Bacillus cereus, Bacillus thuringiensis, foodborne outbreaks, biopesticide The Biological Hazards (BIOHAZ) Panel of the European Food Safety Authority (EFSA) would like to respond to the article by Raymond and Federici entitled ‘In defense of Bacillus thuringiensis, the safest and most successful microbial insecticide available to humanity—a response to EFSA’ (Raymond and Federici 2017) in order to clarify some misleading statements and to explain the background of EFSA’s mandate. EFSA does not have any regulatory or enforcement powers and its role is restricted to risk assessment. It is the European Union's policy-making institutions that are the regulators, taking into account not only the scientific advice from EFSA but also socioeconomic parameters. The Scientific Opinion on the risks for public health related to the presence of B. cereus and other Bacillus spp. including B. thuringiensis in foodstuffs (EFSA BIOHAZ Panel 2016) was formulated at the request of the European Commission to update the previous ‘2005 Opinion of the BIOHAZ Panel on Bacillus cereus and other Bacillus spp. in foodstuffs’ (EFSA BIOHAZ Panel 2005). Therefore, the 2016 Opinion covers the whole B. cereus group and does not specifically address B. thuringiensis, nor does it aim to discuss specific features of B. thuringiensis strains used as biopesticides. EFSA was asked to (i) provide an update of information available on pathogenicity, and contributing virulence factors, in the genus Bacillus evaluating specifically the risk to public health arising from the presence of B. thuringiensis in food; (ii) review the microbiological methods available to distinguish between the members of the B. cereus group, to identify different B. thuringiensis strains, and the methods to identify the presence of toxins produced by these microorganisms; (iii) review existing data on natural background prevalence and levels of B. thuringiensis in the environment, and rates of transfer to foodstuffs, including conditions under which this transfer may take place; (iv) indicate, if possible, the maximum levels (number) of Bacillus, and specifically of B. thuringiensis, in food that could be regarded as safe for human consumption; (v) evaluate B. thuringiensis levels in food, at all stages of the food chain, if this microorganism was applied as a PPP (plant protection product) and (vi) provide an update on specific control options to manage the risk caused by B. cereus, B. thuringiensis and other Bacillus spp. and their toxins. This Scientific Opinion is based on the in-depth scrutiny of the available reported data and scientific literature on the role of B. cereus group, in foodborne diseases. A literature review aimed at identifying in a systematic way relevant scientific information on the occurrence and levels of B. thuringiensis in food, at all stages of the food chain, was performed. This review led to the screening of 4903 papers, and in the final evaluation of 80 of these. Among the conclusions of this literature review, the Opinion reports that B. cereus group strains are widespread in the environment and B. thuringiensis strains have been isolated from raw materials used for food processing as well as from a range of diverse types of food in different countries worldwide. The levels of B. thuringiensis isolated from food are very variable and can in some cases be related to the use of biopesticides containing commercial B. thuringiensis strains, but in most cases such potential relationships have not been investigated. The EC provided all the documentation concerning the alleged food poisoning outbreak in Germany. It appeared that the only bacteria that were detected above the generally accepted level belong to the B. cereus group, identified as B. thuringiensis in the salad samples. These organisms could not be discriminated from B. thuringiensis subsp. aizawai (XenTari), which had been sprayed on the salad on the field. The symptoms reported are too generic and insufficient for making aetiological inferences. The Scientific Opinion highlights all open questions related to this alleged foodborne outbreak, stating that it is not clear if those persons who consumed the salad also ate cheese noodles and therefore a synergistic effect between B. thuringiensis and another B. cereus group strain cannot be excluded. Thus, the presence of another B. cereus group strain at low levels in the salad cannot be excluded, although such a strain was not detected in any of the samples. The EFSA Opinion clearly states that the literature review of human foodborne outbreaks described as associated with B. thuringiensis is restricted to two cases (papers). These two papers present only indirect evidence for the involvement of B. thuringiensis and do not directly prove its involvement. In addition, none of the B. thuringiensis isolates investigated were characterised further than to species level; their phylogenetic relationship with strains used as biopesticides was therefore not established. As B. cereus group and B. thuringiensis strains are usually not differentiated in routine clinical or food-poisoning diagnostics, the possibility that some cases of foodborne illness attributed to B. cereus group are actually caused by B. thuringiensis cannot be excluded. In relation to the studies on B. thuringiensis infectivity cited by Raymond and Federici, it is important to note that there is a lack of a good animal model for studies on the enterotoxigenicity of B. cereus group organisms. Thus, based on current knowledge, no final and unequivocal conclusion on the potential of a certain B. cereus strain or B. thuringiesis strain to cause diarrhoeal-associated foodborne diseases (linked to the enterotoxic activity of a B. cereus group strain) in humans is possible. Finally, the Opinion clearly concludes that the different species of the B. cereus group of organisms are intermingled. The high heterogeneity within the B. cereus group population does not allow a separation and designation of distinct species to conserved genetic markers, but is based on virulence-associated factors, including the presence of such factors on mobile genetic elements. These are the main clarifications which we considered necessary in relation to the paper by Raymond and Federici (2017). The BIOHAZ Panel of EFSA invites all interested parties to carefully consider the whole Scientific Opinion in order to have a clear view of the scientific basis underlying its conclusions and recommendations. REFERENCES EFSA BIOHAZ Panel (EFSA Panel on Biological Hazards). Opinion of the scientific Panel on Biological Hazards on Bacillus cereus and other Bacillus spp. in foodstuffs. EFSA J 2005; 175: 1– 48. EFSA BIOHAZ Panel (EFSA Panel on Biological Hazards). Scientific opinion on the risks for public health related to the presence of Bacillus cereus and other Bacillus spp. including Bacillus thuringiensis in foodstuffs. EFSA J 2016; 4524: 1– 93. Raymond B, Federici BA. In defense of Bacillus thuringiensis, the safest and most successful microbial insecticide available to humanity—a response to EFSA. FEMS Microbiol Ecol 2017; 93. https://doi.org/10.1093/femsec/fix084 (10 July 2017, date last accessed). © FEMS 2017. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org
FEMS Microbiology Ecology – Oxford University Press
Published: Jan 1, 2018
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