Estimating sensitivity and specificity of a PCR for boot socks to detect Campylobacter in broiler primary production using Bayesian latent class analysis

The present study compares three different assays for sample collection and detection of Campylobacter spp. in broiler flocks, based on (i) the collection of faecal samples from intestinal organs (caecum), (ii) individual faecal droppings collected from the bedding and (iii) faecal material collected by socks placed on the outside of a pair of boots (boot socks) and used for walking around in the flock. The two first methods are examined for Campylobacter using a culture method (ISO-10272-2:2006), while the boot socks are tested using PCR. The PCR-assay is a genus specific multiplex PCR with primers targeting 16S rDNA in Campylobacter and primers targeting Yersinia ruckerii. Sixty-seven broiler flocks from Austria and 83 broiler flocks from Denmark were included in this prospective study and 89 of these were found to be positive in at least one method (AT: 49 samples, DK: 40 samples) whereas 61 of these were negative in all assays. In Austria samples for the three assays were collected simultaneously, which facilitates a direct comparison of the diagnostic test performance. In Denmark, however, boot socks and faecal droppings were collected three days before slaughter while caecum samples were collected at slaughter. The results were evaluated in the absence of a gold standard using a Bayesian latent class model. Austrian results showed higher sensitivity for PCR detection in sock samples (0.98; Bayesian credible interval (BCI) [0.93-1]) than for culture of faecal droppings (0.86; BCI [0.76-0.91]) or caecal samples (0.92; BCI [0.85-0.97]). The potential impact of Campylobacter introduction within the final three days before slaughter was observed in Denmark, where four flocks were tested negative three days before slaughter, but were detected positive at the slaughterhouse. Therefore the model results for the PCR sensitivity (0.88; BCI [0.83-0.97]) and cultural ISO-method in faecal samples (0.84; BCI [0.76-0.92]) are lower than for caecal samples (0.93; BCI [0.85-0.98]). In our study, PCR detection on boot sock samples is more sensitive than conventional culture. In view of the advantage of rapid results before slaughter and low costs for sampling, especially in combination with existing Salmonella surveillance systems (just another pair of boot socks needed), this method-matrix combination could be a valuable surveillance tool in the broiler primary production.

Analysis of Campylobacter jejuni isolates of various sources for loci associated with Guillain-Barré Syndrome

Campylobacter jejuni is a major cause of the Guillain-Barré syndrome (GBS) and related diseases. These autoimmune diseases are caused by antibodies cross-reacting with the peripheral (GBS) and central neural tissue (Miller Fisher syndrome - MFS, Bicker-staff's brainstem encephalitis - BBE), leading to acute polyneuropathy. Recently, specific gene loci in C. jejuni have been distinguished which are associated with the onset of GBS, despite a molecular or phenotypic clustering. In this study, we used PCR to analyse C. jejuni isolates of different origin (i.e. bovine, poultry, human) for these genes. A total of 196 isolates were tested for cst-II and neuA. Of these, 101 isolates harboured the cst-II locus and 102 the neuA locus. Eighty-six isolates (44%) hold both genes. The frequency of cst-II in different sources of isolates of bovine, poultry and human isolates did not vary significantly (52, 50 and 52%, respectively). In contrast, the neuA locus was less often found in poultry isolates. Two human strains - from a family outbreak of campylobacteriosis (in 1989 in Austria) in which one person developed MFS - harboured both genes. Thus, although only one in more than 3000 patients with Campylobacter-associated enteritis develop GBS, about half of Campylobacter jejuni strains found in different environments are possibly able to cause GBS. These strains almost equally distributed in bovine, poultry and human isolates. Our results suggest that isolates associated with GBS are not selected by environmental or host-specific factors. Accordingly, this study indicates that host factors such as humoral and cellular immunity are possibly responsible for the development of these autoimmune diseases.

Campylobacteriosis in Austria: situation and trends

Campylobacter species are among the most commonly identified causative agents of acute bacterial gastroenteritis in humans worldwide. In Austria, campylobacteriosis has been a notifiable disease since 1996 and its incidence has increased continuously over the past years. Improvement of notification has led to an important increase in knowledge of the epidemiology of this disease in Austria. In addition to existing programs monitoring food safety, implementation of a national surveillance program to monitor antimicrobial resistance and the prevalence of campylobacter in food animals allows continuous surveillance of trends in antimicrobial susceptibility patterns in humans, animals and food, as well as a more comprehensive evaluation of the occurrence of campylobacter in the relevant reservoirs of human infection. Such data make it possible to identify the most important areas for intervention and launch of control strategies. As in other countries around the world, antimicrobial resistance of campylobacter from human, animal and food origin, particularly resistance to fluoroquinolones, is of public health concern in Austria. The magnitude of global trade and foreign travel requires EU-wide and worldwide implementation of control strategies to fight campylobacteriosis.

