[The biological characteristics of dominated agents of acute enteric infections]

In 2003-2012 the rate of increase of morbidity of acute enteric infections caused by opportunistic microorganisms came to 3.6%. In the etiologic structure prevailed Klebsiella pneumoniae, Staphylococcus aureus and Enterobacter cloacae. Their percentage varied from 70.5% to 81.6%. The opportunistic microorganisms isolated from feces of patients with acute enteric infections and individuals from control group characterized by presence of pathogenic factors of broad spectrum. The adhesive characteristics were manifested by 50.8±4.4% of analyzed cultures isolated from patients with symptoms of diarrhea infection and by 19.5±3.5% in control group. The anti-lysozyme activity was manifested correspondingly in 86.2±3.0% and 61.7±4.3% of strains. The anti-complement activity was manifested in 70.8±3.9% and 61.7±4.3% of strains. The anti-interferon activity was manifested in 100% and 95.3±1.9% of strains correspondingly. The level of adhesive activity in E. cloacae (35.0±7.5%) and anti-complement and adhesive activity in K. pneumoniae consisted 100% and 85.0±5.6% of strains isolated from feces of patients with acute enteric infections reliably (p<0.05) exceeded values in individuals from control group.

The mycotoxin deoxynivalenol predisposes for the development of Clostridium perfringens-induced necrotic enteritis in broiler chickens

Both mycotoxin contamination of feed and Clostridium perfringens-induced necrotic enteritis have an increasing global economic impact on poultry production. Especially the Fusarium mycotoxin deoxynivalenol (DON) is a common feed contaminant. This study aimed at examining the predisposing effect of DON on the development of necrotic enteritis in broiler chickens. An experimental Clostridium perfringens infection study revealed that DON, at a contamination level of 3,000 to 4,000 µg/kg feed, increased the percentage of birds with subclinical necrotic enteritis from 20±2.6% to 47±3.0% (P<0.001). DON significantly reduced the transepithelial electrical resistance in duodenal segments (P<0.001) and decreased duodenal villus height (P = 0.014) indicating intestinal barrier disruption and intestinal epithelial damage, respectively. This may lead to an increased permeability of the intestinal epithelium and decreased absorption of dietary proteins. Protein analysis of duodenal content indeed showed that DON contamination resulted in a significant increase in total protein concentration (P = 0.023). Furthermore, DON had no effect on in vitro growth, alpha toxin production and netB toxin transcription of Clostridium perfringens. In conclusion, feed contamination with DON at concentrations below the European maximum guidance level of 5,000 µg/kg feed, is a predisposing factor for the development of necrotic enteritis in broilers. These results are associated with a negative effect of DON on the intestinal barrier function and increased intestinal protein availability, which may stimulate growth and toxin production of Clostridium perfringens.

Expression of regulatory T cells in jejunum, colon, and cervical and mesenteric lymph nodes of dogs naturally infected with Leishmania infantum

Using flow cytometry, we evaluated the frequencies of CD4(+) and CD8(+) T cells and Foxp3(+) regulatory T cells (Tregs) in mononuclear cells in the jejunum, colon, and cervical and mesenteric lymph nodes of dogs naturally infected with Leishmania infantum and in uninfected controls. All infected dogs showed chronic lymphadenitis and enteritis. Despite persistent parasite loads, no erosion or ulcers were evident in the epithelial mucosa. The colon harbored more parasites than the jejunum. Frequencies of total CD4(+), total Foxp3, and CD4(+) Foxp3(+) cells were higher in the jejunum than in the colon. Despite negative enzyme-linked immunosorbent assay (ELISA) serum results for cytokines, levels of interleukin-10 (IL-10), gamma interferon (IFN-γ), transforming growth factor beta (TGF-β), and tumor necrosis factor alpha (TNF-α) were higher in the jejunum than in the colon for infected dogs. However, IL-4 levels were higher in the colon than in the jejunum for infected dogs. There was no observed correlation between clinical signs and histopathological changes or immunological and parasitological findings in the gastrointestinal tract (GIT) of canines with visceral leishmaniasis. However, distinct segments of the GIT presented different immunological and parasitological responses. The jejunum showed a lower parasite load, with increased frequencies and expression of CD4, Foxp3, and CD8 receptors and IL-10, TGF-β, IFN-γ, and TNF-α cytokines. The colon showed a higher parasite load, with increasing expression of IL-4. Leishmania infantum infection increased expression of CD4, Foxp3, IL-10, TGF-β, IFN-γ, and TNF-α and reduced CD8 and IL-4 expression in both the jejunum and the colon.

