Impact of the introduction of a nucleic acid amplification test for Clostridium difficile diagnosis on stool rejection policies

Background

The change from non-molecular to nucleic acid amplification tests (NAATs) is known to increase the detection of Clostridium difficile infection (CDI); however, the impact on stool rejection policies in clinical laboratories is unclear. The current guidelines have reinforced the importance of respecting strict conditions for performing tests on stool samples for CDI diagnosis. The purpose of this study was to estimate whether the implementation of molecular tests has resulted in changes in stool rejection policies between clinical laboratories that introduced NAATs and those that did not.

Results

A survey was conducted to evaluate the change in the number of stool samples rejected and the rejection criteria among 12 hospital laboratories in southwestern France before and after the switch from non-molecular tests to NAATs using retrospective data from June 1 till September 30, 2013 and the same period 2014. Four laboratories introduced NAATs as a second or third step in the process. A total of 1378 and 1297 stools samples were collected in 2013 and 2014, respectively. The mean number of rejected stool samples significantly increased (p < 0.001, Chi square test), with a total of 99 (7.1%) and 147 (11.3%) specimens rejected in 2013 and 2014, respectively. Notably, these laboratories had more stringent criteria and were no longer testing the stool samples of patients with CDI-positive results within 7 days. In contrast, there was a significant decrease in the rate of rejected stool samples (p < 0.001, Chi square test) in the five laboratories that did not adopt NAATs and a less stringent stool rejection policy.

Conclusion

Nucleic acid amplification test implementation improved compliance with recommended stool rejection policies. Laboratories should follow the recommended laboratory algorithm for the CDI diagnosis combined with the correct stool rejection policy.

Electronic supplementary material

The online version of this article (10.1186/s13099-018-0245-x) contains supplementary material, which is available to authorized users.

Epidemiologic cutoff values to separate wild-type from non-wild-type Campylobacter fetus to ciprofloxacin

The aim of the present study was to propose epidemiologic cutoffs that could be used in routine practice to separate wild-type from non-wild-type Campylobacter fetus to ciprofloxacin. A total of 123 C. fetus isolates obtained from human samples were used for this purpose. Based on the determination of inhibition zone diameter, minimum inhibitory concentration, and sequencing of the quinolone resistance determining region in the gyraseA gene, for all tested isolates, the following cutoffs were proposed: ciprofloxacin-wild type if the inhibition zone diameter was ≥22 mm or the minimum inhibitory concentration was ≤0.5 mg/L.

ID: 1023 All-trans retinoic acid targets gastric cancer stem cells and inhibits patient-derived gastric carcinoma tumor growth

Gastric carcinoma is the third leading cause of cancer-related death worldwide. This cancer, most of the time metastatic, is essentially treated by surgery associated with conventional chemotherapy, and has a poor prognosis. The existence of cancer stem cells (CSC) expressing CD44 and a high aldehyde dehydrogenase (ALDH) activity has recently been demonstrated in gastric carcinoma and has opened new perspectives to develop targeted therapy. In this study, we evaluated the effects of all-transretinoic acid (ATRA) on CSCs in human gastric carcinoma. ATRA effects were evaluated on the proliferation and tumorigenic properties of gastric carcinoma cells from patient-derived tumors and cell lines in conventional 2D cultures, in 3D culture systems (tumorsphere assay) and in mouse xenograft models. ATRA inhibited both tumorspheres initiation and growth in vitro, which was associated with a cell-cycle arrest through the upregulation of cyclin-dependent kinase (CDK) inhibitors and the downregulation of cell-cycle progression activators. More importantly, ATRA downregulated the expression of the CSC markers CD44 and ALDH as well as stemness genes such as Klf4 and Sox2 and induced differentiation of tumorspheres. Finally, 2 weeks of daily ATRA treatment were sufficient to inhibit gastric tumor progression in vivo, which was associated with a decrease in CD44, ALDH1, Ki67 and PCNA expression in the remaining tumor cells. Administration of ATRA appears to be a potent strategy to efficiently inhibit tumor growth and more importantly to target gastric CSCs in both intestinal and diffuse types of gastric carcinoma.

Infective endocarditis caused by Streptococcus tigurinus-like organisms

Streptococcus species are important causes of infective endocarditis but species identification remains challenging. We report two cases of infective endocarditis due to Streptococcus tigurinus-like organisms, which were first identified by 16S ribosomal RNA gene sequence analysis and subsequently confirmed using phylogeny based on the analysis of the shetA gene encoding exfoliative toxin.

