A five-gene qPCR signature can classify type 2 asthma comparably to microscopy of induced sputum from severe asthma patients

Asthma is a heterogenous disease characterized by airway inflammation and variable expiratory airflow limitation resulting in variable respiratory symptoms. Characterization of airway inflammation is important to choose the optimal treatment for severe asthma patients eligible for biological treatment. However, counting cells in induced sputum samples are a time-consuming process, highly dependent on personal skills. Replacing eosinophil and neutrophil cell counting with qPCR for transcripts of selected mast cell, and basophil genes may provide more reproducible results.

Aims

The objective of this study was to compare qPCR with microscopy in asthma endotyping.

Methods

A qPCR method measuring five mast cell/basophil genes was applied on induced sputum samples from 30 severe asthma patients and compared with microscopy. Target gene Ct-values (CPA3, GATA2, HDC, MS4A2, TPSAB1/TPSB2) were referenced to household β-actin Ct values as a measure of relative mRNA abundance of the target in each sample. Target/β-actin-ratios in eosinophilic and non-eosinophilic groups determined by microscopy with an eosinophil threshold of 3% in 400 cells were compared using Mann-Whitney U Test. Spearman´s correlations were used to test for correlation between targets vs. FENO and targets vs. blood eosinophil counts.

Results

The study demonstrated a statistical difference in relative mRNA abundance for four mast cell/basophil specific genes. CPA3, GATA2, HDC and MS4A2 were elevated in eosinophilic asthma versus non-eosinophilic asthma patients. The study found that GATA2, CPA3, MS4A2 and TPSAB1/TPSB2 transcripts are positively correlated with FENO. Neither the five mast cell genes nor the five-gene signature correlated with blood eosinophils. The five-gene signature with a target/β-actin-ratio cut-off ≥2 generated sensitivity = 87%, specificity = 94%, NPV = 88% and PPV = 92% compared to microscopy.

Conclusion

This study confirms the contribution of mast cells in the pathogenesis of EA and suggests that mast cell mRNA markers could be one of the biomarkers used to identify EA.

Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans

IMPORTANCE

Intracellular calcium signaling plays an important role in the resistance and adaptation to stresses encountered by fungal pathogens within the host. This study reports the optimization of the GCaMP fluorescent calcium reporter for live-cell imaging of dynamic calcium responses in single cells of the pathogen, Candida albicans, for the first time. Exposure to membrane, osmotic or oxidative stress generated both specific changes in single cell intracellular calcium spiking and longer calcium transients across the population. Repeated treatments showed that calcium dynamics become unaffected by some stresses but not others, consistent with known cell adaptation mechanisms. By expressing GCaMP in mutant strains and tracking the viability of individual cells over time, the relative contributions of key signaling pathways to calcium flux, stress adaptation, and cell death were demonstrated. This reporter, therefore, permits the study of calcium dynamics, homeostasis, and signaling in C. albicans at a previously unattainable level of detail.

Comparative Effectiveness Analyses of Salvage Prostatectomy and Salvage Radiotherapy Outcomes Following Focal or Whole-Gland Ablative Therapy (High-Intensity Focused Ultrasound, Cryotherapy or Electroporation) for Localised Prostate Cancer

AIMS

Ablative therapy, such as focal therapy, cryotherapy or electroporation, aims to treat clinically significant prostate cancer with reduced treatment-related toxicity. Up to a third of patients may require further local salvage treatment after ablative therapy failure. Limited descriptive, but no comparative, evidence exists between different salvage treatment outcomes. The aim of this study was to compare oncological and functional outcomes after salvage robot-assisted radical prostatectomy (SRARP) and salvage radiotherapy (SRT).

MATERIALS AND METHODS

Data were collected prospectively and retrospectively on 100 consecutive SRARP cases and 100 consecutive SRT cases after ablative therapy failure in a high-volume tertiary centre.

RESULTS

High-risk patients were over-represented in the SRARP group (66.0%) compared with the SRT group (48.0%) (P = 0.013). The median (interquartile range) follow-up after SRARP was 16.5 (10.0-30.0) months and 37.0 (18.5-64.0) months after SRT. SRT appeared to confer greater biochemical recurrence-free survival at 1, 2 and 3 years compared with SRARP in high-risk patients (year 3: 86.3% versus 66.0%), but biochemical recurrence-free survival was similar for intermediate-risk patients (year 3: 90.0% versus 75.6%). There was no statistical difference in pad-free continence at 12 and 24 months between SRARP (77.2 and 84.7%) and SRT (75.0 and 74.0%) (P = 0.724, 0.114). Erectile function was more likely to be preserved in men who underwent SRT. After SRT, cumulative bowel and urinary Radiation Therapy Oncology Group toxicity grade I were 25.0 and 45.0%, grade II were 11.0 and 11.0% and grade III or IV complications were 4.0 and 5.0%, respectively.

CONCLUSION

We report the first comparative analyses of salvage prostatectomy and radiotherapy following ablative therapy. Men with high-risk disease appear to have superior oncological outcomes after SRT; however, treatment allocation does not appear to influence oncological outcomes for men with intermediate-risk disease. Treatment allocation was associated with a different spectrum of toxicity profile. Our data may inform shared decision-making when considering salvage treatment following focal or whole-gland ablative therapy.

734 Evaluation of A Webinar Based Surgical Teaching Course (EDUCATE) - A Prospective Cohort Study

Aim

Anecdotal evidence suggests Foundation Year (FY) doctors start surgical rotations with less confidence than medical rotations. The study aimed to determine the effect of a national webinar-based surgical teaching course on participants’ confidence, and to assess attitudes surrounding undergraduate surgical education.

Method

This prospective cohort study is reported with reference to STROBE guidelines and received ethical approval. A series of 15 free-access webinars was developed based on the Royal College of Surgeons Undergraduate Curriculum. An expert-validated questionnaire was used to collect data before and after the course. Inclusion criteria were UK-based medical students and FY doctors who attended at least one webinar. The primary outcome was confidence in completing common tasks during surgical rotations.

Results

Completed pre-course (484) and post-course (352) questionnaires yielded 92 paired samples (63% female). 85% were medical students, representing 29 UK universities, and 15% FY doctors. Mean confidence in assessing, investigating, and implementing initial management of surgical conditions was greater after the intervention (p ≤ 0.001). Mean confidence in managing on-call tasks and starting a surgical FY job was also higher post-course greater (p ≤ 0.001). These improvements correlated with webinar attendance (p ≤ 0.05). 27.1% of participants were satisfied with the quality of undergraduate surgical education. 22.9% agreed that surgical placements prepared them well to manage surgical tasks.

