Table 1.
Set of the 19 B. cereus strains used in this study.
| B. cereus strain | Origin | Genotype clade (group) | Toxin gene profiling | Toxin titer NheB | Toxicity Vero | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ces | hbl | nhe | cytK2 | hlyII | inhA1 | nprA | profile | ||||||
| 14294-3 (M6) | Ice cream | Food | I (III) | − | + | + | + | − | + | + | A | m | m |
| SDA KA96 | Raw milk | Food | I (III) | − | + | + | + | − | + | + | A | hi | hi |
| INRA A3 | Starch | Food | II (IV) | − | + | + | + | − | + | + | A | lo | lo |
| INRA C3 | Past. Carrot | Food | II (IV) | − | + | + | + | − | + | + | A | hi | hi |
| 6/27/S | Human feces | Diarrheal | II (IV) | − | + | + | + | − | + | + | A | m | m |
| F3175/03 (D7) | Human feces | Diarrheal | II (IV) | − | + | + | + | − | + | + | A | hi | m |
| RIVM BC 934 | Lettuce | Food | II (IV) | − | + | + | + | − | + | + | A | lo | lo |
| F528/94 | Beef and chow mein and rice, food poisoning outbreak | Diarrheal | I (II) | − | + | + | − | + | + | + | C | lo | lo |
| F837/76 | Human, postoperative infection | hbl reference | I (III) | − | + | + | − | + | + | + | C | hi | hi |
| RIVM BC 126 | Human feces | Diarrheal | I (II) | − | + | + | − | − | + | + | C | hi | hi |
| MHI86 | Infant food | Food | I (III) | − | − | + | + | − | + | + | D | lo | lo |
| F4429/71 | Vanilla pudding | Diarrheal | I (III) | − | − | + | + | − | + | + | D | hi | hi |
| RIVM BC 964 | Kebab | Food | II (IV) | − | − | + | + | + | + | + | D | hi | hi |
| F3162/03 (D8) * | Human feces | Clinical | I (III) | − | − | + | + | − | + | + | D | lo | hi |
| MHI226 ** | Milk and milk products | Food | I (III) | − | − | + | − | + | + | + | F | lo | lo |
| NVH 0075−95 | Stew with vegetables, foodpoisoning | nhe reference | I (III) | − | − | + | − | − | + | + | F | hi | hi |
| WSBC10035 | Past. Milk | Food | I (III) | − | − | + | − | − | + | + | F | hi | hi |
| RIVM BC 90 | Human feces | Diarrheal | I (III) | − | − | + | − | − | + | + | F | lo | lo |
| 7/27/S | Human feces | Diarrheal | I (III) | − | − | + | − | − | + | + | F | hi | hi |
Genotyping was performed by sequence analyses of the genetic markers spoIIIAB and panC, toxin profiling by PCR analyses using specific primers for ces, enterotoxin genes and virulence factors, toxin titers were determined by sandwich EIAs against NheB and toxicity was analyzed by WST-1-bioassay on Vero cells. Isolates were classified highly (hi), medium (m) or low (lo) toxic according to their cytotoxicity (hi: >500; m: 250-500; lo: <250) and NheB titers (hi: >4000; m: 2000-4000; lo: <2000).
, strain showed high toxicity but particularly low NheB titers due to binding failure of mab 2B11 in sandwich EIA (A. Didier, in preparation).
, sequence analysis revealed a truncated hbl operon; as strain is not able to produce Hbl L2 and Hbl B protein (negative in EIAs), it was allocated to profile F.