Determination of the toxic potential of Bacillus cereus isolates by quantitative enterotoxin analyses.
Haemolysin BL (HBL) and non-haemolytic enterotoxin (Nhe), each consisting of three components, represent the major enterotoxins produced by Bacillus cereus. To evaluate the expression of these toxins, a set of 100 B. cereus strains was examined. Molecular biological characterization showed that 42% of the strains harboured the genes for HBL and 99% for Nhe. The production of all Nhe and HBL components were analyzed using specific antibodies and, in culture supernatants, detectable levels of HBL and Nhe were found for 100% of hbl-positive and 96% of nhe-positive strains. The concentrations of the HBL-L(2) and NheB component ranged from 0.02 to 5.6 microg mL(-1) and from 0.03 to 14.2 microg mL(-1), respectively. Comparison of the amount of NheB produced by food poisoning and food/environmental strains revealed that the median value for all food poisoning strains was significantly higher than for the food/environmental isolates. The data presented in this study provide evidence that specific and quantitative determination of the enterotoxins is necessary to evaluate the toxic potential of B. cereus. In particular, the level of Nhe seems to explain most of the cytotoxic activity of B. cereus isolates and may indicate a highly diarrheic potential.
Moravek
Maximilian
M
Institute for Hygiene and Technology of Food of Animal Origin, Veterinary Faculty, University of Munich, Oberschleissheim, Germany. m.moravek@mh.vetmed.uni-muenchen.de
Dietrich
Richard
R
Buerk
Christine
C
Broussolle
Véronique
V
Guinebretière
Marie-Hélène
MH
Granum
Per Einar
PE
Nguyen-The
Christophe
C
Märtlbauer
Erwin
E
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D001409:Bacillus cereus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000633:toxicity; D002522:Chlorocebus aethiops; D003967:Diarrhea / Q000382:microbiology; D004768:Enterotoxins / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000633:toxicity; D004783:Environmental Microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D005517:Foodborne Diseases / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006460:Hemolysin Proteins; D006801:Humans; D016133:Polymerase Chain Reaction; D013045:Species Specificity; D014709:Vero Cells
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D004768:Enterotoxins; D006460:Hemolysin Proteins; C040792:enterotoxin, Bacillus cereus; C083961:hemolysin BL protein, Bacillus