[Porphyromonas gingivalis promotes the occurrence of esophageal squamous cell carcinoma via an inflammatory microenvironment].

Objective: To investigate the role of an inflammatory microenvironment induced by Porphyromonasgingivalis (P. gingivalis) in the occurrence of esophageal squamous cell carcinoma (ESCC) in mice. Methods: A total of 180 C57BL/6 mice were randomly divided into 6 groups, i.e. control group, P. gingivalis group, 4NQO group, 4NQO + P. gingivalis group, 4NQO + P. gingivalis + celecoxib group, and 4NQO + P. gingivalis + antibiotic cocktail (ABC, including metronidazole, neomycin, ampicillin, and vancomycin) group, with 30 mice in each group, using the random number table. All mice were normalized by treatment with ABC in drinking water for 2 weeks. In the following 2 weeks, the mice in the control group and the P. gingivalis group were given drinking water, while the other 4 groups were treated with 30 µg/ml 4NQO in the drinking water. In weeks 11-12, the mice in the P. gingivalis group, the 4NQO + P. gingivalis group, the 4NQO + P. gingivalis + celecoxib group, and the 4NQO + P. gingivalis + ABC group were subjected to ligation of the second molar in oral cavity followed by oral P. gingivalis infection thrice weekly for 24 weeks in weeks 11-34. In weeks 13-34, the mice in 4NQO + P. gingivalis+celecoxib group and 4NQO + P. gingivalis + ABC group were administered with celecoxib and ABC for 22 weeks, respectively. At the end of 34 weeks, gross and microscopic alterations were examined followed by RT-qPCR and immunohistochemistry to examine the expression profiles of inflammatory- and tumor-molecules in esophagi of mice. Results: At 34 weeks, 4NQO treatment alone did not affect the foci of papillary hyperproliferation, diseased area, and the thickness of the esophageal wall, but significantly enhanced the foci of hyperproliferation (median 1.00, P＜0.05) and mild/moderate dysplasia (median 2.00, P＜0.01). In addition, the expression levels of IL-6 [8.35(3.45,8.99)], IL-1ß [6.90(2.01,9.72)], TNF-α [12.04(3.31,14.08)], c-myc [2.21(1.80,3.04)], pSTAT3, Ki-67, and pH2AX were higher than those in the control group. The pathological changes of the esophageal mucosa were significantly more overt in the 4NQO + P. gingivalis group in terms of the foci of papillary hyperproliferation (median 2.00), diseased area (median 2.51 mm2), the thickness of the esophageal wall (median 172.52 µm), the foci of hyperproliferation (median 1.00, P＜0.05), and mild/moderate dysplasia (median 1.00, P＜0.01). In mice of the 4NQO + P. gingivalis group, the expression levels of IL-6 [12.27(5.35,22.08)], IL-1ß [13.89(10.04,15.96)], TNF-α [19.56(6.07,20.36)], IFN-γ [11.37(8.23,20.07)], c-myc [2.62(1.51,4.25)], cyclin D1 [4.52(2.68,7.83)], nuclear pSTAT3, COX-2, Ki-67, and pH2AX were significantly increased compared with the mice in the control group. In mice of the 4NQO + P. gingivalis group, the diseased area, invasive malignant foci as well as pSTAT3 and pH2AX expression were significantly blunted by celecoxib. Treatment with ABC markedly reduced the papillary hyperproliferative foci, invasive malignant foci, and pSTAT3 expression but not pH2AX. Conclusions: P. gingivalis promotes the occurrence of esophageal squamous cell carcinoma in mice by inducing an inflammatory microenvironment primed with 4NQO induced DNA damage. Clearance of P. gingivalis with ABC or anti-inflammatory intervention holds promise for prevention of esophageal squamous cell malignant pathogenesis via blockage of IL-6/STAT3 signaling and amelioration of inflammation.

