The
source of the causative food vehicle has not been elucidated yet.
Listeriosis patient isolates in Germany have shown a new
identical pulsed-field gel electrophoresis (PFGE) pattern since 2012 (n = 66).
Almost all isolates (Listeria monocytogenes serotype 1/2a) belonged to
cases living in southern Germany, indicating an outbreak with a so far unknown
source.
Case numbers in 2015 are high (n = 28). No outbreak cases outside
Germany have been reported.
Next generation sequencing revealed the unique
cluster type CT1248 and confirmed the outbreak.
Investigations into the source are ongoing. Since
November 2012, a previously not observed pulsed-field gel electrophoresis
(PFGE) pattern in human isolates of invasive L. monocytogenes serotype1/2a
has been detected in Germany with increasing frequency. Altogether 66 outbreak
cases have been recorded, with 28 cases in 2015. Four cases were pregnancy-associated
and six cases died in the course of the disease. Here we provide details of the
ongoing outbreak.
Outbreak description: Since 2009, all
German Listeria isolates submitted to
the National Reference Centre (NRC) for Salmonella and other bacterial enterics
at the Robert-Koch Institute (RKI) or to the Austrian-German binational
reference laboratory (KL) for Listeria at the Austrian Agency for Health and
Food Safety (AGES), have been tested with PFGE for clonal relationship.
Submission of isolates is encouraged by public health authorities but is voluntary
without legal obligation.
Between November 2012 and November 2015, altogether
793 isolates from notified listeriosis cases were typed, which accounted for 45%
of all cases in that period (n=1,765). In southern Germany, this proportion was
higher (ca 60%) and since 2012, human isolates of L. monocytogenes serotype 1/2a with the NRC internal nomenclature
of the AscI/Apa I pattern 13a/54 have been observed.
Regarding
the source of the causative food vehicle, the results showed a heterogeneous
picture. Until now, we have not observed cases with an epidemiological link to
an institution (e.g. hospital infection). Preliminary results largely exclude
fish and cheese products as a possible source but this has to be complemented
by systematic screening of Listeria isolates
collected from food. Based on sequencing results, a PCR protocol aiming to
detect CT1248 was developed for screening of isolates and published on the KL
website.
Source:http://www.eurosurveillance.org/images/dynamic/EE/V20N50/art21336.pdf
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