An outbreak of norovirus gastroenteritis in an Austrian hospital, winter 2006-2007

BACKGROUND

Norovirus is easily spread from person to person by the fecal-oral route and through aerosols or by vehicles such as contaminated food or water. The virus is able to survive in the environment for many days, which enables outbreaks to be prolonged. We describe a norovirus outbreak and its control measures in an Austrian secondary-level hospital during December 2006 - February 2007.

METHODS

A descriptive-epidemiological investigation of the outbreak was undertaken. We also determined outbreak costs, including the estimated lost revenue associated with department closures and the cost of sick leave and cleaning expenses. Selected stool specimens were tested for norovirus RNA.

RESULTS

In the hospital, 90 persons with symptoms and signs consistent with norovirus gastroenteritis with clinical onset between December 1, 2006 and February 13, 2007 were identified. Out of these, 56 patients and 14 persons among the hospital staff fulfilled the definition of an outbreak case (77.8%), and 20 cases (22.2%) were identified as non-outbreak cases including 13 community-acquired cases of norovirus gastroenteritis and 7 clinical-suspected cases of norovirus gastroenteritis associated with health care facilities other than the affected hospital. The Department of Internal Medicine was the mainly affected department (46 patient-cases and 6 staff-cases). Considering hospital patients, who have been hospitalised between December 1, 2006 and February 13, 2007 as cohort at risk of nosocomial norovirus infection, the nosocomial hospital outbreak attack-rate was 5.9% (56/947). A total of 120 hospital staff members worked in the period from December 1 to February 13, which makes an attack-rate among the hospital staff of 11.7% (14/120). Norovirus strain GII.4 variant 2006b was detected, which has been circulating widely in Europe since 2006. The total cost of the outbreak for the Department of Internal Medicine was <euro> 80,138.

CONCLUSIONS

The significant disruption of patient care and the cost of this single nosocomial outbreak support strict implementations of adequate and timely control measures based on evidence-based recommendations.

A foodborne outbreak due to norovirus in Austria, 2007

A foodborne norovirus outbreak occurred after a pre-Christmas celebration among a group of local foresters in Austria in December 2007. A total of 66 persons, 60 participants of the Christmas party and 6 kitchen staff members of the restaurant where the party took place, were identified as the at-risk cohort. Questioning of this cohort was performed by self-report questionnaires or telephone interviews (response rate of 95%). The outbreak attack rate was 33.3% (21 of 63 persons), including two of the kitchen staff. Three stool specimens yielded norovirus genogroup II. Univariate analysis revealed that exposure to a ham roll and pastry was possibly associated with risk of gastroenteritis (risk ratio [RR] of 4.45, 95% CI of 1.91 to 10. RR of 2.44, 95% CI of 0.93 to 6.39). After controlling for the effects of sex, age, and other food items with a log-linear model, ham roll remained significantly associated with disease risk (RR of 3.91, 95% CI of 1.57 to 9.76). Ham roll was most likely contaminated with norovirus during preparation by a disease-free kitchen assistant, whose infant became sick with laboratory-confirmed norovirus gastroenteritis 2 days before the party. Informing food handlers about the possible risk of food contamination with norovirus and training them in the appropriate measures of hand hygiene and environmental disinfection at the working place and at home are essential for preventing food-related norovirus outbreaks. Norovirus-infected household members of healthy food handlers must be considered a possible reservoir for foodborne norovirus outbreaks.

Therapeutic vaccination of chronic hepatitis C nonresponder patients with the peptide vaccine IC41

BACKGROUND & AIMS

IC41 is a synthetic peptide vaccine containing 7 relevant hepatitis C virus (HCV) T-cell epitopes and the T helper cell (Th)1/Tc1 adjuvant poly-L-arginine. IC41 has been shown to be safe and to induce HCV-specific interferon (IFN)-gamma-secreting CD4+ and CD8+ T cells in healthy volunteers. We aimed to investigate whether IC41 is able to induce HCV-specific T-cell responses also in chronic hepatitis C patients.

METHODS

Sixty HLA-A2-positive chronic HCV patients not responding to or relapsing from standard therapy were randomized in a double-blind phase II study into 5 groups to receive 6 vaccinations of IC41 (3 different dose groups), HCV peptides alone, or poly-L-arginine alone.

RESULTS

IC41 was well tolerated, and no drug-related serious adverse events or induction of hepatitis were observed. T-cell proliferation was recorded in up to 67% of patients in the 3 IC41 vaccine groups but only in 17% of patients treated with peptides alone. IFN-gamma enzyme-linked immunospot assay responses were observed exclusively in the IC41 groups with response rates up to 42%. There were 3 RNA responders with transient >1-log declines of HCV serum RNA associated with the strongest IFN-gamma enzyme-linked immunospot assay values within all 60 patients.