Genotyping, antifungal susceptibility, enzymatic activity, and phenotypic variation in Candida albicans from esophageal candidiasis.

BACKGROUND: Esophageal candidiasis is the most frequent form of esophagitis. The pathogenicity of Candida spp. is related to a combination of microbial factors, hydrolytic enzyme secretion and phenotypic switching. This study was designed to investigate esophageal candidiasis, antifungal activity, enzymatic activity patterns, phenotyping, and genotyping profiles of Candida albicans species. METHODS: Nine hundred thirty-three visited patients were evaluated, and esophageal biopsies from patients were included in this study during 2019-2020. Direct smear, Gram staining, and culture on CHROMagar were performed for each sample. Isolated species were identified with conventional procedures and PCR-RFLP. Susceptibility to antifungals was determined according to CLSI guidelines. ABC typing, phenotype switching, hemolysin, proteinase, phospholipase, and esterase activity were also determined with the appropriate protocols. RESULTS: Twenty-three (2.5%) patients (mean age 55.2 years) were diagnosed with esophageal candidiasis. The species isolated were 19(82.6%) C. albicans, 3(13.1%) C. glabrata, and 1(4.3%) C. tropicalis. Genotype A (57.9%) was the predominant type in C. albicans isolates. 50% of C. albicans isolates exhibited a white phenotype. A high level of phospholipase (47.4%), hemolysin (68.4%), and proteinase activity (36.8%) was observed in the C. albicans isolates. Only three C. glabrata isolates displayed non-wild type susceptibility to voriconazole and itraconazole. CONCLUSION: This study shows that C. albicans are still the most frequent isolates from patients with esophageal candidiasis. The predominance of genotype A, the white phenotype, and strong hemolysin activity may indicate a high prevalence of pathogenicity in these isolates. Sensitivity to antifungal drugs was greatest for amphotericin and fluconazole.

Potential roles of Helicobacter pylori treatment, body mass index and waist circumference in the causation of erosive esophagitis: a randomized clinical trial (HEROES-GERD).

BACKGROUND: In recent decades, the prevalence of gastroesophageal reflux disease (GERD) and obesity has been increasing while Helicobacter pylori infection has been decreasing. OBJECTIVE: To evaluate if H. pylori treatment, excess body weight and other anthropometric measurements are associated with incident erosive esophagitis, as a secondary objective of a trial which tested the efficacy of treatment of H. pylori on the symptoms of functional dyspepsia. SUBJECTS/METHODS: Upper gastrointestinal endoscopy and anthropometric assessments were performed, at baseline and after 12 months, in H. pylori positive patients with functional dyspepsia who had no baseline reflux symptoms or esophagitis. Patients were randomly assigned to receive omeprazole, amoxicillin, and clarithromycin (antibiotic group; n = 201) or omeprazole plus placebo (control group; n = 203). The primary outcome was the incidence of esophagitis 12 months after randomization, according to treatment groups, and the association of BMI and other anthropometric measurements. RESULTS: Four hundred and four patients were included (mean age, 46.1 years; 78.7% women). The 12-month follow-up endoscopic esophagitis rates for the antibiotic and control groups were 10.9% (22/201) and 9.4% (19/203), respectively (p = 0.60). The number needed to harm was 67. Baseline anthropometric measurements were performed in 94% (380/404) of patients. The 12-month follow-up esophagitis rates for overweight and normal body weight patients were 13.6% (29/213) and 6.0% (10/167), respectively (p = 0.015); rates for patients with and without increased baseline waist circumference were 15.4% (24/156) and 6.7% (15/224), respectively (p = 0.006). Following logistic regression, only the combination of increased baseline body mass index and waist, but not H. pylori treatment, was independently associated with new-onset esophagitis (OR 2.88; 95% CI: 1.28-6.45). CONCLUSIONS: Excess body weight and concomitant increased waist circumference, but not H. pylori treatment, predicts new-onset esophagitis.

