Helicobacter pylori-coccoid forms and biofilm formation

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

Strategies adopted by gastric pathogen Helicobacter pylori for a mature biofilm formation: Antimicrobial peptides as a visionary treatment

Enormous efforts in recent past two decades to eradicate the pathogen that has been prevalent in half of the world's population have been problematic. The biofilm formed by Helicobacter pylori provides resistance towards innate immune cells, various combinatorial antibiotics, and human antimicrobial peptides, despite the fact that these all are potent enough to eradicate it in vitro. Biofilm provides the opportunity to secrete various virulence factors that strengthen the interaction between host and pathogen helping in evading the innate immune system and ultimately leading to persistence. To our knowledge, this review is the first of its kind to explain briefly the journey of H. pylori starting with the chemotaxis, the mechanism for selecting the site for colonization, the stress faced by the pathogen, and various adaptations to evade these stress conditions by forming biofilm and the morphological changes acquired by the pathogen in mature biofilm. Furthermore, we have explained the human GI tract antimicrobial peptides and the reason behind the failure of these AMPs, and how encapsulation of Pexiganan-A(MSI-78A) in a chitosan microsphere increases the efficiency of eradication.

The role of non-Helicobacter pylori bacteria in the pathogenesis of gastroduodenal diseases

Over the past decade, the development of next-generation sequencing for human microbiota has led to remarkable discoveries. The characterization of gastric microbiota has enabled the examination of genera associated with several diseases, including gastritis, precancerous lesions, and gastric cancer. Helicobacter pylori (H. pylori) is well known to cause gastric dysbiosis by reducing diversity, because this bacterium is the predominant bacterium. However, as the diseases developed into more severe stages, such as atrophic gastritis, premalignant lesion, and gastric adenocarcinoma, the dominance of H. pylori began to be displaced by other bacteria, including Streptococcus, Prevotella, Achromobacter, Citrobacter, Clostridium, Rhodococcus, Lactobacillus, and Phyllobacterium. Moreover, a massive reduction in H. pylori in cancer sites was observed as compared with noncancer tissue in the same individual. In addition, several cases of H. pylori-negative gastritis were found. Among these individuals, there was an enrichment of Paludibacter, Dialister, Streptococcus, Haemophilus parainfluenzae, and Treponema. These remarkable findings suggest the major role of gastric microbiota in the development of gastroduodenal diseases and led us to the hypothesis that H. pylori might not be the only gastric pathogen. The gastric microbiota point of view of disease development should lead to a more comprehensive consideration of this relationship.

An Anaerobic Environment Drives the Harboring of Helicobacter pylori within Candida Yeast Cells

Simple Summary

Helicobacter pylori is a pathogen that is associated with a number of gastric pathologies and has adapted to the gastric environment. Outside this organ, stress factors such as oxygen concentration affect the viability of this bacterium. This study aimed to determine if changes in oxygen concentration promoted the entry of H. pylori into the interior of yeast cells of the Candida genus. Co-cultures of H. pylori and Candida strains in Brucella broth plus 5% fetal bovine serum were incubated under microaerobic, anaerobic, or aerobic conditions. Bacteria-like bodies (BLBs) were detected within yeast cells (Y-BLBs) by optical microscopy, identified by molecular techniques, and their viability evaluated by SYTO-9 fluorescence. Co-cultures incubated under the three conditions showed the presence of Y-BLBs, but the highest Y-BLB percentage was present in H. pylori J99 and C. glabrata co-cultures incubated under anaerobiosis. Molecular techniques were used to identify BLBs as H. pylori and SYTO-9 fluorescence confirmed that this bacterium remained viable within yeast cells. In conclusion, although without apparent stress conditions H. pylori harbors within Candida yeast cells, its harboring increases significantly under anaerobic conditions. This endosymbiotic relationship also depends mostly on the H. pylori strain used in the co-culture.

Abstract

Helicobacter pylori protects itself from stressful environments by forming biofilms, changing its morphology, or invading eukaryotic cells, including yeast cells. There is little knowledge about the environmental factors that influence the endosymbiotic relationship between bacterium and yeasts. Here, we studied if oxygen availability stimulated the growth of H. pylori within Candida and if this was a bacterial- or yeast strain-dependent relationship. Four H. pylori strains and four Candida strains were co-cultured in Brucella broth plus 5% fetal bovine serum, and incubated under microaerobic, anaerobic, or aerobic conditions. Bacteria-like bodies (BLBs) within yeast cells (Y-BLBs) were detected by microscopy. H. pylori was identified by FISH and by PCR amplification of the 16S rRNA gene of H. pylori from total DNA extracted from Y-BLBs from H. pylori and Candida co-cultures. BLBs viability was confirmed by SYTO-9 fluorescence. Higher Y-BLB percentages were obtained under anaerobic conditions and using H. pylori J99 and C. glabrata combinations. Thus, the H. pylori–Candida endosymbiotic relationship is strain dependent. The FISH and PCR results identified BLBs as intracellular H. pylori. Conclusion: Stressful conditions such as an anaerobic environment significantly increased H. pylori growth within yeast cells, where it remained viable, and the bacterium–yeast endosymbiotic relationship was bacterial strain dependent with a preference for C. glabrata.

Lactobacillus spp. for Gastrointestinal Health: Current and Future Perspectives

In recent decades, probiotic bacteria have become increasingly popular as a result of mounting scientific evidence to indicate their beneficial role in modulating human health. Although there is strong evidence associating various Lactobacillus probiotics to various health benefits, further research is needed, in particular to determine the various mechanisms by which probiotics may exert these effects and indeed to gauge inter-individual value one can expect from consuming these products. One must take into consideration the differences in individual and combination strains, and conditions which create difficulty in making direct comparisons. The aim of this paper is to review the current understanding of the means by which Lactobacillus species stand to benefit our gastrointestinal health.

Milk and dairy products as a possible source of environmental transmission of Helicobacter pylori

Helicobacter pylori (H. pylori) is found worldwide, and it is estimated that more than 50% of the population is infected. The presence of H. pylori in the gastrointestinal tract is associated with the occurrence of serious human diseases such as chronic gastritis, duodenal ulcer or gastric cancer. Therefore, the International Agency for Research on Cancer classified H. pylori as a Group 1 carcinogen in 1994. The routes of H. pylori transmission are not yet precisely known. Many authors agree that humans may become infected by H. pylori through foodstuffs. Milk is one of the basic foods of people of all age categories. Helicobacter pylori has been isolated from milk derived from various livestock, such as cows, sheep, goat, camel or buffalo milk. This review research paper indicates that H. pylori may be present in different types of foods and suggests that consumption of milk and selected dairy products may be a source of H. pylori infection for humans.

SpoT-mediated NapA upregulation promotes oxidative stress-induced Helicobacter pylori biofilm formation and confers multidrug resistance

Recently, there is increased incidence of drug-resistant Helicobacter pylori infection. Biofilm formation confers multidrug resistance to bacteria. Moreover, it has been found that the formation of biofilm on the surface of gastric mucosa is an important reason for the difficulty of eradication of H. pylori The mechanisms underlying H. pylori biofilm formation in vivo have not been elucidated. Reactive oxygen species (ROS) released by the host immune cells in response to H. pylori infection cannot effectively clear the pathogen. Moreover, the extracellular matrix of the biofilm protects the bacteria against ROS-mediated toxicity. This study hypothesized that ROS can promote H. pylori biofilm formation and treatment with low concentrations of hydrogen peroxide (H₂O₂) promoted this process in vitro The comparative transcriptome analysis of planktonic and biofilm-forming cells revealed that the expression of SpoT, a (p)ppGpp (guanosine 3'-diphosphate 5'-triphosphate and guanosine 3',5'-bispyrophosphate) synthetase/hydrolase, is upregulated in H₂O₂-induced biofilms and that knockout of spoT inhibited H. pylori biofilm formation. Additionally, this study examined the key target molecules involved in SpoT regulation using weighted gene co-expression network analysis. The analysis revealed that neutrophil-activating protein (NapA; HP0243) promoted H₂O₂-induced biofilm formation and conferred multidrug resistance. Furthermore, vitamin C exhibited anti-H. pylori biofilm activity and downregulated the expression of napA in vitro These findings provide novel insight into the clearance of H. pylori biofilms.

