Investigation of anti-NMDA receptor antibodies in first episode psychosis patients

Introduction

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an autoimmune limbic encephalitis, where psychiatric symptoms are often the initial presentation dominant initially. These patients are mainly admitted to psychiatric wards, due to first episode psychosis (FEP).

Objectives

Multiple studies analysed whether anti-NMDAR antibodies were present in the sera of schizophrenic patients, but results have not verified this hypothesis. It is possible, however, that unknown autoimmune antibodies play a role in FEP, similarly to anti-NMDAR antibodies.

Methods

40 patients with FEP and 30 healthy controls have been recruited to the study. Patients with affective psychosis, drug-related psychosis and patients with diagnosed encephalitis were excluded. The sera were tested with immune fluorescent assays for anti-NMDAR antibodies. A non-specific method was used to test anti-brain antibody activity on monkey-cerebellum and rat-hippocampus slices.

Results

Neither the samples from the 40 patients, nor the samples of healthy controls contained anti-NMDAR antibodies. 14 of the patients’ and only 6 of the healthy controls’ serum showed positive reaction of the neuroendothelium. These results suggest that there is a difference between the groups, although the results are not significant.

Conclusions

None of the 40 patients proved positive for anti-NMDAR antibodies in agreement with previous studies. However, a higher proportion of samples from the FEP group showed activity in the neuroendothelium of non-specific immune fluorescent assays compared to healthy controls. Based on literature and on our experience, it is possible, that unknown autoimmune antibodies play role in FEP.

Disclosure

No significant relationships.

The Development of a Complex FEP Program at Semmelweis University

Introduction First episode psychosis (FEP) programs target the first 3-5 years after the first manifestation of a psychotic episode. Although follow-up results after 10-15 years are mixed, reported results of the first 5-10 years are promising in improving relapse prevention, functional outcomes and reducing mental health care costs, compared to treatment as usual. Objectives Our objective was to develop the first complex FEP program in Hungary. Methods Male and female inpatients, (age:17-40years), hospitalized due to a first psychotic episode and consenting to participate, were included, since 2019 October. Drug induced psychosis and organic background in the etiology of the psychotic episode were excluded. Duration of the program is 2-3 years, based on the individual needs of the patients. The program provides detailed clinical and neuropsychological examinations, MRI, pharmacotherapy, various psychosocial interventions, and support group for relatives. Results Twenty-eight patients [15 male,13 female, mean age=22,4 (18-40)years] were included. The program has been repeatedly limited by COVID-19 pandemic. Psychiatric control, pharmacotherapy, psychoeducation and supportive therapy, however could be continously provided via telepsychiatry, even during the lockdown. During the first 2 years, 90% of the patients remained in treatment, showed good compliance with pharmacotherapy; 10% of the patients were rehospitalized due to relapse. In the presentation, besides clinical experiences, preliminary clinical outcome data will also be presented. Conclusions The first complex FEP program in Hungary, although limited repeatedly by the pandemic, show promising clinical results with low relapse rates and high level of adherence to therapy in the first 2 years after a first psychotic episode.

Changes in the practice of electroconvulsive therapy at Semmelweis University before and during the COVID-19 pandemic

Introduction

The Department of Psychiatry at Semmelweis University is the largest electroconvulsive therapy (ECT) centre in Hungary, where a total number of around 300 treatments are conducted every year. Certain changes were administered in 2018 and 2019 in our logistics and internal protocols that helped to increase the number of treated patients and improve quality of care. The COVID-19 pandemic caused serious disruptions in the Hungarian mental health care system , therefore there was a realistic fear that many patients who required ECT would not receive this form of tretament.

Objectives

Our goal was to assess the effects of the pandemic on our ECT service, and to analyse whether patients were able to receive treatment, despite the logistical difficulties.

Methods

We retrospectively gathered data from our internal documentation to compare the number of ECT treatments with the previous years. We also had to take into account the fluctuation in our general caseload of psychiatric patients, since our Department acted as a COVID-19 treatment centre for several months.

Results

Total number of ECT treatments decreased in 2020 after a peak in 2019, however the numbers were not much lower compared to the years before changes in 2018. Unfortunately, we see a more direct effect of the 3rd wave of the pandemic.

Conclusions

We can conlude that there is a decrease in the number of ECT treatments due to the pandemic, however, the fact that we still provided service in most parts of 2020 and 2021 for patients with the most severe conditions is a serious achivement.

