Listeriosis: a resurgent foodborne infection
1) Austrian Agency for Health and Food Safety (AGES), Binational Austrian–German Listeria Reference Centre, Vienna and 2) Institute for Milk Hygiene,
Milk Technology and Food Science, Department for Farm Animals and Public Veterinary Health, Vienna, Austria
Listeria monocytogenes is the causative agent of human listeriosis, a potentially fatal foodborne infection. Clinical manifestations range
from febrile gastroenteritis to more severe invasive forms, including sepsis, meningitis, rhombencephalitis, perinatal infections, and abor-
tions. In recent years, an increasing rate of listeriosis has been reported in several European countries. These increases primarily reflect
a higher rate of bacteraemic listeriosis in those ‡65 years of age, and are not otherwise correlated with geography, gender, ethnicity,
socioeconomic factors or infectious serotypes. In the late 1980s, an upsurge in listeriosis rates was due to the contamination of a small
number of food products. However, a restricted range of strains was responsible for most of the additional cases at that time, and no
evidence exists for such a pattern since 2001. From a clinical perspective, the importance of isolating the pathogen as a prerequisite for
an accurate epidemiological investigation and ultimately stopping transmission cannot be overemphasized.
Keywords: Foodborne, incidence, lethality, Listeria monocytogenes, listeriosis, review
Corresponding authors and reprint requests: F. Allerberger,Austrian Agency for Health and Food Safety (AGES), BinationalAustrian–German Listeria Reference Centre Spargelfeldstraße 191,1220 Vienna, AustriaE-mail: franz.allerberger@ages.atandM. Wagner, Institute for Milk Hygiene, Milk Technology and FoodScience, Department for Farm Animals and Public Veterinary Health,Veterinaerplatz 1, 1210 Vienna, AustriaE-mail: martin.wagner@vu-wien.ac.at
temperatures, allowing for growth even in properly refriger-
In recent years, an increasing rate of listeriosis has been
Listeriosis is a rare but potentially serious infection caused
reported in several European countries [3–10]. These
by Listeria monocytogenes. This organism can be found
increases primarily reflect a higher rate of bacteraemic liste-
throughout the environment in soil, vegetation and animals.
riosis in those ‡65 years of age, and are not otherwise
The main route of transmission is believed to be through
correlated with geography, gender, ethnicity, socioeconomic
consumption of contaminated food. However, infection can
factors or infectious serotypes [6,7]. The Annual Epidemiolog-
also be transmitted, albeit very rarely, directly
ical Report on Communicable Diseases in Europe 2008 states:
infected animals to humans, as well as between humans [1].
‘‘There appears to have been a significant increasing trend in
In neonatal infections, L. monocytogenes can be transmitted
the listeriosis notification rate in the EU from 2003 to 2006’’
from mother to child in utero or during passage through
[11]. Half (53.8%) of the EU member states with confirmed
the infected birth canal. There are also rare reports of nos-
cases also reported an increasing trend during the 2-year per-
ocomial transmission attributed to contaminated material or
iod 2006–2007 [12]. The cause of this increasing incidence,
patient-to-patient transmission via healthcare workers [1].
which, as shown in Fig. 1, was still ongoing in 2008, in Austria
The bacterium is particularly successful in causing food-
at least, is unknown. A total of 1554 confirmed cases of liste-
borne disease, because it survives food-processing technolo-
riosis were reported from 26 EU member states in 2007. The
gies that rely on acidic or salty conditions [2], and, unlike
EU notification rate was 0.3 per 100 000 population [12].
many pathogens, can continue to multiply slowly at low
Incidences for six EU countries are given in Fig. 2 [13].
ª2009 The AuthorsJournal Compilation ª2009 European Society of Clinical Microbiology and Infectious Diseases
Listeriosis: a resurgent foodborne infection
Number of cases
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
FIG. 1. Absolute number of cases of invasive
listeriosis, Austria 1997–2008 (n = 181).