Dormant phages of Helicobacter pylori reveal distinct populations in Europe

Prophages of Helicobacter pylori, a bacterium known to co-evolve in the stomach of its human host, were recently identified. However, their role in the diversity of H. pylori strains is unknown. We demonstrate here and for the first time that the diversity of the prophage genes offers the ability to distinguish between European populations, and that H. pylori prophages and their host bacteria share a complex evolutionary history. By comparing the phylogenetic trees of two prophage genes (integrase and holin) and the multilocus sequence typing (MLST)-based data obtained for seven housekeeping genes, we observed that the majority of the strains belong to the same phylogeographic group in both trees. Furthermore, we found that the Bayesian analysis of the population structure of the prophage genes identified two H. pylori European populations, hpNEurope and hpSWEurope, while the MLST sequences identified one European population, hpEurope. The population structure analysis of H. pylori prophages was even more discriminative than the traditional MLST-based method for the European population. Prophages are new players to be considered not only to show the diversity of H. pylori strains but also to more sharply define human populations.

Helicobacter pylori generates cells with cancer stem cell properties via epithelial-mesenchymal transition-like changes

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 infections in children]

Campylobacter infections are essentially enteric infections frequently occurring before 15 years of age. The main species responsible for these infections is Campylobacter jejuni. The infection is observed mainly during summertime, and boys are more often affected than girls. The transmission is usually food-borne (poultry or cross-contamination of raw food). Environmental contamination is also possible. In addition to the digestive symptoms, systemic infectious complications or postinfectious complications (joints, neurological) can occur. The infection is more severe in immunosuppressed patients. Conventional diagnosis by culture is now challenged by molecular and immunoenzymatic methods, which have greater sensitivity. An adapted antimicrobial treatment improves the digestive symptoms. A dual antibiotic therapy is necessary in case of systemic infection or secondary localization of the infection.

Matrix-assisted laser-desorption/ionization biotyper: experience in the routine of a University hospital

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.

Matrix-assisted laser-desorption/ionization biotyper: experience in the routine of a University hospital

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.

Identification of Campylobacter species and related organisms by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry

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.

Description and sources of contamination by Campylobacter spp. of river water destined for human consumption in Brittany, France

Presence or absence of Campylobacter spp. in water of five rivers upstream from an intake point for drinking water production was investigated, and isolates genetically compared with human, pig and poultry isolates in order to determine their source. River water and drinking water obtained from these rivers were sampled one time per month, over a period of one year, and tested for Campylobacter. Isolates were typed by PFGE. Campylobacter was not detected in treated drinking water, but 50% of the river samples were contaminated. Contamination was observed on the four seasons. In total, 297 Campylobacter isolates were collected and generated 46 PFGE profiles. Campylobacter jejuni was the most frequently detected species in samples (74.1% of the isolates), followed by Campylobacter coli (17.8%) and Campylobacter lari (8.1%). Forty-two of the 46 PFGE profiles were unique. Only one genotype was detected three times in a river during the year and four genotypes in two different rivers. When compared to animal and human Campylobacter PFGE profiles, 14, 11 and one Campylobacter genotypes from water were genetically closed to human, poultry, and pig Campylobacter genotypes, respectively. The Campylobacter population displayed a high level of genetic diversity, suggesting that contamination originated from various origins. Human, poultry and pig were sources of contamination of the river by Campylobacter. Finally, no Campylobacter were detected in drinking water, indicating that the risk of outbreaks due to consumption of drinking water is low.

Association between entero-hepatic Helicobacter species and Crohn's disease: a prospective cross-sectional study

BACKGROUND

The pathogenesis of Crohn's disease (CD) involved microbial factors. Some Helicobacter species, the so-called entero-hepatic Helicobacters (EHH), can naturally colonize the intestinal surface and have been detected in humans. Aim To look for an association between CD and the presence of EHH DNA in intestinal biopsies.

METHODS

Two groups of patients were included prospectively in a multicentre cross-sectional study: CD patients with an endoscopic post-operative recurrence within 2 years following a surgical resection and controls screened for colorectal polyps or cancer. Intestinal biopsies were taken for Helicobacter culture and Helicobacter 16S DNA detection. If positive, the EHH species were identified with specific PCRs, sequencing and denaturing gradient gel electrophoresis.

RESULTS

In the 165 included patients (73 CD and 92 controls), Helicobacter cultures were negative. PCR was positive in 44% of CD and 47% of controls. After age-adjustment, CD was significantly associated with EHH in intestinal biopsies (OR = 2.58; 95%CI: 1.04-6.67). All EHH species detected were identified as Helicobacter pullorum and the closely related species Helicobacter canadensis.

CONCLUSION

Crohn's disease is associated with the presence of EHH species DNA in intestinal biopsies after adjustment for age. Whether these species play a role in the pathophysiology of CD remains to be determined.

