Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

Helicobacter pylori infection is the major risk factor for gastric adenocarcinoma. The link with gastric adenocarcinoma is partly due to the H. pylori CagA oncoprotein. CagA is responsible for a particular cell phenotype in vitro, the 'hummingbird' phenotype, that corresponds to an elongation of the cells, mimicking an epithelial-mesenchymal transition (EMT). EMT participates in the carcinogenesis process, and is involved in the generation of cancer stem cells (CSCs). However, its involvement in gastric carcinogenesis has yet not been studied. Therefore, the aim of this study was to determine the role of H. pylori in EMT and in the emergence of gastric CSCs. For this purpose, gastric epithelial cells were cocultured with a cagA-positive H. pylori strain or its isogenic-deleted mutants or were transfected with CagA expression vectors. Study of the expression of epithelial and mesenchymal markers showed that H. pylori, via CagA, is responsible for an EMT phenotype associated with an increase in mesenchymal markers as well as CD44 expression, a known gastric CSC marker. Moreover, infection led to an increased ability to migrate, to invade and to form tumorspheres. Cell sorting experiments showed that only the CD44(high) cells induced by H. pylori infection displayed the mesenchymal phenotype and CSC properties in vitro, and had higher tumorigenic properties than CD44(low) cells in xenografted mice. Immunohistochemistry analyses on human and mouse gastric mucosa tissue samples confirmed a high expression of CD44 and mesenchymal markers in H. pylori-infected cases, and in gastric dysplasia and carcinoma. All of these data suggest that H. pylori, via CagA, unveils CSC-like properties by induction of EMT-like changes in gastric epithelial cells.

Campylobacter species, especially Campylobacter jejuni and Campylobacter coli, are a major cause of human bacterial enteritis. Current detection in stools is done essentially by culture on selective and nonselective media with filtration. These methods were compared to 2 molecular biology methods, an in-house real-time PCR and a multiplex PCR named Seeplex Diarrhea ACE Detection, and 3 immunoenzymatic methods, Premier Campy, RidaScreen Campylobacter, and ImmunoCard Stat!Campy. Out of 242 stool specimens tested, 23 (9.5%) fulfilled the positivity criteria, i.e., they were positive by one or both culture methods or, in case of a negative culture, by a positive molecular method and a positive immunoenzymatic method. The striking feature of this study is the low sensitivity of culture, in the range of 60%, in contrast to immunoenzymatic and molecular tests.The incidence of Campylobacter-associated food poisoning has gradually increased, and the organism is now considered to be the leading cause of bacterial gastroenteritis worldwide (4). These infections can also lead to extraintestinal diseases and severe long-term complications (9). Campylobacter jejuni and Campylobacter coli are the most frequently isolated species in this context and in our experience account for 80% and 16%, respectively, of all the isolates received in our laboratory every year (2a). Campylobacter species are bacteria with a special culture requirement, i.e., a microaerobic environment. During stool processing, the bacteria may have long contact with a normal atmosphere, and in addition, the progressive decrease in oxygen tension when gas-generating kits are used may not favor adequate growth. Furthermore, selective media are commonly used, and the antibiotics incorporated may inhibit certain Campylobacter strains. Anecdotal data have shown that spiral or curved bacteria are sometimes observed on stool smears while Campylobacter growth does not occur. In a recent study, DNA sequences of the Campylobacter genome were detected by a metagenomic analysis, while the standard culture methods were negative (5). In a pilot study using real-time PCR as a diagnostic tool, we also detected more campylobacters than with culture, but without being able to confirm that true positives were detected, since, at that time, we did not use multiple detection methods to establish positivity when culture was negative. Some immunoenzymatic tests have already been commercialized for several years, such as the ProSpecT Campylobacter Microplate Assay (Remel) (8) and the RidaScreen Campylobacter (R-Biopharm, Darmstadt, Germany) evaluated in our study. In this study, we took advantage of the availability of several kits to compare Campylobacter detection by molecular methods (2 PCRs) and by 3 immunoenzymatic methods to the standard culture methods. MATERIALS AND METHODS Materials.From 15 June to 30 October 2009, every stool specimen obtained from a symptomatic patient, i.e., a patient with a gastrointestinal illness, who was hospitalized for less than 48 h at Pellegrin H...

Helicobacter pylori infection is now recognized as the main and specific infectious cause of cancer in the world. It is responsible for gastric adenocarcinomas of both intestinal and diffuse types, which are the long-term consequences of the chronic infection of the gastric mucosa. Case-control studies have shown an association between the two, recognized as early as 1994 and further substantiated by interventional studies in which H. pylori eradication has led to the prevention of at least part of the gastric cancers. Experimental studies have highlighted the role of bone marrow-derived cells (BMDCs) and particularly mesenchymal stem cells, in the neoplastic process in about a quarter of the cases and possibly an epithelial-mesenchymal transition (EMT) in the other cases. Different studies have confirmed that chronic infection with H. pylori induces a chronic inflammation and subsequent damage of the gastric epithelial mucosa, leading to BMDC recruitment. Once recruited, these cells home and differentiate by cell-cell fusion with local gastric epithelial cells, bearing local stem cell failure and participating in tissue regeneration. The context of chronic infection and inflammation leads to an EMT and altered tissue regeneration and differentiation from both local epithelial stem cells and BMDC. EMT induces the emergence of CD44+ cells possessing mesenchymal and stem cell properties, resulting in metaplastic and dysplastic lesions to give rise, after additional epigenetic and mutational events, to the emergence of cancer stem cells (CSCs) and adenocarcinoma.

