Adherence, enterotoxigenicity, invasiveness and serogroups inCampylobacter jejuniandCampylobacter colistrains from adult humans with acute enterocolitis

Infection withCampylobacter jejuniInduces Tyrosine-Phosphorylated Proteins into INT-407 Cells

The mechanisms used by Campylobacter jejuni to induce internalization into host intestinal epithelial cells have not been defined. In this study, we obtained evidence that exposure of INT-407 cells to protein kinase inhibitors results in decreased invasion of these cells by C. jejuni in a dose dependent manner. Preincubation of INT-407 cells in the presence of staurosporine, tyrphostin 46 and genistein decreased invasion of these cells by C. jejuni significantly. Moreover, C. jejuni infection of INT-407 cells induced tyrosine phosphorylation of several Triton X-100 soluble proteins with approximate molecular weights of 170, 145, 90, 60 and 55 kDa that were absent or reduced in the presence of genistein in cells after 1 hr of pretreatment. These data suggest that tyrosine protein kinase-linked pathways strongly regulate the internalization of C. jejuni into intestinal epithelial cells.

Campylobacter epidemiology: an aquatic perspective

Members of the genus Campylobacter have established themselves as the most common human gastro-enteric pathogens throughout much of the developed world. The ubiquitous distribution of Campylobacter spp. in animal reservoirs and food products derived thereof make such vehicles primary risk factors in contracting campylobacteriosis. The contamination rates, identification of common pathogenic serotypes and extended survival of Campylobacter in surface waters illustrates the potential, but yet to be quantified, campylobacteriosis risk associated with untreated water. The existence and potential pathogenicity of viable but nonculturable forms of Campylobacter remains a contentious subject. Furthermore, the role of such forms in the epidemiology of Campylobacter related disease and their involvement in the large number of waterborne gastroenteritis outbreaks from which a disease agent cannot be isolated remains to be fully clarified. This article presents a survey of current perspectives with regard to the survival and epidemiology of Campylobacter spp. in natural water systems.

Identification of hyperinvasive Campylobacter jejuni strains isolated from poultry and human clinical sources

Campylobacter jejuni causes gastroenteritis with a variety of symptoms in humans. In the absence of a suitable animal model, in vitro models have been used to study virulence traits such as invasion and toxin production. In this study, 113 C. jejuni isolates from poultry and poultry-related (n=74) environments as well as isolates from human cases (n=39) of campylobacteriosis and bacteraemia were tested for invasiveness using INT 407 cells. The method was sufficiently reproducible to observe a spectrum of invasiveness amongst strains. As a result, strains were classified as low, high and hyper-invasive. The majority of strains (poultry and human) were low invaders (82 % and 88 %, respectively). High invasion was found for 5 % of human strains and 11 % of poultry-related isolates. However, only 1 % of poultry strains were classified as hyperinvasive compared to 13 % of human isolates (P=0.0182). Of those isolates derived from the blood of bacteraemic patients, 20 % were hyperinvasive, though this correlation was not statistically significant. An attempt was made to correlate invasiveness with the presence of seven genes previously reported to be associated with virulence. Most of these genes did not correlate with invasiveness, but gene cj0486 was weakly over-represented, and a negative correlation was observed for the gene ciaB. This trend was stronger when the two genes were analysed together, thus ciaB(-) cj0486(+) was over-represented in high and hyperinvasive strains, with low invaders more commonly found to lack these genes (P=0.0064).