Conclusions

Medical students and FY doctors report low confidence and feel unprepared in managing surgical tasks. Additionally, they report poor satisfaction with undergraduate surgical education. This shortfall may be improved through delivery of a national, accessible, targeted online webinar series and curriculum.

141 New Guidelines to Reduce Unnecessary Blood Tests, Delayed Discharge and Costs Following Robot Assisted Radical Prostatectomy

Objectives

Routine postoperative blood tests (POBT) following robot assisted radical prostatectomy (RARP) are used to evaluate the impact of surgery on pre-existing co-morbidities and to detect early complications. This practice dates back to an era of open surgery, when blood loss and complication rates were higher. We propose new guidelines to improve the specificity of POBT.

Method

The cases of 1040 consecutive patients who underwent a primary or salvage RARP at two large tertiary urology centres in the United Kingdom were retrospectively reviewed to form new guidelines. The new guidelines were prospectively validated in a sample of 300 patients.

Results

Derivation Dataset: 3% and 5% had intra- and post-operative Clavien-Dindo complications, respectively. 15% had clinical concerns postoperatively. 0.9% required perioperative transfusion. 78% had routine blood tests without clinical concerns, none of whom developed a complication. 98% of complications were suspected by clinical judgement. 6% of patients had a discharge delay of ≥ 1 day due to delayed or incomplete blood tests. Validation Dataset: No significant difference existed in complication, clinical concern or transfusion rates between the derivation and validation datasets. Number of POBT requested reduced by 73% (p < 0.001). The new guidelines improved POBT sensitivity for complications from 98% to 100% and specificity from 0% to 74%. Discharge delays reduced from 6% to 0% (p = 0.008). Cost savings were £178 per patient.

Conclusions

Postoperative complications and transfusion following RARP are rare. Routine POBT without clinical indication are unnecessary and inefficient. A guideline-based approach to POBT can reduce costs and optimise discharge without compromising patient safety or care.

283 Salvage Versus Primary Robot-Assisted Radical Prostatectomy: A Propensity-Matched Comparative Effectiveness Study from A High-Volume Tertiary Centre

Aim

Salvage Robot-Assisted Radical Prostatectomy (sRARP) is a potential treatment option for locally recurrent Prostate Cancer after non-surgical primary treatment. There are minimal data comparing outcomes between propensity-matched salvage and primary Robot-Assisted Radical Prostatectomy (RARP). We compare perioperative, oncological, and functional outcomes of sRARP with primary RARP and between sRARP post-whole and focal gland therapy.

Method

1:1 propensity-matched comparison of 146 sRARP with primary RARP from a cohort of 3,852 consecutive patients from a high-volume tertiary centre.

Results

There were no significant differences in patient characteristics between the salvage and primary RARP groups. Grade III-V Clavien-Dindo complication rates were 1.3% and 0% in the salvage and primary groups, respectively (p = 0.310). Median (IQR) follow-up was 16 (10,30) and 21 (13,33) months in the salvage and primary groups, respectively. BCR rates were 30.8% and 13.7% in the salvage and primary groups, respectively (p < 0.001). Pad-free continence rates were 79.1% and 85.4% at two years in the salvage and primary groups, respectively (p = 0.160). ED rates were 95.2% and 77.4% in the salvage and primary groups, respectively (p < 0.001). Comparing the whole gland and focal gland groups, BCR rates were 33.3% and 29.1%, respectively (p = 0.687), pad-free continence rates were 66% and 89.3%, respectively (p = 0.001), and ED rates were 98.3% and 93%, respectively (p = 0.145).

Conclusions

SRARP has similar perioperative but inferior oncological outcomes to primary RARP. Continence rates are similar to primary RARP, but potency is worse. Perioperative and oncological outcomes of sRARP after focal gland therapy are similar but continence outcomes are superior compared to sRARP after whole gland therapy.

81 VIRTUAL: Virtual Interactive Surgical Skills Classroom – An Ongoing Randomized Controlled Trial

Introduction

High costs and inaccessibility are significant barriers to face-to-face basic surgical skills (BSS) training. Virtual classrooms enable the combination of computer-based learning with interactive expert instruction. They may optimise resources and increase accessibility, facilitating larger-scale training with a similar educational benefit. We aim to evaluate the efficacy of virtual BSS classroom training compared to both non-interactive video and face-to-face teaching.

Method

72 medical students will be randomly assigned to three equal intervention groups based on year group and surgical skill confidence. Interventions will be implemented following an instructional video. Group A will practice independently, Group B will receive face-to-face training, and Group C will attend a virtual classroom. Participants will be recorded placing three interrupted sutures with hand tied knots pre- and post-intervention, and Objective Structured Assessment of Technical Skills (OSATS) will be blind marked by two experts. Change in confidence, time to completion and a granular performance score will also be measured. Each intervention’s feasibility and accessibility will be assessed.

Results

Data collection will be completed in January 2021. Significant improvement in OSATS within groups will be indicative of intervention quality. Difference in improvement between groups will determine the relative performance of the interventions.

Conclusions

To our knowledge, this will be the largest randomised control trial investigating virtual BSS classroom training. It will serve as a comprehensive appraisal of the virtual classroom’s suitability as an alternative to face-to-face training. The findings will assist the development and implementation of further resource-efficient training programs during the COVID-19 pandemic and in the future.

1420 ViRtual prOficiency Based prOgression for Robotic Training (VROBOT): A Prospective Cohort Study Protocol

Introduction

Robotic surgery is an evolving field that requires specialist training. Historically, robotic surgery training has lacked standardisation. Recently, training centres have introduced proficiency-based modules and curriculums to certify and progress the skills of novice robotic surgeons. However, training tends to be self-directed and non-interactive. Limited interactive teaching does exist but can be inaccessible and expensive. We aim to validate the effectiveness of the current Fundamentals of Robotic Surgery (FRS) training curriculum with the addition of interactive virtual classroom teaching.

Method

16 novice surgical trainees will be assigned to two training groups. The interventions will be implemented following a one-week robotic skills induction. Both groups will receive access to the FRS curriculum for one week. The intervention group will additionally receive virtual classroom robotic skills training. The primary outcome will be the objective performance scores after training using a synthetic model based on task errors, time taken and contact pressure. In week 3, each group will receive the alternate intervention and objective performance scores will be measured to determine the trajectory of scores.

