Résumé
High prevalence of infections caused by extended-spectrum beta-lactamase [ESBL]-producing isolates, notably Escherichia coli, has been suggested in Egypt. As little is known about the genetic background of these isolates, ESBL-positive E. coli isolates obtained among 520 Enterobacteriaceae prospectively collected [May 2007 -August 2008] from inpatients [n=320] and outpatients [n=200] seen at the Theodor Bilharz Research Institute [Cairo], were characterized. Clinical epidemiology, antibiotic susceptibility, and genetic traits including bla gene, phylogenetic group, ERIC-2 PCR profile, multilocus sequence type [ST] were determined. Among the 520 collected Enterobacteriaceae, were 291 [56%] E. coli and 165 [32%] Klebsiella pneumoniae. A total of 16% of all Enterobacteriaceae were ESBL-producers: 19% in E. coli and 14% in K. pneumoniae. Of the E. coli ESBL-producers, 75% [n=41] were isolated from urine. Rates of ESBL producers did not differ significantly between in and outpatients for E. coli [20 vs 17%] but significantly for non E. coli ESBL producers [18.5 vs 1.2 %: p= 0.0001]. CTX-M-15 was identified in all ESBL producers. Of the E. coli ESBL producers, 40% belonged to phylogenetic group A, 32% to D and 26% to B2. The ERIC-2 PCR method showed genetic background diversity with clusters in each group having profiles indistinguishable to that of previously published clones: complex ST10 and ST131. MLST showed that 75% of E. coli group B2 belonged to clone ST131 and 15% to clones previously detected worldwide, ST73 and ST405. This study illustrates the dissemination of different E. coli clones producing CTX-M-15 in Africa, notably in outpatients
Résumé
The cag pathogenicity island [cagPAI] is one of the major virulence determinants of Helicobacter pylori [H. pylori]. Acquiring virulent strains of H. pylori is associated with increased risk for the development of gastric ulcers or cancer. The aim of this study was to determine H. pylori cagPAI genes pattern among dyspeptic Egyptian patients and its correlation with the varying degrees of the associated chronic gastritis. Histopathological examination, urease test and polymerase chain reaction [PCR] assay were performed for gastric antral biopsies obtained from 106 dyspeptic patients undergoing upper endoscopy. DNA extracts from H. pylori positive cases were analyzed for the presence of cagPAI genes cagA, cagE, cagM, tnpA, tnpB and cagT by using PCR assay. Apparently normal gastric mucosa was seen on endoscopy in 30.2% of dyspeptic patients while gastritis was diagnosed in 69.8% with significant difference [p<0.05]. H.pylori was detected in 71.7% of dyspeptic patients. A strong association was observed between H. pylori infection and gastritis patients [p<0.01]. The positivity rate of any of the cagPAI genes were 65.8% of H. pylori positive cases. Analysis of the entire cagPAI genes revealed that both cagA and cagE were the most predominant genes [30.2% , 18.4% respectively]. cagT and tnpB genes were not detected in all H. pylori positive gastric biopsies. The presence of the entire cagPAI genes was more substantiated in gastritis patients than in those with apparently normal mucosa [p<0.05]. The presence of cagA1/2, cagA3/4, cagM and cagE genes were significantly associated with moderate degree of gastritis [p<0.02], while tnpA gene was mostly detected in marked degree of gastritis [p<0.02]. In conclusion, it can be admitted that infection with virulent strain carrying cag PAI genes may be an indication of the risk of progression of gastric mucosal damage in chronic gastritis patients. In such country as Egypt where there is a high prevalence of H. pylori infection, cagPAI genotyping is important for prediction of the clinical outcome in H. pylori related gastritis aiming at eradication of infection before the progression to severe gastroduodenal diseases
Résumé
Increased expression of inducible nitric oxide synthase [iNOS] has been observed in patients with chronic inflammatory diseases of the gastrointestinal tract leading to sustained production of nitric oxide [NO] which may induce DNA damage. Since Helicobacter pylori [H. pylori] infection produces a state of chronic immunostimmulation in the gastric epithelium and a causal relationship between H. pylori CagA+ strains infection and gastric cancer has been suggested, therefore, our aim was to evaluate the significance of iNOS expression in gastric lesions induced by H. pylori CagA+ strains with correlation to the encountered endoscopic and pathological diagnoses. Eighty four dyspeptic patients underwent endoscopic examination. Four antral gastric biopsies were obtained for detection of H. pylori by histopathological assessment [Giemsa staining], urease test and gene expression of H. pylori using PCR assay. Immunohistochemical staining for iNOS expression and quantitative detection of anti-CagA antibodies were performed. It was found that H. pylori infection was detected in 64.3%, CagA seropositivity in 54.8% and iNOS expression in 61.9%. Anti-CagA antibodies seropositivity and iNOS immunoexpression were significantly related to H. pylori infection. The positive rates of iNOS immunostaining increased with the lesion progression from chronic superficial gastritis to chronic atrophic gastritis to intestinal metaplasia [45.2%, 87.5% and 92.8% respectively]. Positive immunostaining rates of iNOS correlated significantly with H.pylori Cag A seropositivity with respect to both endoscopic and pathologic diagnoses. In conclusion, CagA+ H. pylori strains are associated with enhanced immunoexpression of iNOS in H. pylori-related gastric diseases, therefore they might contribute as risk cofactors that conduces to gastric carcinogenesis. Given the high prevalence of H. pylori gastric diseases and frequent performance level of endoscopic gastric examinations among Egyptian patients, prompt identification of gastric infections caused by H. pylori harboring Cag A virulence factor is necessary for the early eradication of infection before the development of pre-neoplastic lesions