Prevalence and treatment of Helicobacter pylori in patients with blepharitis

How gut microbiota may impact ocular surface homeostasis and related disorders

Changes in the bacterial flora in the gut, also described as gut microbiota, are readily acknowledged to be associated with several systemic diseases, especially those with an inflammatory, neuronal, psychological or hormonal factor involved in the pathogenesis and/or the perception of the disease. Maintaining ocular surface homeostasis is also based on all these four factors, and there is accumulating evidence in the literature on the relationship between gut microbiota and ocular surface diseases. The mechanisms involved are mostly interconnected due to the interaction of central and peripheral neuronal networks, inflammatory effectors and the hormonal system. A better understanding of the influence of the gut microbiota on the maintenance of ocular surface homeostasis, and on the onset or persistence of ocular surface disorders could bring new insights and help elucidate the epidemiology and pathology of ocular surface dynamics in health and disease. Revealing the exact nature of these associations could be of paramount importance for developing a holistic approach using highly promising new therapeutic strategies targeting ocular surface diseases.

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

Management of Helicobacter pylori infection: the Maastricht VI/Florence consensus report

Helicobacter pyloriInfection is formally recognised as an infectious disease, an entity that is now included in the International Classification of Diseases 11th Revision. This in principle leads to the recommendation that all infected patients should receive treatment. In the context of the wide clinical spectrum associated with Helicobacter pylori gastritis, specific issues persist and require regular updates for optimised management.The identification of distinct clinical scenarios, proper testing and adoption of effective strategies for prevention of gastric cancer and other complications are addressed. H. pylori treatment is challenged by the continuously rising antibiotic resistance and demands for susceptibility testing with consideration of novel molecular technologies and careful selection of first line and rescue therapies. The role of H. pylori and antibiotic therapies and their impact on the gut microbiota are also considered.Progress made in the management of H. pylori infection is covered in the present sixth edition of the Maastricht/Florence 2021 Consensus Report, key aspects related to the clinical role of H. pylori infection were re-evaluated and updated. Forty-one experts from 29 countries representing a global community, examined the new data related to H. pylori infection in five working groups: (1) indications/associations, (2) diagnosis, (3) treatment, (4) prevention/gastric cancer and (5) H. pylori and the gut microbiota. The results of the individual working groups were presented for a final consensus voting that included all participants. Recommendations are provided on the basis of the best available evidence and relevance to the management of H. pylori infection in various clinical fields.

Helicobacter pylori infection: Beyond gastric manifestations

Helicobacter pylori (H. pylori) is a bacterium that infects more than a half of world’s population. Although it is mainly related to the development of gastroduodenal diseases, several studies have shown that such infection may also influence the development and severity of various extragastric diseases. According to the current evidence, whereas this bacterium is a risk factor for some of these manifestations, it might play a protective role in other pathological conditions. In that context, when considered the gastrointestinal tract, H. pylori positivity have been related to Inflammatory Bowel Disease, Gastroesophageal Reflux Disease, Non-Alcoholic Fatty Liver Disease, Hepatic Carcinoma, Cholelithiasis, and Cholecystitis. Moreover, lower serum levels of iron and vitamin B12 have been found in patients with H. pylori infection, leading to the emergence of anemias in a portion of them. With regards to neurological manifestations, a growing number of studies have associated that bacterium with multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, and Guillain-Barré syndrome. Interestingly, the risk of developing cardiovascular disorders, such as atherosclerosis, is also influenced by the infection. Besides that, the H. pylori-associated inflammation may also lead to increased insulin resistance, leading to a higher risk of diabetes mellitus among infected individuals. Finally, the occurrence of dermatological and ophthalmic disorders have also been related to that microorganism. In this sense, this minireview aims to gather the main studies associating H. pylori infection with extragastric conditions, and also to explore the main mechanisms that may explain the role of H. pylori in those diseases.

High levels of Helicobacter pylori antigens and antibodies in patients with severe acne vulgaris

BACKGROUND

Helicobacter pylori (H pylori) may play a role in the pathogenesis of extra-intestinal disorders including dermatological diseases.

