Cronobacter Support
04-23-2009, 05:18 PM
1st International Conference on Cronobacter Poster Abstract 5
Development of a screening method for the isolation of Cronobacter.
It has been reported that some strains of Cronobacter do not grow in selective enrichment media commonly used for the isolation of Enterobacteriaceae and that fermentation of sucrose in conjunction with metabolism of 5-bromo-4-chloro-3-indolyl-a-D-glucoside are useful differential tests for Cronobacter. Therefore a differential broth has been developed that enables samples to be screened for potential Cronobacter contamination without incorporating selective agents that may affect the recovery of sensitive strains. The Cronobacter screening broth (CSB) comprises a non-selective base media into which a niche fermentable carbohydrate (sucrose) and a Gram-positive inhibitor (vancomycin) were added to detect the presence of presumptive Cronobacter. Inclusivity and exclusivity of CSB was assessed using 329 strains including 229 target Cronobacter isolates. The broth was further tested using spike and naturally contaminated samples. A parallel comparison with the current FDA BAM method and the ISO/TS 22964 methods for raw materials, line/end products, and factory environment samples was also undertaken. After 24 h at 37°C all Cronobacter strains tested were able to grow in CSB and ferment the sucrose. The Sensitivity and Negative Predict Value (NPV) of CSB in conjunction with chromogenic agar was 100%. The Specificity was 94% and the Positive Predictive Value (PPV) was 97.4%. The CSB screening method was able to detect Cronobacter in spiked and in naturally contaminated samples. Potentially, this screening method can enable the decision to release uncontaminated product after 48 h. As CSB is a differential rather than selective enrichment broth, all Cronobacter strains are able to grow in CSB. This differential screening broth is complementary to any agar medium that incorporates a test for metabolism of alpha-glucopyranoside. The numbers of positive samples found from ingredients and the environment are in line with previous findings that Cronobacter spp. are ubiquitous environmental organisms that can be isolated from various food products as well as from households.
Carol Iversen1, Patrick Druggan2, Han Joosten3, Sandra Schumacher4, Angelika Lehner4, Claudia Feer5, Karl Gschwend5 and Roger Stephan4
1Centre for Food Safety, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. 2Oxoid Ltd., Thermo Fisher Scientific, Basingstoke, Hampshire RG24 8PW, United Kingdom. 3Quality and Safety Department, Nestlé Research Centre, Vers-chez-les-Blanc, CH-1000 Lausanne, Switzerland. 4Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zürich, CH-8057, Zürich, Switzerland. 5QA and Food Safety Department, Hochdorf Nutritec AG, CH-6280 Hochdorf, Switzerland.
Development of a screening method for the isolation of Cronobacter.
It has been reported that some strains of Cronobacter do not grow in selective enrichment media commonly used for the isolation of Enterobacteriaceae and that fermentation of sucrose in conjunction with metabolism of 5-bromo-4-chloro-3-indolyl-a-D-glucoside are useful differential tests for Cronobacter. Therefore a differential broth has been developed that enables samples to be screened for potential Cronobacter contamination without incorporating selective agents that may affect the recovery of sensitive strains. The Cronobacter screening broth (CSB) comprises a non-selective base media into which a niche fermentable carbohydrate (sucrose) and a Gram-positive inhibitor (vancomycin) were added to detect the presence of presumptive Cronobacter. Inclusivity and exclusivity of CSB was assessed using 329 strains including 229 target Cronobacter isolates. The broth was further tested using spike and naturally contaminated samples. A parallel comparison with the current FDA BAM method and the ISO/TS 22964 methods for raw materials, line/end products, and factory environment samples was also undertaken. After 24 h at 37°C all Cronobacter strains tested were able to grow in CSB and ferment the sucrose. The Sensitivity and Negative Predict Value (NPV) of CSB in conjunction with chromogenic agar was 100%. The Specificity was 94% and the Positive Predictive Value (PPV) was 97.4%. The CSB screening method was able to detect Cronobacter in spiked and in naturally contaminated samples. Potentially, this screening method can enable the decision to release uncontaminated product after 48 h. As CSB is a differential rather than selective enrichment broth, all Cronobacter strains are able to grow in CSB. This differential screening broth is complementary to any agar medium that incorporates a test for metabolism of alpha-glucopyranoside. The numbers of positive samples found from ingredients and the environment are in line with previous findings that Cronobacter spp. are ubiquitous environmental organisms that can be isolated from various food products as well as from households.
Carol Iversen1, Patrick Druggan2, Han Joosten3, Sandra Schumacher4, Angelika Lehner4, Claudia Feer5, Karl Gschwend5 and Roger Stephan4
1Centre for Food Safety, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. 2Oxoid Ltd., Thermo Fisher Scientific, Basingstoke, Hampshire RG24 8PW, United Kingdom. 3Quality and Safety Department, Nestlé Research Centre, Vers-chez-les-Blanc, CH-1000 Lausanne, Switzerland. 4Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zürich, CH-8057, Zürich, Switzerland. 5QA and Food Safety Department, Hochdorf Nutritec AG, CH-6280 Hochdorf, Switzerland.