Listeriosis during pregnancy is a serious threat to the
unborn child. One-third of culture-confirmed cases of mater-
nal–fetal infections result in abortion or stillbirth. However,
L. monocytogenes causes two forms of listeriosis: non-invasive
the prognosis for live-born babies is good, even in those
gastrointestinal listeriosis and invasive listeriosis. In immuno-
severely ill [10]. Pregnancy-associated cases refer to listerio-
competent individuals, non-invasive listeriosis develops as a
sis in pregnant women or in the neonates (up to 28 days of
typical febrile gastroenteritis. In immunocompromised adults,
life), and the non-pregnancy-associated cases to older babies
such as the elderly and patients receiving immunosuppressive
(>28 days) [1]. Most maternal infections occur during the
agents, listeriosis can manifest as septicaemia or meningoen-
third trimester of pregnancy, when T-cell immunity is most
cephalitis. Invasive listeriosis can also be acquired by the
impaired. Infected women typically develop non-specific flu-
fetus from its infected mother via the placenta [13]. Perinatal
like symptoms but may remain asymptomatic. Listeriosis has
listeriosis can lead to abortion, birth of a stillborn fetus or a
rarely been observed during the first trimester [14].
baby with generalized infection (granulomatosis infantiseptica),
In non-pregnancy-associated cases, listeriosis mainly mani-
and sepsis or meningitis in the neonate. Neonatal listeriosis
fests as meningoencephalitis or septicaemia. The median
is subdivided into two clinical forms: early-onset (usually
incubation period is estimated to be 3 weeks. Outbreak
defined as occurring within the first week of life) and late-
cases have occurred 3–70 days following a single exposure
onset. The late-onset type may occur from one to several
to an implicated product. The onset of meningoencephalitis,
which is rare in pregnant women, can be sudden, with fever,
intense headache, nausea, vomiting and signs of meningeal
irritation, or may be subacute, particularly in an immunocom-
promised or elderly host. Rhombencephalitis involving the
brainstem is an unusual form of listeriosis. L. monocytogenes
can also produce a wide variety of focal infections; cases of
conjunctivitis, skin infection, lymphadenitis, hepatic abscess,
pleuropulmonary infection, joint infection, osteomyelitis,
pericarditis, myocarditis, arteritis, necrotizing fasciitis and
endophthalmitis have been described [1,15–18]. In Europe,
approximately 10–20% of clinical cases are pregnancy-associ-
Cases/100 000
ated (including neonates within the first 4 weeks of birth),
but the majority of cases occur in non-pregnant immuno-
compromised individuals, especially the elderly. Approxi-
mately 10% of patients have no known risk factor or
underlying disease predisposing them to infection with Listeria
[6]. In Austria in 1997–2007, patients without known risk
FIG. 2. Listeriosis incidence in six EU countries, 1999–2007 (modi-
fied from Eurosurveillance, with permission).
45.2 years; median, 46.6 years). The overall mean age of the
Journal Compilation ª2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 16, 16–23
Clinical Microbiology and Infection, Volume 16 Number 1, January 2010
Austrian non-pregnancy-associated listeriosis patient in that
181 cases of invasive listeriosis documented in Austria from
period was 64.3 years (median, 66.2 years; range, 0.8–
1997 until 2008, only one patient was human immunodefi-
93.5 years), i.e. significantly greater than the age of patients
ciency virus-positive [6] (unpublished data, F.A.). A partial
explanation may lie in the experimental observation that
resistance to listeriosis appears to be mediated by lym-
phocytes that do not carry CD4 or CD8 markers [24].