AIMS

This study aimed to assess the levels of H pylori antigen and antibody in patients with acne vulgaris (AV).

METHODS

This cross-sectional study compared the levels of fecal H pylori antigen and serum H pylori antibody in 100 patients with AV and 100 age and sex-matched healthy volunteers. Patients with AV were classified into mild, moderate, and severe according to the Global Acne Grading Scale. Levels of fecal H pylori antigen and serum H pylori antibodies were assessed using commercially available enzyme-linked immune-sorbent assay.

RESULTS

The patients with severe AV had significantly higher levels of fecal H pylori antigen as compared to the patients with mild AV, moderate AV, and healthy controls (P < .001). The patients with severe AV had significantly higher serum H pylori antibody as compared to the patients with mild AV, moderate AV, and healthy controls (P = .001). The levels of fecal H pylori antigen and serum H pylori antibody in the patients with mild AV were not significantly different from those in the patients with moderate AV (P = .49 and P = .05, respectively).

CONCLUSION

The patients with severe AV had higher levels of fecal H pylori antigen and serum H pylori antibody as compared to the patients with mild and moderate AV and with healthy controls. The indicators of H pylori infection were positively correlated with the severity and duration of AV.

The microbiome and ophthalmic disease

IMPACT STATEMENT

This review describes a growing body of research on relationships between the microbiome and eye disease. Several groups have investigated the microbiota of the ocular surface; dysregulation of this delicate ecosystem has been associated with a variety of pro-inflammatory states. Other research has explored the effects of the gastrointestinal microbiota on ophthalmic diseases. Characterizing the ways these microbiotas influence ophthalmic homeostasis and pathogenesis may lead to research on new techniques for managing ophthalmic disease.

The evaluation of the effect of Helicobacter pylori infection on choroidal thickness

BACKGROUND/AIMS

To evaluate the effects of Helicobacter pylori infection on choroidal thickness (CT) using enhanced depth imaging spectral domain-optical coherence tomography (SD-OCT).

MATERIALS AND METHODS

A total of 63 right eyes of 63 patients who tested positive for H. pylori (Group 1) and 46 right eyes of 46 patients who tested negative for H. pylori (Group 2) were evaluated. The CTs at the subfoveal area and at 1 mm ranging up to 3 mm from the fovea at the nasal and temporal quadrants were measured and compared. After the eradication of H. pylori, the CT values were also compared with the pre-eradication values in 38 patients.

RESULTS

The mean age of patients was 43.6}9.5 years in Group 1 and 46.6}11.5 years in Group 2 (p=0.13). Differences in CT values between Groups 1 and 2 before and after H. pylori eradication were not statistically significant (p>0.05 for all values).

CONCLUSION

The CT values of H. pylori positive and H. pylori negative patients were similar. Eradication of H. pylori infection appears to have produced no change in short-term CT.

Helicobacter pylori and extragastric diseases: A review

Helicobacter pylori (H. pylori) infection is very common and affects approximately half of the world population. It causes gastric diseases, but some authors have reported an association of H. pylori infection with other systemic manifestations beginning in 1994. The list of potential effects of H. pylori outside the stomach includes a number of extragastric manifestations and we focused on neurological, dermatological, hematologic, ocular, cardiovascular, metabolic, allergic, and hepatobiliary diseases. This review discusses these important reported manifestations that are not related to the gastrointestinal tract.

Are optic nerve heads of patients with helicobacter pylori infection more susceptible to glaucomatous damage?

BACKGROUND

To compare retinal nerve fiber layer thicknesses (RNFLT) of patients with or without Helicobacter pylori infection and to reveal the possible RNFLT changes after H. pylori eradication.

MATERIALS AND METHODS

Sixty-five eyes of 65 patients that tested positive for H. pylori (Group 1) and 48 eyes of 48 patients that tested negative for H. pylori (Group 2) were included. RNFLT analyses were performed with spectral-domain (SD) optical coherence tomography (OCT) in a total of five regions: the superior, inferior, nasal, and temporal quadrants and the average. Then, a comparison was made between groups. After H. pylori eradication in 38 patients, RNFLTs were compared with both pre-eradication values and Group 2.