Differential responses of cecal microbiota to fishmeal, Eimeria and Clostridium perfringens in a necrotic enteritis challenge model in chickens

Clostridium perfringens causes enteric diseases in animals and humans. In poultry, avian-specific C. perfringens strains cause necrotic enteritis, an economically significant poultry disease that costs the global industry over $2 billion annually in losses and control measures. With removal of antibiotic growth promoters in some countries this disease appears to be on the rise. In experimental conditions used to study disease pathogenesis and potential control measures, reproduction of the disease relies on the use of predisposing factors such as Eimeria infection and the use of high protein diets, indicating complex mechanisms involved in the onset of necrotic enteritis. The mechanisms by which the predisposing factors contribute to disease progression are not well understood but it has been suggested that they may cause perturbations in the microbiota within the gastrointestinal tract. We inspected changes in cecal microbiota and short chain fatty acids (SCFA) induced by Eimeria and fishmeal, in birds challenged or not challenged with C. perfringens. C. perfringens challenge in the absence of predisposing factors did not cause significant changes in either the alpha or beta diversity of the microbiota nor in concentrations of SCFA. Moreover, there was no C. perfringens detected in the cecal microbiota 2 days post-challenge without the presence of predisposing factors. In contrast, both fishmeal and Eimeria caused significant changes in microbiota, seen in both alpha and beta diversity and also enabled C. perfringens to establish itself post challenge. Eimeria had its strongest influence on intestinal microbiota and SCFA when combined with fishmeal. Out of 6 SCFAs measured, including butyric acid, none were significantly influenced by C. perfringens, but their levels were strongly modified following the use of both predisposing factors. There was little overlap in the changes caused following Eimeria and fishmeal treatments, possibly indicating multiple routes for progressing towards clinical symptoms of necrotic enteritis.

Case of acute pancreatitis associated with Campylobacter enteritis

A 25-year-old man was admitted with the chief complaints of right flank pain, watery diarrhea, and fever. Blood tests revealed high levels of inflammatory markers, and infectious enteritis was diagnosed. A stool culture obtained on admission revealed no growth of any significant pathogens. Conservative therapy was undertaken with fasting and fluid replacement. On day 2 of admission, the fever resolved, the frequency of defecation reduced, the right flank pain began to subside, and the white blood cell count started to decrease. On hospital day 4, the frequency of diarrhea decreased to approximately 5 times per day, and the right flank pain resolved. However, the patient developed epigastric pain and increased blood levels of the pancreatic enzymes. Abdominal computed tomography revealed mild pancreatic enlargement. Acute pancreatitis was diagnosed, and conservative therapy with fasting and fluid replacement was continued. A day later, the blood levels of the pancreatic enzymes peaked out. On hospital day 7, the patient passed stools with fresh blood, and Campylobacter jejuni/coli was detected by culture. Lower gastrointestinal endoscopy performed on hospital day 8 revealed diffuse aphthae extending from the terminal ileum to the entire colon. Based on the findings, pancreatitis associated with Campylobacter enteritis was diagnosed. In the present case, a possible mechanism of onset of pancreatitis was invasion of the pancreatic duct by Campylobacter and the host immune responses to Campylobacter.

