community- and hospital-acquired infections—in debilitated
individuals, for example, those with underlying disease or who
have received medical instrumentation, as indicated earlier.
In this context, they have caused urinary tract infections,
bacteremia, endocarditis, neonatal central nervous system
infections and intra-abdominal and pelvic infections. 12 E.
faecalis is isolated from the majority (80 percent) of human
enterococcal infections, with the remainder mainly associated
with E. faecium. The main concern about Enterococcus spp.
(faecalis and faecium) in food has been with the potential for
horizontal gene transfer of factors associated with virulence
and antibiotic resistance. 12 A major focus of research related to
Enterococcus spp. has been with those strains that have antibiotic
resistance (particularly, but not limited to vancomycin
resistance). This was highlighted with a volunteer feeding study
in which an animal-derived Enterococcus strain with vancomycin
resistance was transferred to a human strain within the
intestinal tract of three of six human volunteers. 55 Hence, there
is concern that introduction of an antibiotic-resistant strain
could transfer such resistance to normal human flora (e.g.,
other Enterococcus spp. or related strains) that would then persist
and result in a difficult-to-control infection should the patient
become debilitated under some circumstances. However,
although this potential exists, the human strain transformants
were transient in the experiment.
Antibiotic Resistance and Virulence Factors
of NRRL B-2354, ATCC 8459 and NCIMB
2699
The strain known as NCIMB 2699 that was deposited
as ATCC 8459 with an accession date of January 8, 1978,
appears to have no unusual antibiotic resistance. The site
at www.ncimb.com/results.php indicates sensitivity to a
number of antibiotics, including penicillin, streptomycin,
chloramphenicol, tetracycline, polymyxin b and novobiocin.
The site does not reference any antibiotic resistance associated
with this strain. The site indicates that the strain was originally
isolated from cheese.
Need for Further Research
This paper assumes that the strains represented to be the
same in various culture collections have remained so, and
mutations have not occurred. This assumption should be
verified, better methods to confirm the identity of these strains
should be employed and more comprehensive screening for
antibiotic resistance should be performed.
Conclusion
It is my opinion that food manufacturers should not be
discouraged from the use of E. faecium NRRL B-2354. n
Jeffrey L. Kornacki, Ph.D., is president of Kornacki Microbiology Solutions
Inc. in Madison, WI and is an adjunct assistant professor in the University of
Georgia’s Department of Food Science.
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