Comparison of five PCR methods for detection of Helicobacter pylori DNA in gastric tissues

Utility of diagnostic tests for detection of Helicobacter pylori in children in northeastern Mexico

BACKGROUND

The presence of Helicobacter pylori in pediatric population has been associated with recurrent abdominal pain (RAP), although this association is unclear. One of the major problems in studying the role of H. pylori in RAP is that methods used to detect the bacteria in children have poor sensitivity and specificity. The aims of the present study were to determine the prevalence of H. pylori in pediatric patients with RAP in northeastern Mexico and to assess the diagnostic utility of invasive tests and serology in this population.

METHODS

A total of 40 patients (mean age, 7.9 years; range 2-16 years; F: M, 0.81), who underwent an endoscopy procedure for RAP, were studied. The presence of H. pylori was assessed using invasive diagnostic tests (culture, rapid urease test, polymerase chain reaction and histology) and one non-invasive test: determination of IgG antibodies. The prevalence of H. pylori in the present group and the diagnostic utility for each test were evaluated.

RESULTS

The prevalence of H. pylori in the present pediatric group with RAP was 12.5-42.5% depending on the criteria of positivity used. The non-invasive methods (serology) had acceptable values in sensitivity and specificity in comparison with invasive tests.

CONCLUSIONS

This is the first report on prevalence of H. pylori in pediatric patients with RAP from the northeastern region of Mexico. The prevalence of H. pylori was low compared with the adult population in the same geographic region. Serology had the best diagnostic utility.

Detection of Helicobacter pylori by enzyme-linked immunosorbent assay of thermophilic helicase-dependent isothermal DNA amplification

An enzyme-linked immunosorbent assay (ELISA) of thermophilic helicase-dependent isothermal DNA amplification (tHDA) was developed for detection of Helicobacter pylori. The primers targeting ureC were used for the amplification of bacterial DNA by the isothermal digoxigenin (DIG)-labeling tHDA process, resulting in the accumulation of DIG-labeled DNA amplicons. The amplicons were denatured using heat and then hybridized with a specific biotinylated DNA probe, which was noncovalently immobilized on streptavidin-coated microtiter plate. The hybrids were colorimetrically detected by the addition of an anti-DIG antibody HRP conjugate and 2,2-azino-di-(3-ethylbenzthiazolinsulfonate) substrate solution. Results obtained from the gastric biopsy samples showed 90% and 95.7% of sensitivity and specificity, respectively, in comparison with culture results, and 96.6% and 96.8% of sensitivity and specificity, respectively, in comparison with those of the histologic studies. This assay significantly reduces the time needed for the identification of H. pylori and has the potential to facilitate early detection of this gastrointestinal pathogen.

Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA and babA2 genotypes in Thai dyspeptic patients

OBJECTIVES

To investigate the prevalence of the vacA, cagA, cagE, iceA, and babA2 genotypes in Helicobacter pylori strains isolated from Thai dyspeptic patients, and to determine whether any correlation exists between these genotypes and clinical manifestations.

METHODS

Helicobacter pylori was examined in 112 patients (62 with non-ulcer dyspepsia (gastritis), 34 with peptic ulcer disease, and 16 with gastric cancer (GCA)), detected by culture or direct detection from gastric biopsies. Allelic variants of the vacA, cagA, cagE, iceA, and babA2 genotypes were identified by using the polymerase chain reaction.

RESULTS

The positive rates for the vacAs1, vacAs2, cagA, cagE, iceA1, iceA2, and babA2 genes in H. pylori of dyspeptic patients were 100%, 0%, 98.2%, 88.4%, 45.5%, 33.1%, and 92%, respectively. The allelic variant vacAs1m1 was more prevalent (58%) than vacAs1m2 (42%). The cagA and cagE genes were commonly found together (87.5%). The most predominant genotypes were vacAs1m1, cagA, cagE, iceA1, and babA2. The various genes alone or in combination had no statistically significant association with the clinical outcomes (p>0.05).

CONCLUSION

Neither single gene nor combination of vacA, cagA, cagE, iceA, and babA2 genes was significantly helpful in predicting the clinical outcome of H. pylori infection in Thai patients. The high prevalence of these genes in H. pylori isolated from Thai patient groups suggests that H. pylori strains are geographically dependent.

Absence of Helicobacter pylori in the oral cavity of 10 non-dyspeptic subjects demonstrated by real-time polymerase chain reaction

Helicobacter pylori plays a significant role in gastric disease. However, the presence of this bacterium in the oral cavity remains controversial. The aim of the present study was to detect and quantify H. pylori in 29 different sites of the oral cavity in non-dyspeptic subjects by means of real-time polymerase chain reactions (PCR). Ten subjects without gastric symptoms were studied. Samples from unstimulated saliva, three sites of the tongue, oral mucosa, and 12 sites of both supragingival and subgingival plaque were collected from each subject. DNA was extracted from the oral samples and analysed for the presence of H. pylori by real-time PCR (LightCycler) using JW23/22 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Amplification efficiency for the LightCycler 2.0 runs ranged from 1.8 to 2.4. Melting curve analysis identified all the positive control capillaries, which contained H. pylori reference DNA, as a single and narrow peak at a melting temperature between 84.5 and 84.9 degrees C. All the negative control capillaries with no template control and the 29 oral samples from each subject showed either no melting peaks or broad melting peaks below 80 degrees C, which were considered as primer dimers. Therefore, H. pylori was not detected from any of the 290 oral samples. As a conclusion, H. pylori seems not to be permanently present in the oral cavity of a non-dyspeptic population.

Use of a combination of brushing technique and the loop-mediated isothermal amplification method as a novel, rapid, and safe system for detection of Helicobacter pylori

Gastric mucosal biopsy is widely used in the detection of Helicobacter pylori but is associated with a number of problems, including false-negative results due to sampling error and massive bleeding after biopsy. Given the extended period required to culture H. pylori, detection would be further improved by the use of rapid detection methods such as PCR. Here, we developed a rapid, safe, and convenient method for collecting H. pylori which combines endoscopic brushing with the loop-mediated isothermal amplification (LAMP) method. The specificity and sensitivity of LAMP were examined using nine urease-generating non-H. pylori bacterial species, Escherichia coli, Clostridium perfringens, Campylobacter jejuni, Helicobacter hepaticus, and 51 H. pylori strains. Results showed that H. pylori-specific LAMP primers amplified H. pylori DNA only and that the lowest detection limit of the LAMP reaction was 10(2) CFU. Brushing and biopsy samples taken from 200 patients with peptic ulcer at Nagoya University Hospital and a regional health care center were subjected to both LAMP and culturing. No adverse effects such as severe bleeding or penetration occurred during the procedure. By LAMP assay, 123 patients were confirmed as H. pylori positive when brushing technique samples were assayed, whereas only 100 were positive when biopsy samples were assayed. Culture assay detected H. pylori in 117 patients when it was combined with the brushing technique and in 96 when it was combined with biopsy. Combination of the endoscopic brushing technique with LAMP is considered a useful and safe system for identifying H. pylori infection.