Characterization of multidrug-resistant Salmonella enterica serovars Indiana and Enteritidis from chickens in Eastern China

A total of 310 Salmonella isolates were isolated from 6 broiler farms in Eastern China, serotyped according to the Kauffmann-White classification. All isolates were examined for susceptibility to 17 commonly used antimicrobial agents, representative isolates were examined for resistance genes and class I integrons using PCR technology. Clonality was determined by pulsed-field gel electrophoresis (PFGE). There were two serotypes detected in the 310 Salmonella strains, which included 133 Salmonella enterica serovar Indiana isolates and 177 Salmonella enterica serovar Enteritidis isolates. Antimicrobial sensitivity results showed that the isolates were generally resistant to sulfamethoxazole, ampicillin, tetracycline, doxycycline and trimethoprim, and 95% of the isolates sensitive to amikacin and polymyxin. Among all Salmonella enterica serovar Indiana isolates, 108 (81.2%) possessed the blaTEM, floR, tetA, strA and aac (6')-Ib-cr resistance genes. The detected carriage rate of class 1 integrons was 66.5% (206/310), with 6 strains carrying gene integron cassette dfr17-aadA5. The increasing frequency of multidrug resistance rate in Salmonella was associated with increasing prevalence of int1 genes (rs = 0.938, P = 0.00039). The int1, blaTEM, floR, tetA, strA and aac (6')-Ib-cr positive Salmonella enterica serovar Indiana isolates showed five major patterns as determined by PFGE. Most isolates exhibited the common PFGE patterns found from the chicken farms, suggesting that many multidrug-resistant isolates of Salmonella enterica serovar Indiana prevailed in these sources. Some isolates with similar antimicrobial resistance patterns represented a variety of Salmonella enterica serovar Indiana genotypes, and were derived from a different clone.

Influence of NleH effector expression, host genetics, and inflammation on Citrobacter rodentium colonization of mice

The Escherichia coli NleH1 and NleH2 virulence proteins differentially regulate host transcription of innate immunity genes. The mouse pathogen Citrobacter rodentium encodes one NleH protein, which functions equivalently to E. coli NleH1. We examined the impact of host genetics and intestinal inflammation on the contribution of NleH to C. rodentium colonization of mice differing in LPS responsiveness. NleH expression was detrimental to C. rodentium in C57BL/10ScNJ mice, which do not mount LPS-induced inflammatory responses. This phenotype was reversed if inflammation was induced by chemical means. C. rodentium that expressed both E. coli NleH1 and NleH2 was hypervirulent in C3H/HeJ mice.

[A case of severe enteritis induced by adjuvant chemotherapy for colon cancer]

A 77-year-old man underwent surgery for sigmoid colon cancer. He was diagnosed with Stage IIIa colon cancer; there- fore, we initiated oral administration of adjuvant chemotherapy comprising uracil/tegafur(UFT)plus Leucovorin(LV). However, chemotherapy was stopped after 21 days because of fatigue and diarrhea. He recovered after 3 weeks, and we administered the same regimen with a dose reduction. However, he again experienced fatigue and diarrhea after 20 days; therefore, chemotherapy was discontinued. Subsequently, he was hospitalized 8 times for conditions such as diarrhea, hypoalbuminemia, and fever. Computed tomography revealed thickening of the transverse colonic wall and colonoscopy revealed colitis, which we believe was induced by UFT plus LV. Twelve months after the last chemotherapy session, he was diagnosed with Clostridium difficile colitis. Therefore, we initiated the oral administration of vancomycin, which resulted in rapid recovery from colitis. However, he developed liver metastasis and died 29 months after the initiation of chemotherapy. We believe that this severe case of intractable colitis was caused by UFT plus LV. Therefore, we report this case with a review of the literature on enteritis induced by fluorouracil-based anticancer agents in Japan.

Sodium alginate ameliorates indomethacin-induced gastrointestinal mucosal injury via inhibiting translocation in rats

AIM: To investigate the effects of sodium alginate (AL-Na) on indomethacin-induced small intestinal lesions in rats.