In addition, it is likely that many cases are prevented by
routine Pneumocystis jirovecii prophylaxis with trimethoprim–
Clusters, suspected or confirmed to represent community
outbreaks, have contributed to the recent increased inci-
dence in some countries. In 2005, ten cases of listeriosis in a
small area of Switzerland were due to locally made and dis-
tributed soft cheese [19]. In 2006, the Czech Republic expe-
Listeriosis is diagnosed by a positive culture from a normally
rienced one large outbreak, involving 78 patients, of whom
sterile site. L. monocytogenes can be readily cultured from
13 died; here also, soft cheese was identified as the source
clinical specimens such as blood, cerebrospinal fluid (CSF),
[3]. During the period 2006–2007, Germany recorded an
amniotic fluid, placenta, meconium, lochia, gastric washings
outbreak of 16 cases caused by presliced ready-to-eat (RTE)
or ear swabs from newborns, by directly plating the material
delicatessen meat (sausage salad) (International Meeting on
onto blood agar plates and incubating overnight at 35°C in
Emerging Diseases and Surveillance, 2009, Abstract 10.098).
an ambient atmosphere. Stool specimens (other than meco-
In 2008, Austria experienced an outbreak of febrile gastro-
nium) should be selectively enriched for Listeria before being
enteritis, including three cases of invasive listeriosis associ-
plated on selective agar media. Classic cold enrichment over
ated with jellied pork contaminated with L. monocytogenes
months is no longer necessary. PCR is the only test utilized
[20]. However, the overall proportion of cases related to
for rapid detection of L. monocytogenes in clinical specimens.
clusters remained stable and low; therefore, these clusters
The PCR assay is particularly useful when prior administra-
did not account for the increased incidence in Austria.
tion of antimicrobial agents is likely to compromise culture.
Various test protocols were evaluated for CSF samples
and tissue samples (fresh or in paraffin blocks). Gram staining
Whereas much has now been learned about epidemic listeri-
and microscopic examination of CSF or meconium permit
osis, little is known about sporadic listeriosis, which, in fact,
only a presumptive diagnosis. For clinical specimens, the
represents the majority of cases [5]. Dietary risk factors for
importance of isolating the pathogen as a prerequisite for
sporadic listeriosis have been assessed through case–control
an epidemiological investigation and appropriate infection
studies. In a study conducted during the period 1986–1987
control cannot be overstressed [25].
in the USA, case patients were significantly more likely than
Because listeriosis during pregnancy is serious and difficult
controls to have eaten uncooked or non-reheated hot dogs
to diagnose, blood cultures should be considered for any
(frankfurters) or undercooked chicken. An estimated 20% of
pregnant woman presenting with fever, especially if accompa-
the overall risk of listeriosis was thought to be attributable to
nied by flu-like or gastrointestinal symptoms [26]. Vaginal or
consumption of these foods [21]. Another study performed
stool cultures are not helpful in diagnosis, because some
in the USA from 1988 to 1990 found that case patients were
women are asymptomatic carriers [26]. Indeed, faecal car-
significantly more likely than controls to have eaten soft
riage of L. monocytogenes occurs in 1–15% of the population
cheeses or delicatessen foods [22]. Other exposures associ-
[27]; the incidence of women carrying L. monocytgenes in the
ated with an increased risk of sporadic disease included
recent use of antacids, laxatives or H2-receptor antagonists
Listerial rhombencephalitis is a rare manifestation of liste-
[22]. Dietary risk factors for sporadic listeriosis were also
riosis. In contrast to other listerial infections of the central
examined in a study in Denmark; drinking unpasteurized milk
nervous system (CNS), the majority of listerial rhomben-
or eating pate´ were the only risk factors identified [23].
cephalitis cases occur in previously healthy adults; no cases
Although listeriosis is said to be 100–1000 times more
have been reported in infants [28]. Blood cultures may or
common in patients with AIDS than in the age-matched gen-
may not reveal growth of the organism in these cases.
