed countries whereas it has been rated up to 80% of the adult population in developing countries like Iran. Hp infection can be detected by various diagnostic methods. Culturing biopsy specimens and Rapid Urease Test [RUT] are the most common and reliable tests which can manifest Hp infection through proper sampling but these methods are invasive ones due to the need for endoscopy procedure in isolation of biopsy specimen. Application of serological assays are being increasingly used for epidemiological studies and detecting systemic immune responses toward past Hp infection. ELISA assays are the most popular techniques particularly in cases with no previous treatment. In this study we tested three imported IgG ELISA kits which are available for clinical diagnostics in detecting host sero-reactivity to Hp infection and compared them with a home made IgG ELISA kit. Histology and RUT were used as the gold standard tests for determination of Hp positive vs. Hp negative subjects using biopsy specimens from antrum. Sensitivity, specificity, accuracy and other required criteria were evaluated for each ELISA kit. According to the results the original criteria [Sensitivity and specificity] for each kit were as follows: BIOHIT [41.6%, 100%], Trinity [100%, 86.6%], Pishtaz [100%, 86.6%], Home made [100%, 92.6%]. Evaluation of these different IgG ELISA kits originating from different parts of the world and cross comparison of the results indicated that the cut off values should be refined for user country in order to obtain the highest sensitivity and specificity. These differences can be due to the vast geographic heterogeneity among Hp antigens. Furthermore, this study showed that home made ELISA kit can be substituted for imported ELISA kits due to its valid serological criteria