Search

Key Clinical Message Repeated experimental reinfection of two subjects indicates that Helicobacter pylori infection does not promote an immune response protective against future reinfection. Our results highlight the importance of preventing reinfection after eradication, through public health initiatives, and possibly treatment of family members. They indicate difficulties for vaccine development, especially therapeutic vaccines.

Isolates of Helicobacter pylori can be classified phylogeographically. High genetic diversity and rapid microevolution are a hallmark of H. pylori genomes, a phenomenon that is proposed to play a functional role in persistence and colonization of diverse human populations. To provide further genomic evidence in the lineage of H. pylori and to further characterize diverse strains of this pathogen in different human populations, we report the finished genome sequence of Sahul64, an H. pylori strain isolated from an indigenous Australian. Our analysis identified genes that were highly divergent compared to the 38 publically available genomes, which include genes involved in the biosynthesis and modification of lipopolysaccharide, putative prophage genes, restriction modification components, and hypothetical genes. Furthermore, the virulence-associated vacA locus is a pseudogene and the cag pathogenicity island (cagPAI) is not present. However, the genome does contain a gene cluster associated with pathogenicity, including dupA. Our analysis found that with the addition of Sahul64 to the 38 genomes, the core genome content of H. pylori is reduced by approximately 14% (∼170 genes) and the pan-genome has expanded from 2,070 to 2,238 genes. We have identified three putative horizontally acquired regions, including one that is likely to have been acquired from the closely related Helicobacter cetorum prior to speciation. Our results suggest that Sahul64, with the absence of cagPAI, highly divergent cell envelope proteins, and a predicted nontransportable VacA protein, could be more highly adapted to ancient indigenous Australian people but with lower virulence potential compared to other sequenced and cagPAI-positive H. pylori strains.

Background. Helicobacter pylori can be isolated from patients using the string test but contaminating oral and nasopharyngeal microflora need to be suppressed by rapid plating out onto selective culture media. Recently, use of this diagnostic method was enhanced by using a novel transport medium to collect specimens from subjects in a remote Australian clinic over 1300 km from the laboratory. Methods. Retrieved string tests were transported to the laboratory in chilled polystyrene boxes in 5 ml screw-cap bottles with 3 ml of a brain heart infusion broth plus antibiotics. These were 20 g/ml vancomycin, 10 g/ml trimethoprim, 10 g/ml cefsulodin, and 10 g/ml amphotericin B. A comparison was made between subjects who gargled with a chlorhexidine mouthwash before swallowing the string test and those who did not. Results. Forty-five urea breath test-positive subjects were tested and H. pylori was isolated from 34 of them. Successful culture was achieved from string tests that were in transit for up to 29 hours and where the maximum temperature in the transport box was 14 °C. The additional use of a mouthwash had a marked effect on the isolation rate. H. pylori was cultured from 75% of subjects who gargled but only from 39% who did not. Conclusions. This methodology and transport medium can broaden the use of the string test to more remote geographic areas where endoscopy is not feasible so that H. pylori isolates may still be obtained for diagnostic and epidemiologic studies. The value of this promising methodology of collection and transport should be assessed in a controlled study.

Helicobacter pylori infection may be the most common chronic bacterial infection worldwide; however, the prevalence varies between countries and is usually linked to socioeconomic conditions. Gastric cancer is one of the most frequent cancers in developing countries and usually about the seventh most common in developed countries. This article explores the relation of H. pylori to gastric adenocarcinoma and lymphoma. The pathophysiology, epidemiology, screening, clinical presentation, treatment, and prevention are discussed.