Results

Significant objective performance improvement following the intervention will be indicative of intervention quality.

Conclusions

This will be the first feasibility study evaluating the efficacy of interactive virtual robotic surgery training. It will determine the effect size of virtual classroom training on the development of basic robotic surgical skills in addition to the proficiency-based FRS curriculum. The findings will assist the development and implementation of further resource-efficient virtual robotic surgical skills training programs.

O43 Virtual: virtual interactive surgical skills classroom: a randomized controlled trial (protocol)

Introduction

High costs and inaccessibility are significant barriers to face-to-face basic surgical skills (BSS) training. Virtual classrooms enable the combination of computer-based learning with interactive expert instruction. They may optimise resources and increase accessibility, facilitating larger-scale training with a similar educational benefit. We aim to evaluate the efficacy of virtual BSS classroom training compared to both non-interactive video and face-to-face teaching.

Method

72 medical students will be randomly assigned to three equal intervention groups based on surgical skills experience and confidence. Interventions will be implemented following an instructional video. Group A will practice independently, Group B will receive face-to-face training, and Group C will attend a virtual classroom. Participants will be recorded placing three interrupted sutures with hand tied knots pre- and post-intervention. Objective Structured Assessment of Technical Skills (OSATS) will be blind marked by two experts.

Result

Change in confidence, time to completion and a novel granular performance score will also be measured. Each intervention’s feasibility and accessibility will be assessed. Significant improvement in OSATS within groups will be indicative of intervention quality. Difference in improvement between groups will determine the relative performance of the interventions.

Conclusion

This will be the largest randomised control trial investigating virtual BSS classroom training. It will serve as a comprehensive appraisal of the suitability of virtual classrooms as an alternative to face-to-face training. The findings will assist the development and implementation of further resource-efficient training programs during the COVID-19 pandemic and beyond.

Take-home Message

This is the first RCT assessing virtual basic surgical skill classroom training and serves as a comprehensive appraisal of the suitability of virtual classrooms as an alternative to face-to-face training. The findings will assist the development and implementation of further resource-efficient training programs during the COVID-19 pandemic and in the future.

O50 New guidelines to reduce unnecessary blood tests, delayed discharge and costs following robot assisted radical prostatectomy

Introduction

Routine postoperative blood tests (POBT) are used to evaluate the impact of surgery on pre-existing co-morbidities and to detect early complications. This practice dates back to an era of open surgery, when blood loss and complication rates were higher. We propose new guidelines to improve the specificity of POBT.

Method

The cases of 1040 consecutive patients who underwent a primary or salvage RARP at two large tertiary urology centres in the United Kingdom were retrospectively reviewed, and new guidelines were designed. The guidelines were prospectively validated in a cohort of 300 patients.

Result

Derivation Dataset 3% and 5% had intra- and post-operative Clavien-Dindo complications, respectively. 15% had clinical concerns postoperatively. 0.9% required perioperative transfusion. 78% had routine blood tests without clinical concerns, none of whom developed a complication. 98% of complications were suspected by clinical judgement. 6% of patients had a discharge delay of ≥ 1 days due to delayed or incomplete blood tests.

Validation Dataset No significant difference existed in complication, clinical concern or transfusion rates between the derivation and validation datasets. New guidelines improved sensitivity for complications from 98% to 100% and specificity from 0% to 74%. The number of blood tests requested reduced by 73% (P < 0.001). Discharge delays reduced from 6% to 0% (P = 0.008). Cost savings were £178 per patient.

Conclusion

Postoperative complications and transfusion following RARP are rare. Routine POBT without clinical indication are unnecessary and inefficient. A guideline-based approach to POBT can reduce costs and optimise discharge without compromising patient safety or care.

Take-home Message

Routine postoperative blood tests following robot assisted radical prostatectomy are often unnecessary. A guideline-based approach can reduce costs and optimise patient care.

429 National Evaluation of Confidence and Preparedness for Surgical Rotations in Medical Students and Foundation Year Doctors

Introduction

Limited published and anecdotal evidence suggests foundation year (FY) doctors start their surgical rotations with lower confidence than medical rotations. This may be due to insufficient undergraduate practical teaching related to common surgical rotations. This study aimed to evaluate the confidence and preparedness for surgical rotations of medical students and FY doctors.

Method

An expert-validated questionnaire was distributed nationally to UK medical students and FY doctors. The primary outcome was confidence in completing common tasks during surgical rotations.

Results

491 participants (84% medical students, 16% FYs) were recruited from 36 UK medical schools. 80% were likely to pursue a career in surgery however only 7% felt confident about starting a surgical FY job. 66% felt neutral or unsatisfied about the quality of medical school surgical teaching, and 80% indicated that placements did not prepare them well to manage common FY surgical tasks. The internal reliability of the questionnaire was high (=0.939).

Conclusions

Medical students and FY doctors lack confidence and preparation for surgical jobs. High-quality, practically grounded educational courses such as the National Surgical Teaching Society (NSTS) webinar curriculum could improve confidence and preparedness for surgical rotations. Further research evaluating the benefits of such courses is warranted.

Detection and Identification of Bacillus cereus, Bacillus cytotoxicus, Bacillus thuringiensis, Bacillus mycoides and Bacillus weihenstephanensis via Machine Learning Based FTIR Spectroscopy

The Bacillus cereus group comprises genetical closely related species with variable toxigenic characteristics. However, detection and differentiation of the B. cereus group species in routine diagnostics can be difficult, expensive and laborious since current species designation is linked to specific phenotypic characteristic or the presence of species-specific genes. Especially the differentiation of Bacillus cereus and Bacillus thuringiensis, the identification of psychrotolerant Bacillus mycoides and Bacillus weihenstephanensis, as well as the identification of emetic B. cereus and Bacillus cytotoxicus, which are both producing highly potent toxins, is of high importance in food microbiology. Thus, we investigated the use of a machine learning approach, based on artificial neural network (ANN) assisted Fourier transform infrared (FTIR) spectroscopy, for discrimination of B. cereus group members. The deep learning tool box of Matlab was employed to construct a one-level ANN, allowing the discrimination of the aforementioned B. cereus group members. This model resulted in 100% correct identification for the training set and 99.5% correct identification overall. The established ANN was applied to investigate the composition of B. cereus group members in soil, as a natural habitat of B. cereus, and in food samples originating from foodborne outbreaks. These analyses revealed a high complexity of B. cereus group populations, not only in soil samples but also in the samples from the foodborne outbreaks, highlighting the importance of taking multiple isolates from samples implicated in food poisonings. Notable, in contrast to the soil samples, no bacteria belonging to the psychrotolerant B. cereus group members were detected in the food samples linked to foodborne outbreaks, while the overall abundancy of B. thuringiensis did not significantly differ between the sample categories. None of the isolates was classified as B. cytotoxicus, fostering the hypothesis that the latter species is linked to very specific ecological niches. Overall, our work shows that machine learning assisted (FTIR) spectroscopy is suitable for identification of B. cereus group members in routine diagnostics and outbreak investigations. In addition, it is a promising tool to explore the natural habitats of B. cereus group, such as soil.