Study of Helicobacter pullorum proinflammatory properties on human epithelial cells in vitro

BACKGROUND AND AIMS

Helicobacter pullorum is an enterohepatic Helicobacter species of avian origin detected in patients with acute diarrhoea and inflammatory bowel disease. The aim of the present study was to determine whether H pullorum exerts a direct effect on human intestinal epithelial cells in vitro and to characterise the bacterial mechanisms and the signalling pathways involved.

MATERIALS AND METHODS

The proinflammatory properties of H pullorum from human and avian origins were measured on human gastric (AGS) and intestinal (CaCo-2 and HT-29) epithelial cell lines after co-culture with different H pullorum strains, and the extent of nuclear factor-kappaB (NF-kappaB) involvement was determined.

RESULTS

All of the H pullorum strains tested stimulated interleukin 8 (IL8) secretion by the three cell lines. Similar results were obtained with heat-killed H pullorum. Incubation of cells with filtered H pullorum culture supernatants did not stimulate IL8 secretion. The same observation was made when bacterial adherence was inhibited by Transwell inserts. H pullorum induced NF-kappaB activation and rapid nuclear translocation as demonstrated by immunofluorescent staining and cellular fractionation. NF-kappaB involvement was confirmed by using the specific inhibitor SN50 and small interfering RNA (siRNA) which abolished H pullorum-induced IL8 production.

CONCLUSIONS

H pullorum strains stimulate IL8 secretion by human gastric and intestinal epithelial cell lines. This effect requires bacterial adherence and probably lipopolysaccharides, and is mediated by NF-kappaB signalling. The present study strengthens the argument that H pullorum is a potent human pathogen and highlights its putative role in acute and chronic digestive diseases such as inflammatory bowel disease.

A large multi-pathogen waterborne community outbreak linked to faecal contamination of a groundwater system, France, 2000

A large waterborne outbreak of infection that occurred during August 2000 in a local community in France was investigated initially via a rapid survey of visits to local physicians. A retrospective cohort study was then conducted on a random cluster sample of residents. Of 709 residents interviewed, 202 (28.5%) were definite cases (at least three liquid stools/day or vomiting) and 62 (8.7%) were probable cases (less than three liquid stools/day or abdominal pain). Those who had drunk tap water had a three-fold increased risk for illness (95% CI 2.4-4.0). The risk increased with the amount of water consumed (chi-square trend: p < 0.0001). Bacteriological analyses of stools were performed for 35 patients and virological analyses for 24 patients. Campylobacter coli, group A rotavirus and norovirus were detected in 31.5%, 71.0% and 21% of samples, respectively. An extensive environmental investigation concluded that a groundwater source to this community had probably been contaminated by agricultural run-off, and a failure in the chlorination system was identified. This is the first documented waterborne outbreak of infection involving human C. coli infections. A better understanding of the factors influencing campylobacter transmission between hosts is required.

Development of a real-time PCR for the identification of Bordetella pertussis and Bordetella parapertussis

This study describes a real-time PCR assay for the detection and identification of Bordetella pertussis and Bordetella parapertussis. The assay is based on amplification of a fragment from the repeat sequence regions IS481 and IS1001 found in B. pertussis and B. parapertussis, respectively, with subsequent species identification by melting curve analysis using SYBR Green chemistry. Discrimination between the two species was straightforward, as the corresponding melting points showed a significant difference of 7 degrees C. The assay was evaluated first with reference strains and retrospective human clinical samples, and then prospectively with 132 human clinical specimens received between March 2003 and December 2005. The assay allowed the rapid detection of 22 positive clinical samples, of which 15, including one fatal case, were not identified by standard culture techniques. The new assay was sensitive and specific, and can be implemented easily using any real-time PCR apparatus.

Evaluation of moxalactam with the BD phoenix system for detection of methicillin resistance in coagulase-negative staphylococci

The performance of moxalactam with the BD Phoenix system for the detection of methicillin resistance in coagulase-negative staphylococci was evaluated by use of a collection of 186 strains. Moxalactam was a better drug as an indicator of methicillin resistance for mecA-positive strains than oxacillin and cefoxitin were. For strains other than Staphylococcus saprophyticus, a moxalactam MIC >16 microg/ml was indicative of methicillin resistance.

Prospective multicentre study on antibiotic resistance of Helicobacter pylori strains obtained from children living in Europe

AIM

To prospectively assess the antibacterial resistance rate in Helicobacter pylori strains obtained from symptomatic children in Europe.

METHODS

During a 4-year period, 17 paediatric centres from 14 European countries reported prospectively on patients infected with H pylori, for whom antibiotic susceptibility was tested.

