Hazel M. Mitchell

Asia-Pacific consensus guidelines on gastric cancer prevention

Background and Aim:  Gastric cancer is a major health burden in the Asia–Pacific region but consensus on prevention strategies has been lacking. We aimed to critically evaluate strategies for preventing gastric cancer.

Global Epidemiology of Campylobacter Infection

SUMMARY Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Growth Phase-Dependent Response of Helicobacter pylori to Iron Starvation

ABSTRACT Iron is an essential nutrient that is often found in extremely limited available quantities within eukaryotic hosts. Because of this, many pathogenic bacteria have developed regulated networks of genes important for iron uptake and storage. In addition, it has been shown that many bacteria use available iron concentrations as a signal to regulate virulence gene expression. We have utilized DNA microarray technology to identify genes of the human pathogen Helicobacter pylori that are differentially regulated on a growth-inhibiting shift to iron starvation conditions. In addition, the growth phase-dependent expression of these genes was investigated by examining both exponential and stationary growth phase cultures. We identified known iron-regulated genes, as well as a number of genes whose regulation by iron concentration was not previously appreciated. Included in the list of regulated factors were the known virulence genes cagA, vacA, and napA. We examined the effect of iron starvation on the motility of H. pylori and found that exponential- and stationary-phase cultures responded differently to the stress. We further found that while growing cells are rapidly killed by iron starvation, stationary-phase cells show a remarkable ability to survive iron depletion. Finally, bioinformatic analysis of the predicted promoter regions of the differentially regulated genes led to identification of several putative Fur boxes, suggesting a direct role for Fur in iron-dependent regulation of these genes.

Gene expression profiling of Helicobacter pylori reveals a growth-phase-dependent switch in virulence gene expression.

ABSTRACT The global pattern of growth-phase-dependent gene expression of Helicobacter pylori during in vitro culture was analyzed by using a high-density DNA microarray. To detect consistent coordinated gene expression in this bacterium, temporal changes in transcription were assessed in two independent time courses. Cluster analysis of the expression profiles highlighted a major switch in gene expression during the late log-to-stationary phase transition that we have termed the Log-Stat switch. Statistical analysis of the genes that were significantly induced or repressed during the Log-Stat switch revealed that many of these genes were related to virulence. Among these, expression of the genes for the neutrophil activating protein (napA) and the major flagellin subunit (flaA) were significantly induced. Additionally, the expression of a number of genes involved in iron homeostasis changed dramatically at this switch; the gene for the iron-storage protein, pfr, was induced, while the genes for two putative iron uptake proteins, fecA and frpB, were significantly repressed. These data suggest that the late log phase may correspond to the most virulent phase of growth in H. pylori and may be intimately related to its pathogenesis. The use of microarrays to analyze the kinetics of the transcriptional response of a bacterial pathogen to a changing environment has enabled the discovery of previously unappreciated relationships between genes by elucidation of coordinated gene expression profiles.

Helicobacter pylori infection in children : potential clues to pathogenesis

Children (227) undergoing endoscopy for upper gastrointestinal symptoms were investigated for the presence of Helicobacter pylori infection. The histological response to H. pylori infection and the presence of antral nodularity and peptic ulceration were noted. Symptomatic adults (258) undergoing endoscopy were also investigated for the presence of nodularity. H. pylori infection was detected historically in 32 of 227 (14.1%) children. Of those children infected with H. pylori, half (50%) had antral nodular gastritis. Of 139 H. pylori positive adults 22 (15.8%) showed nodularity. The active component of the histological response was found to be minimal or lacking in the majority of children infected with H. pylori. Twelve of the 227 children (5.3%) had peptic ulcer disease. Of these, nine were duodenal and three gastric ulcers. Of the nine children with duodenal ulceration three (33%) were infected with H. pylori. As a result of this study we conclude that (a) although antral nodularity occurs more frequently in children it is not exclusive to childhood, (b) the polymorphonuclear response in children is less than that reported in adults, and (c) peptic ulcer disease is rare in children and the present study would suggest that in children it is less frequently associated with H. pylori infection than in adults.

Multidonor intensive faecal microbiota transplantation for active ulcerative colitis: a randomised placebo-controlled trial