Staphylococcus aureus Entrance into the Dairy Chain: Tracking S. aureus from Dairy Cow to Cheese

Staphylococcus aureus is one of the most important contagious mastitis pathogens in dairy cattle. Due to its zoonotic potential, control of S. aureus is not only of great economic importance in the dairy industry but also a significant public health concern. The aim of this study was to decipher the potential of bovine udder associated S. aureus as reservoir for S. aureus contamination in dairy production and processing. From 18 farms, delivering their milk to an alpine dairy plant for the production of smeared semi-hard and hard cheese. one thousand hundred seventy six one thousand hundred seventy six quarter milk (QM) samples of all cows in lactation (n = 294) and representative samples form bulk tank milk (BTM) of all farms were surveyed for coagulase positive (CPS) and coagulase negative Staphylococci (CNS). Furthermore, samples from different steps of the cheese manufacturing process were tested for CPS and CNS. As revealed by chemometric-assisted FTIR spectroscopy and molecular subtyping (spa typing and multi locus sequence typing), dairy cattle represent indeed an important, yet underreported, entrance point of S. aureus into the dairy chain. Our data clearly show that certain S. aureus subtypes are present in primary production as well as in the cheese processing at the dairy plant. However, although a considerable diversity of S. aureus subtypes was observed in QM and BTM at the farms, only certain S. aureus subtypes were able to enter and persist in the cheese manufacturing at the dairy plant and could be isolated from cheese until day 14 of ripening. Farm strains belonging to the FTIR cluster B1 and B3, which show genetic characteristics (t2953, ST8, enterotoxin profile: sea/sed/sej) of the recently described S. aureus genotype B, most successfully contaminated the cheese production at the dairy plant. Thus, our study fosters the hypothesis that genotype B S. aureus represent a specific challenge in control of S. aureus in the dairy chain that requires effective clearance strategies and hygienic measures already in primary production to avoid a potential transfer of enterotoxic strains or enterotoxins into the dairy processing and the final retail product.

Collaborative survey on the colonization of different types of cheese-processing facilities with Listeria monocytogenes

Cross-contamination via equipment and the food-processing environment has been implicated as the main cause of Listeria monocytogenes transmission. The aim of this study, therefore, was to determine the occurrence and potential persistence of L. monocytogenes in 19 European cheese-processing facilities. A sampling approach in 2007-2008 included, respectively, 11 and two industrial cheese producers in Austria and the Czech Republic, as well as six Irish on-farm cheese producers. From some of the producers, isolates were available from sampling before 2007. All isolates from both periods were included in a strain collection consisting of 226 L. monocytogenes isolates, which were then typed by serotyping and pulsed-field gel electrophoresis (PFGE). In addition, metabolic fingerprints from a subset of isolates were obtained by means of Fourier-transform infrared (FTIR) spectroscopy. PFGE typing showed that six processing environments were colonized with seven persistent PFGE types of L. monocytogenes. Multilocus sequence typing undertaken on representatives of the seven persisting PFGE types grouped them into distinct clades on the basis of country and origin; however, two persistent strains from an Austrian and an Irish food processor were shown to be clonal. It was concluded that despite the fact that elaborate Hazard Analysis and Critical Control Point concepts and cleaning programs are applied, persistent occurrence of L. monocytogenes can take place during cheese making. L. monocytogenes sanitation programs could be strengthened by including rapid analytical tools, such as FTIR, which allow prescreening of potentially persistent L. monocytogenes contaminants.

An increase in serum tryptase even below 11.4 ng/mL may indicate a mast cell-mediated hypersensitivity reaction: a prospective study in Hymenoptera venom allergic patients

BACKGROUND

During a systemic hypersensitivity reaction (SR), an increase in serum tryptase compared to the baseline value is an indicator of mast cell activation, most often due to an IgE-mediated mechanism.

OBJECTIVE

To study the relevance of an increase in serum tryptase below the upper normal value of 11.4 ng/mL.

METHODS

Serum tryptase levels were measured in 35 patients with Hymenoptera venom hypersensitivity before and during venom exposure. Of these, 20 developed SR to stings or following venom injections during immunotherapy (reactors), while 15 tolerated reexposure to stings or venom injections during immunotherapy without SR (non-reactors). Serum tryptase was estimated at 2, 5 and 24 h after exposure and was compared to a baseline value obtained before or at least 72 h after exposure.

RESULTS

Considering circadian variation of serum tryptase, a relative increase to ≥135% of the baseline value (relative delta bound) was defined to indicate mast cell activation. Such an increase was observed in 17 of 20 reactors (85%), but none of 15 non-reactors. A serum tryptase of ≥11.4 ng/mL following venom exposure was observed in eight of the 20 reactors (40%) and 2 (13.3%) of the 15 non-reactors. Both these non-reactors also had an elevated baseline serum tryptase.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum tryptase values obtained during a suspected hypersensitivity reaction must always be compared to a baseline value. A relative tryptase increase to ≥135% of the baseline value during a suspected hypersensitivity reaction indicates mast cell activation even below 11.4 ng/mL.

Shift from farm to dairy tank milk microbiota revealed by a polyphasic approach is independent from geographical origin

Detailed information on the natural microbial community present in raw milk, especially on the non-cultivable part of the milk microbiota, is rather limited as research in the past mainly focused on the detection of bacterial pathogens or microorganisms responsible for the deterioration of raw milk. In frame of the EU project BIOtracer raw milk samples from three different European countries were analyzed to gain a deeper insight into the diversity of the natural bacterial flora of raw milk by combining culture-dependent and -independent methods. Fourier-transform infrared (FTIR) spectroscopy was used as rapid and cost efficient metabolic fingerprinting technique to monitor the cultivable microbiota of raw milk. In addition, direct sequencing was applied to acquire additional information on the non-cultivable part of the bacterial raw milk flora. Subsequent performed biostatistical analysis revealed a high correlation between the data gathered by culture-dependent and independent methods. Both methods revealed significant differences between the microbiota of farm and dairy tank milk, which appeared to be rather independent from geographical regions. Based on the results from FTIR and direct sequencing, the predominant bacterial raw milk flora was determined, representative isolates were selected and two model floras, representative for farm tank milk and dairy bulk tank milk, were compiled. These bacterial model floras for raw milk are now available for the Biotracer partners and can be used for validation purposes or contamination scenarios. The knowledge gained on the variation range of the normal raw milk microbiota will help to identify raw milk with divergent microbiota, pointing towards potential pathogen contaminations.