eral population, it is somewhat surprising that it is not seen
Serological responses to commercially available whole cell
more commonly, given the ubiquity of the organism. Among
ª2009 The AuthorsJournal Compilation ª2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 16, 16–23
Listeriosis: a resurgent foodborne infection
suspensions O and H) are not diagnostic, because of anti-
should be taken to establish and document true penicillin
genic cross-reactivity between L. monocytogenes and other
allergy prior to starting treatment with these second-line
Gram-positive bacteria such as staphylococci, enterococci
agents. Transplacental passage of erythromycin has been
and Bacillus species [29]. Furthermore, patients with culture-
shown to provide subtherapeutic concentrations in both the
confirmed listeriosis have been known to have undetectable
amniotic fluid and fetal serum [36]. Therefore, many experts
antibody levels. Positive serological findings must be treated
recommend using an alternative. Vancomycin has also been
with caution and, in cases other than rhombencephalitis,
used in cases of bacteraemic listerial infection [37]. However,
exact diagnosis should be based on detection of the patho-
the results obtained from a model of rhombencephalitis in
gen. Serological responses to listeriolysin O (LLO) are sup-
gerbils strongly suggest that intravenous vancomycin is unli-
posed to be more reliable [30]. An ELISA for the detection
kely to be effective in patients with CNS infection [35]. Lin-
of anti-LLO IgG in human serum and plasma is commercially
ezolid is another agent that has been used successfully to
available (DIATHEVA, Fano, Italy). LLO, a polypeptide pro-
treat listerial infections [38]. Other antibiotics used in cases
tein secreted by L. monocytogenes, is a major virulence factor
of listeriosis include meropenem and rifampicin [39]. It has
produced by all pathogenic L. monocytogenes strains but
been speculated that, at least in the immunocompromised
released in the culture medium only at low levels. For this
host, the addition of rifampicin, which is effective against
reason, the LLO protein, used in the DIATHEVA assay as
intracellular L. monocytogenes and will penetrate the CSF,
test antigen, is expressed in Escherichia coli.
could help to eradicate residual bacteria [32]. Resistance has
been reported with rifampicin monotherapy [33]. Kayser
et al. [40] reported, as early as 1989, good in vitro activity of
meropenem. Another study with this antibiotic showed good
activity in experimental meningitis in guinea pigs [41].
In vitro, L. monocytogenes is susceptible to a wide range of
L. monocytogenes reproduces in the reticuloendothelial sys-
antibiotics, with the exception of fosfomycin, first-generation
tem and survives intracellularly after uptake by macrophages
quinolones and third-generation cephalosporins, although a
[33]. The bone marrow might be a unique niche for L. mono-
few exceptional strains exist. Susceptibility testing is usually
cytogenes [42]. This means that the organism cannot be
performed using Mueller–Hinton agar, with or without blood
reached by certain antibiotics; this might contribute to the
(5% horse blood or 5% sheep blood) [31]. For trimetho-
differences between in vitro and in vivo results. Macrolides
prim–sulphamethoxazole, the blood is lysed. Antimicrobial
and quinolones accumulate within host cells and may attack
in vitro susceptibilities of Listeria have not changed markedly
the intracellular Listeria organisms. Moxifloxacin may be a
over the past 35 years [31,32]. Although optimal therapy has
promising candidate; however, no clinical trials have provided
not been verified by randomized clinical studies, penicillin
firm evidence [43]. L. monocytogenes is intrinsically resistant
or ampicillin alone, or in combination with gentamicin, are
to nalidixic acid (MIC >128 mg/L) and shows decreased sus-
considered to be the drugs of choice. The clinically effective
ceptibility to therapeutically important fluoroquinolones, such
antibiotics penicillin and ampicillin are only bacteriostatically
as ciprofloxacin (MIC 0.5 – 2 mg/L) [44]. In an animal model,
effective against L. monocytogenes, thus emphasizing the impor-
ciprofloxacin was only weakly active in the spleen, liver and
tance of the body’s own cellular defence mechanisms [33].
