1,370 research outputs found
Isolate Specific Cold Response of Yersinia enterocolitica in Transcriptional, Proteomic, and Membrane Physiological Changes
Yersinia enterocolitica, a zoonotic foodborne pathogen, is able to withstand low temperatures. This psychrotrophic ability allows it to multiply in food stored in refrigerators. However, little is known about the Y. enterocolitica cold response. In this study, isolate-specific behavior at 4°C was demonstrated and the cold response was investigated by examining changes in phenotype, gene expression, and the proteome. Altered expression of cold-responsive genes showed that the ability to survive at low temperature depends on the capacity to acclimate and adapt to cold stress. This cold acclimation at the transcriptional level involves the transient induction and effective repression of cold-shock protein (Csp) genes. Moreover, the resumption of expression of genes encoding other non-Csp is essential during prolonged adaptation. Based on proteomic analyses, the predominant functional categories of cold-responsive proteins are associated with protein synthesis, cell membrane structure, and cell motility. In addition, changes in membrane fluidity and motility were shown to be important in the cold response of Y. enterocolitica. Isolate-specific differences in the transcription of membrane fluidity- and motility-related genes provided evidence to classify strains within a spectrum of cold response. The combination of different approaches has permitted the systematic description of the Y. enterocolitica cold response and gives a better understanding of the physiological processes underlying this phenomenon
Campylobacter jejuni genes Cj1492c and Cj1507c are involved in host cell adhesion and invasion
Background
Campylobacter jejuni (C. jejuni) has been assigned as an important food-borne pathogen for human health but many pathogenicity factors of C. jejuni and human host cell responses related to the infection have not yet been adequately clarified. This study aimed to determine further C. jejuni pathogenicity factors and virulence genes based on a random mutagenesis approach. A transposon mutant library of C. jejuni NCTC 11168 was constructed and the ability of individual mutants to adhere to and invade human intestinal epithelial cells was evaluated compared to the wild type. We identified two mutants of C. jejuni possessing altered phenotypes with transposon insertions in the genes Cj1492c and Cj1507c. Cj1492c is annotated as a two-component sensor and Cj1507c is described as a regulatory protein. However, functions of both mutated genes are not clarified so far.
Results
In comparison to the wild type, Cj::1492c and Cj::1507c showed around 70â80% relative motility and Cj::1492c had around 3-times enhanced adhesion and invasion rates whereas Cj::1507c had significantly impaired adhesive and invasive capability. Moreover, Cj::1492c had a longer lag phase and slower growth rate while Cj::1507c showed similar growth compared to the wild type. Between 5 and 24 h post infection, more than 60% of the intracellular wild type C. jejuni were eliminated in HT-29/B6 cells, however, significantly fewer mutants were able to survive intracellularly. Nevertheless, no difference in host cell viability and induction of the pro-inflammatory chemokine IL-8 were determined between both mutants and the wild type.
Conclusion
We conclude that genes regulated by Cj1507c have an impact on efficient adhesion, invasion and intracellular survival of C. jejuni in HT-29/B6 cells. Furthermore, potential signal sensing by Cj1492c seems to lead to limiting attachment and hence internalisation of C. jejuni. However, as the intracellular survival capacities are reduced, we suggest that signal sensing by Cj1492c impacts several processes related to pathogenicity of C. jejuni
Overlap of Antibiotic Resistant Campylobacter jejuni MLST Genotypes Isolated From Humans, Broiler Products, Dairy Cattle and Wild Birds in Lithuania
Antimicrobial resistance was determined for 341 thermophilic Campylobacter jejuni isolates obtained from human clinical cases (n = 101), broiler products (n = 98), dairy cattle (n = 41) and wild birds (n = 101) with known multilocus sequence types (MLST) in Lithuania. The minimum inhibitory concentration (MIC) values for ciprofloxacin, tetracycline, gentamicin, ceftriaxone and erythromycin were determined with the agar dilution method. MIC values were compared with MLST types to find possible associations among isolation source, sequence type and resistance to antibiotics. The proportions of resistant strains were 94.2% (human), 95% (wild birds), 100% (broiler products) and 100% (dairy cattle) for one of the tested antibiotics. Most frequently, resistance to ciprofloxacin was observed (91.5%), followed by