Josette Raymond

Comparative evaluation of 29 commercial Helicobacter pylori serological kits

Serology is a noninvasive diagnostic method for the detection of Helicobacter pylori infection. Many commercial kits are now on the market. It is necessary to assess their performances to help the user to choose the most appropriate.

From array-based hybridization of Helicobacter pylori isolates to the complete genome sequence of an isolate associated with MALT lymphoma

Backgroundelicobacter pylori infection is associated with several gastro-duodenal inflammatory diseases of various levels of severity. To determine whether certain combinations of genetic markers can be used to predict the clinical source of the infection, we analyzed well documented and geographically homogenous clinical isolates using a comparative genomics approach.ResultsA set of 254 H. pylori genes was used to perform array-based comparative genomic hybridization among 120 French H. pylori strains associated with chronic gastritis (n = 33), duodenal ulcers (n = 27), intestinal metaplasia (n = 17) or gastric extra-nodal marginal zone B-cell MALT lymphoma (n = 43). Hierarchical cluster analyses of the DNA hybridization values allowed us to identify a homogeneous subpopulation of strains that clustered exclusively with cag PAI minus MALT lymphoma isolates. The genome sequence of B38, a representative of this MALT lymphoma strain-cluster, was completed, fully annotated, and compared with the six previously released H. pylori genomes (i.e. J99, 26695, HPAG1, P12, G27 and Shi470). B38 has the smallest H. pylori genome described thus far (1,576,758 base pairs containing 1,528 CDSs); it contains the vacA s2m2 allele and lacks the genes encoding the major virulence factors (absence of cag PAI, bab B, bab C, sab B, and hom B). Comparative genomics led to the identification of very few sequences that are unique to the B38 strain (9 intact CDSs and 7 pseudogenes). Pair-wise genomic synteny comparisons between B38 and the 6 H. pylori sequenced genomes revealed an almost complete co-linearity, never seen before between the genomes of strain Shi470 (a Peruvian isolate) and B38.ConclusionThese isolates are deprived of the main H. pylori virulence factors characterized previously, but are nonetheless associated with gastric neoplasia.

Evolutionary History of Helicobacter pylori Sequences Reflect Past Human Migrations in Southeast Asia

The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

Primary antibiotic resistance and associated mechanisms in Helicobacter pylori isolates from Senegalese patients

BackgroundAntibiotic combination therapy for Helicobacter pylori eradication must be adapted to local resistance patterns, but the epidemiology of H. pylori resistance to antibiotics is poorly documented in Africa. The aim was to determine the antibiotic resistance rates, as well as the associated molecular mechanisms, of strains isolated in Dakar, Senegal.MethodsOne hundred and eight H. pylori strains were isolated between 2007 and 2009 from 108 patients presenting with upper abdominal pain to the Gastroenterology Department of Le Dantec Hospital. Antimicrobial susceptibility testing was performed for amoxicillin, clarithromycin, metronidazole, levofloxacin and tetracyclin using the E-test method. Mutations in the 23S rRNA gene of clarithromycin-resistant strains and in gyrA and gyrB of levofloxacin-resistant strains were investigated.ResultsIsolates were characterized by no resistance to amoxicillin (0%), tetracycline (0%), and very low rate of resistance to clarithromycin (1%), but a high rate of resistance to metronidazole (85%). The clarithromycin-resistant strain displayed the A2143G mutation. A worrying rate of levofloxacin resistance was detected (15%). N87I and D91N were the most common mutations in the quinolone-resistance-determining region of gyrA.ConclusionsThe first-line empirical regimen for H. pylori eradication in Senegal should include clarithromycin. Increasing rates of fluoroquinolone resistance detected should discourage the use of levofloxacin-containing regimens without prior antimicrobial susceptibility testing.

Distribution of Spontaneous gyrA Mutations in 97 Fluoroquinolone-Resistant Helicobacter pylori Isolates Collected in France

ABSTRACT We determined the prevalence of gyrA mutations conferring fluoroquinolone resistance in 97 Helicobacter pylori isolates collected in France from 2007 to 2010. Ninety-four harbored one or two mutations already found in the quinolone resistance determining region (QRDR) of gyrA (for T87I, n = 23; for N87K, n = 32; for D91N, n = 30; for D91G, n = 7; for D91Y, n = 6), 2 harbored a mutation never previously described (D91H and A88P), and one strain was resistant (ciprofloxacin MIC of 8 mg/liter) without a detected mutation conferring this resistance in gyrA or gyrB genes.

