Published Date: 2003-06-05 23:50:00
Subject: PRO> Listeriosis, new prevention regulations - USA
Archive Number: 20030605.1385
LISTERIOSIS, NEW PREVENTION REGULATIONS - USA
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Thu, 5 Jun 2003 08:04:09 +0100
From: Pablo Nart <firstname.lastname@example.org>
Source The State.com (South Carolina, USA) Thu, 5 Jun 2003 [edited]
USDA: Companies Must Share Listeria Plans
Months after a deadly outbreak of _Listeria monocytogenes_, the USA
Agriculture Department says it will require 2500 companies that make
hot dogs and deli meats to come up with plans for preventing the
harmful bacteria from contaminating their products.
Companies also must test areas such as walls, equipment, and
countertops and share the results with inspectors, said Elsa Murano,
head of the department's food safety division.
"The rule is tough, it's fair, it's based on science," she said Wed,
4 Jun 2003. Plants that don't comply could be shut down by
inspectors, Murano said.
Under the regulations, companies will have flexibility in their
prevention efforts. They are allowed to add germ-killing ingredients
such as sodium lactate to the meat or to use a hot wash. Those that
do both can tout it on their product label. Those that do only one
procedure will face greater testing by government officials. Federal
inspectors will continue to randomly test plants for _L.
The bacterium is difficult to control because it may persist in
ready-to-eat meats after they are precooked at the plant. Consumers
can prevent sickness by cooking the meat.
Companies aren't allowed to use irradiation to kill germs on such
meats because the Food and Drug Administration has not approved it
for those products. The technology, which involves using gamma rays
or electricity to sanitize meat, is allowed on ground beef.
The Agriculture Department has been working on the listeria rule
since 2001, when it first was proposed by the Clinton administration.
Consumer groups have criticized the department for taking so long to
come up with the regulation, arguing that it could have sped up
recalls of products linked to a listeriosis outbreak last fall. The
outbreak sickened 53 people, killed 8, and caused 3 miscarriages.
[Deaths generally occur in immunocompromised hosts and fetuses. -
Murano said it took months to finish the rule because the agency was
completing studies that would determine the best way to prevent
listeria. Advocates complained that the new regulations don't
specify how often companies should test surfaces and products. They
also said the rule should require companies to warn pregnant women
and people with weak immune systems to reheat products before eating
"We hope that this regulatory approach, coupled with the scientific
strategies employed by meat and poultry companies, will help us
achieve our mutual goal: producing ready-to-eat meat and poultry
products that consumers can enjoy with confidence," said J. Patrick
Boyle, president of the American Meat Institute.
Because it's an interim rule, the industry and public can comment on
the rule and the government can make changes over the next 18 months.
However, it is slated to go into effect in September 2003.
[Byline: Emily Gersema, Associated Press]
[As reflected by a number of significant outbreaks of _L.
monocytogenes_ in recent years and posted on ProMED-mail, listeriosis
is clearly a major food-borne problem. The infection is most
significant among pregnant women; miscarriages often occur due to
infection of the placenta and fetus. In the immune-deficient host,
meningitis and bacteremia occur.
Treatment of precooked meats can diminish the risk of the
transmission of this Gram-positive bacillus. A variety of organic
acids can be used as additives to inhibit the bacterium, as
demonstrated by the following 2 abstracts:
Mbandi E, Shelef LA: Enhanced antimicrobial effects of combination of
lactate and diacetate on _Listeria monocytogenes_ and _Salmonella
spp._ in beef bologna. Int J Food Microbiol 2002;76:191-8.
"The antimicrobial activities of salts of organic acids such as
lactate and acetate are well documented, but there is limited
information on their effect when used in combination. We previously
reported enhanced inhibition of _Listeria monocytogenes_ and
_Salmonella enterica_ serovar Enteritidis in sterile comminuted beef
at 5 and 10 degrees C by combinations of sodium lactate (SL) (2.5
percent) and sodium diacetate (SDA) (0.2 percent). The present study
was undertaken to evaluate the inhibitory effect of these salts,
alone and in combination, in ready-to-eat (RTE) meat. Single strains
and 6-strain mixtures of each of the pathogens ( approximately 3 log
CFU/g) were tested in beef bologna during aerobic storage at 5 and 10
degrees C for up to 60 days. The growth rate of the 6-strain mixture
of _Listeria_ was faster than that of the single strain (Scott A) in
the lactate/diacetate-free product.
While each of the salts delayed growth of the listeriae at 5 degrees
C, the effect of their combination was listericidal for the single
strain and listeriostatic for the 6-strain mixture. Enhanced
inhibition by the salt combination was also observed at 10 degrees C.
_Salmonella_ numbers declined to undetectable levels in the untreated
meat product and in each of the treatments after 20-30 days. However,
the decline was more rapid in meat with the combination of the salts
during storage at both 5 and 10 degrees C. Each of the salts further
delayed the growth of the background microflora during storage at 5
degrees C, with their combinations showing the most effect."