CNS [35]. However, the newer derivatives of the quinolones
Addition of gentamicin has not been proven to be clini-
(e.g. levofloxacin and moxifloxacin) exhibit strong bacterici-
cally advantageous, as synergy has only been demonstrated
dal activity against L. monocytogenes [45,46].
in vitro [34]. Moreover, in animal models, gentamicin does
Antimicrobial drugs that are of questionable value in ani-
not reliably show a synergistic effect [35]. A gentamicin-
mal experiments or for the treatment of human listeriosis
supplemented protocol should not be prescribed for preg-
include clindamycin and aminoglycosides when administered
nant women, because of possible teratogenic effects [2,33].
individually [33]. Cephalosporins have hardly any in vitro
As Listeria does not produce b-lactamase, the addition of
effect against L. monocytogenes. The reason is the minimal or
b-lactamase inhibitors in the treatment of listeriosis is
non-existent affinity of listerial penicillin-binding proteins 3
ineffective. There is no relevant difference between the MIC
and 5 for cephalosporins [47]. Despite good in vitro activity,
values of ampicillin alone and ampicillin combined with
even cephalothin had no effect on experimental listeriosis in
sulbactam for the treatment of infection due to L. monocyto-
mice [33]. In addition, cephalothin lacks satisfactory CSF pen-
etration. Reports of therapeutic failures prove that cephalo-
For patients with b-lactam allergy, trimethoprim–sulpha-
sporins are not indicated for the treatment of listeriosis
methoxazole or erythromycin may be considered. Steps
Journal Compilation ª2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 16, 16–23
Clinical Microbiology and Infection, Volume 16 Number 1, January 2010
Fosfomycin was previously considered to be ineffective in
ampicillin and trimethoprim–sulphamethoxazole, for which
treating listeriosis, as revealed by in vitro laboratory data
clinical CLSI breakpoints for Listeria susceptibility testing are
[33]. Therefore, despite achieving theoretically excellent con-
defined, the usual CLSI criteria for staphylococci are applied
centrations in brain and other tissues, fosfomycin has not
been used in the management of listeriosis. However, in
1979, a report demonstrated that fosfomycin might have a
positive effect on L. monocytogenes infections in mice [49].
Recent research has demonstrated that the effect of fosfo-
mycin on L. monocytogenes is dependent on the expression of
At present, there is no immunization available for listeriosis.
the Hpt protein encoded by the hpt gene, which is under the
Engineered live-attenuated L. monocytogenes, which elicits
control of the central virulence regulator protein PrfA. Hpt,
strong cellular immune responses, is currently being evalu-
ated in clinical trials as an anticancer vaccine [55]. The utility,
enables L. monocytogenes to use hexose phosphates from the
or even the feasibility, of eradicating gastrointestinal coloniza-
host cell cytosol as an energy source, enabling intracellular
tion to prevent invasive listeriosis is unexplored. However,
movement. As the virulence regulator gene prfA is switched
asymptomatic individuals at high-risk of listeriosis, who are
off extracellularly, Hpt becomes downregulated and L. mono-
known to have ingested a food implicated in an outbreak,
cytogenes is resistent to fosfomycin in in vitro suceptibility
could reasonably be given 7 days of oral ampicillin or
tests. However, upon upregulation of the virulence regulon
trimethoprim–sulphamethoxazole treatment [20,56].
during infection, L. monocytogenes becomes susceptible to
fosfomycin. BALB/C mice, as used in in vivo tests, survived a
challenge of 108 CFUs per mouse, whereas the LD50 in con-trols was 1.77 · 104 CFUs of L. monocytogenes [50].