CONCLUSIONS

This study showed that the HCV peptide vaccine IC41 can induce HCV-specific Th1/Tc1 responses in a subset of difficult to treat HCV nonresponder patients despite persisting viremia. However, changes in HCV RNA occurred only in single patients. Because strongest T-cell responses were associated with HCV RNA decline, further studies with optimized vaccine regimens and combination therapies have been initiated.

Immunogenicity and safety of a novel therapeutic hepatitis C virus (HCV) peptide vaccine: A randomized, placebo controlled trial for dose optimization in 128 healthy subjects

As interferon/ribavirin-based standard therapy is curative in only about half of HCV patients, there remains an important need for alternatives including vaccines. The novel peptide vaccine IC41 consists of five synthetic peptides harboring HCV T cell epitopes and poly-L-arginine as synthetic adjuvant. In this randomized, placebo-controlled trial, 128 HLA-A2 positive healthy volunteers received four s.c. vaccinations of seven different doses IC41, HCV peptides alone, poly-l-arginine alone or saline solution, every 4 weeks. IC41 was safe and well tolerated. Mild to moderate local reactions were transient. Immunogenicity was assessed using T cell epitope specific [3H]-thymidine proliferation, IFN-gamma ELIspot and HLA-tetramer assays. IC41 induced responses in all dose groups. Higher responder rates were recorded in higher dose groups and increasing number of vaccinations were associated with higher responder rates and more robust responses. Poly-L-arginine was required for the aimed-for Th1/Tc1-type immunity (IFN-gamma secreting T cells).

Stimulation of the immune system by different TBE-virus vaccines

Tick-borne encephalitis (TBE) is one of the most frequent arthropod-transmitted viral diseases in Europe. Different vaccines against TBE-virus have been developed; a thimerosal-free and also albumin-free vaccine [Ticovac (Baxter Hyland Immuno, Vienna)] was approved in 2000. Contrary to previous experience, 779 cases of fever occurred following the first vaccination of children under 15 years of age and in 62 children febrile convulsions were even observed. Consequently, the composition of the vaccine was changed and albumin was again added [FSME-Immun (Baxter Vaccines, Vienna)] in 2001. The new Encepur Kinder (Chiron-Behring, Marburg) from 2002 is a TBE-vaccine for children without any protein as stabilizer but with a relatively high concentration of sucrose, while the former vaccine Encepur K from 1991 contained polygeline as the stabilizer. The induction of the immune system by the different TBE virus vaccines was compared in an in vitro test in order to find an explanation for the unexpected fever attacks. Whole blood was stimulated with complete vaccine suspension, and TNF-alpha, IL-1beta, IL-6, and IL-8 were determined from heparin/EDTA-plasma and culture supernatants. It was shown that Ticovac and the new Encepur Kinder can induce relatively high amounts of TNF-alpha and lower amounts of IL-1beta. An increase of both cytokines was first observed following an incubation of 4 hours, with a maximum after 15 hours. Concentrations returned to base-line values within 26 hours. The behaviour of both cytokines correlates with the febrile phases in children up to two years old. Albumin or other proteins like polygeline and also immunoglobulins prevented a rise of cytokines.

Effects of low concentrations of cadmium on immunoglobulin E production by human B lymphocytes in vitro

Exposure to cadmium (Cd) can cause a variety of biological effects including alterations of immune responses in animals and humans. Both immunosuppression and immunoenhancement have been reported. The present study was aimed at investigating the consequences of exposure to Cd on the human immunoglobulin (Ig) E synthesis, using purified peripheral blood B lymphocytes and IL-4 and anti-human CD40 monoclonal antibody (a-CD40 mAb) as stimuli. Low concentrations of Cd (0.1-10 microM) markedly inhibited production of IgE in a concentration-dependent manner. IgG production, in contrast to IgE, showed a tendency towards being enhanced by Cd, although with a certain individual variability; IgM production was not affected. Cd failed to alter immediate surface expression of the activation markers CD69 and CD23 indicating that early activation events were not impaired. However, the portion of activated B cells was diminished by Cd after stimulation for more than 24 h, paralleled by a concomitant decrease in viability and a subsequent reduction in proliferation. These data suggest that the mechanism of Cd action on activated B cells involved pathways that interrupted an effectively initiated cell activation and induced a cytotoxic signal. Results from this study thus provide further evidence for and new information on the immunotoxic and immunomodulatory effects of Cd on human immune responses.