The diagnosis of clinically significant oesophageal Candida infections: a reappraisal of clinicopathological findings.

AIMS: Distinguishing true oesophageal Candida infections from oral contaminants is a common diagnostic issue. Historically, histological features believed to indicate true infection included epithelial invasion by pseudohyphae and intraepithelial neutrophils. Whether or not these features correlate with endoscopic lesions, symptoms and response to therapy has never been tested in a large cohort. The aim of this study was to determine whether specific histological features correlate with clinical and endoscopic findings when Candida is found in oesophageal biopsies. METHODS AND RESULTS: We reviewed 271 biopsies in which Candida was detected. Cases were evaluated for the presence of desquamated epithelial cells, location/type of fungal forms, neutrophils, and ulceration. Medical records were reviewed for clinical history, endoscopic lesions, and response to antifungal therapy. Statistical analysis was used to determine whether any histological features significantly correlated with clinical variables. There were 120 males and 151 females with a mean age of 42 years. Fifty-nine per cent had symptoms referable to the oesophagus, particularly dysphagia (36%). Most (73%) patients had abnormal endoscopic findings, with plaques, ulcers, or macroscopic evidence of oesophagitis. Seventy-one per cent of patients with documented antifungal therapy showed symptomatic improvement. Overall, there was no statistically significant correlation between any histological feature and presenting symptoms, endoscopic findings, or response to therapy. Importantly, the lack of pseudohyphae, demonstrable invasion of intact epithelium or neutrophilic infiltrates did not exclude clinically significant infection. CONCLUSIONS: We conclude that detection of Candida in oesophageal biopsies is always potentially clinically significant. Treatment decisions should be made on the basis of an integration of clinical, endoscopic and histological findings.

[The state and role of esophagus, stomach, intestinal microbiota in patients with ulcer disease, chronic gastritis, esophagitis.]

The microflora of 64 biopsies taken during fibrogastroduodenoscopy of the mucous membrane of the esophagus, stomach and duodenum in healthy volunteers and 1120 samples obtained from the same parts of the digestive tract in patients with esophagitis, chronic gastritis and peptic ulcer disease were studied. The patients ranged in age from 18 to 62 years. Traditional bacteriological method was used to isolate and identify microorganisms. Staphylococcus spp., Streptococcus spp., Lactobacillus spp., Bacteroides spp., Stomatococcus spp., Enterobacteriaceae, Corynebacterium spp., Micrococcus spp., Neisseria spp., Veilonella spp. were isolated from biopsies of healthy respondents in an average amount from 3.2 to 4.68 lg CFU/g. H.pylori was found in 60% (5.66 lg CFU/g) in the esophagus, in 33.3% of cases (5.12 lg CFU/g) from the fundal part of the stomach, in 44.4% (5.25 lg CFU/g) from the antral part of the stomach, in 5.5% (4.2 lg CFU/g) in the duodenal mucosa. In samples obtained from the inflamed and eroded mucous membrane of the esophagus, stomach and duodenum, opportunistic bacteria of the genera Klebsiella, Enterobacter, Proteus, Pseudomonas, Peptococcus, Actinomyces, yeast fungi of the genus Candida etc. were detected in an amount exceeding 4 lg CFU/g. H. pylori isolated in 6.3-16.7% of patients (4.25-4.6 lg CFU/g) and did not dominate in relation to other microorganisms, and in most cases had a low frequency of its occurrence. In patients with the recurrence of peptic ulcer disease, exacerbation of chronic gastritis and esophagitis, dysbiosis was developed, characterized by an increase in the species and quantitative composition of opportunistic microflora, an increase in its enzymatic and cytotoxic activity, which can contribute to the maintenance of inflammatory and necrotic processes and inhibit the elimination of the pathological process.

Esophageal Mycobacterium avium-intracellulare infection in a bone marrow transplant patient: Case report and literature review.