Detection ofHelicobacter pyloriDNA in peripheral blood from patients with peptic ulcer or gastritis

Cases of Helicobacter bacteremia have been reported from time to time. Helicobacter pylori is the most important representative of Helicobacterium, yet whether it can result in bacteremia has rarely been studied. In this study, we examined H. pylori DNA in peripheral blood and gastric mucosa of patients with peptic ulcer or chronic gastritis by polymerase chain reaction (PCR). We found H. pylori DNA in 15 of 20 gastric samples, and 9 of these specimens were positive for H. pylori culture. H. pylori DNA amplified by PCR was positive in the peripheral blood of three patients, who all had duodenal ulcers. Gastric biopsy specimens from these three patients were all positive for H. pylori genes and H. pylori was isolated from these specimens. After the 16S rRNA gene sequences of three specimens from the same patient were obtained, we found that they were identical, which suggested that they are the same strain. Our findings suggest that H. pylori exists not only in gastric mucosa but also in peripheral blood, and it is possible that H. pylori can result in bacteremia.

In vitro and in vivo activities of Chios mastic gum extracts and constituents against Helicobacter pylori

The extracts and pure major constituents of Chios mastic gum (resin of Pistacia lentiscus var. chia) were tested for their activities against Helicobacter pylori. A total mastic extract without polymer (TMEWP) was prepared after removal of the contained insoluble polymer in order to ameliorate solubility and enhance in vivo activity. Administration of TMEWP to H. pylori SS1-infected mice over the period of 3 months with an average dose of 0.75 mg/day led to an approximately 30-fold reduction in the H. pylori colonization (1.5 log CFU/g of tissue). However, no attenuation in the H. pylori-associated chronic inflammatory infiltration and the activity of chronic gastritis was observed. To further characterize potential active mastic constituents, the TMEWP was separated into an acidic and a neutral fraction. Both were extensively characterized by nuclear magnetic resonance and mass spectroscopy to elucidate the structure of the components contained within each fraction. After chromatographic separation, the acid fraction gave the major triterpenic acids, while the neutral fraction gave several triterpenic alcohols and aldehydes. Mastic extracts and isolated pure triterpenic acids were tested for in vitro activity against a panel of 11 H. pylori clinical strains. The acid fraction was found to be the most active extract (minimum bactericidal concentration [MBC], 0.139 mg/ml), and the most active pure compound was isomasticadienolic acid (MBC, 0.202 mg/ml [0.443 mM]). Our results show that administration of TMEWP may be effective in reducing H. pylori colonization and that the major triterpenic acids in the acid extract may be responsible for such an activity.

Seminested Polymerase Chain Reaction (PCR) for Detecting Helicobacter pylori DNA in Carotid Atheromas

A polymerase chain reaction (PCR) method for the detection of the glmM gene, selected as Helicobacter pylori target sequence, was improved. While performing pathogenicity island cagA gene detection to discriminate pathogenic strains in atherosclerotic carotid samples, several cagA-positive but glmM-negative samples were found. Polymorphisms present in the region amplified in the nested PCR reaction could explain this result; primers were therefore designed to perform a seminested reaction; this modification optimized sensitivity while maintaining specificity. A real-time PCR for Helicobacter DNA detection was also setup. The combination of all 4 PCR reactions detected 83% of H. pylori DNA-positive samples in atherosclerotic carotid tissue, 64% of which were cagA gene positive.

Association of cagA+ Helicobacter pylori with adenotonsillar hypertrophy

Cytotoxin-associated gene A (cagA) of Helicobacter pylori (H. pylori) encodes a highly immunogenic and virulence-associated protein. The presence of cagA(+) H. pylori strains in tonsil and adenoid tissues may affect clinical outcome. The aim of the present study was to determine the presence of H. pylori cagA gene in tonsil and adenoid tissues and to establish the potential association of cagA(+) H. pylori in recurrent adenotonsillitis (RAT) and adenotonsillar hypertrophy (ATH). For this aim, a total of 118 tissue samples (71 tonsil and 47 adenoid tissues) were collected from a total of 71 children: 28 cases with RAT and 43 cases with ATH. The samples were analyzed for glmM gene to detect the infection with H. pylori by polymerase chain reaction (PCR). H. pylori-positive samples were further analyzed for the presence of the cagA gene. The PCR analysis showed that 29 samples (24.6%) were positive for H. pylori. Seventeen out of these 29 samples (58.6%) were found positive for cagA; the cagA gene was detected in 12 samples of ATH and 5 samples of RAT. The presence rate of cagA gene was significantly higher (p < 0.05) in ATH patients than that found in RAT patients. These results suggest that presence of cagA(+) H. pylori may be associated with development of ATH.

No evidence for a direct role of Helicobacter pylori and Mycoplasma pneumoniae in carotid artery atherosclerosis

BACKGROUND

That infections with certain pathogens, by initiating an inflammatory response, may contribute to the development of atherosclerosis is suggested by clinical and experimental evidence.

AIM

To analyse atherosclerotic plaques of the carotid artery, samples of apparently healthy greater saphenous veins and circulating leucocytes from the same individual patients for the presence of Helicobacter pylori and Mycoplasma pneumoniae.

METHODS

Samples from 36 patients undergoing carotid endarterectomy for symptomatic carotid artery stenosis were analysed by polymerase chain reaction for the presence of DNA specific for H. pylori and M. pneumoniae. IgG antibody titres against H. pylori and M pneumoniae and plasma levels of soluble E-selectin, soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 were determined.

RESULTS

M. pneumoniae-specific DNA was detected in the atherosclerotic plaques of 13 of 36 (36.1%) patients, in the saphenous veins of 9 of 36 (25%) patients and in the leucocytes of 27 of 36 (75%) patients. No salient association was observed between the presence of M. pneumoniae-specific DNA in leucocytes and atherosclerotic plaques or veins. A marked correlation between the presence of M. pneumoniae in the respective specimens and the studied inflammatory markers or the presence of anti-M. pneumoniae antibodies was not observed. H. pylori-specific DNA could not be detected in the specimens tested.

CONCLUSIONS

The absence of H. pylori and the random distribution of M. pneumoniae in tissue samples obtained from patients with symptomatic carotid artery stenosis do not support a role for these pathogens in the development of atherosclerosis due to a direct interaction of the bacteria with the vasculature.

