Haitian Variant O1 Strains Manifest Higher Virulence in Animal Models.

causes fatal diarrheal disease cholera in humans due to consumption of contaminated water and food. To instigate the disease, the bacterium must evade the host intestinal innate immune system; penetrate the mucus layer of the small intestine, adhere and multiply on the surface of microvilli and produce toxin(s) through the action of virulence associated genes. O1 that has caused a major cholera outbreak in Haiti contained several unique genetic signatures.

In vivo fluid accumulation-inhibitory, anticolonization and anti-inflammatory and in vitro biofilm-inhibitory activities of methyl gallate isolated from Terminalia chebula against fluoroquinolones resistant Vibrio cholerae.

Acute Vibrio cholerae infection triggers significant inflammatory response and immense fluid secretion in the intestine. In the present study, methyl gallate (MG) isolated from Terminalia chebula was evaluated to determine the in vivo fluid accumulation-inhibitory, anticolonization and anti-inflammatory and in vitro biofilm-inhibitory activities against multi-drug resistant (MDR) V. cholerae.

Antimicrobial activity of ellagic acid against Helicobacter pylori isolates from India and during infections in mice.

Objectives: Because of the rise in antimicrobial resistance, an inexpensive, diet-based treatment against Helicobacter pylori infection would be of great interest. The present study was performed to assess the in vitro effects of ellagic acid against clinical H. pylori strains that were resistant to antibiotics used for therapy and also to observe the morphological structure following treatment with ellagic acid.

-induced ER-Mitochondrial calcium dynamics promotes calpain/caspase-12/caspase-9 mediated apoptosis in fish macrophages.

is a natural fish pathogen. It induces apoptosis in headkidney macrophages (HKM) of catfish, sp though the mechanism remains largely unknown. We observed triggers calcium (Ca) insult in the sub-cellular compartments which elicits pro-apototic ER-stress factor CHOP.

Characterization of E-type colicinogenic plasmids from Shigella sonnei.

Colicinogenic plasmids encode toxic proteins which have antagonistic activity against closely related bacteria. This study describes the molecular characterization of three colicinogenic plasmids designated as pSSE3, pSSE and pSSE2, each with a molecular size of ∼6 kb, identified in clinical isolates of Shigella sonnei. Sequence analysis revealed that pSSE and pSSE2 shared extensive sequence homology with each other and with Escherichia coli E-type colicinogenic plasmids.

Live and heat-killed probiotic Lactobacillus casei Lbs2 protects from experimental colitis through Toll-like receptor 2-dependent induction of T-regulatory response.

Inflammatory bowel disease (IBD) is a group of inflammatory disorders of the intestine caused by dysregulated T-cell mediated immune response against commensal microflora. Probiotics are reported as therapeutically effective against IBD. However, variable efficacy of the live probiotic strains, difference in survival and persistence in the gut between the strains and the lack of insight into the mechanisms of probiotic action limit optimal therapeutic efficacy.

Helicobacter pylori plasticity region genes are associated with the gastroduodenal diseases manifestation in India.

Background: Almost all Helicobacter pylori infected person develop gastritis and severe gastritis is supposed to be the denominator of peptic ulcer diseases, which may lead to gastric cancer. However, it is still an enigma why few strains are associated with ulcer formation, while others are not related with any disease outcome. Although a number of putative virulence factors have been reported for H.

Cytotoxic and Inflammatory Responses Induced by Outer Membrane Vesicle-Associated Biologically Active Proteases from Vibrio cholerae.

Proteases in Vibrio cholerae have been shown to play a role in its pathogenesis. V. cholerae secretes Zn-dependent hemagglutinin protease (HAP) and calcium-dependent trypsin-like serine protease (VesC) by using the type II secretion system (TIISS).

Calcium and Superoxide-Mediated Pathways Converge to Induce Nitric Oxide-Dependent Apoptosis in Mycobacterium fortuitum-Infected Fish Macrophages.

Mycobacterium fortuitum causes 'mycobacteriosis' in wide range of hosts although the mechanisms remain largely unknown. Here we demonstrate the role of calcium (Ca+2)-signalling cascade on M. fortuitum-induced apoptosis in headkidney macrophages (HKM) of Clarias sp.

Intracellular and membrane-damaging activities of methyl gallate isolated from Terminalia chebula against multidrug-resistant Shigella spp.

Shigella spp. (Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei) cause bacillary dysentery (shigellosis), which is characterized by bloody mucous diarrhoea. Although a variety of antibiotics have been effective for treatment of shigellosis, options are becoming limited due to globally emerging drug resistance.

The Vibrio cholerae extracellular chitinase ChiA2 is important for survival and pathogenesis in the host intestine.

In aquatic environments, Vibrio cholerae colonizes mainly on the chitinous surface of copepods and utilizes chitin as the sole carbon and nitrogen source. Of the two extracellular chitinases essential for chitin utilization, the expression of chiA2 is maximally up-regulated in host intestine. Recent studies indicate that several bacterial chitinases may be involved in host pathogenesis.

Trends in the epidemiology of pandemic and non-pandemic strains of Vibrio parahaemolyticus isolated from diarrheal patients in Kolkata, India.

A total of 178 strains of V. parahaemolyticus isolated from 13,607 acute diarrheal patients admitted in the Infectious Diseases Hospital, Kolkata has been examined for serovar prevalence, antimicrobial susceptibility and genetic traits with reference to virulence, and clonal lineages. Clinical symptoms and stool characteristics of V.

Comparative analysis of different oral approaches to treat Vibrio cholerae infection in adult mice.