Mycobacterium avium-intracellulare complex (MAC) is the most common cause of nontuberculous mycobacterial (NTM) disease in humans. We report a case of esophageal MAC disease in a patient who had allogeneic bone marrow transplant for acute lymphoblastic leukemia. Although pulmonary MAC in immunocompromised host is not uncommon, there are only a few cases of NTM-associated esophageal mass reported. Our report and literature review highlight the importance of considering MAC in the differential diagnosis of dysphagia or odynophagia.

[Esophageal actinomycosis in patients with HIV infection]. / Actinomicosis esofágica en pacientes con infección por VIH.

Esophageal pathology is common in patients with HIV, frequently due to Candida, cytomegalovirus or herpes virus. However, esophageal actinomycosis is a rare infection, even in patients with HIV. We report the case of a 33-year-old male patient, with a recent diagnosis of HIV who was admitted for fever, odynophagia, dysphagia and retrosternal pain. Upper gastrointestinal endoscopy evidenced multiple esophageal ulcers and the histopathological report of the esophageal biopsy described a chronic esophagitis with colonies of PAS positive bacilli, compatible with Actinomyces, initiating favorable antimicrobial therapy. Although it is an uncommon disease, about one-third of cases of esophageal actinomycosis occur in patients with HIV infection, and endoscopic biopsies are required to define diagnosis and appropriate treatment.

Mucosal inflammation in Candida esophagitis has distinctive features that may be helpful diagnostically.

The diagnosis of Candida esophagitis can be challenging when the epithelium containing Candida filamentous forms is not readily seen or is entirely sloughed away. Mucosal inflammation could be helpful diagnostically, if distinctive. However it is thought to be nonspecific in Candida esophagitis. The goal of this retrospective study was to identify features of mucosal inflammation helpful in alerting a pathologist to the possibility of Candida esophagitis when Candida mycelia are not readily observed. The study group consisted of 99 consecutive cases of Candida esophagitis and a control group of 64 consecutive cases of reflux esophagitis diagnosed at our institution from 2008-2016. Band-like superficial intraepithelial neutrophils and increased intraepithelial lymphocytes were observed in 75 and 67% of Candida esophagitis cases, respectively and only in 14 and 19% of reflux esophagitis cases, respectively (p < .0001). Intraepithelial lymphocytes were peripapillary or CD4-predominant in 75% of Candida esophagitis cases with increased lymphocytes, in contrast to 17% of reflux esophagitis cases (p = .0011). Concurrent presence of intraepithelial neutrophils and increased lymphocytes showed increased specificity for Candida esophagitis and was observed in 61% of patients with Candida esophagitis and only in 2% of patients with reflux esophagitis (p < .0001). In addition, superficial band-like neutrophils were observed concurrently with increased peripapillary lymphocytes or CD4-predominant lymphocytes in 35 and 50% of Candida esophagitis cases, respectively, in contrast to no reflux esophagitis cases. Basal cell hyperplasia and elongation of stromal papillae were frequent in both groups. The data suggest that when Candida microorganisms are not readily observed, concurrent presence of superficial band-like neutrophils and increased lymphocytes may be indicative of Candida etiology of active esophagitis.

Infections of the esophagus: an update on risk factors, diagnosis, and management.

Infectious esophagitis is a leading cause of esophagitis worldwide. While esophageal infections have traditionally been associated with immunocompromised patients, these disorders are becoming increasingly recognized in immunocompetent individuals. The three most common etiologies of infectious esophagitis are Candida, herpes simplex virus, and cytomegalovirus. Human papilloma virus infection can also involve the esophagus in the form of ulcerative lesions and papillomas. Less common etiologies include various other fungal, bacterial, and viral organisms. This review provides a comprehensive update on risk factors, diagnosis, and management of both common and less common infections of the esophagus.

Dysphagia, Hyperglycemia, and Presyncope.