Increased rate of Helicobacter pylori infection detected by PCR in biopsies with chronic gastritis

Histology is considered a sensitive method for detection of Helicobacter pylori, in gastric biopsies. We investigated the diagnostic potential of qualitative nested (nPCR) and quantitative PCR (qPCR) for detection of H. pylori using different primers on 126 archived gastric biopsies with inflammation and correlated the inflammatory changes with the presence and density of bacteria. H. pylori was detected in 42.8% biopsies by histology and PCR, an additional 15 samples were positive exclusively by PCR: nPCR was positive in all histologically positive samples, but qPCR failed to detect H. pylori in 10 biopsies. The inflammatory score was significantly higher in biopsies positive for H. pylori only by PCR showed a significant higher inflammatory score compared with negative biopsies (mean of neutrophils score, 1.60 vs. 0.90, P < 0.01; mean of mononuclear cells score, 2.27 vs. 1.67, P < 0.01), whereas the inflammatory score was similar compared with biopsies positive for H. pylori by histology (mean of neutrophils score, 1.60 vs. 1.56, not significant; mean of mononuclear cells score, 2.27 vs. 2.20, not significant). A weak correlation between inflammatory score and the density of H. pylori detected by histology was observed. The mean values of H. pylori DNA were significantly higher in histologic-positive than in histologic negative biopsies. We have shown that PCR can detect H. pylori in about 20% of histologic-negative gastric biopsies, indicating the clinical relevance of H. pylori detection by PCR in biopsies with characteristic inflammatory changes.

Is Helicobacter pylori a pathogenic agent of the cervix uteri?

BACKGROUND

Helicobacter pylori is a gram-negative, microaerophilic rod-shaped bacterium that lives beneath the gastric mucosal layers, on the surface of epithelial cells. Gastric infection with this organism causes inflammation of the gastric mucosa, which can lead to gastritis, duodenal or gastric ulcers and even in rare cases to gastric carcinoma or MALT lymphoma. Approximately 50% of the population of the entire world is believed to be infected with H. pylori, but the exact route of transmission is still uncertain. It has been speculated that the cervix, with its endocervical columnar epithelium and acidic mucous layer, might provide a suitable environment for H. pylori. H. pylori might be a pathogenic agent for cervical infection. In order to address this issue we studied H. pylori in the endocervical tissue.

METHODS

To investigate our hypothesis, we examined cervical tissue using PCR, culture, and Gram-stain. Thirty-three cervices from women who underwent total hysterectomy for noninvasive non-cervical benign uterine diseases were analyzed in this study. Twenty-one patients had cervicitis and 12 patients were included as controls.

RESULTS

Of the 29 patients studied, none showed evidence of H. pylori infection. H. pylori was not detected by PCR, histology, or culture.

CONCLUSIONS

We could not detect H. pylori in the cervix of patients with cervicitis. H. pylori-infected patients' cervices remain to be investigated, and a larger study is needed to draw firm conclusions.

Rapid detection of clarithromycin resistance in Helicobacter pylori using a PCR-based denaturing HPLC assay

OBJECTIVES

We evaluated a new approach for the rapid detection of clarithromycin resistance in Helicobacter pylori, based on PCR and denaturing HPLC (DHPLC).

METHODS

A 180 bp fragment of the 23S rRNA gene was amplified using DNA from 81 clinical H. pylori isolates (51 isolates were shown to be resistant to clarithromycin by Etest), and, directly, from 101 gastric biopsies from patients with digestive diseases, who were infected with H. pylori as assessed by a 13C-urea breath test, histology and/or culture. DHPLC was used to detect mutations in all the PCR products.

RESULTS

DHPLC profiles for the 30 susceptible isolates all showed homoduplex peaks; the resistant isolates consistently generated heteroduplex peaks that were easily distinguishable from the wild-type H. pylori reference strain. Sequencing revealed point mutations in all the resistant isolates. Overall, five different mutations were detected. Four of these mutations (A2142G, A2142C, A2143G and T2182C) are known to be associated with clarithromycin resistance; the remaining mutation (C2195T) has not been previously described. This novel single-base substitution was found in combination with the common mutation A2143G. Of the biopsies tested, 25 specimens generated heteroduplexes due to sequence alterations (mutation A2142G, A2142C or A2143G). In one of these specimens, A2143G was found together with the novel mutation T2221C; in another, a mixture of wild-type and mutant (A2143G) sequences was detected. For 20 culture-positive out of the 25 biopsies DHPLC results confirmed the presence of clarithromycin resistance.

CONCLUSIONS

Our results suggest that the PCR-DHPLC assay is a valid tool for rapid assessment of clarithromycin resistance in H. pylori and that in the future it could be used directly on biopsy specimens, avoiding the need for culture-based methods.

Heterogeneity of cag genotypes and clinical outcome of Helicobacter pylori infection

Helicobacter pylori infecting strains may include colony subtypes with different cytotoxin-associated gene (cag) genotypes. We sought to determine whether the cag heterogeneity of infecting strains is related to the clinical outcome of infection. Gastric biopsies for culture and histologic study were taken from 19 patients infected with cagA-positive strains (6 with duodenal ulcer, 8 with atrophic gastritis, and 5 with nonatrophic gastritis). For each biopsy, DNA was extracted from 10 single colonies and from a sweep of colonies. Polymerase chain reaction (PCR) for cagA and cagE (both located in the right half of cag) and virB11 (located in the left half of cag) was performed. Random amplified polymorphic DNA PCR (RAPD-PCR) and sequencing of glmM PCR product were performed to verify strain identity of colonies with different cag genotypes. In all patients, PCR from sweeps were positive for cagA, showing that all specimens contained cagA-positive H. pylori subtypes. In 11 patients, PCR products from all colonies were positive for cagA, cagE, and virB11, but in 8 patients, PCR products from varying numbers of colonies were negative for 1 or more cag genes. RAPD-PCR and sequencing of glmM PCR product confirmed the strain identities of colonies with different cag genotypes. We detected cag deletions in 6 of 8, 2 of 5, and 0 of 6 patients with atrophic gastritis, nonatrophic gastritis, and duodenal ulcer, respectively (P = .02). In conclusion, changes in cag genotype in single colony isolates from subjects infected with cagA-positive H. pylori strains are more common in atrophic than in nonatrophic gastritis or duodenal ulcer. These findings are consistent with host-induced (acid secretion?) adaptive changes in cag genotype during infection.

Polymerase chain reaction based analysis of the cytotoxin associated gene pathogenicity island of Helicobacter pylori from saliva: an approach for rapid molecular genotyping in relation to disease status

BACKGROUND AND AIMS

The genetic composition of the intricate cytotoxin associated gene pathogenicity island (cag PAI) of Helicobacter pylori is known to significantly influence the outcome of the disease. Hence, analysis of complete cag PAI of H. pylori isolated from saliva would be of immense importance in standardizing saliva as a reliable non-invasive diagnostic specimen and also to evaluate the type of H. pylori infection. The aim of the present study was to analyze the genes of cag PAI of H. pylori for their presence and correlating them with the disease status of the patients.