RESULTS

A total of 1233 patients were reported from Northern (3%), Western (70%), Eastern (9%) and Southern Europe (18%); 41% originated from outside Europe as indicated by mother's birth-country; 13% were <6 years of age, 43% 6-11 years of age and 44% >11 years of age. Testing was carried out before the first treatment (group A, n = 1037), and after treatment failure (group B, n = 196). Overall resistance to clarithromycin was detected in 24% (mean, A: 20%, B: 42%). The primary clarithromycin resistance rate was higher in boys (odds ratio (OR) 1.58; 1.12 to 2.24, p = 0.01), in children <6 years compared with >12 years (OR 1.82, 1.10 to 3.03, p = 0.020) and in patients living in Southern Europe compared with those living in Northern Europe (OR 2.25; 1.52 to 3.30, p<0.001). Overall resistance rate to metronidazole was 25% (A: 23%, B: 35%) and higher in children born outside Europe (A: adjusted. OR 2.42, 95% CI: 1.61 to 3.66, p<0.001). Resistance to both antibiotics occurred in 6.9% (A: 5.3%, B: 15.3%). Resistance to amoxicillin was exceptional (0.6%). Children with peptic ulcer disease (80/1180, 6.8%) were older than patients without ulcer (p = 0.001).

CONCLUSION

The primary resistance rate of H pylori strains obtained from unselected children in Europe is high. The use of antibiotics for other indications seems to be the major risk factor for development of primary resistance.

Association of serum pepsinogen with atrophic body gastritis in Costa Rica

Individuals with atrophic gastritis (AG), especially atrophic body gastritis (ABG), are at increased risk of developing gastric cancer. Serum concentrations of pepsinogens (PG) have been proposed as markers for ABG. The aim of this study was to determine the risk factors for AG and ABG and the potential of using serum PG concentrations to detect ABG in a dyspeptic population in Costa Rica, which is one of the countries with the highest incidence and mortality rates of gastric cancer in the world. Seven biopsy specimens, a fasting blood sample and a questionnaire concerning sociodemographic factors were obtained from 501 consecutive dyspeptic patients. The serum PGI level and the PGI/PGII ratios were significantly lower in patients with ABG than in other groups (P<0.000). A cut-off point of 3.4 led to a sensitivity of 91.2% in identifying ABG, a negative predictive value of 98.1%, but a positive predictive value of only 11.2%. Helicobacter pylori were present in 93% of the patients and all those with peptic ulcers were positive. AG was associated with increased age, lower body mass index, high alcohol intake and low fruit consumption. ABG was associated with age, alcohol consumption and PGI/PGII<3.4. In dyspeptic patients with a high prevalence of H. pylori infection, serum PG levels provide an assessment of ABG but it is necessary to introduce other serological and genetic markers in order to achieve a better specificity. Those markers could be serum antibodies to H. pylori-CagA, cytokine gene polymorphisms or others.

Should we eradicate Helicobacter pylori before prescribing an NSAID? Result of a placebo-controlled study

OBJECTIVE

(1) To determine the prevalence of gastrointestinal (GI) symptoms in patients with and without Helicobacter pylori infection and treated with non-steroidal anti-inflammatory drugs (NSAIDs) and (2) to estimate the impact of H. pylori eradication on these symptoms.

METHODS

This was a multicentric, community-based, randomized, case-control study. Patients presenting with a rheumatic disorder motivating the prescription of an NSAID for at least 2 wks were stratified in two groups (H. pylori-positive and H. pylori-negative) by a serological doctor test and H. pylori-positive patients divided further into two subgroups, receiving either an eradication treatment (group 1) or a placebo (group 2). The main outcome measure was the prevalence of GI symptoms estimated in groups 1 and 2 and in noninfected patients (group 3) at weeks 2, 6, and 12.

RESULTS

Among H. pylori-negative patients (n=145), GI symptoms were present in 42.6%, 21.4%, and 10.0% at weeks 2, 6, and 12, respectively. In groups 1 and 2, GI symptoms were present in 57.7% and 40.7%, respectively, at week 2 (p= 0.03); 24.7% and 23% at week 6 (p= 0.85); and 9.4% and 17.3% at week 12 (p= 0.13). The prevalence of GI symptoms at week 2 was similar in group 2 and in the H. pylori-negative group (p= 0.77). The highest prevalence of symptoms at week 2 in group 1 was essentially due to diarrhea. The prevalence of GI symptoms was the same for groups 1 and 3 at week 12, and higher in group 2, but the difference did not reach statistical significance.

CONCLUSIONS

The short-term (6 wks) GI tolerance of conventional NSAIDs does not differ whether or not the patients are infected by H. pylori. The tendency observed for the medium term (12 wks) deserves to be confirmed.