Disclosure

No significant relationships.

Pulmonary surfactant as a versatile biomaterial to fight COVID-19

The COVID-19 pandemic has wielded an enormous pressure on global health care systems, economics and politics. Ongoing vaccination campaigns effectively attenuate viral spreading, leading to a reduction of infected individuals, hospitalizations and mortality. Nevertheless, the development of safe and effective vaccines as well as their global deployment is time-consuming and challenging. In addition, such preventive measures have no effect on already infected individuals and can show reduced efficacy against SARS-CoV-2 variants that escape vaccine-induced host immune responses. Therefore, it is crucial to continue the development of specific COVID-19 targeting therapeutics, including small molecular drugs, antibodies and nucleic acids. However, despite clear advantages of local drug delivery to the lung, inhalation therapy of such antivirals remains difficult. This review aims to highlight the potential of pulmonary surfactant (PS) in the treatment of COVID-19. Since SARS-CoV-2 infection can progress to COVID-19-related acute respiratory distress syndrome (CARDS), which is associated with PS deficiency and inflammation, replacement therapy with exogenous surfactant can be considered to counter lung dysfunction. In addition, due to its surface-active properties and membrane-interaction potential, PS can be repurposed to enhance drug spreading along the respiratory epithelium and to promote intracellular drug delivery. By merging these beneficial features, PS can be regarded as a versatile biomaterial to combat respiratory infections, in particular COVID-19.

Surfactant Protein B Promotes Cytosolic SiRNA Delivery by Adopting a Virus-like Mechanism of Action

RNA therapeutics are poised to revolutionize medicine. To unlock the full potential of RNA drugs, safe and efficient (nano)formulations to deliver them inside target cells are required. Endosomal sequestration of nanocarriers represents a major bottleneck in nucleic acid delivery. Gaining more detailed information on the intracellular behavior of RNA nanocarriers is crucial to rationally develop delivery systems with improved therapeutic efficiency. Surfactant protein B (SP-B) is a key component of pulmonary surfactant (PS), essential for mammalian breathing. In contrast to the general belief that PS should be regarded as a barrier for inhaled nanomedicines, we recently discovered the ability of SP-B to promote gene silencing by siRNA-loaded and lipid-coated nanogels. However, the mechanisms governing this process are poorly understood. The major objective of this work was to obtain mechanistic insights into the SP-B-mediated cellular delivery of siRNA. To this end, we combined siRNA knockdown experiments, confocal microscopy, and focused ion beam scanning electron microscopy imaging in an in vitro non-small-cell lung carcinoma model with lipid mixing assays on vesicles that mimic the composition of (intra)cellular membranes. Our work highlights a strong correlation between SP-B-mediated fusion with anionic endosomal membranes and cytosolic siRNA delivery, a mode of action resembling that of certain viruses and virus-derived cell-penetrating peptides. Building on these gained insights, we optimized the SP-B proteolipid composition, which dramatically improved delivery efficiency. Altogether, our work provides a mechanistic understanding of SP-B-induced perturbation of intracellular membranes, offering opportunities to fuel the rational design of SP-B-inspired RNA nanoformulations for inhalation therapy.

THU0032 MODIFIED PEPTIDES AS A NOVEL IMMUNOTHERAPY FOR RHEUMATOID ARTHRITIS

Background:

Rheumatoid arthritis (RA) is a highly prevalent and severe systemic autoimmune disease associated with permanent disability and strong socio-economic burdens. Currently, there is no therapeutic treatment and RA patients rely on lifelong, costly treatments. Imcyse develops modified peptides eliciting antigen specific cytolytic CD4 T cells (cCD4+) that induce apoptosis of antigen presenting cells (APC) in a contact dependent manner. cCD4+ also induce apoptosis of autoantigen-specific bystander T-cells, activated by the same APC thus eliminating the risk of general immunosuppression. Peptides consist of MHC class II T cell epitopes of a target autoantigen modified in their flanking region by the addition of an amino acid sequence containing a thiol-disulphide oxidoreductase active motif1.

Objectives:

The goal of this study was to synthesize modified peptides from a target RA autoantigen and test their potency to generatein vitrospecific and cytolytic CD4+ T cells from RA patients.

Methods:

We designed modified peptides from a target RA autoantigen after in silico and in vitro assessment to identify MHC II core binding region, HLA class II binding capacities and physiochemical properties.