Optimization of pre- treatments with Propidium Monoazide and PEMAX™ before real-time quantitative PCR for detection and quantification of viable Helicobacter pylori cells

Accurate detection of H. pylori in different environmental and clinical samples is essential for public health strtdudies. Now, a big effort is being made to design PCR methodologies that allow for the detection of viable and viable but non-culturable (VBNC) H. pylori cells, by achieving complete exclusion of dead cells amplification signals. The use of DNA intercalating dyes has been proposed. However, its efficacy is still not well determined. In this study, we aimed to test the suitability of PMA and PEMAX™ dyes used prior to qPCR for only detecting viable cells of H. pylori. Their efficiency was evaluated with cells submitted to different disinfection treatments and confirmed by the absence of growth on culture media and by LIVE/DEAD counts. Our results indicated that an incubation period of 5 min for both, PMA and PEMAX™, did not affect viable cells. Our study also demonstrated that results obtained by using intercalating dyes may vary depending on the cell stress conditions. In all dead cell's samples, both PMA and PEMAX™ pre-qPCR treatments decreased the amplification signal (>10³ Genomic Units (GU)), although none of them allowed for its disappearance confirming that intercalating dyes, although useful for screening purposes, cannot be considered as universal viability markers. To investigate the applicability of the method specifically to detect H. pylori cells in environmental samples, PMA-qPCR was performed on samples containing the different morphological and viability states that H. pylori can acquire in environment. The optimized PMA-qPCR methodology showed to be useful to detect mostly (but not only) viable forms, regardless the morphological state of the cell.

Cholestenone functions as an antibiotic against Helicobacter pylori by inhibiting biosynthesis of the cell wall component CGL

Helicobacter pylori, a pathogen responsible for gastric cancer, contains a unique glycolipid, cholesteryl-α-D-glucopyranoside (CGL), in its cell wall. Moreover, O-glycans having α1,4-linked N-acetylglucosamine residues (αGlcNAc) are secreted from gland mucous cells of gastric mucosa. Previously, we demonstrated that CGL is critical for H. pylori survival and that αGlcNAc serves as antibiotic against H. pylori by inhibiting CGL biosynthesis. In this study, we tested whether a cholesterol analog, cholest-4-en 3-one (cholestenone), exhibits antibacterial activity against H. pylori in vitro and in vivo. When the H. pylori standard strain ATCC 43504 was cultured in the presence of cholestenone, microbial growth was significantly suppressed dose-dependently relative to microbes cultured with cholesterol, and cholestenone inhibitory effects were not altered by the presence of cholesterol. Morphologically, cholestenone-treated H. pylori exhibited coccoid forms. We obtained comparable results when we examined the clarithromycin-resistant H. pylori strain "2460." We also show that biosynthesis of CGL and its derivatives cholesteryl-6-O-tetradecanoyl-α-D-glucopyranoside and cholesteryl-6-O-phosphatidyl-α-D-glucopyranoside in H. pylori is remarkably inhibited in cultures containing cholestenone. Lastly, we asked whether orally administered cholestenone eradicated H. pylori strain SS1 in C57BL/6 mice. Strikingly, mice fed a cholestenone-containing diet showed significant eradication of H. pylori from the gastric mucosa compared with mice fed a control diet. These results overall strongly suggest that cholestenone could serve as an oral medicine to treat patients infected with H. pylori, including antimicrobial-resistant strains.

Growth Phase Dependent Cell Shape of Haloarcula

Several haloarchaea are reported to be pleomorphic, while others exhibit remarkable shapes, such as squares. Recently, Haloferax volcanii was found to alter its morphology during growth. Cells are motile rods in early exponential phase, and immotile plates in stationary phase. It is unknown if this growth phase dependent cell shape alteration is a specific feature of Hfx. volcanii, or conserved amongst haloarchaea. Here, we studied the cell shape and motility of two haloarchaea species Haloarcula hispanica and Haloarcula californiae. With a combination of light and electron microscopy, we observed that both strains undergo a growth phase dependent morphological development, albeit in a slightly different fashion as Hfx. volcanii. For both Haloarcula strains, the cell size is changing throughout growth. Cell shape seems to be related with motility, as highly motile cells on semi-solid agar plates are predominantly rod-shaped. We conclude that the growth phase dependent cell morphology alteration might be a common feature amongst haloarchaea, and that cell shape is generally linked with a motile life style. The conservation of this phenomenon underscores the importance of studies of the molecular mechanisms regulating cell shape in archaea.

Clinical and laboratory importance of detecting Helicobacter pylori coccoid forms for the selection of treatment

Helicobacter pylori grows and multiplies in the gastrointestinal tract (GIT) in about half of the world’s population. The prevalence of diseases associated with this bacterium is steadily increasing, which makes it necessary to search for optimal therapy aimed at eradication of this bacterium. Such diseases, for example, include gastric ulcer (GU) and chronic gastritis (CG). Unfortunately, modern possibilities for eradication therapy do not always make it possible to cure patients, and relapses often occur if it is cured. Nowadays, a particular topical issue has arisen, which concerns the resistance of Helicobacter pylori to therapies, because the effectiveness of medication used in clinics decreases every year. One of the mechanisms favouring tolerance to antibiotics is the transformation into a different morphological form – coccoid. This form of the bacterium was discovered quite a long time ago. Nevertheless, the question of its importance in clinical practice remains open to this day. Modern studies are aimed at understanding the role of coccoid forms of H. pylori in the survival of the population of these bacteria and at clarifying their role in the pathogenesis of gastrointestinal diseases. It is not known whether it is necessary to evaluate the contamination of a given morphological form of a bacterium of the gastric mucosa in clinical practice and its influence on the development of diseases etc. This article presents an overview and analysis of modern ideas about H. pylori coccoid forms and answers to the main questions posed in the last 10 years regarding the study of coccoid forms. Additionally, our results present a comparison of expression of virulence factors in coccoid and spiral forms of H. pylori.

Where to Biopsy to Detect Helicobacter pylori and How Many Biopsies Are Needed to Detect Antibiotic Resistance in a Human Stomach

This study aims to determine the gastric distribution, density, and diversity of Helicobacter pylori infection. Subtotal resection of the stomachs of three H. pylori-infected and asymptomatic obese patients were collected after a sleeve gastrectomy. Distribution and density of H. pylori were determined using culture and RT-PCR on multiple gastric sites (88, 176, and 101 biopsies per patient). Diversity of H. pylori strains was studied using antibiotic susceptibility testing, random amplified polymorphism DNA (RAPD) typing and cagA gene detection on single-colony isolates (44, 96, and 49 isolates per patient). H. pylori was detected in nearly all analyzed sites (354/365 biopsies, 97%). Antral density was higher in one patient only. The three stomachs were almost exclusively infected by an antibiotic-susceptible strain. One clarithromycin-resistant isolate in one biopsy was detected in two stomachs (1/44 and 1/49 isolates), while in the third one, eight (8/96 isolates) metronidazole-resistant isolates were detected. DNA typing showed infection with cagA-negative strains for one patient, cagA-positive strains for a second patient and the third patient was infected with two different strains of distinct cagA genotypes. Infection with H. pylori is shown to spread to the whole surface of the stomach, but a possibility of minor sub-population of antibiotic-resistant clones, undetectable in routine practice.