METHODS: Gastric injury was assessed by measuring ulcerated legions 4 h after indomethacin (25 mg/kg) administration. Small intestinal injury was assessed by measuring ulcerated legions 24 h after indomethacin (10 mg/kg) administration. AL-Na and rebamipide were orally administered. Myeloperoxidase activity in the stomach and intestine were measured. Microvascular permeability, superoxide dismutase content, glutathione peroxidase activity, catalase activity, red blood cell count, white blood cell count, mucin content and enterobacterial count in the small intestine were measured.

RESULTS: AL-Na significantly reduced indomethacin-induced ulcer size and myeloperoxidase activity in the stomach and small intestine. AL-Na prevented increases in microvascular permeability, superoxide dismutase content, glutathione peroxidase activity and catalase activity in small intestinal injury induced by indomethacin. AL-Na also prevented decreases in red blood cells and white blood cells in small intestinal injury induced by indomethacin. Moreover, AL-Na suppressed mucin depletion by indomethacin and inhibited infiltration of enterobacteria into the small intestine.

CONCLUSION: These results indicate that AL-Na ameliorates non-steroidal anti-inflammatory drug-induced small intestinal enteritis via bacterial translocation.

Inflammation and colorectal cancer, when microbiota-host mutualism breaks

Structural changes in the gut microbial community have been shown to accompany the progressive development of colorectal cancer. In this review we discuss recent hypotheses on the mechanisms involved in the bacteria-mediated carcinogenesis, as well as the triggering factors favoring the shift of the gut microbiota from a mutualistic to a pro-carcinogenic configuration. The possible role of inflammation, bacterial toxins and toxic microbiota metabolites in colorectal cancer onset is specifically discussed. On the other hand, the strategic role of inflammation as the keystone factor in driving microbiota to become carcinogenic is suggested. As a common outcome of different environmental and endogenous triggers, such as diet, aging, pathogen infection or genetic predisposition, inflammation can compromise the microbiota-host mutualism, forcing the increase of pathobionts at the expense of health-promoting groups, and allowing the microbiota to acquire an overall pro-inflammatory configuration. Consolidating inflammation in the gut, and favoring the bloom of toxigenic bacterial drivers, these changes in the gut microbial ecosystem have been suggested as pivotal in promoting carcinogenesis. In this context, it will become of primary importance to implement dietary or probiotics-based interventions aimed at preserving the microbiota-host mutualism along aging, counteracting deviations that favor a pro-carcinogenic microbiota asset.

Effects of rifaximin on indomethacin-induced intestinal damage in guinea-pigs

AIM

Enterobacterial translocation into the gut mucosa is the first step required for activation of neutrophils and inducible nitric oxide synthase (iNOS), involved in the pathogenesis of indomethacin-induced intestinal lesions. Rifaximin may limit NSAID-associated intestinal damage by decreasing the bacterial load. We aimed to study the effect of rifaximin on indomethacin-induced intestinal damage in guinea-pigs.

MATERIALS AND METHODS

Twenty-four guinea pigs, equally divided in four interventional groups (A-D), received indomethacin, given orally once daily (30 mg/kg) for three consecutive days. In groups B, C, D different doses of rifaximin (50 mg/kg, 100 mg/kg and 200 mg/kg) were given orally two hours before indometachin administration. Semi-quantitative grades were measure for gross findings, degenerative lesions, neutrophils and eosinophils infiltrates and iNOS immunopositivity. Statistical comparisons used Mann Whitney Test, with a Bonferroni correction for alpha (p ≤ 0.016).

RESULTS

Statistical analysis of graded gross findings, microscopic degenerative lesions, endothelium damage and iNOS immunopositivity found no difference between A and B groups. Significant fewer gross findings (U = 3, p = 0.015), microscopic degenerative lesions (U = 2, p = 0.008) and lower grades for iNOS immunopositivity (U = 0, p = 0.002) were found in group C compared with group A. In group D, significant lower grades for iNOS immunopositivity were obtained (U = 0, p = 0.002) compared with group A and fewer degenerative lesions without reaching statistical significance (U = 4, p = 0.026).

CONCLUSIONS

100 mg/kg of rifaximin proved efficient in preventing gut degenerative lesions induced by indomethacin in a guinea pig model, the iNOS activity being significantly decreased.