ceftriaxone with 60.4%, and tetracycline (37.8%). However only three C. jejuni strains were resistant to erythromycin (0.9%) and all tested thermophilic Campylobacter strains were sensitive to gentamicin. Most of the examined C. jejuni isolates (80.6%) showed resistance to at least one of three profiles: CIP+AXO (28.1%), TET+CIP+AXO (26.7%) and CIP (25.8%). Statistically significant differences in resistance to tetracycline were found between C. jejuni strains obtained from cattle (85.4%) and broiler products (64.3%) (P < 0.05). The majority (87.1%) of the tested strains from wild birds were resistant to ciprofloxacin (P < 0.05). The results showed that strains of novel STâs showed significantly lower resistance to ceftriaxone (P < 0.05). The ST-21 (CC21) (78.8%) was identified with significantly higher multidrug resistance relatively to other tested STâs in this study. Our results emphasize the high antimicrobial resistance of phylogenetically diverse C. jejuni strains isolated from different sources including specific genotypes of wild birdâs strains in Lithuania. The results support the opinion that not only broiler products but cattle and wild birds may be a reservoir of resistant C. jejuni and stipulate a risk of spread or resistant bacteria. There is increasing need for broad surveillance and control measures to track changes and pathways of antimicrobial resistance of C. jejuni in epidemiologically distinct populations
Motility related gene expression of Campylobacter jejuni NCTC 11168 derived from high viscous media
Flagellation is one of the major virulence factors of Campylobacter jejuni (C. jejuni), enabling bacterial cells to swarm in rather high viscous fluids. The aim of this study was to determine the impact of the surrounding viscosity on the expression of motility related genes of C. jejuni. Therefore, bacterial RNA was extracted from liquid cultures as well as from bacterial cells recovered from the edge and the center of a swarming halo from high viscous media. The expression pattern of selected flagellar and chemotaxis related genes was investigated by RT-PCR. Higher mRNA levels of class 1 and lower levels of class 2 and 3 flagellar assembly genes were detected in cells derived from the edge of a swarming halo than in cells from the center. This indicates different growth states at both locations within the swarming halo. Furthermore, higher mRNA levels for energy taxis and motor complex monomer genes were detected in high viscous media compared to liquid culture, indicating higher demand of energy if C. jejuni cells were cultivated in high viscous media. The impact of the surrounding viscosity should be considered in future studies regarding motility related questions
The transcriptional response of Arcobacter butzleri to cold shock
Arcobacter (A.) butzleri is an emerging zoonotic pathogen associated with gastrointestinal diseases, such as abdominal cramps and diarrhea, and is widely detected in animals, showing a high prevalence in poultry and seafood. The survival and adaptation of A. butzleri to cold temperatures remains poorly studied, although it might be of interest for food safety considerations. To address this, growth patterns of eight A. butzleri isolates were determined at 8 °C for 28 days. A. butzleri isolates showed strainâdependent behavior: six isolates were unculturable after day 18, one exhibited declining but detectable cell counts until day 28 and one grew to the stationary phase level. Out of 13 A. butzleri cold shockârelated genes homologous to Escherichia coli, 10 were upâregulated in response to a temperature downshift to 8 °C, as demonstrated by reverse transcriptionâquantitative PCR. Additionally, we compared these data with the coldâshock response in E. coli. Overall, we provide a deeper insight into the environmental adaptation capacities of A. butzleri, which we find shares similarities with the E. coli coldâshock response
Lessons from a Meta-Analysis of Murine Infection Studies
Background: Only limited information is available about the immunopathogenic
properties of Arcobacter infection in vivo. Therefore, we performed a meta-
analysis of published data in murine infection models to compare the
pathogenic potential of Arcobacter butzleri with Campylobacter jejuni and
commensal Escherichia coli as pathogenic and harmless reference bacteria,
respectively. Methodology / Principal Findings: Gnotobiotic IL-10-/- mice
generated by broad-spectrum antibiotic compounds were perorally infected with
A. butzleri (strains CCUG 30485 or C1), C. jejuni (strain 81-176) or a
commensal intestinal E. coli strain. Either strain stably colonized the murine
intestines upon infection. At day 6 postinfection (p.i.), C. jejuni infected
mice only displayed severe clinical sequelae such as wasting bloody diarrhea.