Development of a real-time fluorescence resonance energy transfer PCR to identify the main pathogenic Campylobacter spp

A simple real-time fluorescence resonance energy transfer (FRET) PCR, targeting the gyrA gene outside the quinolone resistance-determining region, was developed to identify Campylobacter jejuni and Campylobacter coli. These species were distinguished easily, as the corresponding melting points showed a difference of 15 degrees C. A second assay using the same biprobe and PCR conditions, but different PCR primers, was also developed to identify the less frequently encountered Campylobacter fetus. These assays were applied to 807 Campylobacter isolates from clinical specimens. Compared to phenotypic identification tests, the FRET assay yielded the same results for all except three of the isolates. Analysis by standard PCR and 16S rDNA sequencing demonstrated that two of these isolates were hippurate-negative C. jejuni strains, resulting in an erroneous phenotypic identification, while the third was an isolate of C. coli that contained a gyrA gene typical of C. jejuni, resulting in misidentification by the FRET assay. The FRET assay identified more isolates than standard PCR, which failed to yield amplification products with c. 10% of isolates. It was concluded that the FRET assays were rapid, reliable, reproducible and relatively cost-efficient, as they require only one biprobe and can be performed directly on boiled isolates.

Association of Helicobacter species with hepatitis C cirrhosis with or without hepatocellular carcinoma

BACKGROUND AND AIMS

Recent studies have suggested that bacterial coinfection with Helicobacter species in patients already infected with hepatitis C virus (HCV) could be involved in the development of cirrhosis and hepatocellular carcinoma (HCC). A retrospective cross sectional study was performed in order to explore the association between Helicobacter species and HCV associated liver diseases.

METHODS

The presence of Helicobacter species was tested by polymerase chain reaction on liver samples from four groups of patients.

RESULTS

Helicobacter 16S rDNA was found in only 4.2% of liver samples from control patients (n=24) and in 3.5% of liver samples from patients with non-cirrhotic chronic hepatitis C (n=29) while it was found in 68.0% of liver samples from patients with HCV positive cirrhosis without HCC (n=25) as well as in 61.3% of cirrhotic liver samples from patients with HCV positive cirrhosis and HCC (n=31). In addition, when the HCC tumour tissue was tested (n=21), 90.5% of samples were positive. DNA from Helicobacter pylori- and Helicobacter pullorum-like organisms was found.

CONCLUSIONS

There is an association between the presence of Helicobacter species DNA in the liver and hepatitis C cirrhosis, with or without HCC. Indeed, the presence of these bacteria could be the result of structural changes in the liver. Alternatively, Helicobacter species could be a co-risk factor in HCV chronic liver diseases. This result warrants prospective studies to determine the possible causal role of these bacteria in the progression of chronic hepatitis C.

Helicobacter pylori infection and gastric MALT lymphoma

Helicobacter pylori infection is implicated in the development of two different gastric cancers: gastric adenocarcinoma and gastric MALT lymphoma. The association with the gastric MALT lymphoma is strong and causal. It is currently the only cancer which can be treated by a simple antibiotic treatment. However, the evolution of an H. pylori infection towards lymphoma is exceptional. Host susceptibility factors and environmental factors predisposing a patient to lymphoma have not yet been determined. The bacterial factors are currently being identified.

Identification of a genetic marker of Helicobacter pylori strains involved in gastric extranodal marginal zone B cell lymphoma of the MALT-type

BACKGROUND AND AIMS

Gastric extranodal marginal zone B cell lymphoma of the mucosa associated lymphoid tissue (MALT)-type (MZBL) is a rare complication of Helicobacter pylori infection. Currently, no bacterial factor has been associated with the development of this disease. Our aim was to identify genes associated with lymphoma development.

METHODS

We used subtractive hybridisation as a tool for comparative genomics between H pylori strains isolated from a patient with gastric MZBL and from a patient with gastritis only.

RESULTS

When gastric MZBL strains were compared with gastritis strains, two open reading frames (ORFs) were significantly associated with gastric MZBL: JHP950 (74.4% v 48.7%, respectively; p = 0.023) and JHP1462 (25.6% v 2.6%, respectively; p = 0.004). The prevalence of JHP950 was 48.8% (p = 0.024) in duodenal ulcer strains and 39.3% (p = 0.006) in gastric adenocarcinoma strains, which makes this ORF a specific marker for gastric MZBL strains. In contrast, the prevalence of JHP1462 was 16% (p = 0.545) and 35.7% (p = 0.429) in duodenal ulcer and adenocarcinoma strains, respectively. These ORFs were present in reference strain J99 but not in reference strain 26695. JHP950 is located in the plasticity zone whereas the other, JHP1462, is located outside. Both encode for H pylori putative proteins with unknown functions.