[Extract] We read with interest the recent cross-sectional survey of Helicobacter pylori infection in remote and urban Aboriginal populations in Western Australia.[1] The prevalence of H. pylori was shown to be consistent with that in developing countries. This is not surprising, given the high prevalence of diseases such as chronic suppurative otitis media, rheumatic fever, scabies, and tuberculosis affecting Aboriginal peoples — all of which relate to poverty and overcrowding.[2] Aboriginal and Torres Strait Islander people have a massively disproportionate share of the overcrowded households in Australia. In the 2001 Census, Aboriginal people in WA accounted for 53% and 93% of the two-bedroom and three-bedroom households that accommodated seven to nine and ten or more people, respectively (from 3% of the population).[3]

Summary Background : Lactoferrin, a multifunctional glycoprotein, is known to have anti-microbial actions. Bovine lactoferrin and recombinant human lactoferrin have been shown to inhibit Helicobacter pylori, and more recently recombinant human lactoferrin was found to significantly increase the eradication rate of H. pylori when added to standard triple therapy. Aim : To determine the efficacy, safety and tolerability of recombinant human lactoferrin as a therapy in suppressing or eliminating H. pylori infection in subjects with minimal upper gastrointestinal symptoms who have not previously been treated. Subjects and methods : Nine healthy subjects with minimal upper gastrointestinal symptoms and a positive urea breath test were recruited. None of the volunteers had previously been treated for H. pylori. Subjects received 5 × 1.0 g human recombinant lactoferrin daily for 5 or 14 days. Breath tests were repeated during therapy and shortly after to check for eradication. The safety and tolerability of the drug were assessed by physical examination, by monitoring adverse events, and clinical laboratory evaluation. Results : No conversion of the urea breath test from positive to negative was observed and there was no consistent change in urea breath test count to indicate a possible suppression of H. pylori. Conclusion : Lactoferrin, given as a single agent, does not eradicate H. pylori infection.

The evolution rate and genetic changes that occur during chronic infection with Helicobacter pylori have been analysed, but little is known about the genomic changes during the initial, acute bacterial infection phase. Here we analyse the rate and pattern of genome evolution in H. pylori from the genomes of two input strains isolated from human volunteers with asymptomatic infection, and the genomes of two output strains collected 20 and 44 days after re-infection. Similarly, we analyse genome evolution in bacteria from the genome sequences of input and output strains sequentially taken after experimental infection of a rhesus macaque. The estimated mutation rate reveals a mutation burst during the acute infection phase that is over 10 times faster than the mutation rate during chronic infection, and orders of magnitude faster than mutation rates in any other bacteria. The elevated frequency of mutations in outer membrane protein genes suggests that the mutation burst facilitates rapid host adaptation of the bacteria.

The use of polymerase chain reaction (PCR) for successful detection and characterization of microorganisms, including Helicobacter pylori , from clinical and environmental specimens, has been well documented and is being used more widely.

The human gastric pathogen Helicobacter pylori is usually acquired during childhood and, in the absence of treatment, chronic infection persists through most of the host's life. However, the frequency and importance of H. pylori transmission between adults is underestimated. Here we sequenced the complete genomes of H. pylori strains that were transmitted between spouses and analysed the genomic changes. Similar to H. pylori from chronic infection, a significantly high proportion of the determined 31 SNPs and 10 recombinant DNA fragments affected genes of the hop family of outer membrane proteins, some of which are known to be adhesins. In addition, changes in a fucosyltransferase gene modified the LPS component of the bacterial cell surface, suggesting strong diversifying selection. In contrast, virulence factor genes were not affected by the genomic changes. We propose a model of the genomic changes that are associated with the transmission and adaptation of H. pylori to a new human host. Published version

SummaryBackground Helicobacter pylori eradication rates with standard triple therapy are declining worldwide. The optimal management of H. pylori is evolving and new treatment combinations for antibiotic resistant H. pylori strains are required, especially for patients with penicillin allergy. Aim To review the effectiveness of alternative antibiotic combinations and necessity of pre-antibiotic sensitivity testing. Methods A total of 310 consecutive patients who had failed at least one course of standard 7-day triple therapy initially prescribed by their physicians were included in this study between year 2007 and 2011. Antibiotics were prescribed based on pre-antibiotic sensitivity tests and, if any, patient's allergy to penicillin. Results In 98.7% of the patients' samples, H. pylori was successfully cultured. The proportion resistant to clarithromycin and metronidazole was 94.1% and 67.6% respectively, with 65% resistant to both. For the in-house primary quadruple therapy, with Proton pump inhibitor, Amoxicillin, Rifabutin and Ciprofloxacin (PARC), H. pylori was successfully eradicated in 95.2% of patients. For patients allergic to amoxicillin, an alternative quadruple therapy using Proton pump inhibitor, Bismuth subcitrate, Rifabutin and Ciprofloxacin (PBRC) gave an eradication rate of 94.2%. Patients needing alternative salvage therapy were given novel personalised combinations consisting of bismuth, rifabutin, tetracycline or furazolidone; the eradication rate was 73.8%. Conclusions Patients who present with antibiotic resistant H. pylori can be confidently treated with PARC, PBRC or other personalised salvage therapies. These regimens can be used when treatment options are limited by penicillin allergy. Pre-treatment H. pylori antibiotic sensitivity tests contributed to the high eradication rate in this study.