Pigbel in the 21st century: still here, and still in need of an effective surveillance system

Pigbel remains a likely significant cause of morbidity and mortality in the highlands of Papua New Guinea (PNG), two decades after the administration of pigbel vaccination ceased. There is a need for an effective surveillance program for pigbel to better understand the disease burden and to target communities for preventive strategies. This paper reviews the epidemiology, pathogenesis, recent history and current data on the burden of pigbel in PNG. We propose a surveillance program based on clinical recognition of likely cases and laboratory confirmation using an ELISA assay for Clostridium perfringens type C beta-toxin. Research aimed at validating this approach in the clinical setting is outlined.

Lawsonia intracellularis-associated ulcerative and necro-hemorrhagic enteritis in 5 weanling foals

This report describes 5 cases of fatal Lawsonia intracellularis-associated ulcerative and necro-hemorrhagic enteritis in weanling Thoroughbred and Standardbred foals. The lesions are similar to those of the L. intracellularis-associated ulcerative and necro-hemorrhagic enteritis syndrome in pigs. Two foals had concurrent severe typhlo-colitis as a result of a large burden of encysted cyathostomes. The clinical, diagnostic, and therapeutic challenges, and the potential complications encountered during the management of such cases are discussed.

Impact and management of Campylobacter in human medicine--US perspective

Viruses, enteric bacteria and parasites can all produce similar syndromes of acute enteritis, although the pathophysiology and molecular pathogenesis may vary widely. The severity of acute enteritis varies greatly, and only a small fraction of cases undergo medical evaluation. There are over 200 000 000 episodes of acute enteritis annually in the USA, of which approximately 75 000 000 are foodborne. Fewer than 20% of estimated cases have a known etiology. Nearly half of the more than 4 000 000 cases of known foodborne bacterial enteritis are attributed to Campylobacter infections. The FoodNet active population-based surveillance system has demonstrated geographic variation in the incidence of Campylobacter infection, and generally declining incidence since 1996. Campylobacter jejuni infections vary in severity and duration. Antimicrobial therapy, especially if administered early, may hasten clinical resolution by 2-3 days. Therapy is generally restricted to individuals with moderate-to-severe disease and high-risk individuals (underlying immunodeficiency, chronic illness, extremes of age, etc.). Approximately 10-15% of C. jejuni isolates are fluoroquinolone resistant, although most strains are macrolide susceptible. Several acute intra-abdominal as well as extraintestinal complications can occur following C jejuni enteritis, although bacteremia and metastatic infection are rare, except in high-risk patients. Post-infectious syndromes include post-dysenteric bowel dysfunction, the less frequent but more severe reactive arthritis (1%), and Guillain-Barre syndrome (0.1%). The recent demonstration that antibiotic administration for Escherichia coli O157:H7 hemorrhagic enteritis increases the risk of hemolytic-uremic syndrome 5-10-fold forces reconsideration of empirical broad-spectrum antibiotic therapy for acute hemorrhagic enteritis, and supports narrow-spectrum erythromycin therapy for acute enteritis.

Massive lower gastrointestinal haemorrhage in a teenager caused by Campylobacter enteritis

A 14-year-old boy presented with a very unusual complication of massive lower gastrointestinal bleeding mimicking bleeding from Meckel's diverticulum who needed blood transfusions and required mini-exploration. He was found to have Campylobacter enteritis with bleeding from multiple mucosal ulcers in the ileocaecal region, which is presented with a review of the literature.

How do swine practitioners and veterinary pathologists arrive at a diagnosis of Clostridium perfringens type A enteritis in neonatal piglets?