CD4+ T cells were purified from PBMC of a newly diagnosed seropositive RA patient and co-cultured with autologous APC in the presence of the modified peptide. The CD4+ T cells were restimulated periodically. Peptide’s ability to generate specific CD4+ T cells was evaluated by flow cytometric analysis of the expression of surface activation marker CD154 (CD40L). The peptide specific CD4+ T cell lines were sorted based on their surface CD154 expression. Their pro-apoptotic activity was assessed after overnight (O/N) co-culture of CD4+ T cells with fluorescent tracer labelled autologous lymphoblastoid cells lines (LCL). Flow cytometry quantification of LCL apoptosis was measured by annexin V staining. MHC II restriction of CD4+ T cells was demonstrated by the addition of blocking antibodies against HLA-DR, DP or DQ molecules.

Results:

CD4+ T cells were in vitro expanded after six consecutive stimulations with the peptide. We investigated their specificity by flow cytometry and showed that 69% of CD4+ T cells that were stimulated O/N in the presence of the peptide expressed the activation marker CD154 versus 29% of CD4+ T cells that were stimulated in its absence. These cells were sorted based on CD154 expression following specific stimulation. Cell enrichment was then assessed by flow cytometric analysis. Data showed that more than 91% (background 3%) were peptide specific based on CD154 expression.

After co-culture of CD4+ T cells with LCL, in independent experiments, Annexin V binding was detected on peptide loaded LCL, ranging from 69% to 89%, while when LCL were kept unloaded these values were between 30% and 55%, respectively, indicating that when specifically activated, these CD4+ T cells had pro-apoptotic activity. When both the peptide and blocking antibodies against HLA-DR, DP or DQ molecules added in the co-culture the pro-apoptotic activity was inhibited by 68%, 20% and 25%, respectively.

Conclusion:

The preliminary but very promising data show that our modified peptide generates peptide-specific CD4+ T cells with lytic properties that lyse target APC in an HLA class II specific manner. Our plan is to show that these CD4+ T cells can also induce apoptosis in bystander T cells and to further validate our results in additional RA donors.

References:

[1]Carlier, V. A., Vanderelst, L., Janssens, W. & Jacquemin, M. G. Increased Synapse Formation Obtained by T Cell Epitopes Containing a CxxC Motif in Flanking Residues Convert CD4 + T Cells into Cytolytic Effectors.7, (2012).

Disclosure of Interests:

Eleni Araklioti Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Ludivine Herman Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Ngoc Quynh Nhu Nguyen Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Roxana Roohi Ahangarani Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Milos Erak Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Bernard Lauwerys: None declared, Patrick Durez Speakers bureau: AbbVie, Bristol-Myers Squibb, Celltrion, Eli Lilly, Pfizer, Sanofi, Vincent Geenen: None declared, Aaron Winkler Shareholder of: Shareholder of Pfizer, Inc, Employee of: Full time employee of Pfizer, Inc, Marcelle Van Mechelen Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Luc Vander Elst Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region, Vincent Carlier Grant/research support from: This work was supported by Pfizer Inc. and by Walloon Region

Evaluation of the impact of tumor HPV status on outcome in patients with locally advanced unresectable head and neck squamous cell carcinoma (HNSCC) receiving cisplatin, 5-fluorouracil with or without docetaxel: a subset analysis of EORTC 24971 study

Background

EORTC 24971 was a phase III trial demonstrating superiority of induction regimen TPF (docetaxel, cisplatin, 5-fluorouracil) over PF (cisplatin/5-fluorouracil), in terms of progression-free (PFS) and overall survival (OS) in locoregionally advanced unresectable head and neck squamous cell carcinomas. We conducted a retrospective analysis of prospectively collected data aiming to evaluate whether only HPV(-) patients (pts) benefit from adding docetaxel to PF, in which case deintensifying induction treatment in HPV(+) pts could be considered.

Patients and methods

Pretherapy tumor biopsies (blocks or slides) were assessed for high-risk HPV by p16 immunohistochemistry, PCR and quantitative PCR. HPV-DNA+ and/or p16+ tumors were subjected to in situ hybridization (ISH) and HPV E6 oncogene expression qRT-PCR analysis. Primary and secondary objectives were to evaluate the value of HPV/p16 status as predictive factor of treatment benefit in terms of PFS and OS. The predictive effect was analyzed based on the model used in the primary analysis of the study with the addition of a treatment by marker interaction term and tested at two-sided 5% significance level.