Gross disease was accompanied by increased numbers of colonic apoptotic cells
and distinct immune cell populations including macrophages and monocytes, T
and B cells as well as regulatory T cells upon pathogenic infection. Whereas
A. butzleri and E. coli infected mice were clinically unaffected, respective
colonic immune cell numbers increased in the former, but not in the latter,
and more distinctly upon A. butzleri strain CCUG 30485 as compared to C1
strain infection. Both, A. butzleri and C. jejuni induced increased secretion
of pro-inflammatory cytokines such as IFN-Îł, TNF, IL-6 and MCP-1 in large, but
also small intestines. Remarkably, even though viable bacteria did not
translocate from the intestines to extra-intestinal compartments, systemic
immune responses were induced in C. jejuni, but also A. butzleri infected mice
as indicated by increased respective pro-inflammatory cytokine concentrations
in serum samples at day 6 p.i. Conclusion / Significance: A. butzleri induce
less distinct pro-inflammatory sequelae as compared to C. jejuni, but more
pronounced local and systemic immune responses than commensal E. coli in a
strain-dependent manner. Hence, data point towards that A. butzleri is more
than a commensal in vertebrate hosts
Effect of peracetic acid solutions and lactic acid on microorganisms in on-line reprocessing systems for chicken slaughter plants
During poultry slaughter and processing, microbial cross-contamination between individual chickens is possible, as well as from one slaughter animal to the next without direct contact. One option for reducing the risk of cross-contamination is to decrease the number of microorganisms on contact surfaces by using disinfectants. The aim is to decontaminate the surfaces coming into direct contact with the carcasses. In the present study, the effectiveness of different disinfectants was investigated in laboratory settings, simulating the conditions in the slaughterhouses and in a chicken slaughterhouse. For this, an artificial residue substance (consisting of yeast extract, albumin, and agar) was developed, tested, and included in the assays. Two disinfectants were tested under laboratory conditions: lactic acid (5 and 6.67%) and peracetic acid (0.33 and 0.5%). At the slaughterhouse, peracetic acid (0.021%) was used. In the laboratory tests, it was found that the peracetic acid solution had the highest disinfection potential with respect to an Escherichia coli strain (reduction >4 log CFU mLâ1) at 0.5% without an artificial residue substance. The tested lactic acid solutions also showed the highest disinfection potential against a Pseudomonas aeruginosa strain, without an artificial residue substance. When applying the artificial residue substance, the reduction potential of lactic acid and peracetic acid was decreased to less than 1.4 log CFU mLâ1. Application of peracetic acid in the slaughterhouse reduced the number of total aerobic bacteria by more than 4 log CFU mLâ1 and the number of Enterobacteriaceae by more than 3 log CFU mLâ1, depending on the place of sampling
Molecular Targets in Campylobacter Infections
Human campylobacteriosis results from foodborne infections with Campylobacter bacteria such as Campylobacter jejuni and Campylobacter coli, and represents a leading cause of bacterial gastroenteritis worldwide. After consumption of contaminated poultry meat, constituting the major source of pathogenic transfer to humans, infected patients develop abdominal pain and diarrhea. Post-infectious disorders following acute enteritis may occur and affect the nervous system, the joints or the intestines. Immunocompromising comorbidities in infected patients favor bacteremia, leading to vascular inflammation and septicemia. Prevention of human infection is achieved by hygiene measures focusing on the reduction of pathogenic food contamination. Molecular targets for the treatment and prevention of campylobacteriosis include bacterial pathogenicity and virulence factors involved in motility, adhesion, invasion, oxygen detoxification, acid resistance and biofilm formation. This repertoire of intervention measures has recently been completed by drugs dampening the pro-inflammatory immune responses induced by the Campylobacter endotoxin lipo-oligosaccharide. Novel pharmaceutical strategies will combine anti-pathogenic and anti-inflammatory effects to reduce the risk of both anti-microbial resistance and post-infectious sequelae of acute enteritis. Novel strategies and actual trends in the combat of Campylobacter infections are presented in this review, alongside molecular targets applied for prevention and treatment strategies
MLST genotypes of Campylobacter jejuni isolated from broiler products, dairy cattle and human campylobacteriosis cases in Lithuania
Background Campylobacter (C.) jejuni is the leading cause of human
campylobacteriosis worldwide. We performed a molecular epidemiological study
to investigate the genetic relationship among C. jejuni strains isolated from
human diarrhoeal patients, broiler products and dairy cattle in Lithuania.
Methods The C. jejuni isolates from human clinical cases, dairy cattle and
broiler products were genotyped using multilocus sequence typing (MLST).
Allele numbers for each housekeeping gene, sequence type (ST), and clonal
complex (CC) were assigned by submitting the DNA sequences to the C. jejuni
MLST database (http://pubmlst.org/campylobacter). Based on the obtained
sequence data of the housekeeping genes a phylogenetic analysis of the strains
was performed and a minimum spanning tree (MST) was calculated. Results Among
the 262 C. jejuni strains (consisting of 43 strains isolated from dairy
cattle, 102 strains isolated from broiler products and 117 clinical human C.
jejuni strains), 82 different MLST sequence types and 22 clonal complexes were
identified. Clonal complexes CC21 and CC353 predominated among the C. jejuni
strains. On ST-level, five sequence types (ST-5, ST-21, ST-50, ST-464 and
ST-6410) were dominating and these five STs accounted for 35.9% (n = 94) of
our isolates. In addition, 51 (19.5%) C. jejuni strains representing 27
(32.9%) STs were reported for the first time in the PubMLST database
(http://pubmlst.org/campylobacter). The highest Czekanowski index or
proportional similarity index (PSI) was calculated for C. jejuni strains
isolated from human campylobacteriosis cases and broiler products (PSI = 0.32)
suggesting a strong link between broiler strains and human cases. The PSI of
dairy cattle and human samples was lower (PSI = 0.11), suggesting a weaker
link between bovine strains and human cases. The calculated Simpsonâs index of
all C. jejuni isolates showed a high genetic diversity (D = 0.96). Conclusion
Our results suggest that broiler products are the most important source of
human campylobacteriosis in Lithuania. The study provides information on MLST
type distribution and genetic relatedness of C. jejuni strains from humans,
broiler products and dairy cattle in Lithuania for the first time, enabling a
better understanding of the transmission pathways of C. jejuni in this
country
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