A questionnaire was administered to 22 veterinary practitioners and 17 veterinary pathologists to investigate the methods used for diagnosis of Clostridium perfringens type A enteritis in neonatal pigs. Practitioners generally diagnosed C. perfringens type A associated enteritis by age of onset of diarrhea (between 1 to 7 days of age). Most practitioners (95%) were moderately to very confident in their diagnosis. Pathologists generally diagnosed C. perfringens type A associated enteritis by combinations of isolation of the organism, genotyping or detecting the toxins of the organism, and ruling out other pathogens through histopathology. Almost half (41%) of the pathologists were not confident of their diagnosis. This study reports that the current diagnostic method for C. perfringens type A enteritis is not specific, and although many pathologists expressed reservations about making a diagnosis of C. perfringens type A enteritis, most practitioners were confident in their diagnosis, even though reported clinical signs of clostridial diarrhea are similar to those of a number of other enteric diseases.

The rabbit as an infection model for equine proliferative enteropathy

The objective of this study was to demonstrate the susceptibility of rabbits to Lawsonia intracellularis obtained from a case of clinical equine proliferative enteropathy (EPE). This is a preliminary step toward developing a rabbit infection model for studying pathogenesis and therapy of EPE in horses. Nine does were equally assigned to 3 groups. Animals in 2 groups (Group 1 and Group 2) were orally inoculated with different doses of cell-cultured L. intracellularis. Controls (Group 3) were sham-inoculated. Feces and blood were collected before the rabbits were infected and at 7, 14, and 21 days post-infection (DPI). Serum immunoglobulin G (IgG) titers were measured using an immunoperoxidase monolayer assay (IPMA) and fecal samples were analyzed with quantitative polymerase chain reaction (qPCR). A doe from each group was euthanized at 7, 14, and 21 DPI for collection and evaluation of intestinal samples. Tissues were stained by routine hematoxylin and eosin (H&E) method and immunohistochemistry (IHC) with L. intracellularis-specific mouse monoclonal antibody. At 14 DPI, serologic responses were detected in both infected groups, which maintained high titers through to 21 DPI. Lawsonia intracellularis DNA was detected in the feces of Group 2 on 7 DPI and in both infected groups on 14 DPI. Gross lesions were apparent in Group 1 and Group 2 on 14 DPI. Immunohistochemistry confirmed L. intracellularis antigen within cells of rabbits in Group 1 and Group 2 on 7, 14, and 21 DPI. No lesions, serologic response, shedding, or IHC labeling were found in Group 3 rabbits. This study describes an EPE rabbit model that simulates natural infection, as typical lesions, immune response, and fecal shedding were present.

The successful experimental induction of necrotic enteritis in chickens by Clostridium perfringens: a critical review

Necrotic enteritis (NE) is one of the most important enteric diseases in poultry and is a high cost to the industry worldwide. It is caused by avian-specific, Necrotic Enteritis Beta toxin (NetB)-producing, strains of Clostridium perfringens that also possess in common other virulence-associated genes. In Europe the disease incidence has increased since the ban on in-feed "growth promoting" antibiotics. Because of this, many recent studies of NE have focused on finding different ways to control the disease, and on understanding its pathogenesis. Frustratingly, reproduction of the disease has proven impossible for some researchers. This review describes and discusses factors known to be important in reproducing the disease experimentally, as well as other considerations in reproducing the disease. The critical bacterial factor is the use of virulent, netB-positive, strains; virulence can be enhanced by using tpeL- positive strains and by the use of young rather than old broth cultures to increase toxin expression. Intestinal damaging factors, notably the use of concurrent or preceding coccidial infection, or administration of coccidial vaccines, combined with netB-positive C. perfringens administration, can also be used to induce NE. Nutritional factors, particularly feeding high percentage of cereals containing non-starch polysaccharides (NSP) (wheat, rye, and barley) enhance disease by increasing digesta viscosity, mucus production and bacterial growth. Animal proteins, especially fish meal, enhance C. perfringens proliferation and toxin production. Other factors are discussed that may affect outcome but for which evidence of their importance is lacking. The review compares the different challenge approaches; depending on the aim of particular studies, the different critical factors can be adjusted to affect the severity of the lesions induced. A standardized scoring system is proposed for international adoption based on gross rather than histopathological lesions; if universally adopted this will allow better comparison between studies done by different researchers. Also a scoring system is provided to assist decisions on humane euthanasia of sick birds.