It is generally recommended that patients should be trea-
Listeriosis is essentially a foodborne disease, and this is no
ted for at least 14 days [33]. Even if a host appears to be
longer questioned. The upsurge in listeriosis rates in the late
clinically improved, the intracellular concentration resulting
1980s was due to contamination of a variety of food prod-
from short-course antibiotic treatment may not be sufficient
ucts, including coleslaw, unpasteurized milk and Mexican-style
for complete sterilization. Indeed, in immunosuppressed
soft cheese [1]. A restricted range of strains was responsible
patients, relapses have been reported after 2 weeks of peni-
for most of the additional cases at that time, and most
cillin therapy [51]. In pregnancy, there are additional consid-
human cases are still associated with L. monocytogenes sero-
erations, such as adequate treatment of the placenta, and
vars 1/2a, 1/2b and 4b. Whereas the number of reported
potential ongoing infection of the fetus or placenta. There
cases was quite stable during the period 1996–2002, an
has been concern that placental infection may not be clini-
increase was observed again during the period 2003–2007.
cally apparent, but could progress once antibiotic therapy
Currently, it appears that the numbers of cases of listeriosis
has been withdrawn. For this reason, some experts have sug-
are stable in some countries, or, as in Germany, have
gested at least 3–4 weeks of treatment during pregnancy
returned to those recorded previously.
[37]. Patients with rhombencephalitis should be treated with
The reasons for the changing incidence of listeriosis
antibiotics for at least 6 weeks [28].
remain unclear. No evidence exists for a causative role of
Although there are no data concerning the efficacy of anti-
gradual demographic or behavioural changes. Cairns and
microbials in listerial gastroenteritis, it could be argued that,
Payne [7] postulated that this phenomenon might be a
in both symptomatic and asymptomatic persons known to
consequence of changes in government policy regarding busi-
have ingested a food implicated in an outbreak, and who
ness practices that have had widespread effects on food pro-
have a high risk of invasive disease because of underlying
cessing, distribution and preparation. Goulet et al. [5]
illness, pregnancy or age (elderly), it might be prudent to
hypothesized that the recently reduced salt content in RTE
administer oral amoxycillin or trimethoprim–sulphamethox-
products may contribute to the growth of the organism, if
azole for 7 days [20]. Recently developed protocols employ-
present as a contaminant, and increase the likelihood of
ing gerbils and genetically engineered mice now allow the
infection when these products are consumed by susceptible
effect of antibotics to be studied in animal models relevant
individuals. The food industry reduced the salt content of
selected products, such as RTE meat products, in response
The CLSI has not yet provided specific guidelines for in vitro
to recommendations in 2002 from food safety agencies, ask-
ing for a 20% reduction in average salt intake, spread over
ª2009 The AuthorsJournal Compilation ª2009 European Society of Clinical Microbiology and Infectious Diseases, CMI, 16, 16–23
Listeriosis: a resurgent foodborne infection
5 years, in order to prevent disease attributable to hyperten-
Important control strategies from public health agencies
sion-related conditions. Wagner et al. [57] studied samples
include developing and maintaining timely and effective disease
of RTE foodstuffs in Vienna, Austria. They found 4.8% of 946
surveillance programmes, as well as promptly investigating
samples collected from 103 supermarkets to be positive for
clusters of listeriosis cases. Routine characterization of
L. monocytogenes, with five smoked fish samples exceeding
human, food and environmental isolates, and utilization of
the tolerated limit of 100 CFUs per gram of food. Products
large-scale subtype databases, will hopefully facilitate Europe-
showing the highest contamination rate were fish and sea-
wide outbreak detection and control in the near future [60].
food (19.4%), followed by raw meat sausages (6.3%), soft
cheese (5.5%) and cooked meat products/pate´s (4.5%). The
overall contamination rate of 640 RTE foodstuffs collected at
the household level was 1.7%. Importantly, most high-risk
foods were collected from households of elderly individuals.