Since the discovery that Helicobacter pylori causes a range of pathologies in the stomachs of infected humans, it has become apparent that Helicobacters are found in a diverse range of animal species where they are frequently associated with disease. In 2003 and 2004, there were two outbreaks of increased mortality associated with gastric bleeding and weight-loss in a captive colony of the Australian marsupial, the Stripe-faced Dunnart (Sminthopsis macroura). The presence of gastric pathology led to an investigation of potential Helicobacter pathogenesis in these animals. Histological examination revealed the presence of gastritis, and PCR analysis confirmed the presence of Helicobacter infection in the stomachs of these marsupials. Surprisingly, sequencing of 16S rRNA from these bacteria identified the species as H. pylori and PCR confirmed the strain to be positive for the important pathogenesis factor, cagA. We therefore describe, for the first time, an apparent reverse zoonotic infection of Stripe-faced Dunnarts with H. pylori. Already prone to pathological effects of stress (as experienced during breeding season), concomitant H. pylori infection appears to be a possible essential but not sufficient co-factor in prototypic gastric bleeding and weight loss in these marsupials. The Stripe-faced Dunnart could represent a new model for investigating Helicobacter-driven gastric pathology. Infections from their human handlers, specifically of H. pylori, may be a potential risk to captive colonies of marsupials.

Haemophilus influenzae is a V factor-dependent species. A plasmid conferring V factor independence in Haemophilus parainfluenzae and Haemophilus ducreyi was transferred to plasmid-free H. influenzae Rd by DNA transformation. The growth characteristics of the transformants in a complex and a chemically defined medium were compared, and the ability of several exogenous pyridine nucleotides and precursors to support growth was examined. Although the transformants appeared to be V factor independent in a complex medium, in a chemically defined medium they exhibited both V factor-dependent and nicotinamide-dependent growth. Because of the inability of the plasmid-free H. influenzae Rd to utilize nicotinamide for growth, it was concluded that the genes conferring this function were plasmid linked. Our results indicate that the V factor requirement, as it is presently defined, is not suitable to serve as a definitive taxonomic criterion for species determination in the family Pasteurellaceae.

To determine and compare the prevalence of Helicobacter pylori in an urban and a remote rural Western Australian Indigenous community.Cross-sectional study of Helicobacter pylori status determined by urea breath tests between mid-January 2003 and the end of June 2004.520 self-selected fasting participants, comprising 270 members of the Martu community at Jigalong, Punmu and Parnngurr in the East Pilbara region (129 men, 141 women; age range, 2-90 years) and 250 people from the Perth Indigenous community (96 men, 154 women; age range, 3-75 years.The overall prevalence of H. pylori was 76%, but the prevalence in the remote rural community was 91%, compared with 60% in the urban community. The odds of having H. pylori were six times greater for rural than for urban participants (odds ratio [OR], 6.34; 95% CI, 3.89-10.33). Further, the overall odds of H. pylori infection in males (rural and urban combined) were greater than for females (OR, 1.61; 95% CI, 1.02-2.54). In both communities, the prevalence of infection remained relatively constant after the age of 10.The prevalence of H. pylori in the two Indigenous communities was two to three times higher than that in the non-Indigenous Australian population and higher than that shown in previous studies in Indigenous Australians.