Results

Of 358, 119 pts had available tumor samples and 58 of them had oropharyngeal cancer. Median follow-up was 8.7 years. Sixteen of 119 (14%) evaluable samples were p16+ and 20 of 79 (25%) evaluable tumors were HPV-DNA+. 13 of 40 pts (33%) assessed with HPV-DNA ISH and 12 of 28 pts (43%) assessed for HPV E6 mRNA were positive. The preplanned analysis showed no statistical evidence of predictive value of HPV/p16 status for PFS (P = 0.287) or OS (P = 0.118).

Conclusions

The incidence of HPV positivity was low in the subset of EORTC 24971 pts analyzed. In this analysis only powered to detect a large treatment by marker interaction, there was no statistical evidence that treatment effect found overall was different in magnitude in HPV(+) or HPV(-) pts. These results do not justify selection of TPF versus PF according to HPV status.

Reduction of Mycobacterium avium ssp. paratuberculosis in colostrum: Development and validation of 2 methods, one based on curdling and one based on centrifugation

The aim of this study was to develop and validate 2 protocols (for use on-farm and at a central location) for the reduction of Mycobacterium avium ssp. paratuberculosis (MAP) in colostrum while preserving beneficial immunoglobulins (IgG). The on-farm protocol was based on curdling of the colostrum, where the IgG remain in the whey and the MAP bacteria are trapped in the curd. First, the colostrum was diluted with water (2 volumes colostrum to 1 volume water) and 2% rennet was added. After incubation (1 h at 32°C), the curd was cut and incubated again, after which whey and curd were separated using a cheesecloth. The curd was removed and milk powder was added to the whey. Approximately 1 log reduction in MAP counts was achieved. A reduction in total proteins and IgG was observed due to initial dilution of the colostrum. After curd formation, more than 95% of the immunoglobulins remained in the whey fraction. The semi-industrial protocol was based on centrifugation, which causes MAP to precipitate, while the IgG remain in the supernatant. This protocol was first developed in the laboratory. The colostrum was diluted with skimmed colostrum (2 volumes colostrum to 1 volume skimmed colostrum), then skimmed and centrifuged (at 15,600 × g for 30 min at room temperature). We observed on average 1.5 log reduction in the MAP counts and a limited reduction in proteins and IgG in the supernatant. To obtain a semi-industrial protocol, dairy pilot appliances were evaluated and the following changes were applied to the protocol: after 2:1 dilution as above, the colostrum was skimmed and subsequently clarified, after which the cream was heat treated and added to the supernatant. To investigate the effect of the colostrum treatment on the nutritional value and palatability of the colostrum and the IgG transfer, an animal experiment was conducted with 24 calves. Six received the dam's colostrum, 6 were given untreated purchased colostrum (control), and 2 groups of 6 calves received colostrum treated according to both of the above-mentioned methods. No significant differences were found between the test groups and the dam's colostrum group in terms of animal health, IgG uptake in the blood serum, milk, or forage uptake. Two protocols to reduce MAP in colostrum (for use on-farm or at a central location) were developed. Both methods preserve the vital IgG.

A 10-day vacancy period after cleaning and disinfection has no effect on the bacterial load in pig nursery units

BACKGROUND

Biosecurity measures such as cleaning, disinfection and a vacancy period between production cycles on pig farms are essential to prevent disease outbreaks. No studies have tested the effect of a longer vacancy period on bacterial load in nursery units.

METHODS

The present study evaluated the effect of a 10-day vacancy period in pig nursery units on total aerobic flora, Enterococcus spp., Escherichia coli, faecal coliforms and methicillin resistant Staphylococcus aureus (MRSA). Three vacancy periods of 10 days were monitored, each time applied in 3 units. The microbiological load was measured before disinfection and at 1, 4, 7 and 10 days after disinfection.

RESULTS

No significant decrease or increase in E. coli, faecal coliforms, MRSA and Enterococcus spp. was noticed. Total aerobic flora counts were the lowest on day 4 after disinfection (i.e. 4.07 log CFU/625 cm2) (P < 0.05), but the difference with other sampling moments was limited (i.e. 0.6 log CFU/625 cm2) and therefore negligible. Furthermore, this observation on day 4 was not confirmed for the other microbiological parameters. After disinfection, drinking nipples were still mostly contaminated with total aerobic flora (i.e. 5.32 log CFU/625 cm2) and Enterococcus spp. (i.e. 95 % of the samples were positive) (P < 0.01); the feeding troughs were the cleanest location (total aerobic flora: 3.53 log CFU/625 cm2 and Enterococcus spp.: 50 % positive samples) (P < 0.01).

