9/21/2016 Dose Virulence Factors and Mechanisms of Pathogenicity ·Total dose ranges from5×104-5×10n Emetic toxin(cereulide)causes vomiting and cells nausea Total number of B.cereus required to cyclic dodecadepsipeptide contains three repeats of four amino acids produce enough toxin to cause illness is and or oxyacids:D-Oxy-Leu-D-Ala-L- Oxy-Val-L-Val Food containing 103 bacteria gram is potent cytotoxin that destroys mitochondria not safe to eat -ionophore with a high affinity to potassium cations -causes loss of the membrane potential and uncoupling of oxidative phosphorylation in the mitochondria Virulence Factors and Mechanisms of Cereulide Pathogenicity Enterotoxins cause diarrhea Table82 Properties of the emetic tooin cereulide -5 different proteins possible Trait (genome sequencing) 2 Antigenic point Detected through microslide diffusion tests Cytotaxic No Heat stobility 90 min at 121C pH stability Stablea p出2-11 In food (rice and milk)at 25-32C 5 9/21/2016 5 Dose • Total dose ranges from 5 x 104 - 5 x 1011 cells • Total number of B. cereus required to produce enough toxin to cause illness is 105 - 108 • Food containing > 103 bacteria / gram is not safe to eat Virulence Factors and Mechanisms of Pathogenicity Emetic toxin (cereulide) causes vomiting and nausea - cyclic dodecadepsipeptide - contains three repeats of four amino acids and / or oxyacids: D-Oxy-Leu—D-Ala—L￾Oxy-Val—L-Val - potent cytotoxin that destroys mitochondria - ionophore with a high affinity to potassium cations - causes loss of the membrane potential and uncoupling of oxidative phosphorylation in the mitochondria Cereulide Virulence Factors and Mechanisms of Pathogenicity Enterotoxins cause diarrhea - 5 different proteins possible (genome sequencing) - Antigenic - Detected through microslide diffusion tests