METHODS

One hundred and twenty patients (55 duodenal ulcer [DU], 25 gastric ulcer and 40 non-ulcer dyspepsia [NUD]) were investigated for the present study. Eight pairs of oligonucleotide primers (cagA1, cagA2, cagAP1, cagAP2, cagE, cagT, LEC1 and LEC2) of five different loci; cagA, cagA promoter region, cagE which represents cagI region, cagT and LEC representing cagII were used to detect the presence of the cag PAI genes by polymerase chain reaction.

RESULTS

The comprehensive analysis of the genes constituting cag PAI showed almost equivalent prevalence of all the genes between both the study groups (ulcer and NUD) included. Little significant difference was found in the percentage distribution in both the clinical groups. cagE and cagT were found in a larger proportion of the ulcer group (92.5% and 96.2%) compared with the NUD group (77.5% and 85%), respectively.

CONCLUSION

Saliva could be efficiently used as a non-invasive source for H. pylori and cagT might be an important locus of the cag PAI, thus greatly influencing the disease condition of the subjects.

Detection of Chlamydia pneumoniae and Helicobacter pylori in atherosclerotic plaques of carotid artery by polymerase chain reaction

OBJECTIVES

A possible role of some microorganisms has been proposed in the pathogenesis of atherosclerosis, but it is still an unresolved issue. We investigated the presence of Chlamydia pneumoniae and Helicobacter pylori DNA in carotid artery atherosclerotic plaques by using PCR.

METHODS

One hundred and four patients with atherosclerotic diseases were included. The study group consisted of 52 atherosclerotic plaque specimens obtained from the carotid arteries of patients who had carotid endarterectomy and the control group consisted of 52 specimens obtained from the macroscopically healthy regions of ascending aorta in patients who had undergone coronary artery bypass grafting. The presence of C. pneumoniae and H. pylori DNA in endarterectomy specimens were demonstrated by PCR.

RESULTS

C. pneumoniae DNA was detected in 16 of 52 (30.8%) atherosclerotic plaques and 1 of 52 (1.9%) macroscopically healthy ascending aorta wall specimens (P < 0.001). H. pylori DNA was detected in 9 of 52 (17.3%) atherosclerotic plaques and none of the controls (P = 0.003).

CONCLUSIONS

The higher incidence of C. pneumoniae and H. pylori DNA in atherosclerotic plaques suggests that these microorganisms may play a role in the pathogenesis of atherogenesis.

Detection of Helicobacter pylori in children with otitis media with effusion: a preliminary report

OBJECTIVE

To determine the presence of Helicobacter pylori in the middle ear effusion of patients with otitis media with effusion (OME) by polymerase chain reaction (PCR).

STUDY DESIGN

A prospective study in patients with OME.

METHODS

The study was performed in 38 patients with OME who were admitted to the ENT Clinic, Firat University from June 2003 to April 2004. In all cases, a myringotomy operation (with or without placement of a ventilation tube) was carried out. The effusion samples aspirated from the middle ear were analyzed with PCR assay.

RESULTS

A total of 55 aspiration samples collected from 38 children ranging in age from 2 to 12 were included in the study. Fifteen of the subjects were girls, and 23 were boys. In 17 patients, both ears demonstrated effusions, whereas in 21 patients, only one ear had effusions. Nine (16.3%) of 55 the middle ear effusion samples were shown to be H. pylori positive by PCR.

CONCLUSIONS

H. pylori was detected in the middle ear effusion of some patients with OME. These results may have interesting implications for a possible role of H. pylori in OME. In addition, these results suggest that further studies are needed to investigate the role of H. pylori in the etiology of OME.

Heme Oxygenase-1 Is Expressed in Carotid Atherosclerotic Plaques Infected byHelicobacter pyloriand Is More Prevalent in Asymptomatic Subjects

BACKGROUND AND PURPOSE

It is not well established what are the features, if any, that distinguish symptomatic from asymptomatic carotid atherosclerotic plaques. Inducible heme oxygenase-1 (HO-1) is a component of cellular defense mechanisms against oxidative stress. We aimed to assess the presence of Helicobacter pylori (H pylori) and the expression of HO-1 in carotid atherosclerotic plaques of patients with and without prior neurologic symptoms attributable to the operated artery.

METHODS

We examined 25 symptomatic and 23 asymptomatic carotid atherosclerotic plaques removed during endarterectomy and 7 normal carotid arteries obtained at autopsy. We investigated the presence of H pylori DNA in the vessel wall and performed immunohistochemical detection of HO-1.

RESULTS

H pylori DNA was present in 28 plaques and HO-1 was expressed in 30 plaques. HO-1 was found in 27 H pylori-positive specimens but in only 3 H pylori-negative specimens (P<0.001). All 7 normal carotid arteries were negative for both H pylori and HO-1. Although 82% of asymptomatic specimens were positive for H pylori and 87% for HO-1, only 36% of symptomatic specimens were positive for both H pylori and HO-1 (P<0.01).

CONCLUSIONS

This study suggests a strong association between H pylori infection and expression of HO-1 in carotid atherosclerotic plaques. There was a substantial prevalence of these features in specimens obtained from asymptomatic subjects.

Rapid identification of pathogenic bacteria by capillary electrophoretic analysis of rRNA genes

Molecular diagnosis is playing an increasingly important role in the rapid detection and identification of pathogenic organisms in clinical samples. The genetic variation of ribosomal genes in bacteria offers an alternative to culturing for the detection and identification of these organisms. Here 16S rRNA and 16S-23S rRNA spacer region genes were chosen as the amplified targets for single-strand conformation polymorphism (SSCP) and restriction fragment length polymorphism (RFLP) capillary electrophoresis analysis and bacterial identification. The multiple fluorescence based SSCP method for the 16S rRNA gene and the RFLP method for the 16S-23S rRNA spacer region gene were developed and applied to the identification of pathogenic bacteria in clinical samples, in which home-made short-chained linear polyacrylamide (LPA) was used as a sieving matrix; a higher sieving capability and shorter analysis time were achieved than with a commercial sieving matrix because of the simplified template preparation procedure. A set of 270 pathogenic bacteria representing 34 species in 14 genera were analyzed, and a total of 34 unique SSCP patterns representing 34 different pathogenic bacterial species were determined. Based on the use of machine code to represent peak patterns developed in this paper, the identification of bacterial species becomes much easier.