The Puzzle of Coccoid Forms of Helicobacter pylori: Beyond Basic Science

Helicobacter pylori (H. pylori) may enter a non-replicative, non-culturable, low metabolically active state, the so-called coccoid form, to survive in extreme environmental conditions. Since coccoid forms are not susceptible to antibiotics, they could represent a cause of therapy failure even in the absence of antibiotic resistance, i.e., relapse within one year. Furthermore, coccoid forms may colonize and infect the gastric mucosa in animal models and induce specific antibodies in animals and humans. Their detection is hard, since they are not culturable. Techniques, such as electron microscopy, polymerase chain reaction, loop-mediated isothermal amplification, flow cytometry and metagenomics, are promising even if current evidence is limited. Among the options for the treatment, some strategies have been suggested, such as a very high proton pump inhibitor dose, high-dose dual therapy, N-acetycysteine, linolenic acid and vonoprazan. These clinical, diagnostic and therapeutic uncertainties will represent fascinating challenges in the future.

Mucoid and coccoid Helicobacter pylori with fast growth and antibiotic resistance

BACKGROUND

In this study, one Helicobacter pylori isolate, from gastric biopsy of a dyspeptic patient that turned into mucoid-coccoid (MC) form upon consecutive subcultures, was identified. The culturability, antibiotic resistance, and lipid contents of MC were compared with those of non-mucoid (NM) spiral H pylori.

MATERIALS AND METHODS

Mucoid-coccoid and NM H pylori were subcultured on Brucella blood agar (BBA) and incubated under aerobic and microaerobic atmospheres at 37°C. Cultures were examined for colony characteristics and bacterial morphology after 1-3 days. The isolates were identified by biochemical tests and detection of H pylori-16S rDNA. Antibiogram was performed with currently used antibiotics for H pylori eradication. Cellular lipid contents were extracted and analyzed by gas chromatography.

RESULTS

Compared with pin-pointed and glistening colonies of NM H pylori that appeared under microaerobic conditions, MC H pylori grew well in consecutive subcultures under aerobic and microaerobic atmospheres and produced white patches of mucoid colonies. MC exhibited coccoid and NM spiral morphology. Both isolates were catalase, oxidase, and urease positive and contained 16S rDNA. Compared with NM that was susceptible to almost all the antibiotics, MC was resistant to all the antibiotics. Lipid analyses showed high frequency of unsaturated fatty acids and cholesterol in MC.

CONCLUSIONS

Coccoid forms with high fatty acid and cholesterol contents that show resistance to antibiotics might resist against other stressful conditions such as gastric acidity and immune response. Moreover, mucoid property may enhance resistance of coccoids to stresses. With mucoid-coccoid lifestyle, H pylori may establish a chronic infection refractory to antimicrobial therapy.

Helicobacter pylori: Survival in cultivable and non-cultivable form in artificially contaminated Mytilus galloprovincialis

Several studies report the presence of Helicobacter pylori (H. pylori) in seawater either free or attached to planktonic organism. After considering the role played by plankton in the food chain of most aquatic ecosystems and the possible role that seafood products can assume in the transmission of H. pylori to humans, the aim of this study was to assess the survival of H. pylori in artificially contaminated Mytilus galloprovincialis (M. galloprovincialis). A traditional culture method and a reverse transcriptase-PCR (RT-PCR) assay were employed to detect the mRNA of known virulence factor (VacA) which can be considered use a marker of bacterial viability. The obtained results clearly show that H. pylori is able to survive in artificially contaminated mussels for 6 days (2 days in a cultivable form and 4 days in a non-cultivable form).

Potential Role of Biofilm Formation in the Development of Digestive Tract Cancer With Special Reference to Helicobacter pylori Infection

Bacteria are highly social organisms that communicate via signaling molecules and can assume a multicellular lifestyle to build biofilm communities. Until recently, complications from biofilm-associated infection have been primarily ascribed to increased bacterial resistance to antibiotics and host immune evasion, leading to persistent infection. In this theory and hypothesis article we present a relatively new argument that biofilm formation has potential etiological role in the development of digestive tract cancer. First, we summarize recent new findings suggesting the potential link between bacterial biofilm and various types of cancer to build the foundation of our hypothesis. To date, evidence has been particularly convincing for colorectal cancer and its precursor, i.e., polyps, pointing to several key individual bacterial species, such as Bacteroides fragilis, Fusobacterium nucleatum, and Streptococcus gallolyticus subsp. Gallolyticus. Then, we further extend this hypothesis to one of the most common bacterial infection in humans, Helicobacter pylori (Hp), which is considered a major cause of gastric cancer. Thus far, there has been no direct evidence linking in vivo Hp gastric biofilm formation to gastric carcinogenesis. Yet, we synthesize the information to support an argument that biofilm associated-Hp is potentially more carcinogenic, summarizing biological characteristics of biofilm-associated bacteria. We also discuss mechanistic pathways as to how Hp or other biofilm-associated bacteria control biofilm formation and highlight recent findings on Hp genes that influence biofilm formation, which may lead to strain variability in biofilm formation. This knowledge may open a possibility of developing targeted intervention. We conclude, however, that this field is still in its infancy. To test the hypothesis rigorously and to link it ultimately to gastric pathologies (e.g., premalignant lesions and cancer), studies are needed to learn more about Hp biofilms, such as compositions and biological properties of extracellular polymeric substance (EPS), presence of non-Hp microbiome and geographical distribution of biofilms in relation to gastric gland types and structures. Identification of specific Hp strains with enhanced biofilm formation would be helpful not only for screening patients at high risk for sequelae from Hp infection, but also for development of new antibiotics to avoid resistance, regardless of its association with gastric cancer.

Impact of the Gastro-Intestinal Bacterial Microbiome on Helicobacter-Associated Diseases

Helicobacter pylori is a bacterium that selectively infects the gastric epithelium of half of the world population. The microbiome, community of microorganisms gained major interest over the last years, due to its modification associated to health and disease states. Even if most of these descriptions have focused on chronic disorders, this review describes the impact of the intestinal bacterial microbiome on host response to Helicobacter associated diseases. Microbiome has a direct impact on host cells, major barrier of the gastro-intestinal tract, but also an indirect impact on immune system stimulation, by enhancing or decreasing non-specific or adaptive response. In microbial infections, especially in precancerous lesions induced by Helicobacter pylori infection, these modifications could lead to different outcome. Associated to data focusing on the microbiome, transcriptomic analyses of the eukaryote response would lead to a complete understanding of these complex interactions and will allow to characterize innovative biomarkers and personalized therapies.

Helicobacter pylori: A foodborne pathogen?

