Metabolomic analysis of low and high biofilm-forming Helicobacter pylori strains

The biofilm-forming-capability of Helicobacter pylori has been suggested to be among factors influencing treatment outcome. However, H. pylori exhibit strain-to-strain differences in biofilm-forming-capability. Metabolomics enables the inference of spatial and temporal changes of metabolic activities during biofilm formation. Our study seeks to examine the differences in metabolome of low and high biofilm-formers using the metabolomic approach. Eight H. pylori clinical strains with different biofilm-forming-capability were chosen for metabolomic analysis. Bacterial metabolites were extracted using Bligh and Dyer method and analyzed by Liquid Chromatography/Quadrupole Time-of-Flight mass spectrometry. The data was processed and analyzed using the MassHunter Qualitative Analysis and the Mass Profiler Professional programs. Based on global metabolomic profiles, low and high biofilm-formers presented as two distinctly different groups. Interestingly, low-biofilm-formers produced more metabolites than high-biofilm-formers. Further analysis was performed to identify metabolites that differed significantly (p-value < 0.005) between low and high biofilm-formers. These metabolites include major categories of lipids and metabolites involve in prostaglandin and folate metabolism. Our findings suggest that biofilm formation in H. pylori is complex and probably driven by the bacterium' endogenous metabolism. Understanding the underlying metabolic differences between low and high biofilm-formers may enhance our current understanding of pathogenesis, extragastric survival and transmission of H. pylori infections

Elucidation of the Metabolic Network ofHelicobacter pyloriJ99 and Malaysian Clinical Strains by Phenotype Microarray

Background: Helicobacter pylori colonizes almost half of the human population worldwide. H. pylori strains are genetically diverse, and the specific genotypes are associated with various clinical manifestations including gastric adenocarcinoma, peptic ulcer disease (PUD), and nonulcer dyspepsia (NUD). However, our current knowledge of the H. pylori metabolism is limited. To understand the metabolic differences among H. pylori strains, we investigated four Malaysian H. pylori clinical strains, which had been previously sequenced, and a standard strain, H. pylori J99, at the phenotypic level. Materials and Methods: The phenotypes of the H. pylori strains were profiled using the Biolog Phenotype Microarray system to corroborate genomic data. We initiated the analyses by predicting carbon and nitrogen metabolic pathways from the H. pylori genomic data from the KEGG database. Biolog PM aided the validation of the prediction and provided a more intensive analysis of the H. pylori phenomes. Results: We have identified a core set of metabolic nutrient sources that was utilized by all strains tested and another set that was differentially utilized by only the local strains. Pentose sugars are the preferred carbon nutrients utilized by H. pylori. The amino acids l-aspartic acid, d-alanine, and l-asparagine serve as both carbon and nitrogen sources in the metabolism of the bacterium. Conclusion: The phenotypic profile based on this study provides a better understanding on the survival of H. pylori in its natural host. Our data serve as a foundation for future challenges in correlating interstrain metabolic differences in H. pylori

Corrigendum to “Phenotypic Detection of Metallo-β-Lactamase in Imipenem-ResistantPseudomonas aeruginosa”

The Acknowledgments section of the article titled “Phenotypic Detection of Metallo-β-Lactamase in Imipenem-Resistant Pseudomonas aeruginosa” [1] has been revised as follows: This paper is supported by University of Malaya-Ministry of Education (UM-MoE) High Impact Research (HIR) Grant UM.C/625/1/HIR/MoE/CHAN-02 (Account no. H-50001-A000013) and University of Malaya PPP Grant (Vote PS296/2007B). The authors would like to thank Professor Emeritus Yunsop Chong and Professor Kyungwon Lee from the Department of Clinical Pathology and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea, for kindly providing the IMP-1, SIM-1, and VIM-2 β-lactamase producing Acinetobacter spp. and P. aeruginosa strains for use as positive controls

Prevalence of Helicobacter pylori antibiotic resistance pattern in Malaysia

Helicobacter pylori is well-known for its high genomic diversity and rapid genetic mutation by both natural transformation and inter-or intra-species conjugation. Therefore, eradication of H. pylori will be made difficult when antibiotic resistence was developed towards current treatment regimen. Although previous studies had shown low resistence rate towards major antibiotics such as clarithromycin, levofloxcin, amoxicillin and tetracycline in the Malaysian population, increasing migration of foreign workers might disrupt the gene pool

Prevalence of Serum Celiac Antibodies in a Multiracial Asian Population-A First Study in the Young Asian Adult Population of Malaysia