RESULTS

The groups were similar in terms of age and gender. Temporal quadrant RNFLT was thinner in Group 1 than in Group 2 (P=.02). After H. pylori eradication, RNFLTs did not differ from pre-eradication values in Group 1 (P>.05 for all), whereas temporal quadrant RNFLT after H. pylori eradication was thinner compared to Group 2 (P=.03).

CONCLUSIONS

H. pylori may cause the localized defects on RNFL that are the early signs of glaucoma.

The association of Helicobacter pylori with choroidal and retinal nerve fiber layer thickness

PURPOSE

To investigate the effect of Helicobacter pylori (H. pylori) infection on choroidal thickness (CT) and retinal nerve fiber layer thickness (RNFLT).

METHODS

The study included 25 patients with H. pylori infection and 25 healthy individuals as the control group. Helicobacter pylori patients were classified as the pre-treatment (Group 1; n: 25) and the post-treatment (Group 2; n: 25). RNFLT and CT were measured before and after treatment of H. pylori infection, using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Heidelberg, Germany). The axial length and intraocular pressure were also measured.

RESULTS

The mean subfoveal CT was 320.96 ± 29.15 μm in Group 1 and 287.48 ± 49.17 in the control group (p = 0.007), while the mean subfoveal CT did not show any difference between Group 2 and the control group (p > 0.05). No statistically significant difference was determined between the H. pylori patients and the control group in respect of RNFLT values (p > 0.05).

CONCLUSIONS

CT increases during H. pylori infection and returns to the normal range within 6 weeks of treatment. RNFLT does not show any change during H. pylori infection. The data related to the subfoveal CT may be useful in understanding the pathogenesis of central serous chorioretinopathy developing in H. pylori patients.

No Association between CagA- and VacA-Positive Strains of Helicobacter pylori and Primary Open-Angle Glaucoma: A Case-Control Study

INTRODUCTION

Glaucoma is a public health issue worldwide, particularly in Africa. In Cameroon, the prevalence rate of primary open-angle glaucoma (POAG) ranges between 4.5% and 8.2%. Helicobacter pylori (HP) has been implicated in digestive and extra-digestive diseases, including glaucoma. The objective of this work was to evaluate the implication of CagA- and VacA-positive strains of HP in POAG using a case-control design.

METHODS

An analytical study was conducted from October 2013 to December 2013. Participants were recruited in eye care centers in Yaoundé. Enzyme-linked immunosorbent assays (ELISAs) were carried out in the La Grace Laboratory in Yaoundé.

RESULTS

The total sample consisted of 50 POAG patients and 31 controls with a mean age of 58.5 ± 12.2 years and 45.5 ± 14.6 years, respectively. The prevalence rates of HP in the POAG and control groups were 74% (37/50) and 87% (27/31), respectively (P = 0.125). The prevalence rates of CagA-positive HP seropositivity in the POAG and control groups were 26% and 22.58%, respectively (P = 0.47), and the prevalence rates of VacA-positive HP participants were 6% and 0%, respectively (P = 0.22).

CONCLUSION

The HP prevalence rates among POAG patients and controls were 74% and 87%, respectively. There was no significant difference between prevalence rates of HP in the POAG and control groups. There was no association between POAG and CagA- or VacA-positive HP infection.

The Rate of Helicobacter pylori Seropositivity in a Group of Korean Patients with HLA-B27-Associated Acute Anterior Uveitis

Purpose

To investigate an association between Helicobacter pylori seropositivity and HLA-B27-positive acute anterior uveitis (AAU) in Korean patients.

Methods

Retrospective analysis was performed with data from 106 patients previously diagnosed with AAU without clinical evidence of spondyloarthropathy. Serum immunoglobulin G antibodies to H. pylori were measured by enzyme-linked immunosorbent assay, and HLA typing was performed using polymerase chain reaction of DNA amplification. We included 72 non-uveitis patients and 35 age- and sex-matched healthy controls in the study.