A multiplex real-time PCR for identifying and differentiating B. anthracis virulent types

Bacillus anthracis is closely related to the endospore forming bacteria Bacillus cereus and Bacillus thuringiensis. For accurate detection of the life threatening pathogen B. anthracis, it is essential to distinguish between these three species. Here we present a novel multiplex real-time PCR for simultaneous specific identification of B. anthracis and discrimination of different B. anthracis virulence types. Specific B. anthracis markers were selected by whole genome comparison and different sets of primers and probes with optimal characteristic for multiplex detection of the B. anthracis chromosome, the B. anthracis pXO1 and pXO2 plasmids and an internal control (IC) were designed. The primer sets were evaluated using a panel of B. anthracis strains and exclusivity was tested using genetically closely related B. cereus strains. The robustness of final primer design was evaluated by laboratories in three different countries using five different real-time PCR thermocyclers. Testing of a panel of more than 20 anthrax strains originating from different locations around the globe, including the recent Swedish anthrax outbreak strain, showed that all strains were detected correctly.

Evaluation of Bacillus strains as model systems for the work on Bacillus anthracis spores

Available strain collections of Bacillus anthracis and Bacillus cereus were screened for B. cereus strains sharing major genotypic characteristics with B. anthracis. Based on the comparison of partial spoIIIAB sequences, whole genome sequences and MLST, a strain set representing different lineages including candidate model strains for B. anthracis was compiled. Spores from the selected strain set and two B. anthracis strains were prepared according to a newly optimized protocol transferable to biosafety level-3 (BSL3) conditions and phenotypic characteristics including scanning electron microscopy (SEM), heat inactivation, and germination were evaluated. Two B. cereus isolates were identified that were genetically related to B. anthracis and showed high similarity to B. anthracis spores in their heat inactivation profile and their response to the germinants l-alanine and inosine. In addition, these isolates were also mimicking B. anthracis on modified PLET, a selective plating medium for B. anthracis, and shared various other biochemical characteristics with B. anthracis. Therefore these two strains are not only appropriate models for B. anthracis in experiments based on spore characteristics but also in trials working with plating media. These two strains are now used within the BIOTRACER consortium as validated models for B. anthracis and will facilitate the development and optimization of tracing and detection systems for B. anthracis in the food and feed chain.

Prevalence of emetic Bacillus cereus in different ice creams in Bavaria

In this study, 809 samples of ice cream from different sources were investigated by using cultural methods for the presence of presumptive Bacillus cereus. Isolates from culture-positive samples were examined with a real-time PCR assay targeting a region of the cereulide synthetase gene (ces) that is highly specific for emetic B. cereus strains. The samples were collected from ice cream parlors and restaurants that produced their own ice cream and from international commercial ice cream companies in different regions of Bavaria during the summer of 2008. Presumptive B. cereus was found in 508 (62.7%) ice cream samples investigated, and 24 (4.7%) of the isolates had the genetic background for cereulide toxin production. The level of emetic B. cereus in the positive samples ranged from 0.1 to 20 CFU/g of ice cream.

A novel therapeutic option in Cogan diseases? TNF-alpha blockers

Cogan's syndrome is characterized by noninfectious, interstitial keratitis combined with a vestibulo-auditory deficit. Despite therapy with corticosteroids in combination with immunosuppressive agents, relapses occurred in two subjects and the clinical course suggested a progression of the disease. Treatment with anti-TNF-alpha was started leading to a rapid and sustained clinical remission for over 2 respectively 3 years.

Diagnostic real-time PCR assays for the detection of emetic Bacillus cereus strains in foods and recent food-borne outbreaks

Cereulide-producing Bacillus cereus can cause an emetic type of food-borne disease that mimics the symptoms provoked by Staphylococcus aureus. Based on the recently discovered genetic background for cereulide formation, a novel 5' nuclease (TaqMan) real-time PCR assay was developed to provide a rapid and sensitive method for the specific detection of emetic B. cereus in food. The TaqMan assay includes an internal amplification control and primers and a probe designed to target a highly specific part of the cereulide synthetase genes. Additionally, a specific SYBR green I assay was developed and extended to create a duplex SYBR green I assay for the one-step identification and discrimination of the two emesis-causing food pathogens B. cereus and S. aureus. The inclusivity and exclusivity of the assay were assessed using a panel of 100 strains, including 23 emetic B. cereus and 14 S. aureus strains. Different methods for DNA isolation from artificially contaminated foods were evaluated, and established real-time assays were used to analyze two recent emetic food poisonings in southern Germany. One of the food-borne outbreaks included 17 children visiting a day care center who vomited after consuming a reheated rice dish, collapsed, and were hospitalized; the other case concerned a single food-poisoning incident occurring after consumption of cauliflower. Within 2 h, the etiological agent of these food poisonings was identified as emetic B. cereus by using the real-time PCR assay.

Toxin gene profiling of enterotoxic and emetic Bacillus cereus

Very different toxins are responsible for the two types of gastrointestinal diseases caused by Bacillus cereus: the diarrhoeal syndrome is linked to nonhemolytic enterotoxin NHE, hemolytic enterotoxin HBL, and cytotoxin K, whereas emesis is caused by the action of the depsipeptide toxin cereulide. The recently identified cereulide synthetase genes permitted development of a molecular assay that targets all toxins known to be involved in food poisoning in a single reaction, using only four different sets of primers. The enterotoxin genes of 49 strains, belonging to different phylogenetic branches of the B. cereus group, were partially sequenced to encompass the molecular diversity of these genes. The sequence alignments illustrated the high molecular polymorphism of B. cereus enterotoxin genes, which is necessary to consider when establishing PCR systems. Primers directed towards the enterotoxin complex genes were located in different CDSs of the corresponding operons to target two toxin genes with one single set of primers. The specificity of the assay was assessed using a panel of B. cereus strains with known toxin profiles and was successfully applied to characterize strains from food and clinical diagnostic labs as well as for the toxin gene profiling of B. cereus isolated from silo tank populations.

Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group

One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains were classified into three groups: emetic toxin (cereulide)-producing strains (n=17), strains connected to diarrheal foodborne outbreaks (n=40) and food-environment strains (n=43), these latter not producing the emetic toxin. Our study revealed a shift in growth limits towards higher temperatures for the emetic strains, regardless of their origin. None of the emetic toxin-producing strains were able to grow below 10 degrees Celsius. In contrast, 11% (9 food-environment strains) out of the 83 non-emetic toxin-producing strains were able to grow at 4 degrees Celsius and 49% at 7 degrees Celsius (28 diarrheal and 13 food-environment strains). non-emetic toxin-producing strains. All emetic toxin-producing strains were able to grow at 48 degrees Celsius, but only 39% (16 diarrheal and 16 food-environment strains) of the non-emetic toxin-producing strains grew at this temperature. Spores from the emetic toxin-producing strains showed, on average, a higher heat resistance at 90 degrees Celsius and a lower germination, particularly at 7 degrees Celsius, than spores from the other strains. No difference between the three groups in their growth kinetics at 24 degrees Celsius, 37 degrees Celsius, and pH 5.0, 7.0, and 8.0 was observed. Our survey shows that emetic toxin-producing strains of B. cereus have distinct characteristics, which could have important implication for the risk assessment of the emetic type of B. cereus caused food poisoning. For instance, emetic strains still represent a special risk in heat-processed foods or preheated foods that are kept warm (in restaurants and cafeterias), but should not pose a risk in refrigerated foods.

Cereulide synthetase gene cluster from emetic Bacillus cereus: structure and location on a mega virulence plasmid related to Bacillus anthracis toxin plasmid pXO1

BACKGROUND

Cereulide, a depsipeptide structurally related to valinomycin, is responsible for the emetic type of gastrointestinal disease caused by Bacillus cereus. Recently, it has been shown that this toxin is produced by a nonribosomal peptide synthetase (NRPS), but its exact genetic organization and biochemical synthesis is unknown.

RESULTS

The complete sequence of the cereulide synthetase (ces) gene cluster, which encodes the enzymatic machinery required for the biosynthesis of cereulide, was dissected. The 24 kb ces gene cluster comprises 7 CDSs and includes, besides the typical NRPS genes like a phosphopantetheinyl transferase and two CDSs encoding enzyme modules for the activation and incorporation of monomers in the growing peptide chain, a CDS encoding a putative hydrolase in the upstream region and an ABC transporter in the downstream part. The enzyme modules responsible for incorporation of the hydroxyl acids showed an unusual structure while the modules responsible for the activation of the amino acids Ala and Val showed the typical domain organization of NRPS. The ces gene locus is flanked by genetic regions with high homology to virulence plasmids of B. cereus, Bacillus thuringiensis and Bacillus anthracis. PFGE and Southern hybridization showed that the ces genes are restricted to emetic B. cereus and indeed located on a 208 kb megaplasmid, which has high similarities to pXO1-like plasmids.

CONCLUSION

The ces gene cluster that is located on a pXO1-like virulence plasmid represents, beside the insecticidal and the anthrax toxins, a third type of B. cereus group toxins encoded on megaplasmids. The ces genes are restricted to emetic toxin producers, but pXO1-like plasmids are also present in emetic-like strains. These data might indicate the presence of an ancient plasmid in B. cereus which has acquired different virulence genes over time. Due to the unusual structure of the hydroxyl acid incorporating enzyme modules of Ces, substantial biochemical efforts will be required to dissect the complete biochemical pathway of cereulide synthesis.

[Emergency due to allergy: the therapy--adrenaline for physicians and patients]

Emergency due to allergy may proceed within minutes to life-threatening respiratory and circulatory problems. Therefore, after diagnosis prompt and correct therapy might be vital. Because of its effect on alpha-, beta1-, and beta2-receptors, adrenaline is the treatment of choice in emergency due to allergy. For fear of cardiovascular side effects, often adrenaline is withheld even in case of anaphylaxis. If given properly such as an intramuscular injection the danger of undesirable side effects, however, is small. After a systemic, allergic reaction each patient needs to be equipped with rescue medications. If an adrenaline-containing device is prescribed--nowadays with EpiPen and the metered-dose inhaler Primatene Mist 2 systems are available--, the patient must get a correct instruction in its use. In case of a severe allergic reaction, antihistamines and corticosteroids are given in second line. Following any systemic allergy, an allergological work-up should be required. Only through exact diagnosis and profound patient's education, recurrences can be avoided, and in some cases, specific immunotherapy is indicated.

Emetic toxin formation of Bacillus cereus is restricted to a single evolutionary lineage of closely related strains

An in-depth polyphasic approach was applied to study the population structure of the human pathogen Bacillus cereus. To assess the intraspecific biodiversity of this species, which is the causative agent of gastrointestinal diseases, a total of 90 isolates from diverse geographical origin were studied by genetic [M13-PCR, random amplification of polymorphic DNA (RAPD), multilocus sequence typing (MLST)] and phenetic [Fourier transform Infrared (FTIR), protein profiling, biochemical assays] methods. The strain set included clinical strains, isolates from food remnants connected to outbreaks, as well as isolates from diverse food environments with a well documented strain history. The phenotypic and genotypic analysis of the compiled panel of strains illustrated a considerable diversity among B. cereus connected to diarrhoeal syndrome and other non-emetic food strains, but a very low diversity among emetic isolates. Using all typing methods, cluster analysis revealed a single, distinct cluster of emetic B. cereus strains. The isolates belonging to this cluster were neither able to degrade starch nor could they ferment salicin; they did not possess the genes encoding haemolysin BL (Hbl) and showed only weak or no haemolysis. In contrast, haemolytic-enterotoxin-producing B. cereus strains showed a high degree of heterogeneity and were scattered over different clusters when different typing methods were applied. These data provide evidence for a clonal population structure of cereulide-producing emetic B. cereus and indicate that emetic strains represent a highly clonal complex within a potentially panmictic or weakly clonal background population structure of the species. It may have originated only recently through acquisition of specific virulence factors such as the cereulide synthetase gene.