There have been over 80 documented cases of swallow syncope-a rare form of reflex or neurally mediated syncope-with most cases associated with an underlying esophageal disorder. Here, we describe the first reported case of swallow syncope or presyncope caused by an infectious esophagitis. Our 65-year-old patient initially developed dysphagia, odynophagia, and presyncope with swallowing. This lead to nutrition and medication avoidance behavior, which was followed by the development of diabetic ketoacidosis. The diagnosis of swallow presyncope was confirmed with a provocative swallow study demonstrating 8 s sinus arrest, and an underlying cause of Candida esophagitis was found by upper endoscopy. Symptoms completely resolved after treatment with micafungin.

[Enhanced microscopic diagnosis of oesophageal candidiasis through additional cytospin analysis of the fixative of oesophageal biopsies]. / Verbesserte mikroskopische Diagnostik des ösophagealen Soorbefalls durch zusätzliche Zytospin-Analyse der Fixationslösung von Ösophagusbiopsien.

To confirm or to refute the diagnosis of candida oesophagitis as the most common infectious disease of the oesophagus is a standard diagnostic procedure in histopathology. The fungal hyphae colonise mainly the superficial layers of the oesophageal squamous mucosa. Tangentially cut sections of oesophageal biopsies in the paraffin block might lead to a false negative result concerning mycotic infection. The aim of this study was to investigate whether cytospin analysis of the formalin fixative in which the biopsies were stored and transported would be a tool to close the diagnostic gap.Oesophageal biopsies from 150 consecutive patients with the clinical diagnosis or question "candida" or "candida oesophagitis" have been investigated. The biopsies were routinely processed and stained with haematoxylin and eosin and periodic acid-Schiff reaction. In parallel, the fixative fluid, usually disposed of after use, was processed by using a cytospin centrifuge and prepared for cytological proof of fungal hyphae. The cytology slides were also stained with periodic acid-Schiff reaction. In this blind study, the pathologist investigating the results of one procedure was unaware of the results of the second procedure.Out of 89 positive cytology cases, 64 cases (71,9 %) also showed a positive histology result. In the remaining 25 cases (28,1 %), fungal hyphae were seen only after re-evaluation of the original histology slides (n = 6) or in further serial sections using the complete tissue in the block (n = 5). In 14 cases, no hyphae could be detected histologically. Only in one of the 61 cytospin-negative cases was candida seen in histology.Our results show that diagnosing oesophageal candidiasis can be improved by more than one quarter using the formalin fixative for cytospin cytology.

Black esophagus: a case report.

INTRODUCTION: Acute esophageal necrosis, also known as black esophagus, is a rare digestive complication, frequently manifested by an upper gastrointestinal hemorrhage and occurs in patients with comorbidities. AIM: To report the case of a patient with a black esophagus revealed by an upper gastrointestinal hemorrhage. OBSERVATION: A 72-year-old patient with a history of diabetes mellitus, hypertension and ischemic heart disease was hospitalized in surgical intensive care unit for hemorrhagic shock induced by cholecystectomy. On the 7th postoperative day, the patient developed acute hematemesis. Gastroscopy showed circumferential necrosis, localized in the middle and lower third of the esophagus and stopped abruptly at the gastroesophageal junction. Gastric mucosa was strictly normal. The bulb and the first part of duodenum showed multiple superficial ulcers without signs of recent hemorrhage. The patient was placed on absolute diet and total parenteral nutrition associated with high-dose intravenous proton pump inhibitor. Second-look gastroscopy, performed six days later, showed a significant improvement in esophageal lesions. The evolution was marked by the occurrence of pneumonia complicated by septic shock which caused patient's death. CONCLUSION: Black esophagus is a rare pathology of multifactorial etiology. Treatment is based on proton pump inhibitors in combination with resuscitation measures to control comorbidities. Mortality remains high due to the seriousness of comorbid disease states often associated with this condition.

Esophageal tuberculosis with coexisting opportunistic infections in a renal allograft transplant recipient.