Evaluation of a New Serologic Test for Diagnosis of Helicobacter pylori Infection in Children

Abstract A new semiquantitative enzyme immunoassay (Platelia Helicobacter pylori; Sanofi Diagnostics Pasteur, France) was evaluated and compared with two other serological assays (Gap-test IgG; Bio-Rad, France; and Cobas Core; Roche, Switzerland) for the diagnosis of Helicobacter pylori infection in children. The three tests were compared with the examination of biopsy samples obtained from 160 dyspeptic subjects (mean age, 9±4.7 years). Discrepant results were studied using an immunoblot technique. The response obtained for the Platelia assay in children was significantly lower than that obtained in a previously described population of 92 adults (Helicobacter pylori-negative mean ratios, 0.376 vs. 0.504, P<0.000783;Helicobacter pylori-positive mean ratios, 1.95 vs. 2.67, P<0.000003). Thus, the optimal cut-off for children (0.80) was lower than the one recommended for adults (1.10). According to the Receiver Operating Characteristic (ROC) curve analysis and to the Wilcoxon value, the Platelia and Cobas Core assays showed the highest discriminatory properties (Wilcoxon value, 0.94 for both) compared with the Gap-test IgG (Wilcoxon value, 0.91). When the newly established cut-off value (0.80) was used, the performance of Platelia was equivalent to that of Cobas Core (sensitivity: 94.4% for each; respective specificities, 86.8% and 90.6%). The Gap-test IgG had a lower sensitivity (maximum, 79%) and a higher specificity (maximum, 95.3%), but there were difficulties in interpretation because its grey zone encompassed 12% of the sera. In conclusion, the results showed good performance of the Platelia Helicobacter pylori assay and confirmed the merit of a specific cut-off value for use of this test in children.

Population Genetic Structure and Isolation by Distance of Helicobacter pylori in Senegal and Madagascar

Helicobacter pylori has probably infected the human stomach since our origins and subsequently diversified in parallel with their human hosts. The genetic population history of H. pylori can therefore be used as a marker for human migration. We analysed seven housekeeping gene sequences of H. pylori strains isolated from 78 Senegalese and 24 Malagasy patients and compared them with the sequences of strains from other geographical locations. H. pylori from Senegal and Madagascar can be placed in the previously described HpAfrica1 genetic population, subpopulations hspWAfrica and hspSAfrica, respectively. These 2 subpopulations correspond to the distribution of Niger-Congo speakers in West and most of subequatorial Africa (due to Bantu migrations), respectively. H. pylori appears as a single population in Senegal, indicating a long common history between ethnicities as well as frequent local admixtures. The lack of differentiation between these isolates and an increasing genetic differentiation with geographical distance between sampling locations in Africa was evidence for genetic isolation by distance. The Austronesian expansion that started from Taiwan 5000 years ago dispersed one of the 10 subgroups of the Austronesian language family via insular Southeast Asia into the Pacific and Madagascar, and hspMaori is a marker for the entire Austronesian expansion. Strain competition and replacement of hspMaori by hpAfrica1 strains from Bantu migrants are the probable reasons for the presence of hspSAfrica strains in Malagasy of Southeast Asian descent. hpAfrica1 strains appear to be generalist strains that have the necessary genetic diversity to efficiently colonise a wide host spectrum.

Expansion of European vacA and cagA alleles to East-Asian Helicobacter pylori strains in Cambodia.

Helicobacter pylori infection is associated with gastric cancer (GC). The highest incidence rates have been described in Asia, but regional variations exist that do not match the distribution of infection prevalence rates. The aim of the study was to examine the possible contribution of H. pylori virulence factors to geographic differences in the incidence of GC across East and Southeast Asia. We studied 66 isolates from Cambodian patients that had previously been assigned to two genetic populations based on sequences of seven housekeeping genes, namely hpEurope (n = 34, 51.5%) and hpEastAsia, subpopulation hspEAsia (n = 32, 48.5%). These strains were characterized with respect to vacA polymorphism and cagA status by PCR, and the CagA C-terminal region was sequenced. We also sequenced the complete cagA gene from 10 hpEurope and 10 hspEAsia strains chosen at random. The cagA gene was present in 92.4% of the 66 isolates and was mainly of Western type (n = 36, 59.0%). hspEAsia strains carrying East-Asian CagA and the m1-type vacA allele (15.2%) were less frequent among the 66 Cambodian isolates than reported in East Asian countries, a finding that might partly explain the intermediate incidence of GC in Cambodia, and by extension, in Southeast Asia (except for Vietnam). The observed high prevalence of s1a alleles (34.4%) and Western CagA (28.1%) among hspEAsia strains indicates frequent introgression of European vacA and cagA alleles into East Asian H. pylori strains. This expansion might have severe consequences for individual disease outcome.

Impact of human migrations on diversity of Helicobacter pylori in Cambodia and New Caledonia.

Helicobacter pylori is a major gastric bacterial pathogen, presumed to have established itself in the human stomach approximately 100,000 years ago. Helicobacter pylori co‐evolved with its host, and human migrations shaped the expansion and the diversity of strains around the world. Here, we investigated the population structure and the genomic diversity of H. pylori in New Caledonia and Cambodia, where humans of different origins are living.

L’éradication de Helicobacter pylori : revenir vers les principes de l’antibiothérapie

hpg.2011.0569 Auteur(s) : Dominique Lamarque1 dominique.lamarque@apr.aphp.fr, Josette Raymond2 1 Hopital Ambroise-Pare, Service d’hepato-gastroenterologie, 9, avenue Charles-de-Gaulle, 92104 Boulogne-Billancourt Cedex, France 2 Universite Paris-Descartes, Hopital Cochin, Bacteriologie, 27 rue du Faubourg-Saint-Jacques, 75679 Paris Cedex 14, France A l’issue de la conference de consensus de 1996, l’eradication de Helicobacter pylori paraissait simple [1, 2]. Les etudes randomisees [...]