Lipooligosaccharide locus classes are associated with certain Campylobacter jejuni multilocus sequence types

The lipooligosaccharide (LOS) locus class was determined using polymerase chain reaction (PCR) in 335 Finnish Campylobacter jejuni strains isolated from humans, poultry and bovines with known multilocus sequence types. The results revealed an association between clonal complexes/sequence types (STs) and LOS locus classes. Based on these results, we further predicted the LOS locus classes distribution among the STs of 209 additional C. jejuni strains from Finnish human domestically acquired infections. Non-sialylated LOS locus classes were associated with STs that comprised ≈55% of patient strains. Sialylated LOS locus classes A and B were associated with STs infrequently isolated, whereas class C was correlated with the ST-21 complex, found in ≈14% of human strains. A combination of the LOS locus class and multilocus sequence type may provide new information on the epidemiology and association of C. jejuni strains with certain disease outcomes.     

Mucosal and systemic immunity to Campylobacter jejuni in rabbits after gastric inoculation.

The mucosal and systemic immune responses to Campylobacter jejuni were studied in rabbits receiving gastric inoculation with live organisms. A lavage procedure was used to facilitate repeated monitoring of the intestinal immune response to C. jejuni. Immunity to C. jejuni was determined by secondary challenge by using the removable intestinal tie adult rabbit diarrhea (RITARD) model and monitoring for resistance to colonization and bacteremia. Oral-gastric inoculation of normal rabbits produced a transient intestinal colonization without diarrhea. C. jejuni serotypes differed in their ability to colonize the intestines of rabbits and to stimulate primary intestinal and serum antibody responses. Animals previously colonized were resistant to recolonization and the development of bacteremia after homologous challenge by the RITARD procedure but were not resistant to heterologous challenges. Anticampylobacter intestinal and serum IgA titers before this secondary infection were the most reliable predictors of resistance to colonization and bacteremia.     

Patterns of quinolone susceptibility in Campylobacter jejuni associated with different gyrA mutations

AIMS: To investigate the diversity of genetic mutation in the quinolone resistance-determining region (QRDR) of gyrA in clinical isolates and laboratory-derived mutants of Campylobacter jejuni resistant to ciprofloxacin (CipR) and to determine the influence of this mutation on the susceptibility of the organisms to different quinolone antibiotics. METHODS: Laboratory-derived CipR mutants were obtained from C. jejuni NCTC 11 168 and six quinolone-sensitive faecal isolates (parent prototypes) grown in sub-inhibitory concentrations of ciprofloxacin. Initial mutants found to be CipR were designated 'primary mutants' and subjected to a repeat of this process to select 'secondary mutants' with increased resistance. The susceptibility of the mutants and an additional six clinical isolates of CipR C. jejuni to seven quinolone antibiotics was determined by measuring their MICs. The QRDR of gyrA in all strains was amplified by PCR, sequenced and compared with that of the L04566 C. jejuni gyrA gene. RESULTS: All six CipR clinical isolates contained a Thr-86-Ile mutation. This was also the commonest mutation found amongst the laboratory derived CipR strains. Other derived mutations in the in vitro derived CipR group included Asp-90-Asn, Thr-86-Ala, and a previously unreported double mutation, Asp-85-Tyr and Thr-86-Ile. Strains with the Thr-86-Ile mutation had the highest MICs to seven different quinolones. CipR strains with other single mutations had a lower range of MICs. There were no additional QRDR mutational changes detected in secondary mutants even where MICs to the fluoroquinolones were higher than in primary mutants. CONCLUSIONS: Thr-86-Ile mutations were common in both clinical and laboratory derived CipR strains. Other mutations found amongst the latter strains were more sensitive to the fluoroquinolones. Different QRDR changes in gyrA differentially affected the susceptibility of CipR C. jejuni to the various fluoroquinolones.     

Problems in identification of Campylobacter jejuni associated with acquisition of resistance to nalidixic acid.

In a patient with campylobacteriosis, we observed development of resistance to nalidixic acid and norfloxacin under adequate treatment with the latter antibiotic. Isolates before and after treatment differed in their total protein profile but were otherwise identical with respect to enzymatic activity, serotype, crude membrane protein profiles, and other phenotypic characteristics.     

Antibodies to Campylobacter jejuni in patients with acute enteritis

In 233 patients with acute diarrhoea in paired sera Campylobacter antibodies classes IgG and IgA were assessed by the ELISA method. As antigen the external membrane protein of the strain Campylobacter jejuni was used. Raised IgG levels (greater than 50 u.) and/or IgA (greater than 80 u.) were found in 15% of all examined patients. A quadruple increase of values in one or both classes was recorded in 12.4% of the patients. The incidence of antibodies against Campylobacter jejuni provides evidence that this infectious agent is frequent in this country. Antibodies class IgA suggest by their dynamics acute contact with the Campylobacter antigen. On the other hand, IgG antibodies are not of major importance in newly diagnosed disease.     