Genotypic and phenotypic stability of Helicobacter pylori markers in a nine-year follow-up study of patients with noneradicated infection

The cagA gene, alleles of the vacA gene,random amplified polymorphic DNA (RAPD), and neutrophil activating capacity (HpNAC) were used to examine paired H. pylori isolates from 10 noneradicated individuals 9 years apart. Paired isolates from each patient were indistinguishable with regard to vacA alleles, RAPD, and HpNAC. Isolates from nine patients showed concordance for the cagA gene, which was not detected in the recent isolate of the tenth patient. Antibodies to CagA were, however, demonstrated in the serum specimens 9 years apart and were also present in two other patients whose paired isolates were cagA-, indicating the existence of both cagA+ and cagA-organisms, with the latter predominating in some patients. The present study suggests a greater stability of phenotypic and genotypic markers of H. pylori than previously regarded. This might be true for a community with low infection and transmission rates. Complementary techniques like microarrays might, however, disclose evolutionary changes not identified here.

Identification of helicobacter species in human liver samples from patients with primary hepatocellular carcinoma

AIMS

Several studies have shown the presence of helicobacter species in the human biliary tract and in the intestinal tract of animals. Experimental infection by Helicobacter hepaticus in mice causes chronic hepatitis and hepatocellular carcinoma (HCC). This study investigated whether helicobacter species could be detected in the liver of patients with HCC.

METHODS

Liver samples from 20 patients with primary liver carcinoma diagnosed by histopathology and 16 controls without primary liver carcinoma were studied. Histology with standard and immunohistochemical stains, culture, and polymerase chain reaction (PCR) amplification using helicobacter genus specific 16S rRNA primers were used to detect the presence of bacteria. Amplified products were identified by Southern hybridisation and sequencing. A search for other genes specific for Helicobacter pylori was also performed.

RESULTS

Helicobacter species 16S rDNA was found in eight of 20 samples of primary liver carcinoma, whereas none of the controls harboured this rDNA. Six helicobacter specific PCR amplicons were sequenced and were found to have 98.5-99.0% similarity to the 16S rDNA of H pylori. Of the eight positive samples, seven were positive in PCR using 26 kDa protein primers and six showed morphological and immunohistochemical evidence of H pylori. The cagA and glmM genes were detected in only two samples. The vacA and rps4 genes were not detected.

CONCLUSIONS

Helicobacter can be present in the liver of patients with primary liver carcinoma and is probably linked to the carcinogenic process in the liver.

Diagnosis of helicobacter pylori infection by polymerase chain reaction: is it worth it?

The aim of this study was to determine to what degree polymerase chain reaction (PCR) was superior to histology and culture, and whether a noncommercial urease test was of value, in detecting Helicobacter pylori in gastric biopsy specimens. Gastric biopsy specimens from the antrum and corpus of 134 consenting patients were subjected to PCR, targeting the glmM (ureC) gene, histology, culture, and a rapid urease test. PCR detected H. pylori in the biopsy specimens from 59 patients. All methods showed a high degree of sensitivity and specificity, but histology gave 2 false-negatives, and culture and the urease test gave 1 false-negative compared with PCR. PCR of a glmM gene segment was superior to the other methods for the detection of H. pylori infection and was comparable to histology in terms of cost. Nevertheless, in this study, histology and culture were found to be relatively reliable methods for examining gastric biopsy specimens.

The diagnostic value of endoscopy and Helicobacter pylori tests for peptic ulcer patients in late post-treatment setting

Background

Guidelines for management of peptic ulcer patients after the treatment are largely directed to detection of H. pylori infection using only non-invasive tests. We compared the diagnostic value of non-invasive and endoscopy based H. pylori tests in a late post-treatment setting.

Methods

Altogether 34 patients with dyspeptic complaints were referred for gastroscopy 5 years after the treatment of peptic ulcer using a one-week triple therapy scheme. The endoscopic and histologic findings were evaluated according to the Sydney classification. Bacteriological, PCR and cytological investigations and ¹³C-UBT tests were performed.

Results

Seventeen patients were defined H. pylori positive by ¹³C-UBT test, PCR and histological examination. On endoscopy, peptic ulcer persisted in 4 H. pylori positive cases. Among the 6 cases with erosions of the gastric mucosa, only two patients were H. pylori positive. Mucosal atrophy and intestinal metaplasia were revealed both in the H. pylori positive and H. pylori negative cases. Bacteriological examination revealed three clarithromycin resistant H. pylori strains. Cytology failed to prove validity for diagnosing H. pylori in a post-treatment setting.

Conclusions

In a late post-treatment setting, patients with dyspepsia should not be monitored only by non-invasive investigation methods; it is also justified to use the classical histological evaluation of H. pylori colonisation, PCR and bacteriology as they have shown good concordance with ¹³C-UBT. Moreover, endoscopy and histological investigation of a gastric biopsy have proved to be the methods with an additional diagnostic value, providing the physician with information about inflammatory, atrophic and metaplastic lesions of the stomach in dyspeptic H. pylori positive and negative patients. Bacteriological methods are suggested for detecting the putative antimicrobial resistance of H. pylori, aimed at successful eradication of infection in persistent peptic ulcer cases.

Development of two PCR-based techniques for detecting helical and coccoid forms of Helicobacter pylori

The primary mode of transmission of Helicobacter pylori, a human pathogen carried by more than half the population worldwide, is still unresolved. Some epidemiological data suggest water as a possible transmission route. H. pylori in the environment transforms into a nonculturable, coccoid form, which frequently results in the failure to detect this bacterium in environmental samples by conventional culture techniques. To overcome limitations associated with culturing, molecular approaches based on DNA amplification by PCR have been developed and used for the detection of H. pylori in clinical and environmental samples. Our results showed the glmM gene as the most promising target for detection of H. pylori by PCR amplification. Under optimal amplification conditions, glmM-specific primers generated PCR-amplified products that were specific for H. pylori and some other Helicobacter species. Genome sequence analysis revealed the existence of a conserved region linked to a hypervariable region upstream of the 16S rRNA gene of H. pylori. Selective PCR primer sets targeting this sequence were evaluated for the specific detection of H. pylori. One primer set, Cluster2 and B1J99, were shown to be highly specific for H. pylori strains and did not produce any PCR products when other Helicobacter species and other bacterial species were analyzed. In tests with 32 strains of H. pylori, 6 strains of other Helicobacter species, 8 strains of Campylobacter jejuni, and 21 strains belonging to different genera, the primers for glmM were selective for the Helicobacter genus and the primers containing the region flanking the 16S rRNA gene were selective for H. pylori species only. The combination of two sensitive PCR-based methods, one targeting the glmM gene and the other targeting a hypervariable flanking region upstream of the 16S rRNA gene, are complementary to each other. Whereas the glmM-specific primers provide a rapid, sensitive presumptive assay for the presence of H. pylori and closely related Helicobacter spp., the primers for sequences flanking the 16S rRNA gene can confirm the presence of H. pylori and locate the potential source of this bacterium.