Results

Of the 106 patients with AAU, 41 (38.7%) were HLA-B27-positive, and 45 (42.5%) were seropositive for H. pylori. Patients with HLA-B27-positive AAU had a significantly lower prevalence of H. pylori seropositivity compared to those with HLA-B27-negative AAU and healthy controls (24.4% vs. 53.8%, p = 0.003; 24.4% vs. 57.1%, p = 0.004, respectively). In the non-uveitis group, however, HLA-B27-positive patients exhibited similar H. pylori seropositivity prevalence to HLA-B27-negative patients and healthy controls (45.5% vs. 55.7%, p = 0.529; 45.5% vs. 57.1%, p = 0.497, respectively). In multivariate analysis, a low prevalence of H. pylori seropositivity was significantly associated with HLA-B27-positive AAU (odds ratio = 0.340, 95% confidence interval 0.135–0.855, p = 0.022).

Conclusions

Our results suggest an inverse association between H. pylori seropositivity and HLA-B27-positive AAU. Further investigation of this association is needed, given the low prevalence of H. pylori seropositivity observed in patients with HLA-B27-positive AAU.

A Comprehensive Review on Dry Eye Disease: Diagnosis, Medical Management, Recent Developments, and Future Challenges

Dry eye syndrome (DES) or keratoconjunctivitis sicca (KCS) is a common disorder of the tear film caused by decreased tear production or increased evaporation and manifests with a wide variety of signs and symptoms. The present review from interpretation of the literature gives detailed information on the prevalence, definition, causes, diagnostic tests, and medical management of dry eye disease. A number of systems contribute to the physiological integrity of the ocular surface and disruption of system may or may not produce symptoms. Therefore accurate diagnosis of dry eyes with no or minimal disruption of physiological function is necessary. The paper also discusses different colloidal drug delivery systems and current challenges in the development of topical ophthalmic drug delivery systems for treatment of KCS. Due to the wide prevalence and number of factors involved, newer, more sensitive diagnostic techniques and novel therapeutic agents have been developed to provide ocular delivery systems with high therapeutic efficacy. The aim of this review is to provide awareness among the patients, health care professionals, and researchers about diagnosis and treatment of KCS and recent developments and future challenges in management of dry eye disease.

Helicobacter pylori infection and eye diseases: a systematic review

The connection between Helicobacter pylori (Hp) infection and eye diseases has been increasingly reported in the literature and in active research. The implication of this bacterium in chronic eye diseases, such as blepharitis, glaucoma, central serous chorioretinopathy and others, has been hypothesized. Although the mechanisms by which this association occurs are currently unknown, this review describes shared pathogenetic mechanisms in an attempt to identify a lowest common denominator between eye diseases and Hp infection. The aim of this review is to assess whether different studies could be compared and to establish whether or not Hp infection and Eye diseases share common pathogenetic aspects. In particular, it has been focused on oxidative damage as a possible link between these pathologies. Text word search in Medline from 1998 to July 2014. 152 studies were included in our review. Were taken into considerations only studies that related eye diseases more frequent and/or known. Likely oxidative stress plays a key role. All of the diseases studied seem to follow a common pattern that implicates a cellular response correlated with a sublethal dose of oxidative stress. These alterations seem to be shared by both Hp infections and ocular diseases and include the following: decline in mitochondrial function, increases in the rate of reactive oxygen species production, accumulation of mitochondrial DNA mutations, increases in the levels of oxidative damage to DNA, proteins and lipids, and decreases in the capacity to degrade oxidatively damaged proteins and other macromolecules. This cascade of events appears to repeat itself in different diseases, regardless of the identity of the affected tissue. The trabecular meshwork, conjunctiva, and retina can each show how oxidative stress may acts as a common disease effector as the Helicobacter infection spreads, supported by the increased oxidative damage and other inflammation.