State of local and total humoral immunity in duodenal ulcer with Campylobacter pylori infection

A total of 83 patients with duodenal ulcer and a varying degree of gastric mucosa contamination with C. pylori were examined. Secretory IgA was less frequently detectable in the gastric juice of patients with higher level of gastric mucosa contamination with C. pylori and in lower concentrations than in the patients with a lesser C. pylori contamination. Healing of duodenal ulcer defects was associated with a decrease of gastric mucosa contamination and elevation of secretory IgA content in the gastric juice. The role of serum immunoglobulins in the gastric juice is less significant: IgG and IgA are rarely detected. Salivary content of secretory IgA depended on the gastric mucosa contamination and ulcer stage. Secretory IgA level increased by the ulcer remission, and C. pylori contamination decreased. Normal blood serum IgA, IgG, and IgM ratios were shifted in the patients with C. pylori contamination, particularly so in those with a higher level of contamination. These findings suggest a contribution of local and total immune reactions related to C. pylori to the pathogenesis of duodenal ulcer.     

Heterozygosity at the b mating-type locus attenuates fusion in Ustilago maydis

Mating and pathogenesis of the corn smut fungus, Ustilago maydis, are controlled by two unlinked mating-type loci, a and b. Yeast-like haploids that differ at both loci are compatible and fuse to establish a pathogenic dikaryon. Mating is assayed in vitro by co-inoculation on culture medium containing activated charcoal; compatible combinations have a characteristic fuzzy appearance caused by the growth of aerial hyphae. In general, this test has not been useful for assaying the mating ability of strains that are already mycelial (e.g., those heterozygous at b or at both mating-type loci). Using an assay for cytoduction involving transfer of a mitochondrial marker during transient cell fusion, and engineered strains with defined genotypes, we examined the mating abilities of strains heterozygous or hemizygous at the mating-type loci. The data (which have not been available from conventional pathogenicity or plate mating tests) show that heterozygosity at b attenuates fusion in haploid and diploid strains, whereas strains heterozygous at a retain the ability to fuse with a compatible haploid partner. It appears, therefore, that subsequent fusion events are attenuated once fusion has occurred to establish the U. maydis dikaryon.     

Three cases of cardiac complications associated with Campylobacter jejuni infection and review of the literature

Presented here are three cases of acute cardiac disease (myocarditis, myopericarditis, and acute atrial fibrillation) associated with Campylobacter jejuni infection, followed by a review of the corresponding literature. Since Campylobacter jejuni is the most common cause of human bacterial enteritis in developed countries, these cases emphasize the importance of keeping cardiac complications in mind when treating patients with acute gastroenteritis due to this pathogen.     

Intestinal innate immunity to Campylobacter jejuni results in induction of bactericidal human beta-defensins 2 and 3

Campylobacter jejuni is the most prevalent cause of bacterial diarrhea worldwide. Despite the serious health problems caused by this bacterium, human innate immune responses to C. jejuni infection remain poorly defined. Human beta-defensins, a family of epithelial antimicrobial peptides, are a major component of host innate defense at the gastrointestinal mucosal surface. In this study, the effect of two different C. jejuni wild-type strains on human intestinal epithelial innate responses was investigated. Up-regulation of beta-defensin gene and peptide expression during infection was observed and recombinant beta-defensins were shown to have a direct bactericidal effect against C. jejuni through disruption of cell wall integrity. Further studies using an isogenic capsule-deficient mutant showed that, surprisingly, the absence of the bacterial polysaccharide capsule did not change the innate immune responses induced by C. jejuni or the ability of C. jejuni to survive exposure to recombinant beta-defensins. This study suggests a major role for this family of antimicrobial peptides in the innate immune defense against this human pathogen.     

Altered synthetic response of Campylobacter jejuni to cocultivation with human epithelial cells is associated with enhanced internalization.

Campylobacter jejuni has been shown to bind to and enter epithelial cells in culture. The interaction of C. jejuni with INT 407 epithelial cells was examined to determine whether bacterial protein synthesis is required for either binding or internalization. Chloramphenicol, a selective inhibitor of bacterial protein synthesis, significantly reduced the internalization, but not binding, of C. jejuni compared with untreated controls as determined by protection from gentamicin. Electrophoretic analysis of metabolically labeled proteins revealed that C. jejuni cultured with INT 407 cells synthesized 14 proteins that were not detected in organisms cultured in medium alone. The inhibitory effect of chloramphenicol on internalization was reduced by preincubation of C. jejuni with INT 407 cells. The results indicate that C. jejuni, like some other enteric pathogens, engages in a directed response to cocultivation with epithelial cells by synthesizing one or more proteins that facilitate internalization and suggest that this phenomenon is relevant to the pathogenesis of enteritis caused by C. jejuni.     