Detection of Clostridium perfringens type C in pig herds following disease outbreak and subsequent vaccination

Immunisation of sows using Clostridium perfringens type C toxoid vaccines is recommended to prevent necrotising enteritis (NE) on pig breeding farms. Absence of disease, however, oftentimes leads to the false assumption of pathogens being eradicated. The prevalence of C perfringens type C was determined by PCR in faecal samples of piglets and sows in three Swiss pig breeding farms two to four years after implementation of a vaccination programme following disease outbreaks. C perfringens type C could still be detected several years after an outbreak despite absence of NE. In-herd prevalence of the pathogens varied significantly between the farms and was also lower compared with a farm which experienced a recent outbreak. In conclusion, C perfringens type C can be detected on once-affected farms, even in the absence of NE for several years.

Gibel carp Carassius auratus gut microbiota after oral administration of trimethoprim/ sulfamethoxazole

Trimethoprim/sulfamethoxazole is widely used in the treatment of infectious diseases caused by bacterial pathogens in aquaculture. However, the practice of antibiotic administration can promote the emergence of resistant strains of bacteria and result in a wane in efficacy over time. The objective of this study was to assess the effect of oral treatment with trimethoprim/sulfamethoxazole on the gastrointestinal (GI) microbiota of healthy gibel carp and those affected with bacterial enteritis. By using denaturing gradient gel electrophoresis (DGGE), the changes in the predominant bacterial communities were directly depicted for the first time. The main findings were (1) Actinobacteria, Firmicutes and Proteobacteria were the predominant phyla in the healthy gibel carp intestine; (2) administration of antibiotics had a more profound impact on the intestinal microflora of healthy fish than of the diseased ones; and (3) Enterobacteriaceae might be one of the major drug-resistant bacteria in the gibel carp intestine. This study provides an insight into the effect of antibiotic treatment on the establishment and colonization of fish GI microbiota and speculates on some possible drug-resistant bacteria.

[Pathogenetic importance of helicobacter pylori infection]

H. pylori are etiological factor of human acute and chronic gastritis. Depending on pathogenic factors of microorganism and polymorphism of human genes, chronic gastritis can be a cause for ulcerative enteritis of the duodenum or stomach, gastric adenocarcinoma and MALT-lymphoma development. We revealed genetic features of bacteria, determined the intensity of inflammation, such as pathogenic factors--cag, plastic region of the genome and adhesin coding genes. Epigenetic changes, for example the methylation of E-cadherin gene associated with H pylori, are crucial for carcinogenesis. Thereby, predisposition of chronic gastritis associated with H. pylori to ulcerative enteritis of the duodenum, ulcerative stomach disease or gastric adenocarcinoma depends on topography, the intensity of inflammation and changes of acid production in the stomach.

Inflammation and disintegration of intestinal villi in an experimental model for Vibrio parahaemolyticus-induced diarrhea

Vibrio parahaemolyticus is a leading cause of seafood-borne gastroenteritis in many parts of the world, but there is limited knowledge of the pathogenesis of V. parahaemolyticus-induced diarrhea. The absence of an oral infection-based small animal model to study V. parahaemolyticus intestinal colonization and disease has constrained analyses of the course of infection and the factors that mediate it. Here, we demonstrate that infant rabbits oro-gastrically inoculated with V. parahaemolyticus develop severe diarrhea and enteritis, the main clinical and pathologic manifestations of disease in infected individuals. The pathogen principally colonizes the distal small intestine, and this colonization is dependent upon type III secretion system 2. The distal small intestine is also the major site of V. parahaemolyticus-induced tissue damage, reduced epithelial barrier function, and inflammation, suggesting that disease in this region of the gastrointestinal tract accounts for most of the diarrhea that accompanies V. parahaemolyticus infection. Infection appears to proceed through a characteristic sequence of steps that includes remarkable elongation of microvilli and the formation of V. parahaemolyticus-filled cavities within the epithelial surface, and culminates in villus disruption. Both depletion of epithelial cell cytoplasm and epithelial cell extrusion contribute to formation of the cavities in the epithelial surface. V. parahaemolyticus also induces proliferation of epithelial cells and recruitment of inflammatory cells, both of which occur before wide-spread damage to the epithelium is evident. Collectively, our findings suggest that V. parahaemolyticus damages the host intestine and elicits disease via previously undescribed processes and mechanisms.