Helicobacter pylori (H. pylori) is an organism that is widespread in the human population and is sometimes responsible for some of the most common chronic clinical disorders of the upper gastrointestinal tract in humans, such as chronic-active gastritis, duodenal and gastric ulcer disease, low-grade B-cell mucosa associated lymphoid tissue lymphoma of the stomach, and gastric adenocarcinoma, which is the third leading cause of cancer death worldwide. The routes of infection have not yet been firmly established, and different routes of transmission have been suggested, although the most commonly accepted hypothesis is that infection takes place through the faecal-oral route and that contaminated water and foods might play an important role in transmission of the microorganism to humans. Furthermore, several authors have considered H. pylori to be a foodborne pathogen because of some of its microbiological and epidemiological characteristics. H. pylori has been detected in drinking water, seawater, vegetables and foods of animal origin. H. pylori survives in complex foodstuffs such as milk, vegetables and ready-to-eat foods. This review article presents an overview of the present knowledge on the microbiological aspects in terms of phenotypic characteristics and growth requirements of H. pylori, focusing on the potential role that foodstuffs and water may play in the transmission of the pathogen to humans and the methods successfully used for the detection of this microorganism in foodstuffs and water.

Anti-proliferation effect of blue light-emitting diodes against antibiotic-resistant Helicobacter pylori

BACKGROUND AND AIM

Infection by Helicobacter pylori is implicated in a wide range of upper gastrointestinal diseases. Owing to the rapid emergence of antibiotic-resistant strains of H. pylori, the development of novel treatment modalities for antibiotic-resistant H. pylori infection is a key priority. Blue light-emitting diodes (LED) may represent a unique option owing to their antimicrobial effect. In this study, we aimed to evaluate the anti-proliferative effect of blue LED against antibiotic-resistant H. pylori.

METHODS

Ten antibiotic-resistant strains and one sensitive H. pylori strain were used in this study. After irradiation by blue LED along time course, the viability of H. pylori was evaluated by enumerating colony forming units. Morphological changes in H. pylori were observed using a scanning electron microscope. Reductase activity was measured as an indicator of bacterial cellular activity. Total reactive oxygen species was monitored using fluorescence intensity and fluorescence microscope imaging.

RESULTS

After irradiation by blue LED, the numbers of H. pylori in all the strains were significantly reduced compared with control group. The H. pylori exhibited a short rod-shaped morphology after irradiation; no such change was observed in H. pylori not exposed to blue LED. Re-irradiation of surviving strain after the initial irradiation also exhibited the same anti-proliferation effect. After blue LED irradiation, bacterial cellular activity was lower, and total reactive oxygen species production was significantly higher in blue LED group, compared with that in control.

CONCLUSIONS

Blue LED could be a new treatment to eradicate infection with antibiotic-resistant H. pylori.

Helicobacter pylori Biofilm Formation and Its Potential Role in Pathogenesis

Despite decades of effort, Helicobacter pylori infections remain difficult to treat. Over half of the world's population is infected by H. pylori, which is a major cause of duodenal and gastric ulcers as well as gastric cancer. During chronic infection, H. pylori localizes within the gastric mucosal layer, including deep within invaginations called glands; thanks to its impressive ability to survive despite the harsh acidic environment, it can persist for the host's lifetime. This ability to survive and persist in the stomach is associated with urease production, chemotactic motility, and the ability to adapt to the fluctuating environment. Additionally, biofilm formation has recently been suggested to play a role in colonization. Biofilms are surface-associated communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances. Biofilms pose a substantial health risk and are key contributors to many chronic and recurrent infections. This link between biofilm-associated bacteria and chronic infections likely results from an increased tolerance to conventional antibiotic treatments as well as immune system action. The role of this biofilm mode in antimicrobial treatment failure and H. pylori survival has yet to be determined. Furthermore, relatively little is known about the H. pylori biofilm structure or the genes associated with this mode of growth. In this review, therefore, we aim to highlight recent findings concerning H. pylori biofilms and the molecular mechanism of their formation. Additionally, we discuss the potential roles of biofilms in the failure of antibiotic treatment and in infection recurrence.

A proposed role for diffusible signal factors in the biofilm formation and morphological transformation of Helicobacter pylori

Due to the increasing resistance of Helicobacter pylori to antibiotics, there is a growing need for new strategies for the effective eradication of this pathogen. The inhibition of quorum-sensing activity in most microorganisms leads to a decrease in virulence. A different reaction is observed in H. pylori, as interfering with the production of autoinducer-2 initiates biofilm formation and increases the survival of these bacteria. Therefore, it is believed that there is an alternative way to control the physiological changes of H. pylori exposed to environmental stress. In this article, we present the compounds probably involved in the modulation of H. pylori virulence. Diffusible signal factors (DSFs) are fatty acid signal molecules involved in communication between microbes. DSFs are likely to stimulate H. Pylori transition into a sedentary state that correlates with bacterial transformation into a more resistant coccoid form and initiates biofilm formation. Biofilm is a structure that plays a crucial role in protecting against adverse environmental factors (low pH, oxidative stress, action of immune system) and limiting the effective concentration of antimicrobial substances. This article has suggested and characterized the existence of an alternative DSF-mediated cell-cell signaling of H. pylori, which controls autoaggregative behaviors, biofilm formation, and the transition of microorganisms into the coccoid form.

Significance of dormant forms of Helicobacter pylori in ulcerogenesis

Nearly half of the global population are carriers of Helicobacter pylori (H. pylori), a Gram-negative bacterium that persists in the healthy human stomach. H. pylori can be a pathogen and causes development of peptic ulcer disease in a certain state of the macroorganism. It is well established that H. pylori infection is the main cause of chronic gastritis and peptic ulcer disease (PUD). Decontamination of the gastric mucosa with various antibiotics leads to H. pylori elimination and longer remission in this disease. However, the reasons for repeated detection of H. pylori in recurrent PUD after its successful eradication remain unclear. The reason for the redetection of H. pylori in recurrent PUD can be either reinfection or ineffective anti-Helicobacter therapy. The administration of antibacterial drugs can lead not only to the emergence of resistant strains of microorganisms, but also contribute to the conversion of H. pylori into the resting (dormant) state. The dormant forms of H. pylori have been shown to play a potential role in the development of relapses of PUD. The paper discusses morphological H. pylori forms, such as S-shaped, C-shaped, U-shaped, and coccoid ones. The authors proposes the classification of H. pylori according to its morphological forms and viability.

Identification of Factors Associated with Biofilm Formation Ability in the Clinical Isolates of Helicobacter pylori

Background

A few reports confirm the ability of Helicobacter pylori to form biofilm. However, conclusive data do not exist concerning the factors that favor this ability.

Objectives

Evaluation of the factors associated with the biofilm formation ability of H. pylori including bacterial, physical and chemical, and environmental factors was the research’s aim.

Materials and Methods

H. pylori isolates from gastric biopsy specimens of patients infected chronically were screened for biofilm formation ability. Association of bacterial properties such as motility, auto-aggregation, cell hydrophobicity, and extracellular polymeric substances (EPS) with in vitro biofilm formation ability of H. pylori was evaluated. The effects of environmental factors such as growth-medium, temperature, oxygen-tension, pH, β-cyclodextrin, gastric secreted mucins, and sub-inhibitory concentration of amoxicillin were also evaluated.

Results

Ability of clinical H. pylori isolates to form biofilm in was quantitatively compared. The coccoid shape H. pylori cells were observed by scanning electron microscopy, the images were illustrative of the attachment of cells to form microcolony. The levels of hydrophobicity, motility and auto aggregation of two isolates with highest and lowest biofilm formation ability were the same. However, the signifi cant role of mucins (P < 0.05) in elevating the biofilm formation was observed. Other factors influencing biofilm formation were: pH, atmosphere and sub-MIC of antibiotics.

Conclusion

Mucins have a signifi cant role in elevating the biofilm formation, also pH, atmosphere and sub-MIC of antibiotics influence biofilm formation.