Background: Celiac disease (CD) is an immune-mediated disorder induced by the ingestion of gluten in genetically susceptible persons. The prevalence of CD in Malaysia is unknown. We aim to determine the seroprevalence of CD antibodies and also investigate the correlation between H. pylori infection and CD in the young and healthy multiracial Malaysian population. Methods: Healthy young adult volunteers between the ages of 18-30 years were consecutively recruited from June 2012 to May 2014 at the University of Malaya Medical Centre (UMMC), Kuala Lumpur. Serum samples from all the participants were tested for anti-gliadin antibody immunoglobulin A/immunoglobulin G (IgA/IgG) and anti-tissue transglutaminase antibody (tTG) IgA/IgG. Samples positive for both anti-gliadin and anti-tTG were further validated for anti-human endomysial IgA antibodies (EmA). Serological diagnosis of CD was made when anti-gliadin, anti-tTG and anti-EmA were positive. Results: 562 qualified participants with mean age 24 ± 2.4 years old were recruited into our study. CD was found in 7 participants where most of them were asymptomatic and unaware of their CD status. The median of anti-gliadin and anti-tTG IgA/IgG value was 38.2 U/ml (interquartile range, 28.3-60.4 U/ml) and 49.2 U/ml (interquartile range, 41.1-65.9 U/ml), respectively. Seroprevalence of CD antibodies was 1.9% (6 out of 324) in female while only 0.4% (1 out of 238) in male. Seroprevalence among Malay was 0.8% (2 of 236), Chinese was 1.7% (3 of 177) and Indian was 1.3% (2 of 149). Overall, seroprevalence of CD antibodies in healthy asymptomatic adults in the Malaysian population was 1.25% (95% CI, 0.78%-1.72%). No significant relationship was discovered between CD and H. pylori infection. Conclusions: The seroprevalence of CD antibodies in healthy young adults in the Malaysian population was 1.25% (1 in 100). CD is underdiagnosed and it could be a much greater problem in Malaysia than previously thought

Biogenic synthesis, characterization of antibacterial silver nanoparticles and its cell cytotoxicity

The advanced research and development of silver nanoparticles (AgNPs) is vast due to their incredible applications today. In this work, AgNPs were synthesized using soil derived Pseudomonas putida MVP2. The AgNPs formation on the P. putida cell membrane and its cell free supernatant was studied. The synthesized AgNPs were characterized by UV–visible spectroscopy, scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), energy dispersive X-ray (EDAX) and Fourier transform infrared (FTIR) spectrum analysis. The mode of action of AgNPs on the bacteria was studied against clinically isolated bacterial pathogens, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Helicobacter pylori by membrane integrity, and protein leakage using confocal and electron microscopy. Interestingly, AgNPs had no cytotoxicity under 25 μg/mL and it was toxic at above 50 μg/mL on human epidermoid larynx carcinoma (HEp-2) cells. This study evidenced that biogenic nanoparticles could affect the bacterial replication, protein leakage and eventually cell death. This might be used for active antimicrobial agents for the chronic infections

Gut microbiota and Helicobacter pylori infections

Background: It has been widely accepted that Helicobacter pylori may be the only bacterium that can survive and infect the human stomach. Recently, a few studies using 16S rRNA clone library and other similar approaches showed that the gastric microbiome may be more complex than that. However, the role of interactions between H. pylori and other members of the gastric and gut microbiome in the development and progression of gastroduodenal diseases has not been extensively studied. Objective: The objective of this study is to establish the effects of gut microbiome microbiome in H. pylori infections using germ-free (GF) and specific pathogen-free (SPF) mice models. Methodology: Male GF and SPF C57BL/6 mice of 4–8 weeks of age were infected intragastrically with 109 CFU of rodent-adapted H. pylori strain 7.13 for 2, 8 and 16 weeks. At the end of the respective infection period, the animals were sacrificed. Stomach, liver and brain were harvested for microbiological and histopathological examinations. Synaptophysin and polysynaptic density protein 95 (PSD-95) levels in the brain were evaluated. Blood samples were collected for immunological and hormonal (leptin, total ghrelin and acyl ghrelin) analysis. Results: GF mouse model was established as an alternative animal model for studying H. pylori infections in a microbiota-free in vivo system. Discussion and conclusion: To further characterize the interplay between H. pylori, gut microflora and host, a meta-proteomics and meta-metabo-lomics approach will also be adopted. Outcome of this study will enhance our understanding of the pathogenesis of H. pylori-associated diseases in a systemic in vivo model against a complex multispecies environment