Are Helicobacter species and enterotoxigenic Bacteroides fragilis involved in inflammatory bowel disease?

The aim of this study was to determine if either Helicobacter or enterotoxigenic Bacteroidesfragilis (ETBF) was linked to inflammatory bowel disease (IBD), using PCR. We analyzed the luminal washings and colonic biopsies of 35 patients with IBD and 37 control patients. The presence of Helicobacter was confirmed in the luminal washing of one IBD patient and three control patients and in the biopsies of two IBD patients. Ten of 28 control patients and 8 of 32 IBD patients had a positive luminal washing for the enterotoxin gene. Six of 33 control patients and 4 of 32 IBD patients had positive biopsies. The prevalence of the enterotoxin gene was higher in IBD patients with active disease compared with patients with inactive disease, although it did not achieve statistical significance. In conclusion, Helicobacter was not associated with IBD in our population of patients, although ETBF may be associated with active disease.

Evolutionary trace analysis of the alpha-D-phosphohexomutase superfamily

The alpha-D-phosphohexomutase superfamily is composed of four related enzymes that catalyze a reversible, intramolecular phosphoryl transfer on their sugar substrates. The enzymes in this superfamily play important and diverse roles in carbohydrate metabolism in organisms from bacteria to humans. Recent structural and mechanistic studies of one member of this superfamily, phosphomannomutase/phosphoglucomutase (PMM/PGM) from Pseudomonas aeruginosa, have provided new insights into enzyme mechanism and substrate recognition. Here we use sequence-sequence and sequence-structure comparisons via evolutionary trace analysis to examine 71 members of the alpha-D-phosphohexomutase superfamily. These analyses show that key residues in the active site, including many of those involved in substrate contacts in the P. aeruginosa PMM/PGM complexes, are conserved throughout the enzyme family. Several important regions show class-specific differences in sequence that appear to be correlated with differences in substrate specificity exhibited by subgroups of the family. In addition, we describe the translocation of a 20-residue segment containing the catalytic phosphoserine of phosphoacetylglucosamine mutase, which uniquely identifies members of this subgroup.

In vitro and in vivo inhibition of Helicobacter pylori by Lactobacillus casei strain Shirota

We studied the potential inhibitory effect of Lactobacillus casei strain Shirota (from the fermented milk product Yakult [Yakult Ltd., Tokyo, Japan]) on Helicobacter pylori by using (i) in vitro inhibition assays with H. pylori SS1 (Sydney strain 1) and nine H. pylori clinical isolates and (ii) the in vivo H. pylori SS1 mouse model of infection over a period of 9 months. In vitro activity against H. pylori SS1 and all of the clinical isolates was observed in the presence of viable L. casei strain Shirota cells but not in the cell-free culture supernatant, although there was profound inhibition of urease activity. In vivo experiments were performed by oral administration of L. casei strain Shirota in the water supply over a period of 9 months to 6-week-old C57BL/6 mice previously infected with H. pylori SS1 (study group; n = 25). Appropriate control groups of H. pylori-infected but untreated animals (n = 25) and uninfected animals given L. casei strain Shirota (n = 25) also were included in the study. H. pylori colonization and development of gastritis were assessed at 1, 2, 3, 6, and 9 months postinfection. A significant reduction in the levels of H. pylori colonization was observed in the antrum and body mucosa in vivo in the lactobacillus-treated study group, as assessed by viable cultures, compared to the levels in the H. pylori-infected control group. This reduction was accompanied by a significant decline in the associated chronic and active gastric mucosal inflammation observed at each time point throughout the observation period. A trend toward a decrease in the anti-H. pylori immunoglobulin G response was measured in the serum of the animals treated with lactobacillus, although this decrease was not significant.

Detection of Helicobacter pylori in gastric mucosa of patients with gastroduodenal diseases by PCR-restriction analysis using the RNA polymerase gene (rpoB)

A novel PCR restriction analysis method using the RNA polymerase beta-subunit- coding gene (rpoB) was employed to both detect and identify Helicobacter pylori in biopsy specimens and culture isolates. The rpoB DNAs (458 bp) were specifically amplified by PCR with the Helicobacter-specific primers (HF and HR). Based on the determined rpoB sequences of the culture isolates, an H. pylori-specific restriction site, Tru9I, was found. H. pylori can be identified by observing two discernible DNA fragments (288 and 138 bp) after Tru9I digestion and agarose gel electrophoresis. The rpoB PCR and subsequent restriction analysis (PRA) enabled the specific detection and identification of H. pylori in biopsy specimens from patients with gastroduodenal diseases. The rpoB PRA conferred a compatible or a slightly higher positive rate (53.7%) than did the Campylobacter-like organism (CLO) test (50.4%) and glmM PCR (48.8%), suggesting that it is useful for diagnosing an H. pylori infection without culture in the clinical laboratory.

Oral Helicobacter pylori: can we stomach it?

Helicobacter pylori infection is one of the most common in man. The bacterium primarily resides in the human stomach, where it plays a significant role in gastric disease. If the spread of H. pylori is to be prevented, an understanding of the transmission process is essential. The oral cavity has been proposed as a reservoir for gastric H. pylori, which has been detected by culture and PCR in both dental plaque and saliva. This review will discuss the evidence for the role of the oral cavity in the transmission of gastric H. pylori. Moreover, the difficulties encountered in addressing this topic, possible directions for future research, and the implications for the dental profession are discussed.

Common presence of Helicobacter DNA in the gallbladder of patients with gallstone diseases and controls

BACKGROUND

Several species of Helicobacter colonise the biliary tract of animals and cause hepatobiliary diseases. Helicobacter species have also been identified in the gallbladder of a high proportion of Chilean patients with gallbladder cancer.

AIM

To determine the presence of Helicobacter species, particularly Helicobacter pylori and Helicobacter bilis, in the gallbladder of patients with non-malignant gallbladder diseases and control patients.

PATIENTS AND METHODS

DNA was extracted from gallbladder samples from 122 consecutive patients undergoing cholecystectomy. The presence of Helicobacter genus-specific or Helicobacter pylori and Helicobacter bilis species-specific DNA was determined by polymerase chain reaction and sequence analysis. The presence of Helicobacter pylori-specific immunoglobulin G in the serum (n=84) and bile (n=104) samples was determined by enzyme linked immunosorbent assay.