The investigation of Helicobacter pylori in the dental biofilm and saliva samples of children with dyspeptic complaints

Background

The oral cavity can be an extra-gastric reservoir for Helicobacter pylori (H.pylori). This can play a role in the pathogenesis of halitosis, glossitis, recurrent aphthous stomatitis, and dental caries. The present study was conducted to detect the presence of H.pylori within the dental biofilm and in saliva samples collected from children suffering from dyspepsia and children without any gastrointestinal complaints. Associations with gastric infection, halitosis, and some oral parameters were also evaluated.

Methods

Seventy children (aged between 5–16) with dyspepsia were selected for the study group and control group composed of 30 healthy children without dyspepsia were also included in the study. After detailed oral and clinical examinations for oral parameters, saliva, and supragingival dental biofilm samples were collected for 16S rRNA and 23S rRNA genes detection by real-time polymerase chain reaction (RT-PCR). The presence of gastric H.pylori was evaluated in endoscopic biopsy specimens histopathologically. Halitosis was evaluated by benzoyl-DL-arginine-naphthylamid (BANA) test. Salivary S.mutans and Lactobacilli sp. counts were also carried out by commercial kits.

Results

H.pylori was histopathologically detected amongst 83% of the children with the dyspeptic condition. The detection rate of this bacteria in dental biofilm and saliva samples and halitosis were found relatively higher in the dyspeptic children rather than the control group (p < 0.01). Halitosis was not significantly different between dyspeptic children and those detected with H.pylori (p > 0.05). In the gastric H.pylori positive group with dyspepsia, DMFT/S and dmft/s numbers and plaque indices were found higher than the control group (p < 0.01). Only plaque indices of gastric H.pylori negative group with dyspepsia were found higher than the control group (p < 0.01). S.mutans and Lactobacilli sp. counts were not significantly different between gastric H.pylori positive and negative groups (p > 0.05). Comparing to those with negative for both genes, in children whose dental biofilm and saliva samples were positive for both 16S rRNA and 23S rRNA genes, significantly higher results for halitosis, and DMFS numbers and significantly lower results for dmfs numbers and pH values were found (p < 0.01).

Conclusions

Helicobacter pylori can occur in the oral cavity aside and independently from the stomach. However, the high number of bacteria in the oral cavities of children with gastric H.pylori, an association between the presence of H.pylori and halitosis, DMFS, and pH were found.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-017-0361-x) contains supplementary material, which is available to authorized users.

Effect of biofilm formation by clinical isolates of Helicobacter pylori on the efflux-mediated resistance to commonly used antibiotics

AIM

To evaluate the role of biofilm formation on the resistance of Helicobacter pylori (H. pylori) to commonly prescribed antibiotics, the expression rates of resistance genes in biofilm-forming and planktonic cells were compared.

METHODS

A collection of 33 H. pylori isolates from children and adult patients with chronic infection were taken for the present study. The isolates were screened for biofilm formation ability, as well as for polymerase chain reaction (PCR) reaction with HP1165 and hp1165 efflux pump genes. Susceptibilities of the selected strains to antibiotic and differences between susceptibilities of planktonic and biofilm-forming cell populations were determined. Quantitative real-time PCR (qPCR) analysis was performed using 16S rRNA gene as a H. pylori-specific primer, and two efflux pumps-specific primers, hp1165 and hefA.

RESULTS

The strains were resistant to amoxicillin, metronidazole, and erythromycin, except for one strain, but they were all susceptible to tetracycline. Minimum bactericidal concentrations of antibiotics in the biofilm-forming cells were significantly higher than those of planktonic cells. qPCR demonstrated that the expression of efflux pump genes was significantly higher in the biofilm-forming cells as compared to the planktonic ones.

CONCLUSION

The present work demonstrated an association between H. pylori biofilm formation and decreased susceptibility to all the antibiotics tested. This decreased susceptibility to antibiotics was associated with enhanced functional activity of two efflux pumps: hp1165 and hefA.

Helicobacter pylori-induced premature senescence of extragastric cells may contribute to chronic skin diseases

Helicobacter pylori, one of the most frequently observed bacterium in the human intestinal flora, has been widely studied since Marshall and Warren documented a link between the presence of H. pylori in the gastrointestinal tract and gastritis and gastric ulcers. Interestingly, H. pylori has also been found in several other epithelial tissues, including the eyes, ears, nose and skin that may have direct or indirect effects on host physiology and may contribute to extragastric diseases, e.g. chronic skin diseases. More recently, it has been shown that H. pylori cytotoxin CagA expression induces cellular senescence of human gastric nonpolarized epithelial cells that may lead to gastrointestinal disorders and systemic inflammation. Here, we hypothesize that also chronic skin diseases may be promoted by stress-induced premature senescence (SIPS) of skin cells, namely fibroblasts and keratinocytes, stimulated with H. pylori cytotoxins. Future studies involving cell culture models and clinical specimens are needed to verify the involvement of H. pylori in SIPS-based chronic skin diseases.

In vitro effect of clarithromycin and alginate lyase against helicobacter pylori biofilm

It is now established that the gastric pathogen Helicobacter pylori has the ability to form biofilms in vitro as well as on the human gastric mucosa. The aim of this study is to evaluate the antimicrobial effects of Clarithromycin on H. pylori biofilm and to enhance the effects of this antibiotic by combining it with Alginate Lyase, an enzyme degrading the polysaccharides present in the extracellular polymeric matrix forming the biofilm. We evaluated the Clarithromycin minimum inhibition concentration (MIC) on in vitro preformed biofilm of a H. pylori. Then the synergic effect of Clarithromycin and Alginate Lyase treatment has been quantified by using the Fractional Inhibitory Concentration index, measured by checkerboard microdilution assay. To clarify the mechanisms behind the effectiveness of this antibiofilm therapeutic combination, we used Atomic Force Microscopy to analyze modifications of bacterial morphology, percentage of bacillary or coccoid shaped bacteria cells and to quantify biofilm properties. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1584-1591, 2016.

Pleiomorphism in Mycobacterium

Morphological variants in mycobacterial cultures under different growth conditions, including aging of the culture, have been shown to include fibrous aggregates, biofilms, coccoids, and spores. Here we discuss the diversity in shape and size changes demonstrated by bacterial cells with special reference to pleiomorphism observed in Mycobacterium spp. in response to nutritional and other environmental stresses. Inherent asymmetry in cell division and compartmentalization of cell interior under different growth conditions might contribute toward the observed pleiomorphism in mycobacteria. The regulatory genes comprising the bacterial signaling pathway responsible for initiating morphogenesis are speculated upon from bioinformatic identifications of genes for known sensors, kinases, and phosphatases existing in mycobacterial genomes as well as on the basis of what is known in other bacteria.

Helicobacter pylori Resists the Antimicrobial Activity of Calprotectin via Lipid A Modification and Associated Biofilm Formation

Helicobacter pylori is one of several pathogens that persist within the host despite a robust immune response. H. pylori elicits a proinflammatory response from host epithelia, resulting in the recruitment of immune cells which manifests as gastritis. Relatively little is known about how H. pylori survives antimicrobials, including calprotectin (CP), which is present during the inflammatory response. The data presented here suggest that one way H. pylori survives the nutrient sequestration by CP is through alteration of its outer membrane. CP-treated H. pylori demonstrates increased bacterial fitness in response to further coculture with CP. Moreover, CP-treated H. pylori cultures form biofilms and demonstrate decreased cell surface hydrophobicity. In response to CP, the H. pylori Lpx lipid A biosynthetic enzymes are not fully functional. The lipid A molecules observed in H. pylori cultures treated with CP indicate that the LpxF, LpxL, and LpxR enzyme functions are perturbed. Transcriptional analysis of lpxF, lpxL, and lpxR indicates that metal restriction by CP does not control this pathway through transcriptional regulation. Analyses of H. pylori lpx mutants reveal that loss of LpxF and LpxL results in increased fitness, similar to what is observed in the presence of CP; moreover, these mutants have significantly increased biofilm formation and reduced cell surface hydrophobicity. Taken together, these results demonstrate a novel mechanism of H. pylori resistance to the antimicrobial activity of CP via lipid A modification strategies and resulting biofilm formation.