The marine bacterium Vibrio parahaemolyticus is a leading cause worldwide of gastroenteritis linked to the consumption of contaminated seafood. Despite the prevalence of V. parahaemolyticus-induced gastroenteritis, there is limited understanding of how this pathogen causes disease in the intestine. In part, the paucity of knowledge results from the absence of an oral infection-based animal model of the human disease. We developed a simple oral infection-based infant rabbit model of V. parahaemolyticus-induced intestinal pathology and diarrhea. This experimental model enabled us to define several previously unknown but key features of the pathology elicited by this organism. We found that V. parahaemolyticus chiefly colonizes the distal small intestine and that the organism's second type III secretion system is essential for colonization. The epithelial surface of the distal small intestine is also the major site of V. parahaemolyticus-induced damage, which arises via a characteristic sequence of events culminating in the formation of V. parahaemolyticus-filled cavities in the epithelial surface. This experimental model will transform future studies aimed at deciphering the bacterial and host factors/processes that contribute to disease, as well as enable testing of new therapeutics to prevent and/or combat infection.

PCR-TTGE analysis of 16S rRNA from rainbow trout (Oncorhynchus mykiss) gut microbiota reveals host-specific communities of active bacteria

This study assessed the relative contributions of host genetics and diet in shaping the gut microbiota of rainbow trout. Full sibling fish from four unrelated families, each consisting of individuals derived from the mating of one male and one female belonging to a breeding program, were fed diets containing either vegetable proteins or vegetable oils for two months in comparison to a control diet consisting of only fish protein and fish oil. Two parallel approaches were applied on the same samples: transcriptionally active bacterial populations were examined based on RNA analysis and were compared with bacterial populations obtained from DNA analysis. Comparison of temporal temperature gradient gel electrophoresis (TTGE) profiles from DNA and RNA showed important differences, indicating that active bacterial populations were better described by RNA analysis. Results showed that some bacterial groups were significantly (P<0.05) associated with specific families, indicating that microbiota composition may be influenced by the host. In addition, the effect of diet on microbiota composition was dependent on the trout family.

Salmonella Enteritidis strains from poultry exhibit differential responses to acid stress, oxidative stress, and survival in the egg albumen

Salmonella Enteritidis is the major foodborne pathogen that is primarily transmitted by contaminated chicken meat and eggs. We recently demonstrated that Salmonella Enteritidis strains from poultry differ in their ability to invade human intestinal cells and cause disease in orally challenged mice. Here we hypothesized that the differential virulence of Salmonella Enteritidis strains is due to the differential fitness in the adverse environments that may be encountered during infection in the host. The responses of a panel of six Salmonella Enteritidis strains to acid stress, oxidative stress, survival in egg albumen, and the ability to cause infection in chickens were analyzed. This analysis allowed classification of strains into two categories, stress-sensitive and stress-resistant, with the former showing significantly (p<0.05) reduced survival in acidic (gastric phase of infection) and oxidative (intestinal and systemic phase of infection) stress. Stress-sensitive strains also showed impaired intestinal colonization and systemic dissemination in orally inoculated chickens and failed to survive/grow in egg albumen. Comparative genomic hybridization microarray analysis revealed no differences at the discriminatory level of the whole gene content between stress-sensitive and stress-resistant strains. However, sequencing of rpoS, a stress-regulatory gene, revealed that one of the three stress-sensitive strains carried an insertion mutation in the rpoS resulting in truncation of σ(S). Finding that one of the stress-sensitive strains carried an easily identifiable small polymorphism within a stress-response gene suggests that the other strains may also have small polymorphisms elsewhere in the genome, which likely impact regulation of stress or virulence associated genes in some manner.