Inhibition of bacterial adhesion and salmonella infection in BALB/c mice by sialyloligosaccharides and their derivatives from chicken egg yolk

The effects of an egg-yolk-derived sialyloligosaccharide (YDS), asialo-YDS, and a sialylglycopeptide of YDS (SGP) on bacterial adhesion to intestinal epithelial cells and on Salmonella infection in BALB/c mice were examined. YDS, its derivative asialo-YDS, and SGP strongly inhibited the binding of Salmonella enteritidis but not E. coli K-88 to a human epithelial cell line, Caco-2. In a Salmonella infection experiment using BALB/c mice, oral administration of these reagents effectively prevented the bacteria from proliferating in spleen, as well as preventing lethality. An experiment using radioactive SGP orally administered to mice revealed that the compound was absorbed from the intestine into blood and eliminated via urine within 8 h. However, these reagents did not influence the production of TNF-alpha or NO. in culture macrophages. The results suggest that they inhibit Salmonella infection not by activating macrophages but by inhibiting the entry of bacteria through the gut, suggesting that YDS and its derivatives are useful for preventing Salmonella infection when ingested continuously.

Molecular characterization of invasive and noninvasive Campylobacter jejuni and Campylobacter coli isolates

Campylobacter jejuni is one of the most common causes of bacterial diarrhea worldwide and is the primary bacterial cause of food-borne illness. Adherence to and invasion of epithelial cells are the most important pathogenic mechanisms of Campylobacter diarrhea. Molecular characterization of invasive and noninvasive Campylobacter isolates from children with diarrhea and symptom-free children was performed by random amplified polymorphic DNA techniques (RAPD). A distinct RAPD profile with a DNA band of 1.6 kb was observed significantly more frequently among invasive (63%) than among noninvasive (16%) Campylobacter isolates (P = 0.000005). The 1.6-kb band was named the invasion-associated marker (IAM). Using specifically designed primers, a fragment of 518 bp of the iam locus was amplified in 85% of invasive and 20% of noninvasive strains (P = 0.0000000). Molecular typing with a PCR-restriction fragment length polymorphism assay which amplified the entire iam locus showed a HindIII restriction fragment polymorphism pattern associated mainly with invasive strains. Although cluster analysis of the RAPD fingerprinting showed genetic diversity among strains, two main clusters were identified. Cluster I comprised significantly more pathogenic and invasive isolates, while cluster II grouped the majority of nonpathogenic, noninvasive isolates. These data indicate that most of the invasive Campylobacter strains could be differentiated from noninvasive isolates by RAPD analysis and PCR using specific primers that amplify a fragment of the iam locus.

Detection and characterization of autoagglutination activity by Campylobacter jejuni

In several gram-negative bacterial pathogens, autoagglutination (AAG) activity is a marker for interaction with host cells and virulence. Campylobacter jejuni strains also show AAG, but this property varies considerably among strains. To examine the characteristics of C. jejuni AAG, we developed a quantitative in vitro assay. For strain 81-176, which shows high AAG, activity was optimal for cells grown for < or = 24 h, was independent of growth temperature, and was best measured for cells suspended in phosphate-buffered saline at 25 degrees C for 24 h. AAG activity was heat labile and was abolished by pronase or acid-glycine (pH 2.2) treatment but not by lipase, DNase, or sodium metaperiodate. Strain 4182 has low AAG activity, but extraction with water increased AAG, suggesting the loss of an inhibitor. Strain 6960 has weak AAG with no effect due to water extraction. Our study with clinical isolates suggests that C. jejuni strains may be grouped into three AAG phenotypes. A variant derived from strain 81116 that is flagellate but immotile showed the strong AAG exhibited by the parent strain, suggesting that motility per se is not necessary for the AAG activity. AAG correlated with both bacterial hydrophobicity and adherence to INT407 cells. Mutants which lack flagella (flaA, flaB, and flbA) or common cell surface antigen (peb1A) were constructed in strain 81-176 by natural transformation-mediated allelic exchange. Both AAG activity and bacterial hydrophobicity were abolished in the aflagellate mutants but not the peb1A mutant. In total, these findings indicate that C. jejuni AAG is highly associated with flagellar expression.