Nitazoxanide (NTZ) is an antibiotic with microbiological characteristics similar to those of metronidazole but without an apparent problem of resistance. The aim of this study was the prospective evaluation of NTZ given as a single agent in the treatment of Helicobacter pylori infection. Twenty culture-positive patients with dyspepsia who had previously failed at least one course of H. pylori eradication therapy were enrolled. Subjects received 1 g of NTZ twice daily for 10 days. The safety and tolerability of the drug were assessed by physical examination, monitoring of adverse events, and clinical laboratory evaluation. Urea breath tests (UBTs) were performed 6 weeks posttreatment. H. pylori was isolated from UBT-positive patients by the string test or endoscopy with biopsy, and the MICs for these isolates were compared to those for isolates obtained pretherapy. The levels of tizoxanide, the active deacylated derivative of NTZ, were measured in blood, saliva, and tissue from two patients during treatment. The UBT results were positive for all 20 patients after completion of NTZ therapy. The MIC results demonstrated that the NTZ susceptibilities of none of the strains isolated from the patients posttherapy had changed significantly. No major adverse reactions were observed, but frequent minor side effects were observed. In conclusion, NTZ did not eradicate H. pylori when it was given as a single agent.

Background and Aims The CLOtest® and other rapid urease detection kits are widely used in the endoscopic diagnosis of Helicobacter pylori. A new formulation CLOtest has been developed with the goal of obtaining a positive result more rapidly. The aims of this study were to validate the sensitivity and specificity of the new test and compare the time taken for a positive result to be visible in both the new and standard CLOtest. Methods Patients presenting for endoscopy at three Western Australian hospitals were prospectively enrolled. Gastric mucosal biopsies were obtained for the standard and new CLOtest and for histology. Grading of color change was conducted by staff blinded to the type of CLOtest used and conducted according to a standardized color chart. Helicobacter pylori status was defined by the combination of a positive standard CLOtest and histology, against which the new CLOtest was compared. Results were obtained at 1, 3 and 24 h, and at one center, at 10 min intervals for the first hour. Results Three hundred and thirty-five patients were enrolled. Eighty-eight Helicobacter pylori-positive individuals were identified. At 24 h, the new test correctly identified all 88, with one false-positive result (sensitivity 100%, specificity 99.6%). At 1 h, sensitivity was 93% with a number of early false-positive results reducing specificity to 96%. Compared to the current CLOtest, the new formulation became positive faster at 20 min (P = 0.001, n = 51), but was similar at 1 h (P = 0.06, n = 88) and equivalent at 3 h. Conclusions The new formulation CLOtest is sensitive and specific, with a trend to give early positive results more quickly, although accuracy at 3 and 24 h is the same.

As the scientific community approaches the twentieth anniversary of the first isolation of H. pylori, it appears that despite the wealth of articles published in journals throughout the world every month, there are still many unanswered questions about the microbiology of this bacterium and others in the genus Helicobacter.

Helicobacter pylori was isolated from a swallowed string from 32 of 33 adult subjects (97%) with selective culture media. With this method, antibiotic susceptibility testing and molecular epidemiology studies of H. pylori can be carried out without the need for the collection of specimens by endoscopic biopsy.

The location of the genes coding for NAD independence in four unusual clinical isolates of Haemophilus parainfluenzae was determined by transferring these genes to plasmid-free Haemophilus influenzae Rd by transformation and analysing transformants for the presence of plasmids by agarose gel electrophoresis. All NAD-independent transformants were found to carry a single plasmid species. The plasmids, originally harboured by the four H. parainfluenzae isolates recovered from unrelated sources, were of the same size (5.25 kb). Spontaneous reversion to NAD dependence occurred with a low frequency (0.1 to 0.2% of the progeny of a single clone) in both H. parainfluenzae and H. influenzae Rd. The revertants had lost this small plasmid. Mitomycin C exhibited a plasmid ‘curing’ effect with a frequency of ‘curing’ of between 1 and 6% of the surviving clones. It was concluded that the genes conferring NAD independence were located on the small 5.25 kb plasmid.