We report a renal allograft transplant recipient with esophageal tuberculosis (TB) coinfected with herpes simplex virus (HSV) and Candida. The patient presented with oropharyngeal candidiasis and was started on fluconazole. Upper gastrointestinal endoscopy showed whitish patches with mucosal ulcers in the esophagus. Histopathological examination confirmed TB and HSV infection. The patient recovered after antiviral, antifungal, and anti-tubercular therapy with reduction in immunosuppression. In a TB-endemic zone, TB can coexist with opportunistic infections in an immunocompromised host.

Esophageal mucosa in HIV infection: A"deeper" look at this little spoken organ.

BACKGROUND AND AIM: Although the esophagus is a common site of opportunistic infection in AIDS patients, little is known about the impact of HIV as well as opportunistic infection in the esophageal mucosa. Our aim is to analyze the esophageal immune profile in HIV+ patients with different immunological status with and without the opportunistic Candida infection. METHODS: Immunohistochemistry to CD4+ and CD8+ T-cells, γ-interferon, transforming growth factor-ß, interleukin (IL)-4, IL-6, IL-13, and IL-17 was performed in esophageal samples of 40 chronically HIV+ patients under highly active antiretroviral therapy (16 with Candida esophagitis, 12 virologically non-supressed with blood CD4 count < 500, and 12 virologically suppressed with blood CD4 count > 500; the latter two groups without esophageal candidiasis). The controls were 12 HIV-negative healthy individuals. RESULTS: Esophageal CD4+ T-cell expression in HIV+ patients did not differ from the control group (P = 0.50). Mucosal CD8+ T-cell expression was significantly increased in HIV+ patients (P = 0.0018). Candida esophagitis and virologically non-supressed HIV+ patients with CD4 < 500 showed an increased expression of IL-17 and IL-6 with fewer expressions of γ-interferon, more attenuated in the latter group. Transforming growth factor-ß was increased only in virologically suppressed HIV+ patients with CD4 > 500. IL-4 and IL-13 were similar to the control group. CONCLUSION: In contrast to CD8+ T-cell expression, esophageal CD4+ T-cell expression does not reflect the HIV+ patient's immunological status. T-helper 17 (Th17) response seems to play a role in the esophageal mucosa of virologically non-supressed HIV+ patients with blood CD4 < 500. Candida esophagitis showed a Th1/Th17 response but seems to be dominantly regulated by the Th17 pathway.

Zero-inflated negative binomial mixed model: an application to two microbial organisms important in oesophagitis.

Altered microbial communities are thought to play an important role in eosinophilic oesophagitis, an allergic inflammatory condition of the oesophagus. Identification of the majority of organisms present in human-associated microbial communities is feasible with the advent of high throughput sequencing technology. However, these data consist of non-negative, highly skewed sequence counts with a large proportion of zeros. In addition, hierarchical study designs are often performed with repeated measurements or multiple samples collected from the same subject, thus requiring approaches to account for within-subject variation, yet only a small number of microbiota studies have applied hierarchical regression models. In this paper, we describe and illustrate the use of a hierarchical regression-based approach to evaluate multiple factors for a small number of organisms individually. More specifically, the zero-inflated negative binomial mixed model with random effects in both the count and zero-inflated parts is applied to evaluate associations with disease state while adjusting for potential confounders for two organisms of interest from a study of human microbiota sequence data in oesophagitis.

Acid suppressing therapy as a risk factor for Candida esophagitis.