CONCLUSION

Despite its low prevalence, the ORF JHP1462 can be considered a candidate marker for H pylori strains involved in severe gastroduodenal diseases. In contrast, the ORF JHP950 has a high prevalence, and is the first candidate marker for strains giving rise to an increased risk of gastric MZBL strains. Further confirmation in other studies is needed.

Surveillance of human Campylobacter infections in France--part 2--implementation of national surveillance

In 2001, one year after the study of microbiological laboratories that showed the feasibility of a surveillance of Campylobacter infections, 1389 private laboratories were asked whether they would be willing to participate. The high proportion of positive responses (48%, 661) allowed the implementation on 1 April 2002 of surveillance of human Campylobacter infections.

Second-line treatment for failure to eradicate Helicobacter pylori: a randomized trial comparing four treatment strategies

AIM

To compare the efficacy of different regimens in patients in whom previous Helicobacter pylori eradication therapy has failed.

METHODS

In this study named StratHegy patients (n=287) were randomized to receive one of three empirical triple therapy regimens or a strategy based on antibiotic susceptibility. The empirical regimens were omeprazole, 20 mg b.d., plus amoxicillin, 1000 mg b.d., and clarithromycin, 500 mg b.d., for 7 days (OAC7), clarithromycin, 500 mg b.d., for 14 days (OAC14) or metronidazole, 500 mg b.d., for 14 days (OAM14). In the susceptibility-based strategy, patients with clarithromycin-susceptible strains received OAC14, whilst the others received OAM14. The 13C-urea breath test was performed before randomization and 4-5 weeks after eradication therapy.

RESULTS

In the intention-to-treat analysis, the eradication rates for empirical therapies were as follows: OAC7, 47.4% (27/57); OAC14, 34.5% (20/58); OAM14, 63.2% (36/57); it was 74.3% (84/113) for the susceptibility-based treatment (P<0.01 when compared with OAC7 and OAC14). In patients receiving clarithromycin, the eradication rates were 80% for clarithromycin-susceptible strains and 16% for clarithromycin-resistant strains; in patients receiving OAM14, the eradication rates were 81% for metronidazole-susceptible strains and 59% for metronidazole-resistant strains.

CONCLUSIONS

Eradication rates of approximately 75% can be achieved with second-line triple therapy based on antibiotic susceptibility testing. If susceptibility testing is not available, OAM14 is an appropriate alternative.

Surveillance of human Campylobacter infections in France - Part 1 - Which data? A study of microbiological laboratories, 2000

The frequency of Campylobacter infections in humans, their potential severity, and the existence of preventive measures justify the implementation of a surveillance system for these infections. Before the implementation of the surveillance system, a survey of the Campylobacter diagnostic practices in the laboratories was performed. In the laboratories that responded, most investigated for Campylobacter at least once in 1999. Identification of the Campylobacter species was carried out by 86% of hospital laboratories and 37% of private laboratories. Antibiotic sensitivity tests were carried out by 75% and 32% of them respectively. Many laboratories test for Campylobacter in stool samples using comparable methods showing the feasibility of a surveillance system.

European multicentre validation trial of two new non-invasive tests for the detection of Helicobacter pylori antibodies: urine-based ELISA and rapid urine test

AIM

Non-invasive tests for the assessment of Helicobacter pylori status are now an integral part of the management strategies for patients with dyspepsia. The aim of this study was to evaluate a urine based antibody ELISA and a near patient urine test for the diagnosis of H. pylori infection in a European population.

METHODS

Urine samples were collected from 449 patients (240 females, 209 males, mean age 54 years), with dyspeptic symptoms but no previous H. pylori eradication therapy, at five centres in four European countries. All patients underwent GI endoscopy and biopsies were taken for H. pylori diagnosis. Urine samples were analysed using an IgG ELISA (URINELISA) and a near patient urine test (RAPIRUN). In addition, a serum IgG ELISA (Pyloriset-EIA-GIII), a whole blood test (Pyloriset-Screen) and a 13C-urea breath test were performed.

RESULTS

The sensitivity of the urine based ELISA and the near patient urine test was 90% and 82%, and the specificity 68% and 83%, respectively. The accuracy of the serum ELISA and the whole blood test was comparable with the urine based test.

CONCLUSION

The urine based ELISA and the near patient urine test are just as accurate as the serological tests. This comparable accuracy and complete non-invasiveness of the former gives it an advantage over blood based tests. This limits the application of these tests in general practice.

Second-line treatment for failure to eradicate Helicobacter pylori: a randomized trial comparing four treatment strategies

AIM

To compare the efficacy of different regimens in patients in whom previous Helicobacter pylori eradication therapy has failed.