RESULTS

Helicobacter DNA was detected in 61 (50.0%) gallbladder samples: 29 of 60 (48.3%) patients with symptomatic gallstone, six of 10 (60.0%) patients with asymptomatic gallstones, 11 of 15 (73.3%) patients with other biliary diseases, and 15 of 37 (40.5%) control patients, respectively. Among them, 39 samples were positive for Helicobacter pylori but none were positive for Helicobacter bilis. Sequence analysis of Helicobacter genus-positive samples showed that 56 samples were Helicobacter pylori and five were Helicobacter species 'Liver 3' strain. Overall, there was no significant difference in the detection rate of Helicobacter DNA or the levels of serum and bile Helicobacter pylori-specific immunoglobulin G in the various biliary disease groups compared with control patients. Neither was there any significant difference in the blood biochemistry and liver function tests between patients with positive and negative Helicobacter DNA detection.

CONCLUSION

Helicobacter species' DNA are commonly present in the gallbladder of patients with gallstone diseases and in controls, implying that Helicobacter infection alone may not play a significant role in the formation of gallstones. However, our results do not exclude the possibility of Helicobacter infection as a cofactor in the development of gallstones.

Heterogeneity of cag genotypes in Helicobacter pylori isolates from human biopsy specimens

The Helicobacter pylori chromosomal cluster of genes known as the cytotoxin-associated gene (cag) island may have different compositions in infecting strains. In this study, we analyzed 150 single colonies obtained from gastric biopsy specimens from 10 patients infected with cagA-positive H. pylori strains and sweep isolates (isolates harvested with sweep in different points of the plate) from 6 patients infected with cagA-negative strains. Three loci in the cag island (cagA, cagE, and virB11) and the conserved gene glmM (ureC) were investigated by PCR. The levels of anti-H. pylori and anti-CagA antibodies in patient sera were also measured. For subjects infected with cagA-negative strains, all sweep isolates were also negative for cagE and virB11, suggesting the complete absence of the cag island. For subjects infected with cagA-positive strains, most of the isolates were positive for all three genes studied, whereas 24.7% of the isolates had a partial or total deletion of the cag island. cagA, cagE, and virB11 were, respectively, present in 87.3, 77.3, and 90% of the colonies. The deletion of virB11 was always associated with the deletion of cagA and/or cagE. H. pylori colonies with different cag genotypes were isolated within a single gastric biopsy specimen from 3 of the 10 patients and were further characterized by random amplified polymorphic DNA (RAPD) analysis and by sequencing of an arbitrarily selected gene segment. Although the colonies had different cag genotypes, their RAPD profiles were highly similar within each patient, and the nucleotide sequences of the selected gene segment were identical. All of the patients had detectable antibodies against H. pylori, and 9 of 10 had anti-CagA antibodies. In conclusion, we show that a single infecting H. pylori strain may include variable proportions of colony subtypes with different cag genotypes. The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between cag genotypes and clinical outcomes of H. pylori infections.

Molecular typing of Helicobacter pylori by virulence-gene based multiplex PCR and RT-PCR analysis

BACKGROUND

In recent years, numerous PCR amplification typing methods have been developed for the identification of H. pylori specific virulence genes. To reduce the number of PCR amplifications needed we have previously developed virulence gene based multiplex PCR and RT-PCR assays.

AIM

The aim of the present study was to characterise Helicobacter pylori strains by means of virulence-gene based multiplex PCR and reverse-transcription PCR.

SUBJECTS

Helicobacter pylori clinical reference strains HP-HJM 1-25 originally obtained from routine cultures of clinical gastric biopsy specimens from dyspeptic patients were used in the present study.

METHODS

Helicobacter pylori multiplex PCR and RT-PCR assays were carried out using primer pairs targeting the cagA, vacA, ureA, ureI, hspA (hsp60), and sodB genes and their cDNA.

RESULTS

Unexpected multiplex PCR and RT-PCR patterns were observed by ethidium bromide staining of agarose gels and Southern blot hybridisation analysis. DNA sequence analysis revealed a complex pattern of point mutations, deletions and insertions in the sodB, cagA and vacA genes, respectively. Mutations occurring in the PCR and hybridisation primer binding sites might explain some of the discrepancies previously observed in the expression of these genes. Furthermore, the present data show that coexpression of cagA and vacA transcripts of different sizes may take place in the same strain.

CONCLUSIONS

The multiplex PCR and RT-PCR assay described allows rapid characterisation of H. pylori virulence genes at the DNA and RNA (cDNA) levels. However, extensive DNA sequence analysis seems necessary if one wants to reveal details of mutations occurring in the cagA and vacA genes.

cag pathogenicity island of Helicobacter pylori in Korean children

BACKGROUND

cag pathogenicity island is reported to be a major virulence factor of Helicobacter pylori. The aim of this study was to investigate the status of cag pathogenicity island genes and gastric histology in Korean children with H. pylori gastritis.

METHODS

Helicobacter pylori DNA was extracted from antral biopsy specimens from 25 children with H. pylori gastritis. Specific polymerase chain reaction assays were used for four genes of cag pathogenicity island. The features of gastritis were scored in accordance with the updated Sydney System.

RESULTS

cagA was present in 23 (92%) of 25 children, and cagE in 24 (96%). Twenty-two (88%) children were cagT positive and 19 (76%) virD4 positive. All of the selected genes of the cag pathogenicity island were present in 17 (68%) children and completely deleted in one child. There were no differences in neutrophil activity and chronic inflammation between children infected with intact cag pathogenicity island strains and those with partially or totally deleted-cag pathogenicity island strains.

CONCLUSION

cag pathogenicity island is not a uniform, conserved entity in Korea. Completeness of cag pathogenicity island may not be the major factor to determine the severity of H. pylori gastritis in children.

Prevalence of Helicobacter pylori in Sri Lanka as determined by PCR

Fifty-seven Sinhalese patients were investigated for the presence of Helicobacter pylori by PCR. A prevalence of 70.1%, with 47.5% positive for cagA, was demonstrated. The most common vacA allele was s1am1. There was no significant association between either the s1 allele or the cagA allele and severe gastroduodenal disease. There was an association between the s1 allele and the cagA locus.

A study of recombinant protective H. pylori antigens

AIM: To construct a recombinant vector which can express M_r26000 outer membrane protein (OMP) from Helicobacter pylori (H. pylori), and to obtain the vaccine protecting against H. pylori infection and a diagnostic reagent kit quickly detecting H. pylori infection.

METHODS: The gene encoding the structural M_r26000 outer membrane protein of H. pylori was amplified from H. pylori chromosomal DNA by PCR, and inserted in the prokaryotic expression vector pET32a(+), which was transformed into the Top10 E. coli strain. Recombinant vector was selected, identified and transformed into BL-21(DE3) E. coli strain. The recombinant fusion proteins were expressed. The antigenicity of recombinant protein was studied by ELISA or immunoblotting and immunized Balb/c mice.