CONCLUSIONS

This study indicates that prolonging the vacancy period in nursery units to 10 days after disinfection with no extra biosecurity measures has no impact on the environmental load of total aerobic flora, E. coli, faecal coliforms, MRSA and Enterococcus spp..

Comparison of competitive exclusion with classical cleaning and disinfection on bacterial load in pig nursery units

Background

Colonisation of the environment of nursery units by pathogenic micro-organisms is an important factor in the persistence and spread of endemic diseases in pigs and zoonotic pathogens. These pathogens are generally controlled by the use of antibiotics and disinfectants. Since an increasing resistance against these measures has been reported in recent years, methods such as competitive exclusion (CE) are promoted as promising alternatives.

Results

This study showed that the infection pressure in CE units after microbial cleaning was not reduced to the same degree as in control units. Despite sufficient administration of probiotic-type spores, the analysed bacteria did not decrease in number after 3 production rounds in CE units, indicating no competitive exclusion. In addition, no differences in feed conversion were found between piglets raised in CE and control units in our study. Also, no differences in faecal consistency (indicator for enteric diseases) was noticed.

Conclusion

These results indicate that the CE protocol is not a valuable alternative for classical C&D.

Case report of Salmonella cross-contamination in a food laboratory

Background

This paper describes a case of Salmonella cross-contamination in a food laboratory. In 2012, chocolate bars shipped from Belgium to the USA were prevented from entering the USA because a Salmonella Rissen strain had been isolated from one of the chocolate bars in a Belgian food laboratory. However, a retrospective study of the Salmonella isolates sent from the laboratory to the Belgian National Reference Laboratory for Salmonella revealed that 7 weeks prior, a Salmonella Rissen strain has been isolated from fish meal in the same food laboratory. The chocolate bars were not expected to be contaminated with Salmonella because the ingredients all tested negative during the production process. Furthermore, because Salmonella Rissen is only rarely isolated from food, it was hypothesized that the two Salmonella Rissen isolates belonged to the same strain and that the second isolation event in this laboratory was caused by cross-contamination. To confirm this hypothesis, both Salmonella Rissen isolates were fingerprinted using different molecular techniques. To evaluate the discriminatory power of the techniques used, 11 other Salmonella Rissen isolates from different origins were included in the comparison. Pulsed-field gel electrophoresis, repetitive element palindromic PCR and three random amplified polymorphic DNA PCR assays were used.

Results

Repetitive element palindromic PCR and random amplified polymorphic DNA PCR assays were insufficiently discriminatory, whereas pulsed-field gel electrophoresis using the combination of two restriction enzymes showed sufficient discrimination to confirm the hypothesis.

Conclusions

Although cross-contamination in food laboratories are rarely reported, cross-contamination can always occur. Laboratories should therefore always be aware of the possibility of cross-contamination, especially when enrichment is used in the microbiological analysis. Furthermore, it is advised that results showing isolates of the same serotype isolated in a short time frame from unrelated food products should be interpreted carefully and should be confirmed with additional strain typing.

Isoepoxydon dehydrogenase (idh) gene expression in relation to patulin production by Penicillium expansum under different temperature and atmosphere

