This opinion examines the extent to which toxin production
may be an unrecognised problem amongst some species
of Bacillus and its implications for the continuing
commercial use of this type of additive. The knowledge of
the genetic and biochemical basis for toxin production, the
methods for the detection of Bacillus toxins and the recommendations
for how best to ensure the absence of toxins (or
a capacity for toxin production) are reviewed. The SCAN
recommends that, for all future applications involving the
addition of living organisms to animal feed, the use of
strains from B. cereus taxonomic group should be strongly
discouraged. The required studies must to start with taxonomy
of the strain. In the case of micro-organisms belonging
to B. cereus group, studies involving commercially test kits,
laboratory bioassays and PCR-based methods are required
to identify toxins and virulence factors. These studies are
also required for bacilli other than those in the B. cereus
group.
3.3.2.4. Antibiotic resistance proWle and transferability of
resistances. Bacteria may bear transferable resistances. Some
enterococcal strains have shown a resistance to vancomycin
and a capacity to transfer this kind of resistance to other bacteria
species. The SCAN has adopted an opinion on this matter
(European Commission, 2001a,b), which was updated
(European Commission, 2003). In 2005, a new opinion of
FEEDAP Panel of the EFSA has anew updated the criteria
used for the assessment of bacteria for resistance to antibiotics
of human or veterinary importance (EFSA, 2005a). The
aim of this opinion is to provide guidance for developing
studies to show the potential of each bacterial strain (and not
yeast) to bear resistances and to transfer them. The basis of
such evaluation starts with the determination in vitro antibacterial
activity [minimum inhibitory concentration (MIC)]
for a relevant range of antibiotics of human or veterinary
importance. Although the detection of the MIC above the
breakpoint levels identiWed for one or more antimicrobials
requires further investigations to make the distinction
between acquired and intrinsic resistance, the microbiological
breakpoints categorising bacteria as resistant are expressed in
Table 1. When a bacterial strain is known to be resistant to a
speciWc antibiotic, while others species normally are susceptible
to this antibiotic, the applicant should evaluate the reason
for such resistance. If an acquired resistance may be transferred
or if known exogenous resistance genes are present,
the probiotic strain is not considered as suitable for use as
feed additive.
3.3.2.5. The qualiWed presumption of safety concept of microorganisms
in food and feed. The qualiWed presumption of
safety (QPS) approach of micro-organisms in food and
feed (EFSA, 2005b) is a system similar in concept and
purpose to the generally recognised as safe (GRAS) deWnition
used in the USA, but modiWed to take account of
the diVerent regulatory practices in Europe.