METHODS

In this study named StratHegy patients (n=287) were randomized to receive one of three empirical triple therapy regimens or a strategy based on antibiotic susceptibility. The empirical regimens were omeprazole, 20 mg b.d., plus amoxicillin, 1000 mg b.d., and clarithromycin, 500 mg b.d., for 7 days (OAC7), clarithromycin, 500 mg b.d., for 14 days (OAC14) or metronidazole, 500 mg b.d., for 14 days (OAM14). In the susceptibility-based strategy, patients with clarithromycin-susceptible strains received OAC14, whilst the others received OAM14. The 13C-urea breath test was performed before randomization and 4-5 weeks after eradication therapy.

RESULTS

In the intention-to-treat analysis, the eradication rates for empirical therapies were as follows: OAC7, 47.4% (27/57); OAC14, 34.5% (20/58); OAM14, 63.2% (36/57); it was 74.3% (84/113) for the susceptibility-based treatment (P<0.01 when compared with OAC7 and OAC14). In patients receiving clarithromycin, the eradication rates were 80% for clarithromycin-susceptible strains and 16% for clarithromycin-resistant strains; in patients receiving OAM14, the eradication rates were 81% for metronidazole-susceptible strains and 59% for metronidazole-resistant strains.

CONCLUSIONS

Eradication rates of approximately 75% can be achieved with second-line triple therapy based on antibiotic susceptibility testing. If susceptibility testing is not available, OAM14 is an appropriate alternative.

What is the role of serology in assessing Helicobacter pylori eradication?

AIM

To assess the decline in Helicobacter pylori antibodies after eradication of infection.

METHODS

The H. pylori status was determined at entry (D0) by culture and histology performed on antral biopsies and after eradication treatment at day 42 (day 42) and after 6 months (M6) by the 13C-urea breath test. The EIA kits used to determine the anti-H. pylori antibody titre were HM-CAP (immunoglobulin-G) and PP-CAP (immunoglobulin-A) kits (Enteric Products, Inc.) and Pyloriset EIA-G (Orion Diagnostica).

RESULTS

Ninety-three patients were included. For 82 patients who were successfully treated, no kit was sufficiently accurate at D42 to show eradication. The antibody titre decreased for HM-CAP, PP-CAP and Pyloriset EIA-G by a mean of 35.6%, 41.2% and 64.7% between D0 and M6, respectively. According to the cut-off values defined by the manufacturers, 8.5% (PP-CAP, Pyloriset EIA-G) and 9.7% (HM-CAP) of the patients became H. pylori negative at M6. Using a 25% decrease in antibody titre between D0 and M6 as a threshold for H. pylori eradication, specificity was 100% for HM-CAP, 89.9% for Pyloriset EIA-G and 100% for PP-CAP, whereas the sensitivity was 76.8%, 98.8% and 72%, respectively.

CONCLUSION

An antibody titre decrease of 25% at M6 was found to be accurate in confirming H. pylori eradication.

Review article: rebamipide and the digestive epithelial barrier

Rebamipide exerts a positive effect on the digestive epithelial barrier by reinforcing its integrity in normal and in inflammatory conditions, and by normalizing the macromolecular transport across this barrier, increased by Helicobacter infection. Moreover, in mice, rebamipide is capable of diminishing allergic sensitization and of counteracting the inhibitory effect of Helicobacter pylori on oral tolerance to dietary antigens. These properties of rebamipide could explain its anti-inflammatory activity with respect to the digestive mucosa and could provide protection against allergic sensitization to foreign antigens in susceptible individuals.

Review article: the treatment of refractory Helicobacter pylori infection

The occurrence of refractory Helicobacter pylori infection is increasing. When the bacteria are not eradicated it means that the antibiotics have not reached the gastric mucosa at a sufficient concentration and over a sufficient time lapse to kill them. The main reasons for this are poor patient compliance, resistant bacteria, low gastric pH and a high bacterial load. Therefore, when administering a new treatment, it is important to choose antibiotics which do not face resistance problems and which increase the dosage of antisecretory drugs and the duration of treatment and, if possible, to add a topical agent such as bismuth salt. The recommended empirical strategy is to prescribe quadruple therapy or, alternatively, 2-week triple therapy including amoxicillin-metronidazole, tetracycline-metronidazole or amoxicillin-rifabutin. However, when H. pylori is susceptible, clarithromycin can still be used. In the case of a high level of metronidazole resistance, furazolidone can be employed. In each case, it is important to ensure good patient compliance, and counselling is helpful in this regard. However, the best approach remains the prevention of refractory H. pylori infection and, for this purpose, antimicrobial susceptibility testing before first-line therapy is important and should be encouraged.