Penicillium expansum growth and patulin production occur mainly at post-harvest stage during the long-term storage of apples. Low temperature in combination with reduced oxygen concentrations is commonly applied as a control strategy to extend apple shelf life and supply the market throughout the year. Our in vitro study investigated the effect of temperature and atmosphere on expression of the idh gene in relation to the patulin production by P. expansum. The idh gene encodes the isoepoxydon dehydrogenase enzyme, a key enzyme in the patulin biosynthesis pathway. First, a reverse transcription real-time PCR (RT-qPCR) method was optimized to measure accurately the P. expansum idh mRNA levels relative to the mRNA levels of three reference genes (18S, β-tubulin, calmodulin), taking into account important parameters such as PCR inhibition and multiple reference gene stability. Subsequently, two P. expansum field isolates and one reference strain were grown on apple puree agar medium (APAM) under three conditions of temperature and atmosphere: 20 °C - air, 4 °C - air and 4 °C - controlled atmosphere (CA; 3% O2). When P. expansum strains reached a 0.5 and 2.0 cm colony diameter, idh expression and patulin concentrations were determined by means of the developed RT-qPCR and an HPLC-UV method, respectively. The in vitro study showed a clear reduction in patulin production and down-regulation of the idh gene expression when P. expansum was grown under 4 °C - CA. The results suggest that stress (low temperature and oxygen level) caused a delay of the fungal metabolism rather than a complete inhibition of toxin biosynthesis. A good correlation was found between the idh expression and patulin production, corroborating that temperature and atmosphere affected patulin production by acting at the transcriptional level of the idh gene. Finally, a reliable RT-qPCR can be considered as an alternative tool to investigate the effect of control strategies on the toxin formation in food.

Comparison of sampling procedures and microbiological and non-microbiological parameters to evaluate cleaning and disinfection in broiler houses

Cleaning and disinfection of the broiler stable environment is an essential part of farm hygiene management. Adequate cleaning and disinfection is essential for prevention and control of animal diseases and zoonoses. The goal of this study was to shed light on the dynamics of microbiological and non-microbiological parameters during the successive steps of cleaning and disinfection and to select the most suitable sampling methods and parameters to evaluate cleaning and disinfection in broiler houses. The effectiveness of cleaning and disinfection protocols was measured in six broiler houses on two farms through visual inspection, adenosine triphosphate hygiene monitoring and microbiological analyses. Samples were taken at three time points: 1) before cleaning, 2) after cleaning, and 3) after disinfection. Before cleaning and after disinfection, air samples were taken in addition to agar contact plates and swab samples taken from various sampling points for enumeration of total aerobic flora, Enterococcus spp., and Escherichia coli and the detection of E. coli and Salmonella. After cleaning, air samples, swab samples, and adenosine triphosphate swabs were taken and a visual score was also assigned for each sampling point. The mean total aerobic flora determined by swab samples decreased from 7.7±1.4 to 5.7±1.2 log CFU/625 cm2 after cleaning and to 4.2±1.6 log CFU/625 cm2 after disinfection. Agar contact plates were used as the standard for evaluating cleaning and disinfection, but in this study they were found to be less suitable than swabs for enumeration. In addition to measuring total aerobic flora, Enterococcus spp. seemed to be a better hygiene indicator to evaluate cleaning and disinfection protocols than E. coli. All stables were Salmonella negative, but the detection of its indicator organism E. coli provided additional information for evaluating cleaning and disinfection protocols. Adenosine triphosphate analyses gave additional information about the hygiene level of the different sampling points.

Assessment of human exposure to 3rd generation cephalosporin resistant E. coli (CREC) through consumption of broiler meat in Belgium

Acquired resistance of Escherichia coli to 3rd generation cephalosporin antimicrobials is a relevant issue in intensive broiler farming. In Belgium, about 35% of the E. coli strains isolated from live broilers are resistant to 3rd generation cephalosporins while over 60% of the broilers are found to be carrier of these 3rd generation cephalosporin resistant E. coli (CREC) after selective isolation. A model aimed at estimating the exposure of the consumer to CREC by consumption of broiler meat was elaborated. This model consists of different modules that simulate the farm to fork chain starting from primary production, over slaughter, processing and distribution to storage, preparation and consumption of broiler meat. Input data were obtained from the Belgian Food Safety agencies' annual monitoring plan and results from dedicated research programs or surveys. The outcome of the model using the available baseline data estimates that the probability of exposure to 1000 colony forming units (cfu) of CREC or more during consumption of a meal containing chicken meat is ca. 1.5%, the majority of exposure being caused by cross contamination in the kitchen. The proportion of CREC (within the total number of E. coli) at primary production and the overall contamination of broiler carcasses or broiler parts with E. coli are dominant factors in the consumer exposure to CREC. The risk of this exposure for human health cannot be estimated at this stage given a lack of understanding of the factors influencing the transfer of cephalosporin antimicrobial resistance genes from these E. coli to the human intestinal bacteria and data on the further consequences of the presence of CREC on human health.