Helicobacter pylori evades recognition of the host’s immune system by modifying the lipid A component of lipopolysaccharide. These results demonstrate for the first time that the lipid A modification pathway is influenced by the host’s nutritional immune response. H. pylori’s exposure to the host Mn- and Zn-binding protein calprotectin perturbs the function of 3 enzymes involved in the lipid A modification pathway. Moreover, CP treatment of H. pylori, or mutants with an altered lipid A, exhibit increased bacterial fitness and increased biofilm formation. This suggests that H. pylori modifies its cell surface structure to survive under the stress imposed by the host immune response. These results provide new insights into the molecular mechanisms that influence the biofilm lifestyle and how endotoxin modification, which renders H. pylori resistant to cationic antimicrobial peptides, can be inactivated in response to sequestration of nutrient metals.

Water-induced modulation of Helicobacter pylori virulence properties

While the influence of water in Helicobacter pylori culturability and membrane integrity has been extensively studied, there are little data concerning the effect of this environment on virulence properties. Therefore, we studied the culturability of water-exposed H. pylori and determined whether there was any relation with the bacterium’s ability to adhere, produce functional components of pathogenicity and induce inflammation and alterations in apoptosis in an experimental model of human gastric epithelial cells. H. pylori partially retained the ability to adhere to epithelial cells even after complete loss of culturability. However, the microorganism is no longer effective in eliciting in vitro host cell inflammation and apoptosis, possibly due to the non-functionality of the cag type IV secretion system. These H. pylori-induced host cell responses, which are lost along with culturability, are known to increase epithelial cell turnover and, consequently, could have a deleterious effect on the initial H. pylori colonisation process. The fact that adhesion is maintained by H. pylori to the detriment of other factors involved in later infection stages appears to point to a modulation of the physiology of the pathogen after water exposure and might provide the microorganism with the necessary means to, at least transiently, colonise the human stomach.

[Role of Helicobacter pylori coccoid forms in infection and recrudescence]

Helicobacter pylori is a spiral Gram-negative bacillus, which colonizes the human stomach and plays a key role in the pathogenesis of a number of gastroduodenal diseases. However, when expose to environmental stressed conditions, such as increased oxygen tension, extended incubation and exposure to antibiotics, Helicobacter pylori is able to entering the viable but nonculturable state, in which the bacterium modifies its morphology from a spiral to coccoid form, as a manifestation of cell adaptation to these adverse conditions. In gastric tissues, viable coccoid forms may remain latent for long time and retain virulence factors, so these forms possibly contribute to the treatment failures and recurrence of Helicobacter pylori infection and gastroduodenal diseases as well. In this review, we will discuss several aspects of cellular adaptation and survival of Helicobacter pylori, antibiotic susceptibility and virulence of coccoid forms and its involvement with recrudescence.

Methods for Detecting the Environmental Coccoid Form of Helicobacter pylori

Helicobacter pylori is recognized as the most common pathogen to cause gastritis, peptic and duodenal ulcers, and gastric cancer. The organisms are found in two forms: (1) spiral-shaped bacillus and (2) coccoid. H. pylori coccoid form, generally found in the environment, is the transformed form of the normal spiral-shaped bacillus after exposed to water or adverse environmental conditions such as exposure to sub-inhibitory concentrations of antimicrobial agents. The putative infectious capability and the viability of H. pylori under environmental conditions are controversial. This disagreement is partially due to the fact of lack in detecting the coccoid form of H. pylori in the environment. Accurate and effective detection methods of H. pylori will lead to rapid treatment and disinfection, and less human health damages and reduction in health care costs. In this review, we provide a brief introduction to H. pylori environmental coccoid forms, their transmission, and detection methods. We further discuss the use of these detection methods including their accuracy and efficiency.

Association of smoking, alcohol and NSAIDs use with expression of cag A and cag T genes of Helicobacter pylori in salivary samples of asymptomatic subjects

OBJECTIVE

To determine the association of smoking, alcohol and nonsteroidal anti-inflammatory drugs (NSAIDs) use with presence and virulence of Helicobacter pylori (H. pylori) infection in a representative sample of a random adult population of asymptomatic subjects.

METHODS

Non virulent 16S rRNA and virulent cag A and T genes from salivary samples of 854 asymptomatic subjects were determined using polymerase chain reaction. The presence and absence of virulent and non virulent infection was statistically compared with consumption of smoking, alcohol and NSAIDs.

RESULTS

The prevalence of infection in male and female subjects was found to be 69.25% and 66.90%, respectively. The prevalence of infection in the population of asymptomatic subjects with respect to consumption of alcohol was as follows: current (31.22%), former (52.20%) and never (43.58%). The prevalence of infection in the population of asymptomatic subjects with respect to smoking of cigarettes was as follows: current (88.80%), former (57.14%) and never (33.33%). The prevalence of infection in the subject population consuming NSAIDs and not consuming NSAIDs frequently was found to be 82.75% and 21.16%, respectively. Virulence in male and female subjects was found to be 60.00% and 50.00%, respectively. The presence of virulent infection in the population of asymptomatic subjects with respect to consumption of alcohol was as follows: current (28.57%), former (40.15%) and never (50.00%). The prevalence of virulent infection in the population of asymptomatic subjects with respect to smoking of cigarettes was as follows: current (79.32%), former (75.00%) and never (50.00%). The prevalence of virulent infection in the subject population consuming NSAIDs and not consuming NSAIDs frequently was found to be 88.23% and 66.66%, respectively.

CONCLUSIONS

It can be concluded that smoking and NSAIDs consumption are aggravating factors for virulence of H. pylori and alcohol can inhibit H. pylori infection in asymptomatic subjects.

Mechanisms of bacterial morphogenesis: evolutionary cell biology approaches provide new insights

How Darwin's "endless forms most beautiful" have evolved remains one of the most exciting questions in biology. The significant variety of bacterial shapes is most likely due to the specific advantages they confer with respect to the diverse environments they occupy. While our understanding of the mechanisms generating relatively simple shapes has improved tremendously in the last few years, the molecular mechanisms underlying the generation of complex shapes and the evolution of shape diversity are largely unknown. The emerging field of bacterial evolutionary cell biology provides a novel strategy to answer this question in a comparative phylogenetic framework. This relatively novel approach provides hypotheses and insights into cell biological mechanisms, such as morphogenesis, and their evolution that would have been difficult to obtain by studying only model organisms. We discuss the necessary steps, challenges, and impact of integrating "evolutionary thinking" into bacterial cell biology in the genomic era.