RESULTS: The gene of M_r26000 OMP was amplified to be 594 base pairs, 1.1% of the cloned genes was mutated and 1.51% of amino acid residues was changed, but there was homogeneity between them. The recombinant fusion protein encoded objective polypeptides of 198 amino acid residues, corresponding to calculated molecular masses of M_r26000. The level of soluble expression products was about 38.96% of the total cell protein. After purification by Ni-NTA agarose resin columniation, the purity of objective protein became about 90%. The ELISA results showed that recombinant fusion protein could be recognized by patient serum infected with H. pylori and rabbit serum immunized with the recombinant protein. Furthermore, Balb/c mice immunized with the recombinant protein were protected against H. pylori infection.

CONCLUSION: M_r26000 OMP may be a candidate vaccine preventing H. pylori infection.

Molecular evidence of Helicobacter cinaedi organisms in human gastric biopsy specimens

One hundred twenty-six urease-negative gastric biopsy specimens were evaluated for the presence of Helicobacter genus-specific 16S ribosomal DNA (rDNA) and H. pylori-specific glmM DNA sequences by PCR. The species specificity of the glmM PCR assay was demonstrated, as H. pylori was the only Helicobacter species that yielded the expected glmM amplicon. Most urease-negative specimens (118 of 126 specimens) lacked Helicobacter DNA. However, 8 of 126 urease-negative specimens contained Helicobacter 16S rDNA. In order to identify the Helicobacter species present in urease-negative gastric biopsy specimens, 16S rDNA amplicons were cloned and sequenced. Sequence comparisons were performed by analyses of the sequences in public sequence databases. Two samples contained 16S rDNA that was identified as H. cinaedi with 100% identity and that spanned approximately 400 bp (398 and 398 bp, respectively). In contrast, multiple differences (97% identity; 390 of 398 bp) were observed with H. pylori 16S rDNA in this region. This finding was verified by sequencing an overlapping 537-bp fragment within the 5' portion of 16S rDNA. Although the clinical findings were consistent with H. pylori infection (e.g., duodenal ulcer disease), rapid urease testing and DNA sequence analyses suggested the presence of H. cinaedi organisms and the absence of H. pylori in two human antral biopsy specimens. This study represents the first report of an enteric urease-negative helicobacter in the human stomach. Although these organisms were previously associated with extragastric infections, the roles of these organisms in the pathogenesis of chronic gastritis or peptic ulcer disease remain unclear.

Helicobacter pylori and other enteric bacteria in freshwater environments in Mexico City

BACKGROUND

Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and risk factors for infection as well as mode of transmission remain unclear.

METHODS

H. pylori was detected by polymerase chain reaction (PCR) technique in three aquatic systems located in the Mexico City area. In addition, microbiologic cultures and physicochemical parameters were measured. The systems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses.

RESULTS

Twenty-one percent of the samples (16/77) were positive for H. pylori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hybridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, both providing conditions for potential survival of H. pylori and other enteric pathogens in these environments.

CONCLUSIONS

The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a vehicle in the transmission of H. pylori as well as infection by other known enteric pathogens.

Molecular resistance testing of Helicobacter pylori in gastric biopsies

OBJECTIVE

To evaluate simultaneous diagnosis of infection and molecular resistance testing of Helicobacter pylori.

METHODS

Gastric biopsies were obtained from 26 rapid urease-positive and 51 rapid urease-negative test kits used to diagnose H pylori infection. Following glass bead-assisted DNA isolation, amplification of H pylori 16S ribosomal DNA (rDNA), glmM, and 23S rDNA target genes was performed.

RESULTS

Helicobacter pylori DNA was successfully amplified from 100% (26/26) of urease-positive and 3.9% (2/51) of urease-negative gastric biopsies. Subsequent restriction enzyme-mediated digestion of 23S rDNA amplification products revealed that 17% (4/24) of urease-positive and H pylori DNA-positive biopsy specimens contained point mutations (A2142G or A2143G) associated with clarithromycin resistance. Helicobacter pylori DNA from gastric biopsies was successfully amplified 8 weeks following rapid urease testing.

CONCLUSION

Helicobacter pylori genotyping may be used to detect macrolide-resistant H pylori in individuals prior to initiation of therapy or in patients refractory to anti-H pylori therapy. Two urease-negative specimens yielded Helicobacter DNA distinct from that of H pylori and indicated the need for further investigations of Helicobacter species present in the human stomach.

Detection of Helicobacter pylori in human carotid atherosclerotic plaques

BACKGROUND AND PURPOSE

Several lines of evidence point toward a relationship between infection and atherosclerotic vascular disease. Thus, infection and inflammation often precede ischemic neurological events. Transient alterations in coagulation and direct arterial invasion by certain microorganisms have been reported. Helicobacter pylori infection is the major cause of peptic ulcer disease and appears to be a risk factor for ischemic cerebrovascular disease. However, in contrast to other chronic infectious agents, H pylori has not been consistently isolated from atherosclerotic lesions.

METHODS

We investigated the presence of H pylori in 38 atherosclerotic plaques obtained at carotid endarterectomy by using morphological and immunohistochemical techniques and a highly sensitive polymerase chain reaction method. We performed immunohistochemical detection of intercellular adhesion molecule-1, a marker related to inflammatory cell response. We also examined 7 carotid arteries obtained at autopsy from subjects without carotid atherosclerosis.

RESULTS

H pylori DNA was found in 20 of 38 atherosclerotic plaques. Ten of the H pylori DNA-positive plaques also showed morphological and immunohistochemical evidence of H pylori infection. None of 7 normal carotid arteries was positive for H pylori. Intercellular adhesion molecule-1 was expressed in 75% of H pylori-positive plaques and in 22% of H pylori-negative plaques. The presence of the microorganism was associated with male sex but was independent of age, vascular risk factor profile, and prior neurological symptoms.

CONCLUSIONS

H pylori is present in a substantial number of carotid atherosclerotic lesions and is associated with features of inflammatory cell response. This study provides additional evidence of the relationship between H pylori infection and atherosclerotic disease.

Transmission of Helicobacter pyori in an animal model

An experimental murine model was studied to evaluate the orogastrointestinal colonization of Helicobacter pylori and the animal-to-animal transmission. Balb/C mice were infected with H. pylori and housed with uninoculated mice in cages with and without a grate on the floor. Mice were killed after 7, 14, 30, and 45 days, and samples from the esophagus, stomach, small intestine, colon, and rectum were analyzed for H. pylori by PCR and immunohistochemistry and for histological changes. Bacterial colonization was assessed also by culture from stomach samples. H. pylori was cultured by stomach samples of infected mice at 7, 14, and 30 days. Using PCR and immunohistochemistry, H. pylori was detected in inoculated and uninoculated mice in all areas examined, with an high percentage of positive samples in the esophagus and stomach. Moreover transmission was detected, without differences, regardless of whether mice were housed with or without a grate on the floor, supporting an orooral animal transmission.

A comprehensive review of the natural history of Helicobacter pylori infection in children

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life.