BACKGROUND The intestinal microbiota is implicated in the pathogenesis of ulcerative colitis. Faecal microbiota transplantation is a novel form of therapeutic microbial manipulation, but its efficacy in ulcerative colitis is uncertain. We aimed to establish the efficacy of intensive-dosing, multidonor, faecal microbiota transplantation in active ulcerative colitis. METHODS We conducted a multicentre, double-blind, randomised, placebo-controlled trial at three hospitals in Australia. We randomly allocated patients with active ulcerative colitis (Mayo score 4-10) in a 1:1 ratio, using a pre-established randomisation list, to either faecal microbiota transplantation or placebo colonoscopic infusion, followed by enemas 5 days per week for 8 weeks. Patients, treating clinicians, and other study staff were unaware of the assigned treatment. Faecal microbiota transplantation enemas were each derived from between three and seven unrelated donors. The primary outcome was steroid-free clinical remission with endoscopic remission or response (Mayo score ≤2, all subscores ≤1, and ≥1 point reduction in endoscopy subscore) at week 8. Analysis was by modified intention-to-treat and included all patients receiving one study dose. We performed 16S rRNA stool analysis to assess associated microbial changes. This trial is registered with ClinicalTrials.gov, number NCT01896635. The trial has ended; this report presents the final analysis. FINDINGS From November, 2013, to May, 2015, 85 patients were enrolled to our trial, of whom 42 were randomly assigned faecal microbiota transplantation and 43 were allocated placebo. One patient assigned faecal microbiota transplantation and three allocated placebo did not receive study treatment and were excluded from the analysis. The primary outcome was achieved in 11 (27%) of 41 patients allocated faecal microbiota transplantation versus three (8%) of 40 who were assigned placebo (risk ratio 3·6, 95% CI 1·1-11·9; p=0·021). Adverse events were reported by 32 (78%) of 41 patients allocated faecal microbiota transplantation and 33 (83%) of 40 who were assigned placebo; most were self-limiting gastrointestinal complaints, with no significant difference in number or type of adverse events between treatment groups. Serious adverse events occurred in two patients assigned faecal microbiota transplantation and in one allocated placebo. Microbial diversity increased with and persisted after faecal microbiota transplantation. Several bacterial taxa were associated with clinical outcome; in particular, the presence of Fusobacterium spp was associated with lack of remission. INTERPRETATION Intensive-dosing, multidonor, faecal microbiota transplantation induces clinical remission and endoscopic improvement in active ulcerative colitis and is associated with distinct microbial changes that relate to outcome. Faecal microbiota transplantation is, thus, a promising new therapeutic option for ulcerative colitis. Future work should focus on precisely defining the optimum treatment intensity and the role of donor-recipient matching based on microbial profiles. FUNDING Broad Medical Research Program, Gastroenterological Society of Australia, Mount Sinai (New York) SUCCESS fund, University of New South Wales.

Cervical cytology reported as negative and risk of adenocarcinoma of the cervix: no strong evidence of benefit

The relationship between negative cervical cytology reports and risk of adenocarcinoma of the cervix was evaluated in a case-control study of 113 cases and 452 controls. All cases and controls had received at least two negative cytology reports. There was no significant difference between the cases and controls in the number of negative cytology reports or in history of cervical abnormality; while a test for trend in the time since last negative cytology report was significant (P < 0.001), the estimated benefit was very modest. Although the estimates of relative protection were higher in women aged less than 35 years than in women aged 35-69 years, this difference was not statistically significant. These results suggest that cervical screening as practised in the 1970s and 1980s was much less effective in preventing adenocarcinoma than squamous carcinoma of the cervix.

Increased Incidence of Campylobacter pylori Infection in Gastroenterologists: Further Evidence to Support Person-to-Person Transmission of C. pylori

The mode transmission of Campylobacter pylori is still unknown, although several studies have suggested person-to-person transmission. In this study the incidence of active C. pylori infection in an endoscopy staff was compared with that in general practitioners and normal blood donors. Since endoscopy workers are in close contact with patients, many of whom would be likely to have active C. pylori infection, it was likely that there would be an increased incidence of active C. pylori infection in endoscopists if the organism can spread from person to person. The incidence of active C. pylori infection in the group of gastroenterologists was 52%, compared with 21% in an age-matched group of blood donors. This finding was statistically significant (p less than 0.01). In comparison, the incidence of active C. pylori infection in the endoscopy nurses and general practitioners was not statistically different from that in the normal population.

Campylobacter concisus and other Campylobacter species in children with newly diagnosed Crohn's disease

Background: Campylobacter concisus and other members of the Campylobacter genus have recently been suggested as possible etiological agents of Crohns disease (CD). To further investigate this issue we determined the prevalence of these organisms in pediatric patients newly diagnosed with CD. Methods: DNA was extracted from fecal specimens collected from 54 children with CD, 27 noninflammatory bowel disease (non‐IBD), and 33 healthy controls and subjected to polymerase chain reaction (PCR) sequencing. Results: Detection of C. concisus DNA using a newly developed PCR assay targeting the 16S rRNA gene of C. concisus showed that 65% (35/54) of fecal samples from CD children were positive, a prevalence significantly higher than that in the healthy (33%, 11/33, P = 0.008) and non‐IBD controls (37%, 10/27, P = 0.03). The prevalence of all Campylobacter DNA using genus‐specific primers in children with CD was 72% (39/54), which was significantly higher than the 30% (10/33, P = 0.0002) and 30% (8/27, P = 0.0003) observed in healthy and non‐IBD controls, respectively. Conclusions: Given the strengthening evidence for a significantly higher prevalence of C. concisus and other non‐jejuni Campylobacter species in pediatric CD, investigation into the role of these non‐jejuni Campylobacter species in the initiation of human IBD is clearly a priority. (Inflamm Bowel Dis 2009;)

Detection and isolation of Campylobacter species other than C. jejuni from children with Crohn's disease.

ABSTRACT The presence of Campylobacter species other than Campylobacter jejuni and antibodies to Campylobacter concisus in children were investigated. A significantly greater presence of C. concisus and higher levels of antibodies to C. concisus were detected in children with Crohns disease (CD) than in controls. Campylobacter species other than C. jejuni were isolated from intestinal biopsy specimens of children with CD.