Bacillus cereus, the causative agent of an emetic type of food-borne illness

Bacillus cereus is the causative agent of two distinct forms of gastroenteritic disease connected to food-poisoning. It produces one emesis-causing toxin and three enterotoxins that elicit diarrhea. Due to changing lifestyles and eating habits, B. cereus is responsible for an increasing number of food-borne diseases in the industrial world. In the past, most studies concentrated on the diarrhoeal type of food-borne disease, while less attention has been given to the emetic type of the disease. The toxins involved in the diarrhoeal syndrome are well-known and detection methods are commercially available, whereas diagnostic methods for the emetic type of disease have been limited. Only recently, progress has been made in developing identification methods for emetic B. cereus and its corresponding toxin. We will summarize the data available for the emetic type of the disease and discuss some new insights in emetic strain characteristics, diagnosis, and toxin synthesis.

Identification of emetic toxin producing Bacillus cereus strains by a novel molecular assay

Bacillus cereus causes two types of gastrointestinal diseases: emesis and diarrhea. The emetic type of the disease is attributed to the heat-stable depsipeptide cereulide and symptoms resemble Staphylococcus aureus intoxication, but there is no rapid method available to detect B. cereus strains causing this type of disease. In this study, a polymerase chain reaction (PCR) fragment of unknown function was identified, which was shown to be specific for emetic toxin producing strains of B. cereus. The sequence of this amplicon was determined and a PCR assay was developed on this basis. One hundred B. cereus isolates obtained from different food poisoning outbreaks and diverse food sources from various geographical locations and 29 strains from other species belonging to the B. cereus group were tested by this assay. In addition, 49 non-B. cereus group strains, with special emphasis on food pathogens, were used to show that the assay is specific for emetic toxin producing B. cereus strains. The presented PCR assay is the first molecular tool for the rapid detection of emetic toxin producing B. cereus strains.

Quantitative in vivo measurement of glutathione in Arabidopsis cells

A new, non-destructive assay is described to quantify cytoplasmic glutathione (GSH) levels in vivo in single cells or populations of cells from Arabidopsis suspension cultures. Cytoplasmic GSH was labelled with monochlorobimane (MCB) in situ to give a fluorescent GSH-bimane (GSB) conjugate. At low (10-100 microM) concentrations of MCB, labelling was mediated by a glutathione S-transferase, which confers specificity for GSH. HPLC analysis of MCB-labelled low molecular-weight thiols showed that the assay measures the total GSH pool, including the oxidized glutathione. The progress curve for the labelling could be described using Michaelis-Menten kinetics with an apparent KM of 40 microM and Vmax of 470 micromol lcyt -1 min-1. There was no evidence for de novo synthesis of GSH during the labelling period of 2 h, suggesting that control of GSH synthesis is not mediated by feedback control of gamma-glutamylcysteine synthetase in this system. The total cellular level of GSH was calculated from the plateau value of the progress curve, after appropriate calibration, as 830-942 nmol g-1 FW. The volume fraction of cytoplasm was measured from serial optical sections of bimane-labelled cells collected by confocal laser scanning microscopy (CLSM) with excitation 442 nm, or two-photon laser scanning microscopy (TPLSM) with excitation 770 nm. A value of 42 +/- 3% cytoplasm was determined by manual segmentation, and a value of 37 +/- 2% using stereological techniques. Using these figures, values for cytoplasmic [GSH] were estimated to be between 2.7 +/- 0.3 and 3.2 +/- 0.3 mM for cell populations. In addition, measurement of GSH levels in individual cells using CLSM and TPLSM gave values of 3.0 +/- 0.5 and 3.5 +/- 0.7 mM, respectively.

Glutathione biosynthesis in Arabidopsis trichome cells

In Arabidopsis thaliana, trichome cells are specialized unicellular structures with uncertain functions. Based on earlier observations that one of the genes involved in cysteine biosynthesis (Atcys-3A) is highly expressed in trichomes, we have extended our studies in trichome cells to determine their capacity for glutathione (GSH) biosynthesis. First, we have analyzed by in situ hybridization the tissue-specific expression of the genes Atcys-3A and sat5, which encode O-acetylserine(thio)lyase (OASTL) and serine acetyltransferase (SAT), respectively, as well as gsh1 and gsh2, which encode gamma-glutamylcysteine synthetase and glutathione synthetase, respectively. The four genes are highly expressed in leaf trichomes of Arabidopsis, and their mRNA accumulate to high levels. Second, we have directly measured cytoplasmic GSH concentration in intact cells by laser-scanning microscopy after labeling with monochlorobimane as a GSH-specific probe. From these measurements, cytosolic GSH concentrations of 238+/-25, 80+/-2, and 144+/-19 microM were estimated for trichome, basement, and epidermal cells, respectively. Taking into account the volume of the cells measured using stereological techniques, the trichomes have a total GSH content more than 300-fold higher than the basement and epidermal cells. Third, after NaCl treatment, GSH biosynthesis is markedly decreased in trichomes. Atcys-3A, sat5, gsh1, and gsh2 mRNA levels show a decrease in transcript abundance, and [GSH](cyt) is reduced to 47+/-5 microM. These results suggest the important physiological significance of trichome cells related to GSH biosynthesis and their possible role as a sink during detoxification processes.

The role of calcium in blue-light-dependent chloroplast movement in lemna trisulca L

Chloroplast movements are a normal physiological response to changes in light intensity and provide a good model system to analyse the signal transduction pathways following light perception. Blue-light-dependent chloroplast movements were observed in Lemna trisulca using confocal optical sectioning and 3-D reconstruction or photometric measurements of leaf transmission. Chloroplasts moved away from strong blue light (SBL) towards the anticlinal walls (profile position), and towards the periclinal walls (face position) under weak blue light (WBL) over about 20-40 min. Cytoplasmic calcium ([Ca2 + ]cyt) forms part of the signalling system in response to SBL as movements were associated with small increases in [Ca2 + ]cyt and were blocked by antagonists of calcium homeostasis, including EGTA, nifedipine, verapamil, caffeine, thapsigargin, TFP (trifluoperazine), W7 and compound 48/80. Treatments predicted to affect internal Ca2 + stores gave the most rapid and pronounced effects. In addition, artificially increasing [Ca2 + ]cyt in darkness using the Ca2 + ionophore A23187 and high external Ca2 + (or Sr2 + ), triggered partial movement of chloroplasts to profile position analogous to a SBL response. These data are all consistent with [Ca2 + ]cyt acting as a signal in SBL responses; however, the situation is more complex given that both WBL and SBL responses were inhibited to a similar extent by all the Ca2 + -signalling antagonists used. As the direction of chloroplast movement in WBL is exactly opposite to that in SBL, we conclude that, whilst proper regulation of [Ca2 + ]cyt homeostasis is critical for both SBL and WBL responses, additional factors may be required to specify the direction of chloroplast movement.