Effect of Alginate Lyase on Biofilm-GrownHelicobacter pyloriProbed by Atomic Force Microscopy

Helicobacter pylori(H. pylori) is a microorganism with a pronounced capability of adaptation under environmental stress solicitations. Its persistence and antimicrobial resistance to the drugs commonly used in the anti-H. pyloritherapy are associated with the development of a biofilm mainly composed of DNA, proteins, and polysaccharides. A fundamental step to increase the success of clinical treatments is the development of new strategies and molecules able to interfere with the biofilm architecture and thus able to enhance the effects of antibiotics. By using Atomic Force Microscopy and Scanning Electron Microscopy we analyzed the effects of the alginate lyase (AlgL), an enzyme able to degrade a wide class of polysaccharides, on theH. pylorishape, surface morphology, and biofilm adhesion properties. We demonstrated that AlgL generates a noticeable loss ofH. pyloricoccoid form in favor of the bacillary form and reduces theH. pyloriextracellular polymeric substances (EPS).

Biofilms and Helicobacter pylori: Dissemination and persistence within the environment and host

The presence of viable Helicobacter pylori (H. pylori) in the environment is considered to contribute to the levels of H. pylori found in the human population, which also aids to increase its genetic variability and its environmental adaptability and persistence. H. pylori form biofilms both within the in vitro and in vivo environment. This represents an important attribute that assists the survival of this bacterium within environments that are both hostile and adverse to proliferation. It is the aim of this paper to review the ability of H. pylori to form biofilms in vivo and in vitro and to address the inherent mechanisms considered to significantly enhance its persistence within the host and in external environments. Furthermore, the dissemination of H. pylori in the external environment and within the human body and its impact upon infection control will be discussed.

Helicobacter pylori and oral pathology: Relationship with the gastric infection

Helicobacter pylori (H. pylori) has been found in the oral cavity and stomach, and its infection is one of the most frequent worldwide. We reviewed the literature and conducted a Topic Highlight, which identified studies reporting an association between H. pylori-infection in the oral cavity and H. pylori-positive stomach bacterium. This work was designed to determine whether H. pylori is the etiologic agent in periodontal disease, recurrent aphthous stomatitis (RAS), squamous cell carcinoma, burning and halitosis. Record selection focused on the highest quality studies and meta-analyses. We selected 48 articles reporting on the association between saliva and plaque and H. pylori-infection. In order to assess periodontal disease data, we included 12 clinical trials and 1 meta-analysis. We evaluated 13 published articles that addressed the potential association with RAS, and 6 with squamous cell carcinoma. Fourteen publications focused on our questions on burning and halitosis. There is a close relation between H. pylori infection in the oral cavity and the stomach. The mouth is the first extra-gastric reservoir. Regarding the role of H. pylori in the etiology of squamous cell carcinoma, no evidence is still available.

Helicobacter pylori: A chameleon-like approach to life

Helicobacter pylori (H. pylori) is widely adaptable for colonization in human stomachs in more than half of the world’s population. The microorganism is characterized by an unusual capability of arranging itself in both genotypic and phenotypic ways. Stressing conditions, including antimicrobial agents in sub-inhibitory concentrations, facilitate entering the viable but nonculturable state in which bacterial cells acquire the coccoid form. This morphotype represents an important strategy for bacterial survival in unsuitable conditions and also allows escape from the immune system. H. pylori is capable of forming biofilm outside and inside the host. For the bacterial population, the sessile growth mode represents an ideal environment for gene rearrangement, as it allows the acquiring of important tools aimed to improve bacterial “fitness” and species preservation. Biofilm formation in H. pylori in the human host also leads to recalcitrance to antibiotic treatment, thus hampering eradication. These lifestyle changes of H. pylori allow for a “safe haven” for its survival and persistence according to different ecological niches, and strongly emphasize the need for careful H. pylori surveillance to improve management of the infection.

Role of dental plaque, saliva and periodontal disease in Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection is one of the most common bacterial infections in humans. Although H. pylori may be detected in the stomach of approximately half of the world's population, the mechanisms of transmission of the microorganism from individual to individual are not yet clear. Transmission of H. pylori could occur through iatrogenic, fecal-oral, and oral-oral routes, and through food and water. The microorganism may be transmitted orally and has been detected in dental plaque and saliva. However, the role of the oral cavity in the transmission and recurrence of H. pylori infection has been the subject of debate. A large number of studies investigating the role of oral hygiene and periodontal disease in H. pylori infection have varied significantly in terms of their methodology and sample population, resulting in a wide variation in the reported results. Nevertheless, recent studies have not only shown that the microorganism can be detected fairly consistently from the oral cavity but also demonstrated that the chances of recurrence of H. pylori infection is more likely among patients who harbor the organism in the oral cavity. Furthermore, initial results from clinical trials have shown that H. pylori-positive dyspeptic patients may benefit from periodontal therapy. This paper attempts to review the current body of evidence regarding the role of dental plaque, saliva, and periodontal disease in H. pylori infection.

Gastric biopsies: the gap between evidence-based medicine and daily practice in the management of gastric Helicobacter pylori infection

BACKGROUND

Many consider histology to be the gold standard for Helicobacter pylori detection. Because the number and distribution of H pylori organisms vary, particularly in patients taking proton pump inhibitors (PPIs), the American Gastroenterological Association recommends discontinuing PPIs two weeks before endoscopy, and taking biopsies from both the body and antrum.

OBJECTIVE

To assess the influence of clinical practice on the histopathological detection of H pylori infection.

METHODS

Electronic patient records were evaluated for the sites of gastric sampling and PPI use at endoscopy. One hundred fifty cases with biopsies taken from both antrum and body were randomly selected for pathological re-review with special stains. The gastric regions sampled, H pylori distribution and influence of clinical factors on pathological interpretation were assessed.

RESULTS

Between 2005 and 2010, 10,268 biopsies were taken to detect H pylori. Only one region was sampled in 60% of patients (antrum 47%, body 13%). Re-review of biopsies taken from both antrum and body indicated that the correct regions were sampled in only 85 (57%) patients. Of these, 54 were H pylori positive and 96 were H pylori negative. H pylori was present in the antrum in only 15% of the patients and body only in 21%. Of 96 H pylori-negative patients, two were reinterpreted as positive. Forty-seven per cent of patients were taking PPIs at endoscopy, contributing to both false-negative and false-positive diagnoses.

CONCLUSION

Despite national and international guidelines for managing H pylori infection, the American Gastroenterological Association guidelines are infrequently adhered to, with PPIs frequently contributing to false diagnosis; sampling one region only increases the likelihood of missing active infection by at least 15%.

Peptidoglycan remodeling by the coordinated action of multispecific enzymes

The peptidoglycan (PG) cell wall constitutes the main defense barrier of bacteria against environmental insults and acts as communication interface. The biochemistry of this macromolecule has been well characterized throughout the years but recent discoveries have unveiled its chemical plasticity under environmental stresses. Non-canonical D-amino acids (NCDAA) are produced and released to the extracellular media by diverse bacteria. Such molecules govern cell wall adaptation to challenging environments through their incorporation into the polymer, a widespread capability among bacteria that reveals the inherent catalytic plasticity of the enzymes involved in the cell wall metabolism. Here, we analyze the recent structural and biochemical characterization of Bsr, a new family of broad spectrum racemases able to generate a wide range of NCDAA. We also discuss the necessity of a coordinated action of PG multispecific enzymes to generate adequate levels of modification in the murein sacculus. Finally, we also highlight how this catalytic plasticity of NCDAA-incorporating enzymes has allowed the development of new revolutionary methodologies for the study of PG modes of growth and in vivo dynamics.

