Enterococcus faecium NRRL B-2354: Tempest
in a Teapot or Serious Foodborne Pathogen?
Aparticular bacterial strain, now known as Enterococcus faecium NRRL B-2354, has been used within the food industry for a variety of
useful purposes for perhaps the past 64 years. It
is known under various names such as ATCC
8459, NRRL B-2354 and NCIMB 2699. It was
also previously labeled IFO3778, NCDO989,
NCIB 2699 and NCTC 2699.1, 2 However, these last four strain
designations no longer appear to be available. Pathogenic
microorganisms have been grouped into four categories based
upon risk: biosafety level (BSL) 1, 2, 3 and 4. Recently, the
American Type Culture Collection (ATCC) listed all E. faecium
strains as BSL2 pathogens. This is the same category into
which Salmonella and Listeria monocytogenes are grouped. This
has caused concern within various sectors of the food industry,
which have used this particular strain (e.g., NRRL B-2354) for
many decades. BSL1 organisms are regarded as nonpathogenic.
Other culture collections referencing the same strain have not
done so.
NRRL B-2354 should continue to be regarded as “a heat
resistant, spoilage, nonpathogenic organism that has been used
as a test organism for studying the destruction of bacteria…in a
food pilot plant.” 3
An opinion about
Background and Need for E.
faecium NRRL B-2354
Prevention is the focus of the Food Safety
Modernization Act. 4 In particular, section
103 indicates that Chapter IV ( 21 U.S.C. 341
et seq.) is amended by adding section 418
“Hazard Analysis and Risk-based Preventive
Controls,” which includes subsection “(c) Preventive Controls.”
This in part states that “the owner, operator, or agent in charge
of a facility shall identify and implement preventive controls,
including at critical control points...” All food manufacturers
will need to conduct a hazard analysis, the purpose of which is
to identify and implement documented preventative control
measures. Consistent with that approach is the validation
of thermal processes, many of which are too dynamic to
adequately model in a laboratory setting. Thermal processing
of foods can involve drying products, thus lowering their
water activity (aw) as their temperatures increase throughout
the process. It is well documented that the heat resistance of
microbial populations increases as aw decreases. 5 In addition,
microbial lethality should increase as temperature increases,
all things being equal. However, all things are not equal.
These two principles act counter to one another with regard
this nonpathogenic
spoilage organism