Light perception and the role of the xanthophyll cycle in blue-light-dependent chloroplast movements in lemna trisulca L

In most higher plants, chloroplasts move towards the periclinal cell walls in weak blue light (WBL) to increase light harvesting for photosynthesis, and towards the anticlinal walls as an escape reaction, thus avoiding photo-damage in strong blue light (SBL). The photo- receptor(s) triggering these responses have not yet been identified. In this study, the role of zeaxanthin as a blue-light photoreceptor in chloroplast movements was investigated. Time-lapse 3D confocal imaging in Lemna trisulca showed that individual chloroplasts responded to local illumination when one half of the cell was treated with light of different intensity or spectral quality to that received by the other half, or was maintained in darkness. Thus the complete signal perception, transduction and effector system has a high degree of spatial resolution and is consistent with localization of part of the transduction chain in the chloroplasts. Turnover of xanthophylls was determined using HPLC, and a parallel increase was observed between zeaxanthin and chloroplast movements in SBL. Ascorbate stimulated both a transient increase in zeaxanthin levels and chloroplast movement to profile in physiological darkness. Conversely, dithiothreitol blocked zeaxanthin production and responses to SBL and, to a lesser extent, WBL. Norflurazon preferentially inhibited SBL-dependent chloroplast movements. Increases in zeaxanthin were also observed in strong red light (SRL) when no directional chloroplast movements occurred. Thus it appears that a combination of zeaxanthin and blue light is required to trigger responses. Blue light can cause cis-trans isomerization of xanthophylls, thus photo-isomerization may be a critical link in the signal transduction pathway.

Successful immunotherapy with T-cell epitope peptides of bee venom phospholipase A2 induces specific T-cell anergy in patients allergic to bee venom

BACKGROUND

Specific immunotherapy with honeybee venom (BV) is highly effective, but allergic side effects can occur during treatment. Immunotherapy with peptides containing major T-cell epitopes of the relevant allergen or allergens provides an alternative strategy without these problems.

OBJECTIVE

The study investigates the immunologic mechanisms and clinical effects of immunotherapy with T-cell epitope peptides of the major BV allergen, the phospholipase A2 (PLA).

METHODS

Five patients with IgE-mediated systemic allergic reactions to bee stings were treated with a mixture of three T-cell epitope peptides of PLA. Ten patients allergic to BV receiving whole BV immunotherapy served as control subjects. Increasing doses of the peptide mixture, up to a maintenance dose of 100 microg, were administered subcutaneously within 2 months. The patients were then challenged with PLA and 1 week later with a bee sting. The cellular and humoral immune response was measured in vitro.

RESULTS

No allergic side effects were caused by the peptide immunotherapy, and all patients tolerated the challenge with PLA without systemic allergic symptoms. Two patients developed mild systemic allergic reactions after the bee sting challenge. After peptide immunotherapy, specific proliferative responses to PLA and the peptides in peripheral blood mononuclear cells were decreased in successfully treated patients. The production of TH2 and TH1 cytokines was inhibited, and B cells were not affected in their capacity to produce specific IgE and IgG4 antibodies. Their levels increased after allergen challenge in favor of IgG4.

CONCLUSIONS

Immunotherapy of BV allergy with short T-cell peptides of PLA induces epitope-specific anergy in peripheral T cells and changes the specific isotype ratio in a fashion similar to that of conventional immunotherapy in successfully treated patients.

Increased specificity of diagnostic tests with recombinant major bee venom allergen phospholipase A2

BACKGROUND

In diagnosis of type I allergy recombinant allergens have potential advantages over conventional allergenic extracts, both regarding specificity and reproducibility.

OBJECTIVES

We therefore decided to study honey bee venom (BV) and its major allergen phospholipase A2 (PLA) in native and recombinant form for diagnosis of bee sting allergy.

METHOD

We investigated 85 patients with a history of a recent systemic allergic bee sting reaction and positive intracutaneous skin test to BV, and 21 controls with no history of allergic bee sting reaction and negative skin test to BV. Intracutaneous skin tests and determination of specific IgE by ImmunoCAP(R) to BV, native PLA (nPLA) and recombinant PLA (rPLA) were done in all patients and controls.

RESULTS

In skin testing 84 (99%) of the 85 patients reacted to nPLA and 81 (95%) to rPLA, while none of the 21 controls was positive with nPLA or rPLA. Specific serum IgE to BV could be detected in 82 of the patients (96%), to nPLA in 73 (86%) and to rPLA in 66 (78%). Four (19%) of the controls had a positive CAP to BV, one (4.8%) to nPLA and none to rPLA. Analysis of discordant results in CAP showed, that most patients with specific IgE to BV, but not to nPLA and rPLA, had positive skin tests to both PLA preparations and low levels of BV specific IgE. Patients with specific IgE to nPLA but not to rPLA were usually sensitized to minor allergens of BV which contaminated the commercial nPLA.

CONCLUSIONS

PLA is the major allergen in BV. While diagnostic tests with BV are more sensitive, the specificity of tests with PLA, especially rPLA is clearly increased as compared with BV.

Hymenoptera sting anaphylaxis and urticaria pigmentosa: clinical findings and results of venom immunotherapy in ten patients

BACKGROUND

Occasional patients with urticaria pigmentosa and anaphylaxis after Hymenoptera stings have been described. In this situation the question arises: Is anaphylaxis IgE-mediated or induced by pharmacologic mediator release from mast cells?

METHODS

We investigated 10 patients with histologically confirmed urticaria pigmentosa and a history of anaphylaxis after honeybee or Vespula stings before and during immunotherapy with the respective venom.

RESULTS

In eight of 10 patients, an elevated serum tryptase level was found. In two of 10 patients, no venom-specific IgE could be detected by either skin tests or RAST. Five patients had no detectable venom-specific serum IgE, and in the remaining patients the level was low (<1 Phadebas RAST unit). Venom immunotherapy was well tolerated and caused only one mild systemic reaction in a patient during the dose increase phase. Six patients were re-stung while receiving venom immunotherapy: only one had a mild systemic reaction (angioedema) after a Vespula sting.

CONCLUSION

Anaphylactic symptoms after Hymenoptera stings in patients with urticaria pigmentosa are most often IgE-mediated but can occasionally be observed in the absence of IgE sensitization to venom allergens. Venom immunotherapy can be safely and successfully used in patients with urticaria pigmentosa and sting anaphylaxis.