L. monocytogenes has been recognized as a human pathogen
Pulsed-field gel electrophoresis typing of the collected
for more than 80 years. The demographic shift and the wide-
L. monocytogenes isolates revealed a high degree of diversity
spread use of immunosuppressive medications, to treat
among the isolates collected at the household level. More-
malignancy and manage organ transplantation, have increased
over, evidence from EU-wide routine food safety investiga-
the immunocompromised population at increased risk of lis-
tions indicates that a substantial proportion of RTE products
teriosis. Moreover, consumer lifestyles have changed, such
may be contaminated by L. monocytogenes [12]. L. monocytoge-
that less time is available for food preparation and more RTE
nes was detected in 1.8% of RTE meat products and meat
and takeaway foods are consumed. Changes in food produc-
tion and technology have led to the production of foods with
>100 CFUs/g), in 2.5% of RTE products and meat prepara-
longer shelf-lives that are typical ‘Listeria-risk foods’, because
tions of pork (in 0.6% with >100 CFUs/g), in 2.6% of RTE
the bacteria have time to multiply, and the food does not
products and meat preparations of poultry (in 0.7% with
undergo a listericidal process, such as cooking, before con-
>100 CFUs/g), in 1% of soft and semi-soft cheeses made
sumption. Unlike infection with other common foodborne
pathogens, listeriosis is associated with a high case-fatality
>100 CFUs/g), and in 18.3% of RTE fish products (2.4% with
rate of approximately 20–30% [61]. Epidemiological investiga-
>100 CFUs/g) [12]. It is therefore essential to control foods
tions during the past 30 years have shown that epidemic lis-
that permit L. monocytogenes to grow to numbers exceeding
teriosis and sporadic listeriosis are mainly caused by
the arbitrarily defined minimal infectious dose of 105 CFUs
consumption of contaminated food. Nevertheless, despite
per gram or millilitre of foodstuff. However, the dose–
the high rates of contamination of certain foods with L. mon-
response relationship remains unclear [58]. Strain-specific dif-
ocytogenes, listeriosis is a relatively rare disease as compared
ferences in virulence seem to be of the utmost importance.
with other common foodborne illnesses, such as campylob-
Newer risk assessment modelling suggests a 10)9 to 10)13
acteriosis or salmonellosis. However, because of its high
probability of infection with a dose of 100 organisms, and a
case-fatality rate, listeriosis is, after salmonellosis, the second
10)6 to 10)9 probability of infection at 1 000 000 organisms
most frequent cause of foodborne infection-related deaths in
Although exposure to L. monocytogenes cannot be avoided
completely, proper food preparation and storage can
decrease the risk. Pregnant women and immunocompro-
mised individuals should be advised to avoid consumption of
raw milk, unpasteurized soft cheeses, delicatessen meats, hot
The authors declare that they have no conflict of interest.
dogs that are not adequately heated, refrigerated pate´s, and
smoked seafood, because they can be contaminated at a high
level [2]. Avoiding cross-contamination is also an important
protective strategy; all utensils and surfaces should be
washed well after preparation of meat or cutting of prepared
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The Early Flat Anterior Chamber After TrabeculectomyA Randomized, Prospective Study of 3 Methods of ManagementDaniela S. Monteiro de Barros, MD,* Julia B.V. Kuntz Navarro, MD,*Anand V. Mantravadi, MD,* Ghada A. Siam, MD,* Moataz E. Gheith, MD,* Ethan H. Tittler, BA,*Karin A. Baez, MD,* Silvana M. Martinez, MD,* and George L. Spaeth, MD*wfiltration in glaucomatous eyes.1–3 Edmunds and co-P
Gene Bridges GmbH Im Neuenheimer Feld 584 69120 Heidelberg, Germany Tel + 49 (0)6221 13708 11 Fax + 49 (0)6221 13708 29 Email: contact@genebridges.com www.genebridges.com CONTENTS 1 Eppendorf tubes + manual 1. FRT-cm-FRT: PCR template (50 ng/µl, 20µl) 2. This manual Store tube at -20°C Please read The products listed in this manual are for research purposes only. They are no