Porto AC, Franco BD, Sant'anna ES, et al: Viability of a 5-strain
mixture of _Listeria monocytogenes_ in vacuum-sealed packages of
frankfurters, commercially prepared with and without 2.0 or 3.0
percent added potassium lactate, during extended storage at 4 and 100
degrees C. J Food Prot 2002;65:308-15
"The viability of _Listeria monocytogenes_ was monitored on
frankfurters containing added potassium lactate that were obtained
directly from a commercial manufacturer. 8 links (ca. 56 g each) were
transferred aseptically from the original vacuum-sealed bulk packages
into nylon-polyethylene bags. Each bag then received a 4-ml portion
of a 5-strain mixture of the pathogen. Frankfurters containing 2.0 or
3.0 percent potassium lactate were evaluated using 20 CFU per
package, and frankfurters containing 3.0 percent potassium lactate
were evaluated using 500 CFU per package.
The packages were vacuum-sealed and stored at 4 or 10 degrees C for
up to 90 or 60 days, respectively. During storage at 4 degrees C,
pathogen numbers remained at about 1.6 log10 CFU per package over 90
days in packages containing frankfurters with 2.0 percent potassium
lactate that were inoculated with about 20 CFU. In packages
containing frankfurters with 3.0 percent potassium lactate that were
inoculated with about 20 CFU and stored at 4 degrees C, pathogen
numbers remained at about 1.4 log10 CFU per package over 90 days. In
packages containing frankfurters with 3.0 percent potassium lactate
that were inoculated with about 500 CFU and stored at 4 degrees C,
pathogen numbers remained at about 2.4 log10 CFU per package over 90
However, in the absence of any added potassium lactate, pathogen
numbers increased to 4.6 and 5.0 log10 CFU per package after 90 days
of storage at 4 degrees C for starting levels of 20 and 500 CFU per
package, respectively. During storage at 10 degrees C, pathogen
numbers remained at about 1.4 log10 CFU per package over 60 days in
packages containing frankfurters with 2.0 percent potassium lactate
that were inoculated with about 20 CFU. In packages containing
frankfurters with 3.0 percent potassium lactate that were inoculated
with about 20 CFU and stored at 10 degrees C, pathogen numbers
remained at about 1.1 log10 CFU per package over 60 days of storage.
In the absence of any added potassium lactate, pathogen numbers
increased to 6.5 log10 CFU per package after 28 days and then
declined to 5.0 log10 CFU per package after 60 days of storage at 10
degrees C. In packages containing frankfurters with 3.0 percent
potassium lactate that were inoculated with about 500 CFU per
package, pathogen numbers remained at about 2.4 log10 CFU per package
over 60 days of storage at 10 degrees C, whereas in the absence of
any added potassium lactate, pathogen numbers increased to about 6.6
log10 CFU per package within 40 days and then declined to about 5.5
log10 CFU per package after 60 days of storage. The viability of _L.
monocytogenes_ in frankfurter packages stored at 4 and 10 degrees C
was influenced by the pH and the presence or levels of lactate but
not by the presence or levels of indigenous lactic acid bacteria or
by the proximate composition of the product.
These data establish that the addition of 2.0 percent (P < 0.0004) or
3.0 percent (P < 0.0001) potassium lactate as an ingredient in
frankfurters can appreciably enhance safety by inhibiting or delaying
the growth of _L. monocytogenes_ during storage at refrigeration and
This last abstract supports the synergistic use of heat and lactate:
McMahon CM, Doherty AM, Sheridan JJ, et al: Synergistic effect of
heat and sodium lactate on the thermal resistance of _Yersinia
enterocolitica_ and _Listeria monocytogenes_ in minced beef. Lett
Appl Microbiol 1999;28:340-4
"The effect of sodium lactate (NaL) (0, 2.4 or 4.8 percent), in
heating and recovery media, on _Yersinia enterocolitica_ and
_Listeria monocytogenes_ numbers recovered from minced beef heated at
55 degrees C, was examined. Survivors were enumerated on selective
media at pH 5.7/7.4 (_Y. enterocolitica_) or pH 5.7/7.2 (_L.
monocytogenes_). Recovery of the organisms depended on the pH and NaL
levels in the recovery medium. The heat resistance of _Y.
enterocolitica_ (P < 0.001) and _L. monocytogenes_ (P < 0.01)
decreased as the concentration of NaL in the minced beef increased
from 0 to 2.4 percent or 4.8 percent. The thermal destruction of
pathogens in foods processed using mild temperatures may be enhanced
by the addition of 2.4 percent NaL."
Only time and experimentation will show whether irradiation will
further improve the clearance of _L. monocytogenes_ in precooked
meat. - Mod.LL]