Helicobacter pylori as a risk factor for central serous chorioretinopathy: Literature review

Helicobacter pylori (H. pylori), a Gram-negative bacterium, is one of the most frequent causes of gastrointestinal infections worldwide. It has been associated as a pathogen for the human body with many systemic diseases, including different eye diseases. We will focus on a specific eye disease called idiopathic central serous chorioretinopathy (ICSCR). This disease is characterized by a serous detachment of the neurosensory retina in the macular region, which affects the vision to different degrees. Currently, the pathophysiology of ICSCR is not clear and there is no effective treatment. However, several potential risk factors have been elucidated. One of the factors that has more frequently been associated with ICSCR is stress. As H. pylori was identified as a possible etiological factor for occlusive arterial diseases in young people who were particularly stressed, it was thought that H. pylori might also be present in ICSCR. Therefore, some physicians started to test its presence in patents with ICSCR. If H. pylori happened to be associated with ICSCR, the treatment of gastrointestinal infection could also improve visual symptoms and help to remediate this eye disease. Although H. pylori is highly prevalent in the general population, a true correlation seems to exist. We present a review on the relationship between ICSCR and H. pylori.

Can Helicobacter pylori infection influence human reproduction?

Helicobacter pylori (H. pylori) infection could be associated with extra-digestive diseases. Here, we report the evidences concerning the decrease in reproductive potential occurring in individuals infected by H. pylori, especially by strains expressing CagA. This infection is more prevalent in individuals with fertility disorders. Infected women have anti-H. pylori antibodies in cervical mucus and follicular fluid that may decrease sperm motility and cross react immunologically with spermatozoa, conceivably hampering the oocyte/sperm fusion. Infection by CagA positive organisms enhances the risk of preeclampsia, which is a main cause of foetus death. These findings are supported by the results of experimental infections of pregnant mice, which may cause reabsorption of a high number of foetuses and alter the balance between Th1 and Th2 cell response. Infected men have decreased sperm motility, viability and numbers of normally shaped sperm and augmented systemic levels of inflammatory cytokines, such as tumor necrosis factor-α, which may damage spermatozoa. In countries where parasitic infestation is endemic, detrimental effects of infection upon spermatozoa may not occur, because the immune response to parasites could determine a switch from a predominant Th1 type to Th2 type lymphocytes, with production of anti-inflammatory cytokines. In conclusion, the evidences gathered until now should be taken into consideration for future studies aiming to explore the possible role of H. pylori infection on human reproduction.

The effects of Helicobacter pylori infection on intraocular pressure in anterior uveitis

PURPOSE

We investigated the influence of H. pylori infection on intraocular pressure (IOP) in anterior uveitis patients to clarify whether H. pylori infection is related to high IOP in anterior uveitis.

METHODS

In this prospective study, 165 Korean anterior uveitis patients were examined. All patients underwent serological analysis to identify the cause of uveitis, including the presence of H. pylori infection by enzyme-linked immunosorbent assay. Serological values were compared between patients with and without high IOP.

RESULTS

Seropositivity for H. pylori was 69.70% of patients with high IOP and 38.38% of patients with normal IOP (P<0.01).

CONCLUSION

This study suggests that H. pylori infection is associated with high IOP in anterior uveitis.

Future candidates for indications of Helicobacter pylori eradication: do the indications need to be revised?