In this study, we have established an oral phage cocktail therapy in adult mice model and also performed a comparative analysis between phage cocktail, antibiotic and oral rehydration treatment for orally developed Vibrio cholerae infection. Four groups of mice were orally infected with Vibrio cholerae MAK 757 strain. Phage cocktail and antibiotic treated groups received 1×10(8) plaque forming unit/ml (once a daily) and 40mg/kg (once a daily) as an oral dose respectively for consecutive three days after bacterial infection.

Inflammatory diarrhea due to enteroaggregative Escherichia coli: evidence from clinical and mice model studies.

Background: This study was conducted to determine the role of enteroaggregative Escherichia coli (EAEC) in inflammatory diarrhea among hospitalized patients in Kolkata. The inflammatory pathogenesis of EAEC was established in mice model and histopathological studies. Presence of fecal leucocytes (FLCs) can be suspected for EAEC infection solely or as a mixed with other enteric pathogens.

Composition of Escherichia coli population in the neonatal gut: phylogroups and virulence determinants.

The composition of Escherichia coli in the neonatal gut has rarely been studied in developing countries. To gain insight into the composition of E. coli in the neonatal gut and to assess factors that could influence colonization by E.

Hemagglutinating activity is directly correlated with colonization ability of shigellae in suckling mouse model.

The aim of the present study was to explore a new approach based on the hemagglutination (HA) assay to understand the colonization ability of Shigella spp. To study colonization ability, an animal model of 4-day-old suckling mouse, was exploited. We characterized the HA activity of 48 Shigella strains, with erythrocytes collected from rabbit, guinea pig, chicken, and sheep.

Outer membrane vesicles of Shigella boydii type 4 induce passive immunity in neonatal mice.

Like most other Gram-negative bacteria, Shigella releases outer membrane vesicles (OMVs) into the surrounding environment during growth. In this study, we have exploited OMVs of Shigella as a protective immunogen in a mice model against Shigellosis. Distinctive vesicle secretion was noticed from different Shigella strains.

Development of a new guinea-pig model of shigellosis.

Shigellosis is a major form of bacillary dysentery caused by Shigella spp. To date, there is no suitable animal model to evaluate the protective efficacy of vaccine candidates against this pathogen. Here, we describe a successful experimental shigellosis in the guinea-pig model, which has shown the characteristic features of human shigellosis.

Curcumin alleviates matrix metalloproteinase-3 and -9 activities during eradication of Helicobacter pylori infection in cultured cells and mice.

Current therapy-regimens against Helicobacter pylori (Hp) infections have considerable failure rates and adverse side effects that urge the quest for an effective alternative therapy. We have shown that curcumin is capable of eradicating Hp-infection in mice. Here we examine the mechanism by which curcumin protects Hp infection in cultured cells and mice.

Effect of acute and chronic arsenic exposure on growth, structure and virulence of Aeromonas hydrophila isolated from fish.

Aeromonas hydrophila being a ubiquitous bacterium is prone to arsenic exposure. The present study was designed to determine the role of arsenic on growth and virulence of A. hydrophila.

Studies on a novel serine protease of a ΔhapAΔprtV Vibrio cholerae O1 strain and its role in hemorrhagic response in the rabbit ileal loop model.

Background: Two well-characterized proteases secreted by Vibrio cholerae O1 strains are hemagglutinin protease (HAP) and V. cholerae protease (PrtV). The hapA and prtV knock out mutant, V.

Immunogenicity and protective efficacy of Vibrio cholerae outer membrane vesicles in rabbit model.

We show here that oral immunization with purified outer membrane vesicles (OMVs) of Vibrio cholerae induces a prolonged high rise in the protective antibody titre. Rabbit immune sera were vibriocidal against the homologous and against several heterologous V. cholerae strains in vitro.

Emerging trends in the etiology of enteric pathogens as evidenced from an active surveillance of hospitalized diarrhoeal patients in Kolkata, India.

Background: This study was conducted to determine the etiology of diarrhoea in a hospital setting in Kolkata. Active surveillance was conducted for 2 years on two random days per week by enrolling every fifth diarrhoeal patient admitted to the Infectious Diseases and Beliaghata General Hospital in Kolkata.

Results: Most of the patients (76.

Selective deletion of CD8(+) cells upregulated by caspases-1 via IL-18 in mice immunized with major outer membrane protein of Shigella dysenteriae 1 following infection.

Introduction: Mucosal lymphoid changes were observed in cryopreserved rectal tissues obtained from BALB/c mice infected with Shigella dysenteriae 1, immunized with 57-kDa major antigenic outer membrane protein, and infection after immunization.

Discussion: Our data suggested that caspase-3 is downregulated in CD4(+) cells of immunized BALB/c mice following infection with substantial increased expression of interleukin (IL)-2 and interferon (IFN)-gamma, while caspase-1 is upregulated in CD8(+) cells with decreased expression of IL-4 and IL-10. This indicated an involvement of Fas-mediated lytic pathway for selective deletion of CD8(+) cells out of CD3(+) T cells.

Indistinguishable cellular changes in gastric mucosa between Helicobacter pylori infected asymptomatic tribal and duodenal ulcer patients.

Aim: To investigate the changing pattern of different histological parameters occurring in the stomach tissue of Helicobacter pylori (H pylori) infected tribal populations and duodenal ulcer patients among ethnic Bengalis and correlation of the genotypes of H pylori with different histological parameters.

Methods: One hundred and twelve adult individuals were enrolled into this study between 2002 and 2004. Among them, 72 had clinical features of duodenal ulcer (DU) from ethnic Bengali population and 40 were asymptomatic ethnic tribals.