Effect of egg washing on the cuticle quality of brown and white table eggs

Egg washing is currently not permitted within the European Union, with few exceptions. This is mainly because there are concerns that cuticle damage could occur during or after the washing process, as a result of a suboptimal operation. In this study, the cuticle coverage levels of 400 washed or unwashed eggs, derived from either a brown or a white egg-laying flock at the end of lay, were compared. The eggs from older hens inherently have poorer cuticle coverage and as a result arguably constitute a greater risk to consumer safety if they are then washed. Thus, the effects of the washing procedure used in this study on cuticle quality were tested under the worst-case scenario. A standard Swedish egg washing process was used. The cuticle coverage of the eggs was assessed by a colorimeter by quantifying the color difference before and after staining with Tartrazine and Green S. The cuticle of an additional 30 eggs from each of the four groups was then visually assessed by scanning electron microscopy. The staining characteristics of the cuticle varied greatly within each group of eggs and showed that the washing process did not lead to cuticle damage. Scanning electron microscopy confirmed that there was no irreversible damage to the cuticle of the washed eggs and that it was not possible to correctly assign the treatment (washed or not) based on a visual assessment. In conclusion, no evidence could be found to suggest that the washing procedure used in this investigation irreversibly changed the quality of the cuticle.

Sources other than unused sawdust can introduce Klebsiella pneumoniae into dairy herds

A longitudinal study was carried out to detect intramammary infections caused by Klebsiella pneumoniae and to identify potential sources of this bacterial species in the environment of the cows. The study was performed in 6 well-managed Belgian dairy herds from May 2008 to May 2009. Monthly (n=13), unused and used sawdust bedding samples as well as individual quarter milk and feces samples were collected from 10 randomly selected cohort cows in each herd. Cases of clinical mastitis of all lactating cows in the 6 herds were also sampled (n=64). From the 3,518 collected samples, 153 K. pneumoniae isolates were obtained, of which 2 originated from milk (clinical mastitis cases). In feces (n=728), used bedding (n=73), and unused bedding (n=73), respectively, 125 (17.2%), 20 (27.4%), and 6 (8.2%) isolates were found. The isolates were fingerprinted by means of pulsed field gel electrophoresis. In total, 109 different pulsotypes were differentiated, indicating a high degree of genetic diversity within the isolates. All isolates from unused bedding belonged to pulsotypes other than those from the other sources, suggesting that sources other than unused sawdust may introduce K. pneumoniae into the herd. Only 2 pulsotypes contained isolates originating from different sources. Pulsotype 10 was found in milk and used bedding and pulsotype 21 was found in feces and used bedding. The 2 milk isolates originated from 2 cows in the same herd but they belonged to a different pulsotype. The results indicate that K. pneumoniae can be prevalent in the environment without causing significant mastitis problems. Most cows were shedding K. pneumoniae in feces, substantiating findings under very different conditions (i.e., American dairy herds). Contamination of used bedding in the cubicles with K. pneumoniae from feces was confirmed, whereas unused bedding was not an important source of K. pneumoniae for the environment of the cows.

Evaluation of a multiplex-PCR detection in combination with an isolation method for STEC O26, O103, O111, O145 and sorbitol fermenting O157 in food

The aim of the current study was to evaluate a multiplex PCR (mPCR) detection test combined with the evaluation of a previously described isolation method. Minced beef, raw-milk cheese and sprouted seed samples were inoculated with low amounts (7-58 cfu 25 g(-1)) of non-stressed, cold-stressed or freeze-stressed clinical STEC strains, including serogroups O26, O103, O111, O145, sorbitol fermenting (SF) O157 and non-sorbitol fermenting (NSF) O157. The inoculated pathogen was detected using a 24 h-enrichment followed by an mPCR protocol, and in parallel isolated using an enrichment step of 6 and 24 h, followed by selective plating of the enriched broth and selective plating of the immunomagnetic separation (IMS) product. Recovery results were evaluated and compared. Successful mPCR detection and isolation was obtained for non-stressed and cold-stressed STEC cells in minced beef and raw-milk cheese samples, except for serogroups O111 and SF O157. For freeze-stressed cells and sprouted seed samples, false negatives were often found. Isolation was better after 24 h-enrichment compared to 6 h-enrichment. IMS improved in some cases the isolation of non-stressed and cold-stressed cells belonging to serogroups O111 and O157 from minced beef and raw-milk cheese and freeze-stressed cells of all tested serogroups from minced beef.