Studies were reviewed from PubMed for risk factors for the development, recurrence, prevention and therapy of Candida esophagitis, and for mechanisms induced by acid-suppressing therapy potentially influencing these factors. Documented observations included greatly increased Candida populations in the mouth, esophagus, stomach, and upper small intestine induced by acid-suppressing therapy. Among patients without HIV disease, PPI consumers more frequently had developed Candida esophagitis than did non-consumers and had also developed its recurrences more frequently. Similar phenomena associated with H2 -blocker use were less intense, and the possibility of similar phenomena in patients with HIV disease apparently had not yet been examined in spite of their high frequency of this disorder. PPI-induced elimination of the gastric acid barrier is a major mechanism leading to oro-pharyngeal and esophageal candida colonization, while PPI-induced impairment of absorption of most orally administered antifungal agents may limit the prophylactic and therapeutic success of these agents. These observations suggest potential value in limiting PPI use in populations of patients with Candida infections including esophagitis, as well as in patients at risk for their development, and also suggest that post-PPI rebound acid hypersecretion may provide additional anti-Candida benefit. Studies designed to develop the risk-benefit ratios of PPI use in these patients deserve investigation with high priority appropriate for studies in patients with HIV disease.

[THE ROLE OF HELICOBACTER PYLORI IN NORMOMICROBIOCENOSIS AND DYSBACTERIOSIS OF MUCOSAL MICROFLORA OF OESOPHAGOGASTRODUODENAL ZONE IN THE CASES OF PEPTIC ULCER, CHRONIC GASTRITIS AND OESOPHAGITIS].

AIM: Determine the qualitative and quantitative composition of the mucosal microflora of oesophagogastroduodenal zone to determine the location of Helicobocter pylori and its place in normomicrobiocenosis and dysbacteriosis in cases of peptic ulcer, chronic gastritis and oesophagitis. MATERIALS AND METHODS: Clinical and microbiological studies were conducted in 30 healthy individuals-volunteers, 130 patients with peptic ulcer, 36--chronic gastritis and 24--chronic esophagitis. RESULTS OF THE STUDY: Helicobacter pylori in 33% of cases included in normomicrobiocenosis of mucosal microflora oesophagogastroduodenal zone, which consists of 12 genera of microorganisms and carries out all protection functions. The recurrence of peptic ulcer disease, exacerbation of chronic active gastritis and oesophagitis are accompanied by a dysbacteriosis of mucosal microflora with overgrowth of typical and atypical microorganisms for normal biotope with reduced occurrenceof Helicobocter pylori. CONCLUSION: Helicobacter pylori in the biocenosis of mucosal microflora of oesophagogastroduodenal zone is not an infection, has no independent significance in the development of peptic ulcer, chronic gastritis and esophagitis, does not require eradication.

Gastric microbiota is altered in oesophagitis and Barrett's oesophagus and further modified by proton pump inhibitors.

Gastro-oesophageal reflux can cause inflammation, metaplasia, dysplasia and cancer of the oesophagus. Despite the increased use of proton pump inhibitors (PPIs) to treat reflux, the incidence of oesophageal adenocarcinoma has increased rapidly in Europe and in the United States in the last 25 years. The reasons for this increase remain unclear. In this study, we aimed to determine whether the microbiota of the gastric refluxate and oesophageal biopsies differs between patients with heartburn and normal-appearing oesophageal mucosa versus patients with abnormal oesophageal mucosa [oesophagitis or Barrett's oesophagus (BE)] and to elucidate the effect of PPIs on the bacterial communities using 16S rRNA gene pyrosequencing. Significant differences in the composition of gastric fluid bacteria were found between patients with heartburn and normal oesophageal tissue versus patients with oesophagitis or BE, but in the oesophagus-associated microbiota differences were relatively modest. Notably, increased levels of Enterobacteriaceae were observed in the gastric fluid of oesophagitis and BE patients. In addition, treatment with PPIs had dramatic effects on microbial communities both in the gastric fluids and the oesophageal tissue. In conclusion, gastric fluid microbiota is modified in patients with oesophagitis and BE compared with heartburn patients with normal biopsies. Furthermore, PPI treatment markedly alters gastric and oesophageal microbial populations. Determining whether the changes in bacterial composition caused by PPIs are beneficial or harmful will require further investigation.