Pepsinogen A, pepsinogen C, and gastrin as markers of atrophic chronic gastritis in European dyspeptics

Serum levels of pepsinogen and gastrin are parameters that can be used as biomarkers for gastric mucosa. The aim of this study was to validate these serum biomarkers, that is pepsinogen A (PGA), pepsinogen C (PGC), PGA/PGC ratio, and gastrin, as screening tests for precancerous lesions: atrophic chronic gastritis (ACG) or Helicobacter pylori-related corpus-predominant or multifocal atrophy. The study population was comprised of a subsample of 284 patients from the 451 included in the Eurohepygast cohort, between 1995 and 1997. The concentrations of PGA, PGC, and gastrin were measured by radioimmunoassays. Histological diagnosis was the gold standard. Cut-off points were calculated using receiving operator characteristics (ROC) curves. Factors linked to variation of biomarkers were identified using multivariate linear regression. The mean of each biomarker in the sample was: PGA, 77.4 microg x l(-1); PGC, 13.2 microg x l(-1); PGA/PGC, 6.7; and gastrin, 62.4 ng x l(-1). For ACG patients, the areas under the PGA, PGC, PGA/PGC, and gastrin ROC curves were 0.55, 0.62, 0.73, and 0.58, respectively. The best cut-off point for PGA/PGC was 5.6, with sensitivity 65% and specificity 77.9%. For H. pylori-related corpus-predominant or multifocal atrophy, the areas under the respective ROC curves were 0.57, 0.67, 0.84, and 0.69. The best cut-off point for PGA/PGC was 4.7, with sensitivity 77.1% and specificity 87.4%. The results suggested that only the PGA/PGC ratio can be considered as a biomarker for precancerous lesions of the stomach, and may be useful as a screening test.

Efficacy and safety of single-triple capsules of bismuth biskalcitrate, metronidazole and tetracycline, given with omeprazole, for the eradication of Helicobacter pylori: an international multicentre study

BACKGROUND

The high prevalence of Helicobacter pylori resistance to metronidazole demands treatments more effective than standard bismuth-based triple therapy against these strains.

AIM

To evaluate the H. pylori eradication rate in both metronidazole-sensitive and -resistant strains following quadruple therapy using single-triple capsules of bismuth biskalcitrate, metronidazole and tetracycline, given with omeprazole.

METHODS

One hundred and seventy valid patients with duodenal ulcer, gastric ulcer or non-ulcer dyspepsia were treated in eight centres located in five countries. H. pylori was confirmed at baseline using 13C-urea breath test, histology and/or culture. Patients received three single-triple capsules q.i.d. and omeprazole, 20 mg b.d., for 10 days. Each capsule contained bismuth biskalcitrate, 140 mg (as 40 mg Bi2O3 equivalent), metronidazole, 125 mg, and tetracycline, 125 mg. 13C-Urea breath test was repeated at least 4 and 8 weeks post-treatment.

RESULTS

Overall eradication rates were 93% (158/170) by modified intention-to-treat analysis and 97% (142/146) by per protocol analysis. Eradication rates were 93% (40/43) and 95% (38/40) for strains resistant to metronidazole and 95% (82/86) and 99% (75/76) for strains sensitive to metronidazole by modified intention-to-treat and per protocol analysis, respectively.

CONCLUSION

This omeprazole-bismuth biskalcitrate-metronidazole-tetracycline 10-day regimen is a very effective and well-tolerated treatment, which overcomes metronidazole resistance.

Risk factors for failure of Helicobacter pylori therapy--results of an individual data analysis of 2751 patients

AIM

To study risk factors for failure of Helicobacter pylori eradication treatment.

METHODS

Individual data from 2751 patients included in 11 multicentre clinical trials carried out in France and using a triple therapy, were gathered in a unique database. The 27 treatment regimens were regrouped into four categories.

RESULTS

The global failure rate was 25.8% [95% CI: 24-27]. There was a difference in failure rate between duodenal ulcer patients and non-ulcer dyspeptic patients, 21.9% and 33.7%, respectively (P < 10(-6)). In a random-effect model, the risk factors identified for eradication failure in duodenal ulcer patients (n = 1400) were: to be a smoker, and to have received the group 4 treatment, while to receive a 10 day treatment vs. 7 days protected from failure. In non-ulcer dyspeptic patients (n = 913), the group 2 treatment was associated with failure. In both groups, age over 60 was associated with successful H. pylori eradication. There were less strains resistant to clarithromycin in duodenal ulcer patients than in non-ulcer dyspeptic patients. Clarithromycin resistance predicted failure almost perfectly.

CONCLUSION

Duodenal ulcer and non-ulcer dyspeptic patients should be managed differently in medical practice and considered independently in eradication trials.