Paul H In 't Veld

Learn More
The viability of 18 bacterial strains desiccated on anhydrous silica gel and stored at a temperature of 22 degrees C for at least 3 months was determined. According to their stability in the dried state, these strains could be classified into three typical groups. Group 1, containing Gram-positive strains and Salmonella serotypes, was marked by a very slow(More)
The purpose of this study was to determine the prevalence of Campylobacter in fresh vegetables and fruits at retail level in the Netherlands, and to estimate its implications on the importance of vegetables and fruits as risk factor for campylobacteriosis. Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a(More)
Randomly selected food commodities, categorized in product groups, were investigated for the presence and number of Bacillus cereus bacteria. If positive, and when possible, five separate colonies were isolated and investigated for the presence of four virulence factors: presence of genes encoding three enterotoxins (hemolysin BL [HBL], nonhemolytic(More)
AIMS The study describes the effects of heating temperature and exposure time on the thermal stability of cereulide under different conditions (pH, presence/absence of oil phase and cereulide concentration). METHODS AND RESULTS Cereulide heat inactivation was investigated at 100, 121 and 150 degrees C under different alkaline pH values (8.6-10.6) and in(More)
Bacillus cereus produces the emetic toxin cereulide, a cyclic dodecadepsipeptide that can act as a K(+) ionophore, dissipating the transmembrane potential in mitochondria of eukaryotic cells. Because pure cereulide has not been commercially available, cereulide content in food samples has been expressed in valinomycin equivalents, a highly similar cyclic(More)
A reference material containing Bacillus cereus was certified by the Community Bureau of Reference (BCR) for its number of colony-forming particles (cfp) in 0.1 ml reconstituted capsule solution. To this end, a batch of approximately 15,000 capsules was produced and tested for its homogeneity and stability. The variation in the number of cfp between(More)
A reference material (RM) containing Salmonella typhimurium was certified as CRM 507 by the Standards, Measurements and Testing Programme of the European Commission. The material consists of a gelatin capsule filled with artificially contaminated milk powder. The material is certified for the evaluation of presence/absence methods based on the ISO 6579(More)
A reference material for Bacillus cereus was developed based on spray drying of milk artificially contaminated with B. cereus spores. Various properties of the B. cereus spores in the milk powder were determined. The stability of the materials was good with no detectable decrease in the contamination level during 1 1/2 years storage at -20 degrees C or 4(More)
A reference material for staphylococcal enterotoxin A (SEA), was produced by spray-drying the toxin in milk. With this procedure the SEA was distributed homogeneously in the material. For ease of handling the reference material was encased in gelatin capsules, each containing 405 ng of SEA. Simply dissolving the milk powder in distilled water resulted in a(More)
UNLABELLED EPIDEMIOLOGICAL OBSERVATION: On a warm day, during a barbecue that was attended by over 100 guests, a large number became rapidly ill with signs of acute gastroenteritis within a few hours after eating the prepared food. The characteristic symptoms were nausea, vomiting, syncope and in some cases in a later stage, diarrhoea. Sixty patients were(More)