Peptidoglycan plasticity in bacteria: emerging variability of the murein sacculus and their associated biological functions

The peptidoglycan (PG) sacculus once thought to be just a reinforcing, static and uniform structure, is fast becoming recognized as a dynamic cell constituent involved in every aspect of bacterial physiology. Recent advances showed that in addition to 'classical' tasks-as an essential element to define bacterial shape, size, division and resistance to osmotic stress-the sacculus plays very important roles in many other fields. The very few chemical and structural changes that were once considered as bizarre, or maybe exotic exceptions, are now universally accepted as fundamental pieces in bacterial cell wall adaptation to different kinds of environmental stresses; immune response; intra-specific and inter-specific signalling and antibiotics, just to mention a few. Most, if not all, of these implications are a consequence of the enormous adaptability of PG metabolism to cope with changing conditions, a characteristic for which the term plasticity is proposed. Here we overview and comment on a number of recent contributions on the cell wall adaptive responses to environmental challenges that has greatly impacted the already high complexity of the PG biology field. These new evidences have revived the interest in PG plasticity as an exciting and trendy topic in current microbiology which considers this variability as the trustworthy picture of bacterial PG in nature.

Morphological and Bactericidal Effects of Different Antibiotics on Helicobacter pylori

Background:

Helicobacter pylori (H. pylori) is a spiral Gram negative bacteria that can transform to the coccoid form in adverse conditions.

Objectives:

The aim of this study was to determine the in vitro morphological and bactericidal effects of metronidazole, amoxicillin and clarithromycin on H. pylori.

Materials and Methods:

The standard strain 26695 of H. pylori was cultured on Brucella agar (BA) and the minimum inhibitory concentrations (MICs) of three antibiotics were determined by E-test method. The bacteria were exposed to antibiotics at 1/2 MIC, MIC and 2X MIC concentrations in Brucella broth (BB). Induced coccoid forms were confirmed by Gram staining and light microscopy. The viability of cells as well as the susceptibility of viable coccoids to antibiotics were examined using the flow cytometry method.

Results:

All of the three antibiotics at sub-MIC induced coccoid forms. The highest rates of coccoids (> 90%) were induced at 0.008 μg/mL concentration (1/2 MIC) of amoxicillin, 72 hours postexposure. Metronidazole and clarithromycin with 1/2 MIC (0.5 and 0.125 µg/mL respectively) induced lower rates of coccoid forms (60% and 40% respectively). Potent bactericidal effects on coccoids were observed with Metronidazole at 2X MIC and clarithromycin at MIC (0.25 µg/mL) (80 - 90%). Amoxicillin with MIC and 2X MIC had no bactericidal effect on coccoid forms.

Conclusions:

Despite the good in vitro bactericidal effect of amoxicillin on spiral forms of H. pylori, this antibiotic has little effect on induced coccoids that may develop after the inappropriate in vivo antibacterial treatment. Hence, for successful therapy, it is essential not only to eradicate the spiral forms, but to eliminate the viable coccoids.

Detection of Helicobacter pylori in oropharyngeal lymphatic tissue with real-time PCR and assessment of its carcinogenic potential

Helicobacter pylori (HP) is considered a major gastric pathogen with oncogenic potential. The aim of this study was to determine whether HP is present in oropharyngeal lymphoid tissue and whether oropharyngeal HP strains carry virulence factor genes known to be involved in gastric carcinogenesis. The study included 104 subjects (41 patients with tonsillar carcinoma, 38 with chronic tonsillitis and 25 with obstructive sleep apnoea syndrome--OSAS). Detection of specific serum anti-HP antibodies was performed with an ELISA. The presence of HP in tissue was determined by culture and real-time PCR. Detection of virulence factors genes was also performed. Specific antibodies were found in 78.05% of tumour cases, 34.21% of chronic tonsillitis cases, and 72.0% of OSAS cases. The presence of HP in the tissue was detected in 73.91% of tonsillar tumours, 70.0% of tonsillitis cases, and 69.23% of OSAS specimens. The results of the virulence factor gene analysis showed the majority of the s1b (52.4%) and m2 (59.5%) alleles of vacA gene and limited abundance of cagA gene (12.5%). Results confirm that HP may colonise oropharyngeal lymphoid tissue. Oropharyngeal HP colonisation was frequently found in the oropharyngeal cancer group and in patients with benign oropharyngeal diseases. A virulence factor gene analysis showed differences from the predominant strains most commonly found in the stomach. The strains obtained from the oropharynx differed primarily by the lower abundance of the cagA gene and carried the less virulent vacA gene allele combination.

Pilot study: miscellaneous therapy is highly successful for Helicobacter pylori eradication

BACKGROUND

Success in H. pylori eradication with conventional therapies has decreased to unacceptable levels (≤80%). New schemes of combined treatment are currently needed.

AIM

To test a miscellaneous therapy for H. pylori eradication.

METHODS/PATIENTS

Open-label, pilot, single-centre and prospective study. Patients received a 15-day treatment scheme that consisted of 5 initial days of lansoprazole 30 mg b.d., amoxicillin 1 g b.d., and metronidazole 500 mg t.d.s.; days 6 to 10: lansoprazole 30 mg q.d.s. and metronidazole 500 mg t.d.s.; days 11 to 15: lansoprazole 30 mg b.d., clarithromycin 500 mg b.d. and metronidazole 500 mg t.d.s. Each patient underwent an upper endoscopy before treatment and a second follow-up endoscopy at least 4 weeks after therapy. Success was defined on the basis of an eradication rate following a per-protocol analysis ≥95%. Biopsies before and after therapy were obtained for histological evaluation and rapid urease test.

RESULTS

One hundred and twenty-two patients were enrolled and 118 patients completed the study. The eradication rate for H. pylori with miscellaneous therapy was 94% (confidence Interval (CI) 95%, 90-98.3%) in the per-protocol analysis (PP) and 91% (95% CI, 86-96%) in the intention-to-treat (ITT) analysis. Adherence to treatment was 96% (113 patients). Among patients who completed treatment, 55% presented adverse events, mainly nausea and abdominal pain.

CONCLUSION

A miscellaneous therapy, based on the combination of multiple medications in high doses for 2 weeks, and with gastric pH elevation, is a highly effective treatment as a first-line therapy for the eradication of H. pylori.

Assessment of cagE and babA mRNA expression during morphological conversion of Helicobacter pylori from spiral to coccoid

Helicobacter pylori (H. Pylori) is an actively dividing spiral bacterium that changes to coccoid morphology under stressful environments. The infectivity of the coccoids is still controversial. The aim of this study was to determine the viability and expression of two important virulence genes (babA and cagE), in antibiotic-induced coccoid forms. Three strains of H. pylori, the standard 26695 and two clinical isolates (p1, p2) were converted to coccoid form by amoxicillin. Coccoids were identified according to Gram-staining and microscopic morphology. The viability of the cells was analyzed by flow cytometry. The expression of cagE and babA in coccoid forms were evaluated and compared to the spirals by quantitative PCR assay. The coccoid forms were developed after 72 h exposure of H. pylori to ½ MIC of amoxicillin, and the conversion form was completed (100 %) at 144 h in all of three isolates. Flow cytometry analyses showed that the majority of the induced coccoids (90-99.9 %) were viable. Expression of cagE and babA was seen in coccoids; however, in lower rate (cagE, ~3-fold and babA, ~10-fold) than these in spiral forms. Coccoid forms of two clinical isolates significantly expressed higher rate of cagE and babA than standard 26695 strain (P = 0.01). These results suggest that the induced coccoid form of H. pylori is not a passive entity but can actively infect the human by expression of the virulence genes for long time in stomach and probably play a role in chronic and severe disease.