Since the discovery of Helicobacter pylori in 1982, the development of several treatment guidelines has allowed a consensus on the indications for H. pylori eradication. Beyond these currently accepted indications, including various upper gastrointestinal disorders and extragastric diseases, a significant amount of new information regarding H. pylori eradication is emerging. Certain types of acute gastritis, such as nodular gastritis, hypertrophic gastritis, Ménétrier's disease, hemorrhagic gastritis, and granulomatous gastritis are reversible after H. pylori eradication. Further, for chronic gastritis, closed-type atrophic gastritis and complete-type intestinal metaplasia appear to be more reversible after H. pylori eradication than open-type atrophic gastritis and incomplete-type intestinal metaplasia. Eradication can also be considered in subjects younger than 40 years who have a family history of gastric cancer and in subjects with long-term medications that might lead to bleeding (antiplatelet agents) or atrophy (proton pump inhibitors). Emerging evidence indicates that H. pylori eradication could be an effective treatment for some extragastric diseases that are unresponsive to conventional therapy. In such conditions, routine screening for eradication of H. pylori has not previously been recommended; a "test-and-treat" approach is suggested in the aforementioned situations. Given that H. pylori eradication is effective when the gastritis is reversible, future indications should be expanded to include acute gastric lesions that show marked improvement upon H. pylori eradication rather than just focusing on chronic gastric lesions. Future indications for H. pylori eradication should focus more on reversible lesions before preneoplastic conditions develop.

Rosacea treatments: What's new and what's on the horizon?

Rosacea is a common, chronic, cutaneous disorder presenting with recurrent episodes of facial flushing, erythema, papules, pustules and telangiectasias. It is a multifactorial disease and its various clinical presentations probably represent the consequence of combined different triggers upon a specific background. Its management is largely based on long-established treatments empirically tailored to the specific presenting symptoms and no real breakthrough has occurred to date. However, recent insights into the still rather obscure pathophysiology of rosacea seem to open the way for etiologically oriented treatments. These may include, on the one side, the more effective application of traditional drugs, such as tetracyclines and metronidazole, to specifically selected patients or, on the other side, new therapeutic options, such as vitamin D receptor antagonists. It is to be remarked that the quality of most studies evaluating rosacea treatment is rather poor, mainly due to a lack of proper standardization. For a major breakthrough to occur in the management of rosacea, we need both a better understanding of its pathogenesis and the adherence of future clinical trials to clearly defined grading and inclusion criteria, which are crucial for investigators to correctly compare and interpret the results of their work.

Ocular adnexal lymphoma and Helicobacter pylori gastric infection

There is a causal association between Helicobacter pylori (Hp) gastric infection and the development of gastric MALT lymphoma. In contrast, the link between Hp gastric infection and the development of extragastric lymphoma has not been thoroughly investigated. We, therefore, studied the prevalence of gastric Hp infection at initial diagnosis of ophthalmologic and nonophthalmologic extragastric lymphoma patients. Three cohorts of patients were studied: a first one of 83 patients with OAL, a second one of 101 patients with extraophthalmologic extragastric lymphoma, and a third one of 156 control individuals (control) without malignant lymphoma. Gastric Hp infection was investigated by histopathological analysis and Hp-specific PCR assay on gastric biopsy tissue samples. We found gastric Hp infection in 37 OAL patients (45%), in 25 extraophthalmologic extragastric lymphoma cases (25%), and in 18 controls individuals (12%) (P < 0.0001 OAL/C and P < 0.01 OAL/extra-OAL cases). Gastritis was found in 51% and 9% of Hp-positive and Hp-negative lymphoma patients, respectively (P < 10(-4)). Gastric Hp infection only correlated with MALT/LPL lymphoma (P = 0.03). There is a significant association between gastric Hp infection and MALT/LPL OAL. This suggests a novel mechanism of indirect infection-associated lymphomagenesis whereby chronic local antigen stimulation would lead to the emergence of ectopic B-cell lymphoma.

No association between Helicobacter pylori infection or CagA-bearing strains and glaucoma

BACKGROUND AND PURPOSE

Accumulating evidence indicates that a variety of infections contribute to the pathogenesis of glaucoma. The role of Helicobacter pylori infection in glaucoma is controversial.

DESIGN

Prospective, population-based study.

PARTICIPANTS

Patients with various types of glaucoma and a control group of patients with cataract.

METHODS

We evaluated seropositivity to H. pylori and to its cytotoxin-associated gene A (CagA) product in patients with various types of glaucoma and compared the findings to those of a control group of patients with cataract.