格林—巴利综合征相关空肠弯曲菌脂多糖抗原初步分析

用格林－巴利综合征相关性空肠弯曲菌复制动物模型成功后的动物免疫血清对河北省格林－巴利综合征病人分离株空肠弯曲菌、动物来源株空肠弯曲菌及北京对照用人源株空肠弯曲菌及其脂多糖抗原性进行分析。结果显示，发生了典型的格林－巴利综合征样疾病的动物已产生了明显的抗格林－巴利综合征相关性空肠弯曲菌的免疫反应，其抗脂多糖抗体与当地其它来源株空肠弯曲菌有部分交叉反应，与北京分离株空肠弯曲菌无明显交叉反应。说明格林－巴利综合征相关性空肠弯曲菌脂多糖具有其独持的抗原性。支持某些特殊血清型的空肠弯曲菌参与格林－巴利综合征的致病过程。     

Lipooligosaccharide locus class of Campylobacter jejuni: sialylation is not needed for invasive infection

Campylobacter jejuni is a highly diverse enteropathogen that is commonly detected worldwide. It can sometimes cause bacteraemia, but the bacterial characteristics facilitating bloodstream infection are not known. A total of 73 C. jejuni isolates, consecutively collected from blood-borne infections during a 10-year period all over Finland and for which detailed clinical information of the patients were available, were included. We screened the isolates by PCR for the lipooligosaccharide (LOS) locus class and for the presence of the putative virulence genes ceuE, ciaB, fucP, and virB11. The isolates were also tested for γ-glutamyl transpeptidase production. The results were analysed with respect to the clinical characteristics of the patients, and the multilocus sequence types (MLSTs) and serum resistance of the isolates. LOS locus classes A, B, and C, which carry genes for sialylation of LOS, were detected in only 23% of the isolates. These isolates were not more resistant to human serum than those with the genes of non-sialylated LOS locus classes, but were significantly more prevalent among patients with underlying diseases (p 0.02). The fucose permease gene fucP was quite uncommon, but was associated with the isolates with the potential to sialylate LOS (p <0.0001). LOS locus classes and some of the putative virulence factors were associated with MLST clonal complexes. Although some of the bacterial characteristics studied here have been suggested to be important for the invasiveness of C. jejuni, they did not explain why the clinical isolates in the present study were able to cause bacteraemia.     

New World monkey Aotus nancymae as a model for Campylobacter jejuni infection and immunity

Three groups of six monkeys (Aotus nancymae) each were inoculated intragastrically with increasing doses of Campylobacter jejuni. Infection resulted in fecal colonization (100% of monkeys), dose-related diarrhea, and robust immune responses. Colonization duration and diarrhea rate were reduced upon secondary challenge. A. nancymae may be useful for studying anti-Campylobacter vaccine efficacy.     

Susceptibility of Campylobacter jejuni to twenty-three antimicrobial agents

Twenty-three antimicrobial agents, including 4 new broadspectrum beta-lactam antibiotics were tested against 50 clinical isolates of Campylobacter jejuni. The activity of metabolites of metronidazole and tinidazole was also tested. Minimum inhibitory concentrations (MIC) were determined by agar dilution. beta-lactamase production was detected by a chromogenic cephalosporin method. All strains were susceptible to erythromycin, clindamycin, chloramphenicol, furazolidone, aminoglycosides (including gentamicin), cefotaxime and NF-thienamycin. All isolates were resistant to penicillin, cephalothin, cefoperazone, vancomycin, rifampicin and trimethoprim; beta-lactamase was detected in 2% of isolates. Some strains were resistant and others sensitive to the other drugs tested, which included ampicillin, moxalactum tetracycline, metronidazole and tinidazole. The 'hydroxy' metabolites of metronidazole and tinidazole were more active than the parent compounds.     

Virulence of Campylobacter jejuni for chicken embryos is associated with decreased bloodstream clearance and resistance to phagocytosis.

The 11-day-old chicken embryo has been shown to be a useful animal model for comparing the virulence of human isolates of Campylobacter jejuni. Virulence in this system is associated with the ability to invade the chorioallantoic membrane and to survive and proliferate in vivo. In this study, the survival and multiplication of C. jejuni in the embryonic host was investigated. It was possible to enhance the virulence of a relatively avirulent C. jejuni strain by passaging it intravenously through the embryos. The resulting isogenic variants demonstrated enhanced abilities to survive in vivo but were still unable to invade when inoculated onto the chorioallantoic membrane. The bloodstream clearance of C. jejuni was studied, and virulent, but not avirulent, strains persisted and multiplied both in the bloodstream and in embryonic liver. Virulent strains also were cleared significantly more slowly from the bloodstream of adult BALB/c mice after intravenous challenge than were avirulent strains. C. jejuni strains which were cleared slowly in vivo were also ingested slowly in vitro by mouse peritoneal macrophages. Clearance studies in mice pretreated with cobra venom factor demonstrated that opsonization by serum complement was not a prerequisite for clearance of campylobacters from the murine bloodstream.