Background and Aim There are geographical variations in Helicobacter pylori virulence genes; cagA, cagE, vacA and oipA. The present study compared the distribution of these genotypes in major ethnic groups residing in Tehran, Iran and their association with clinical outcomes. Methods A total of 124 H. pylori-positive patients living in Tehran were enrolled in this study. The ethnic distribution was 74 Persians, 33 Turks and 17 other ethnics including Kurds, Lurs, Afghanis and Arabs. The presence of the cagA, cagE and oipA genes and vacA alleles (signal [s] and middle [m] region) were determined by polymerase chain reaction (PCR) from H. pylori DNA. Results The cagA-positive status was predominant in all three ethnic groups (e.g. 65% in Persians and 73% in Turks). In contrast, the cagE-positive status was less than half in Persians (47%) and Turks (30%), whereas it was 77% in other ethnicities (P = 0.008). The predominant vacA genotypes were s1 and m1 in all three ethnic groups (e.g. 68% in Persians and 70% in Turks were s1). There was no significant association between cagA and cagE status or vacA genotypes and clinical outcomes. The oipA-positive strains were more common in non-ulcer dyspepsia (NUD) (63%) than in peptic ulcer patients (15%) (P = 0.001) in Persians, but the association was not observed in other ethnic groups. Conclusion There are some differences in the H. pylori genotypes among the ethnic groups in Iran. However, none of these markers seemed to be clinically helpful in predicting the clinical presentation of a H. pylori infection in Iran.
Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested. INTRODUCTIONEnteropathogenic Escherichia coli (EPEC) is one of the major causes of diarrhoea among children in developing countries (Hernandes et al., 2009;Moura et al., 2009). The pathogenesis of EPEC depends on the locus of enterocyte effacement (LEE), a chromosomal pathogenicity island. The LEE contains a number of different genes, including eae, which has an essential role in inducing a characteristic lesion formation in the intestinal epithelium, termed an attaching and effacing (A/E) lesion (Elliott et al., 1998;Vallance & Finlay 2000;Kaper et al., 2004). The eae gene encodes intimin, a 94 kDa outer-membrane protein that is responsible for the intimate adherence between bacterial and enterocyte membranes (Vallance & Finlay, 2000;Trabulsi et al., 2002). EPEC strains are classified as typical or atypical, according to the presence or absence of the E. coli adherence factor plasmid (EAF) that carries the bfpA gene, which encodes the bundle-forming pili (Hernandes et al., 2009). The most typical EPEC strains belong to the classic O : H serotypes and are eae-and bfpA-positive (Ochoa et al., 2008). The atypical EPEC isolates are eaepositive and bfpA-and stx (the gene encoding shiga-like toxin)-negative. EPEC are among the most important pathogens infecting children under 2 years of age in the developing world (Ochoa et al., 2008). Recent studies indicate that atypical EPEC is more prevalent than typical Abbreviations: EPEC, enteropathogenic Escherichia coli; LEE, locus of enterocyte effacement; PFGE, pulsed-field gel electrophore...
Methicillin resistant Staphylococcus aureus (MRSA), particularly strains with type III staphylococcal cassette chromosome mec (SCCmec), represent a serious human pathogen in Tehran, Iran. The disease-causing capability depends on their ability to produce a wide variety of virulent factors. The prevalence of exotoxin genes and multiple-locus variable number of tandem repeats fingerprinting (MLVF) profile among MRSA isolates, from patients in Tehran, was evaluated by PCR and Multiplex-PCR. The MLVF typing of 144 MRSA isolates with type III SCCmec produced 5 different MLVF types. Generally, 97.2% (140/144) of all the isolates were positive for at least one of the tested exotoxin genes. The most prevalent genes were hld, found in 87.5% (126/144) of the isolates followed by lukE-lukD and hla found in 72.9% (105/144) and 70.1% (101/144) of the isolates, respectively. The tst gene, belonging to MLVF types I, IV and V, was found among three of the isolates from blood and wound samples. The sea gene was detected in 58.3% (84/144) of the isolates and the sed and see genes were found in one isolate with MLVF type V. The coexistence of genes was observed in the 87.5% (126/144) of the isolates. The rate of coexistence of hld with lukE-lukD, hla with lukE-lukD and sea with lukE-lukD were 66.7% (96/144), 44.4% (64/144) and 44.4% (64/144), respectively. The present study demonstrated that MRSA strains with type III SCCmec show different MLVF patterns and exotoxin profiles.
Differences between the colonization sites of Helicobacter pylori might explain the different patterns of H. pylori‐induced gastrointestinal pathology. The migration of H. pylori from the antrum to the gastric body and fundus during omeprazole monotherapy has been reported in H. pylori‐infected subjects. The aim of this study was to determine the influence of pretreatment with omeprazole on later colonization by H. pylori, by use of the rapid urease test, culture, and the polymerase chain reaction on gastric samples obtained from the antrum and gastric body of non‐germ‐free immature rats. Pretreatment of rats with omeprazole did not significantly affect the incidence of H. pylori colonization during the four‐week study. The preferred ecological niche of H. pylori in rats was the antrum rather than the gastric body. This difference was significant in animals not treated with omeprazole but not in treated groups, i.e. frequent injection of omeprazole led to the equal distribution of H. pylori in the antrum and gastric body. If clinical investigations confirm these results more precautions should be taken in omeprazole monotherapy because it is well known that H. pylori colonization of the gastric body is associated with multifocal gastric atrophy, an important risk factor in gastric adenocarcinoma.
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