A large survey of antimicrobial resistance of Helicobacter pylori was performed in France in 2014: 984 patients were enrolled by 75 gastroenterologists all over the country. Among the 783 patients who had never received eradication treatment before, 266 (33.9%) were H. pylori positive. The strains showed a high rate of clarithromycin resistance (22.2%), moderate rate of resistance to levofloxacin (15.4%) and high rate of resistance to metronidazole (45.9%). In all, 187 patients had received previous treatment, of which 115 were H. pylori positive with very high resistance to clarithromycin (73.9%) and metronidazole (78.3%). None of the patients receiving PYLERA (Bismuth salt-Tetracycline HCl-Metronidazole) proton-pump inhibitor developed resistance to tetracycline. A real-time PCR applied to gastric biopsy specimens detected all the cases that were positive by culture as well as 30 additional cases. A good correlation was found between the clarithromycin resistance detected by phenotypic methods and the associated mutations for clarithromycin resistance, which has continued to increase in the last decade but at a lower rate than previously observed.

Matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) is positioned at the forefront of bacterial identification in the future. Its performance needed to be evaluated in a routine Bacteriology laboratory to determine its true benefits. A prospective study was carried out in the Bacteriology laboratory of the Pellegrin University Hospital in Bordeaux, France, from April to May 2009. Bacterial isolates from clinical samples were identified by conventional phenotypic bacteriological methods [Phoenix (Becton-Dickinson) or API strips (bioMérieux)] and in parallel with a mass spectrometer (Ultraflex III TOF/TOF and the biotyper database from Bruker Daltonics). In case of a discrepancy between these results at the genus level, a 16S rRNA and/or rpoB gene sequencing was performed. Of the 1013 bacteria tested, 837 (82.6%) were correctly identified at the species level by MALDI-TOF mass spectrometry (MS) without extraction and 189 after extraction, i.e. 986 (97.3%) were correctly identified at the species level by MALDI-TOF MS, vs. 945 (93.2%) by phenotypic methods. Indeed, the extraction step was necessary for only 15% of the isolates. These results were even better when considering the genus, reaching almost 99% with MALDI-TOF MS and 98% with phenotypic methods. The performance of MALDI-TOF MS is very attractive considering its efficiency and rapidity, and the technique constitutes a precious tool for bacteriological identification in a routine laboratory.

The identification of Campylobacter species and related organisms at the species level has always been difficult using phenotypic methods because of their low metabolic activity, whereas molecular methods are more reliable but time-consuming. In this study, 1007 different strains were identified using three different methods: conventional methods, molecular biology (real-time PCR and sequencing) and matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Molecular methods were considered the gold standard. The accuracy of MALDI-TOF mass spectrometry reached 100% compared with the gold standard for all of the Campylobacter species, except Campylobacter jejuni (99.4%). The accuracy of conventional methods compared with the gold standard ranged from 0% to 100% depending on the species. However, MALDI-TOF mass spectrometry was not able to identify a mixture of two different species present in the same sample in four instances. Finally, MALDI-TOF mass spectrometry is highly recommended to identify Campylobacter spp. as only 0.4% discrepancy was found, whereas conventional methods led to 4.5% discrepancy.

Endoscopic imaging of the stomach is improving. In addition to narrow band imaging, other methods, for example, blue light imaging and linked color imaging, are now available and can be combined with artificial intelligence systems to obtain information on the gastric mucosa and detect early gastric cancer. Immunohistochemistry is only recommended as an ancillary stain in case of chronic active gastritis without Helicobacter pylori detection by standard staining, and recommendations to exclude false negative H. pylori results have been made. Molecular methods using real‐time PCR, droplet digital PCR, or amplification refractory mutation system PCR have shown a high accuracy, both for detecting H. pylori and for clarithromycin susceptibility testing, and can now be used in clinical practice for targeted therapy. The most reliable non‐invasive test remains the 13C‐urea breath test. Large data sets show that DOB values are higher in women and that the cut‐off for positivity could be decreased to 2.74 DOB. Stool antigen tests using monoclonal antibodies are widely used and may be a good alternative to UBT, particularly in countries with a high prevalence of H. pylori infection. Attempts to improve serology by looking at specific immunodominant antigens to distinguish current and past infection have been made. The interest of Gastropanel® which also tests pepsinogen levels was confirmed.