The effect of heavy metals on the immune system at low concentrations

The present study describes the effect of cadmium on lymphokines that cannot be directly traced to an allergen, or antigen in order to be able to explain various immunological processes. Exposure to various environmental pollutants is known to induce epithelial and inflammatory changes, characterized by a release of cytokines and other soluble mediators. Heavy metals like CdCl2 can induce, or inhibit the synthesis and expression of the inflammatory cytokines IL-1beta, IL-4, IL-6, TNF-alpha, IFN-gamma and ICAM-1. Normal human peripherial blood mononuclear cells (PBMCs) were exposed for different periods of times (1 to 96 h) to 0, 5, 25 and 50 micromoles CdCl2, and mRNA for the above cytokines was quantified by RT-PCR. Highly purified blood B cells and PBMCs from healthy donors were stimulated with IL-4 and aCD40 mAb and incubated with non-toxic concentrations of cadmium chloride (0,1-10 micromol). Levels of IgG and IgE were measured in the supernatants. Proliferation and expression of surface markers were determined by measuring [3H]-thymidine incorporation and by flow cytometry. The study showed that the in vitro synthesis of IgE by purified B cells or PBMCs stimulated with IL-4/aCD40 is inhibited by Cd at doses as low as 0,1 microM. Cd was found to inhibit IL-4/aCD40 induced proliferation of purified B cells and PBMCs in a dose dependent fashion. Most strikingly, only IgE but not IgG synthesis of purified B cells was inhibited by Cd. These data suggest that inhibition of IgE synthesis in human B lymphocytes by Cd seems to be a selective effect on immunoglobulin synthesis.

[Waste management--health: a longitudinal study]

Altogether 256 (148 men and 108 women) employees from manual sorting facilities and 120 (98 men and 22 women) employees from compost facilities were examined The main focus of the investigations was in the assessment of the lung-function and the immune-system. A part of employees (87 in sorting and 34 in compost facilities) was observed over a period of 3 years. The lung-function was in the area of the expected values, decreased however from year to year. The concentration of total-IgE increased over the period of 3 years. The observation is from great interest that the difference of the concentration of the total-IgE fluctuated within the 3 years at the employees of manual sorting facilities from +200% to -100% while it amounted to 0% at employees of the compost facilities.

In vitro cytokine mRNA expression in normal human peripheral blood mononuclear cells

OBJECTIVE AND DESIGN

Normal human peripheral blood mononuclear cells (PBMC) were analyzed for basic profiles of mRNA expression of distinct genes during incubation in a standard cell culture system.

MATERIAL

Human PBMC from healthy adult blood donors.

METHODS

Steady-state mRNA expression was measured using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay.

RESULTS

Shortly after isolation and cell seeding, mRNA levels of monocyte-derived cytokines (IL-1alpha, IL-6, and TNF-alpha) were significantly increased, whereas lymphocyte-derived cytokines (IL-4, IFN-gamma) were not affected. Expression levels of monokines returned to basal within 24 h. At later stages of culture, the mRNA levels of all genes studied gradually increased and were significantly elevated after 96 h of incubation.

CONCLUSIONS

Monokine and lymphokine mRNAs respond differently to cell culture even under control conditions. With regard to the enhanced mRNA expression of distinct cytokines in the early stages of culture, human PBMC should not be used for gene expression studies in vitro within 24 h of isolation.

Influence of cadmium on the immune system. Description of stimulating reactions

Allergic diseases, atopy, bronchial asthma and chronic obstructive bronchitis are diseases which can directly or indirectly be traced to changes in the function of the immune system. Epidemiological studies have shown that these allergic diseases have increased in the course of time and that the incidence of obstruction of the respiratory system is clearly higher in polluted regions than in comparable control areas. These diseases are mainly the result of a comprehensive influence on the immune system. The present study describes the influence of pollutants on the behavior of cytokines which cannot be directly traced to an allergen or antigen in order to be able to explain various immunological or pseudo-allergic processes. We have isolated and cultivated PBMC from six donors and exposed them to different concentrations (5, 25, 50 and 100 mumol) of cadmium chloride. After incubation of cells with cadmium, different genes of cytokines were detected on the basis of mRNA by RT-PCR. Hsp70 can be detected in a relatively brief period following stress and there is an excellent correlation between heavy metal dose (stress) and expression of hsp70. In the case of IL-1, and TNF-alpha low concentrations of cadmium chloride increase the expression of these genes, whereas this effect is less noticeable with higher amounts of cadmium. After only one hour of exposure to heavy metals, large volumes of mRNA of IL-6 have been detected. IFN-gamma only reacts at high concentrations of cadmium. Heavy metals may influence immunocompetent cells so that they release several cytokines which may act on a large variety of cells in terms of a proinflammatory reaction. The influence of cytokines as well as the pollutants themselves on fibroblasts, endothelial cells as well as macrophages explains a number of processes which cannot be explained by allergical reactions. At low concentrations, cadmium is able to stimulate the immune system, while at higher concentrations inhibitory and suppressive reactions were observed.