Dichloran rose-bengal chloramphenicol agar: preferred medium for isolating mycotoxigenic fungal contaminants in silage

This study focuses on selecting an optimal growth medium for isolating mycotoxigenic moulds mainly from maize silage. Therefore, both visually non-mouldy and mouldy samples of maize silage were collected from three farms in Belgium. Additionally, the media were evaluated for one grass silo (mouldy and non-mouldy sample) and two beet pulp silos (mouldy). A statistically significant difference (0.01<P<0.05) between the counts of colony-forming units of moulds on the media was observed for the mouldy maize samples. Dichloran rose-bengal chloramphenicol (DRBC) agar gave high colony count results and high macromorphological diversity for all three silage types. Microscopical and molecular identification experiments showed that Penicillium roqueforti, Penicillium paneum and Aspergillus fumigatus were the most prevalent species, which are all potentially toxigenic fungi. The mycotoxins (roquefortin C, patulin, mycophenolic acid, etc.) impose high risks for animal health and production, as well as for carry-over into animal derived products. In conclusion, DRBC was found to be the medium of choice for isolating and enumerating moulds present in maize silage. The results of this study may serve as a foundation for further research on the increasing problem of mould contamination in silage and may indicate which moulds to focus on in further research regarding mycotoxin contamination of this feed commodity.

Limited genetic diversity and gene expression differences between egg- and non-egg-related Salmonella Enteritidis strains

Salmonella Enteritidis strains of egg- and non-egg-related origin were characterized molecularly to find markers correlated with the egg-contaminating property of Salmonella Enteritidis. Isolates were examined by random amplified polymorphic DNA (RAPD), plasmid profiling and phage typing. Furthermore, the presence of 30 virulence genes was tested by PCR. In genetic fingerprinting and gene content, only small differences between the strains were found and no correlation was observed with the origin (egg-related versus non-egg-related). A major RADP group was present in both egg- and non-egg-related strains, but other smaller RAPD groups were present as well in both categories of strains. Phage types PT4 and PT21 were predominant. Differential mRNA expression levels of fimA and agfA under conditions of growth simulating the conditions during egg formation were determined by real-time RT-PCR. Although differences in fimA and agfA expression levels were observed between the strains, these could not be correlated with the origin of the strains (egg-related versus non-egg-related). The highest expression levels of agfA and fimA were only found in two non-egg-related strains, which seemed to be correlated with the presence of a 93 kb plasmid instead of the 60 kb virulence plasmid. Our results seem to indicate only a limited role for at least type I fimbriae (encoded by fim operon) in egg contamination by Salmonella Enteritidis.

Quantification of Campylobacter spp. in chicken carcass rinse by real-time PCR

AIMS

In this study, a real-time quantitative polymerase chain reaction (PCR) method was examined for its ability to quantify Campylobacter spp. in chicken carcass rinses and compared with bacteriological culturing.

METHODS AND RESULTS

The linearity of the real-time PCR quantification protocol was assessed on pure DNA. The amplification efficiency was 100% and the square regression coefficient (R(2)) was 0.998. Quantification was linear over at least 7 log units. Using a crude cell lysate gave the highest sensitivity and the detection limit of the method was 3.3 log CFU per carcass. The statistical correlation between the bacteriological enumeration and the real-time quantitative (Q)-PCR determined using chicken carcasses sampled at the end of the slaughter line was 0.733. The difference in detection levels was probably because of the detection of stressed, dead or viable but not culturable cells by Q-PCR.

CONCLUSION

The real-time Q-PCR method described in this study is a powerful tool for determining the number of Campylobacter cells on carcasses.

SIGNIFICANCE AND IMPACT OF THE STUDY

The real-time Q-PCR method is available to quantify the Campylobacter contamination at the slaughterhouse level and could be used to evaluate primary production.

Characterization of virulence properties of Listeria monocytogenes serotype 4b strains of different origins

In this study, the virulence heterogeneity of Listeria monocytogenes serotype 4b strains of different origins was analysed on different levels. On one hand, the survival of L. monocytogenes strains in synthetic gastric fluid was studied. On the other hand, the pathogenic potential of strains with different inlB expression levels was analysed in an A/J mouse model for gastrointestinal listeriosis. Differences in survival capacity in gastric fluid and in in vivo virulence potential were observed between the tested strains. No clear correlation between the origin and the obtained data could be made. However, these results confirm the existence of heterogeneity in virulence potential of L. monocytogenes serotype 4b strains.