RESULTS

H. pylori infection and CagA seropositivity were detected in 31/51 (60.8%) and 26/51 (51%) glaucoma patients compared with 22/36 (61.1%) and 19/36 (52%) control patients, respectively (P=0.88, 0.67, not significant). Similar rates of H. pylori infection and CagA-positive strain were found in all glaucoma subgroups, and none of them was statistically different from those of controls.

CONCLUSIONS

Neither H. pylori infection nor seropositivity for virulent CagA-bearing H. pylori strains have significant association with the occurrence of glaucoma of any type.

Helicobacter pylori and extragastric diseases

Since the discovery of Helicobacter pylori, several studies have investigated the hypothetical role of this bacterium in various extragastric diseases, e.g. ischemic heart disease, idiopathic thrombocytopenic purpura, iron-deficiency anaemia, and other disorders. The majority of these studies are epidemiological or eradication trials, but there are also case reports and in-vitro studies. Idiopathic thromobocytopenic purpura is the disease that shows the strongest link with H. pylori infection. There is also evidence of a role of CagA-positive H. pylori infection in iron-deficiency anaemia and ischemic heart disease. The association between H. pylori infection and other extragastric diseases remains controversial, being mostly supported by 'case reports', small pilot studies, or just in-vitro data. Further studies are needed to identify whether there is any pathological implication for H. pylori infection in these diseases.

Noxious compounds in exhaled air, a potential cause for ocular manifestations of H. pylori gastrointestinal infection

Helicobacter pylori infection is one of the most common chronic bacterial infections worldwide. In the past few years, a variety of extradigestive disorders have been associated with H. pylori infection. This infection has also been linked to some ophthalmic disorders, including glaucoma, central serous chorioretinopathy, uveitis and blepharitis. Several possible theories to explain pathogenetic mechanism underlying the observed associations have been provided. H. pylori infection causes elaboration of some noxious compounds, including ammonia, hydrogen nitrate and hydrogen cyanide, in exhaled breath of infected individuals. Herein we hypothesize that chronic exposure of ocular surface to these compounds may explain some ophthalmic and also respiratory manifestations of the chronic gastrointestinal infection.

Glaucomatous outflow pathway and oxidative stress

Oxidative free radicals and reactive oxygen species (ROS) are able to affect the cellularity of the human trabecular meshwork (HTM). These findings suggest that intraocular pressure increase, which characterises most glaucomas, is related to oxidative degenerative processes affecting the HTM and specifically its endothelial cells. Much evidence indicates that in this region ROS play a fundamental pathogenic role by reducing local antioxidant activities, inducing outflow resistance and exacerbating the activities of superoxide dismutase and glutathione peroxidase in glaucomatous eyes. Furthermore, hydrogen peroxide induces rearrangement of HTM cells and compromises their integrity. Glaucomatous subjects might have a genetic predisposition rendering them more susceptible to ROS-induced damage. A fairly significant correlation between oxidative DNA damage in the HTM and intraocular pressure increase and visual field defects in glaucomatous patients has been demonstrated. Thus, oxidative stress may play a significant role during glaucoma course initially damaging HTM cells, then contributing to the alteration of the homeostasis between NO and endothelins, and finally through its possible involvement in ganglional cell death. On the whole, these findings support the hypothesis that oxidative damage is an important step in the pathogenesis of primary open-angle glaucoma, and might be a relevant target for both prevention and therapy.

Extragastric manifestations of Helicobacter pylori infection--other Helicobacter species

Recent studies have indicated a strong link between Helicobacter pylori and idiopathic thrombocytopenic purpura and iron deficiency anemia. Interesting results have also been obtained for ischemic heart disease, though most putative associations between H. pylori infection and extragastric disease remain speculative. With regard to other Helicobacter species, Helicobacter felis has been shown to play a role in gastric carcinogenesis in mouse models. An increased susceptibility to cholesterol gallstone formation has been described in animals fed a lithogenic diet and infected with Helicobacter bilis, or co-infected with Helicobacter hepaticus and Helicobacter rodentium. Finally, enterohepatic Helicobacter species have also been exploited to better understand inflammatory bowel disease.