Uptake pathways of clinical and healthy animal isolates of Campylobacter jejuni into INT-407 cells

Campylobacter jejuni isolates obtained from human and animal sources showed different invasion levels into human embryonic intestinal (INT-407) cells. There was no significant relation between the degree of invasion and cytotoxins production. The depolymerization of both microfilaments by cytochalasin-D and microtubules by colchicine, demecolcine and nocodazole or stabilization of microtubules by paclitaxel reduced the invasiveness of C. jejuni, although microfilament depolymerization showed greater inhibition than microtubule depolymerization. Interference with receptor-mediated endocytosis by G-strophanthin and monodansylcadaverine and inhibition of endosome acidification by monensin reduced the number of viable intracellular C. jejuni cells. Furthermore inhibition of only host protein kinases by staurosporine, but not phosphoinositide 3-kinase by wortmannin or protein kinase-C by calphostin-C, significantly reduced invasion of epithelial cells by C. jejuni. These data suggest that the internalization mechanism triggered by C. jejuni is strikingly different from the microfilament-dependent invasion mechanism exhibited by many of the well-studied enteric bacteria such as enteroinvasive strains of Escherichia coli, Salmonella typhimurium, Shigella flexneri, Yersinia enterocolitica and Yersinia pseudotuberculosis.

Pathophysiology of Campylobacter jejuni infections of humans

Campylobacter jejuni and closely related organisms are major causes of human bacterial enteritis. These infections can lead to extraintestinal disease and severe long-term complications. Of these, neurological damage, apparently due to the immune response of the host, is the most striking. This review examines current knowledge of the pathophysiology of the organism. Diversity of C. jejuni isolates in genotypic and phenotypic characteristics now is recognized and clinically relevant examples are presented. Expected future directions are outlined.

Invasive ability of C. jejuni/coli isolates from children with diarrhea and the effect of iron-regulated proteins

The invasive ability of C. jejuni/coli strains isolated from children with diarrhea was studied using an in vitro HEp-2 cell invasion assay. The ratio between the number of intracellular bacteria and the number of bacteria in the inoculum was determined (invasion index). It was found that under anaerobic conditions, there was a significant decrease in the invasion index as compared to standard conditions (5% CO2). Of 11 strains tested, seven were determined as invasive on the basis of invasion indexes within the range of 0.0002-0.01. In a previous study [D. Schwartz et al., Zbl. Bakt. 280, 338-347 (1994)], it was found, that most of the C. jejuni/coli isolates tested produced an outer membrane protein when grown under conditions of iron depletion (IRP). The IRP were detected in eight of the nine strains tested in the present study (five invasive and three non-invasive strains). In one non-invasive strain, IRP was not detected. When kept under conditions of iron depletion, one of the invasive strains exhibited a significant increase in invasive capacity. The results suggest that iron depletion seems to stimulate the invasion capacity of C. jejuni/coli in vitro.

Iron-regulated proteins in outer membranes of Campylobacter jejuni diarrhoea isolates and immune response to the proteins in patients

The outer membrane protein (OMP) profiles from 8 Campylobacter jejuni and 5 Campylobacter coli fecal isolates grown under various conditions were compared by SDS-PAGE. The bacteria were grown under usual conditions, in iron-deficient medium (Dip) and on iron-supplemented medium (Fe). The OMP profiles of most bacterial strains grown under usual conditions, or in the Fe-supplemented medium, contained four major bands of approximately 31, 45, 63-66 and 97 kDa, and in addition, a number of minor bands. It was found that OMP from 10 of 13 strains tested and grown on iron deficient medium contained an intensive band of a protein in the molecular weight region of 76 kDa which was lacking in the OMP of bacteria grown in the presence of iron (iron-regulated protein). Sera from 11 children with C. jejuni infection analyzed by Western blot recognized the 76 kDa bands, in contrast to only one out of 10 control sera from healthy children. The Western-blot experiments demonstrated also various bands of other OMP components, both in OMP-Dip and OMP-Fe. The 45 kDa (porin protein) was recognized by all 11 serum samples from C. jejuni-infected patients and in 8 out of 10 control sera. The data suggested that the 76 kDa iron-regulated protein was expressed by bacteria during infection and it stimulated the immune response in children infected with C. jejuni.