Complete Genome Sequences of Three Clinical Listeria monocytogenes Sequence Type 8 Strains from Recent German Listeriosis Outbreaks

We report here the closed genome sequences of three clinical Listeria monocytogenes strains of multilocus sequence typing (MLST) sequence type 8 (ST8). These strains are representatives of three separate listeriosis outbreak clusters (Alpha1, Pi4, and Sigma1) that affected Germany between 2012 and 2020.Peer Reviewe

COVID-19-Pandemie führte zu starkem Rückgang von darmpathogenen Erregern

Im Zuge der im März 2020 zur Bewältigung der COVID-19-Pandemie ergriffenen Infektionsschutzmaßnahmen wurde nicht nur ein abrupter Rückgang von Atemwegserkrankungen beobachtet, sondern im Verlauf des Jahres auch ein in diesem Maße nicht erwarteter Rückgang von bakteriellen Enteritiden. Abgebildet wurde dieser Trend durch die erfassten Fallzahlen im Meldesystem gemäß Infektionsschutzgesetz. Trotz einer geringeren Anzahl von Erkrankungsfällen bzw. Einsendungen konnte das Nationale Referenzzentrum für Salmonellen und andere bakterielle Enteritiserreger die integrierte molekulare Surveillance von ausgewählten lebensmittelbedingten darmpathogenen Infektionserregern (S. enterica, EHEC, L. monocytogenes, Shigella und Campylobacter) erfolgreich fortführen und ausbauen.Peer Reviewe

Genome‑wide insights into population structure and host specifcity of Campylobacter jejuni

The zoonotic pathogen Campylobacter jejuni is among the leading causes of foodborne diseases worldwide. While C. jejuni colonises many wild animals and livestock, persistence mechanisms enabling the bacterium to adapt to host species' guts are not fully understood. In order to identify putative determinants influencing host preferences of distinct lineages, bootstrapping based on stratified random sampling combined with a k-mer-based genome-wide association was conducted on 490 genomes from diverse origins in Germany and Canada. We show a strong association of both the core and the accessory genome characteristics with distinct host animal species, indicating multiple adaptive trajectories defining the evolution of C. jejuni lifestyle preferences in different ecosystems. Here, we demonstrate that adaptation towards a specific host niche ecology is most likely a long evolutionary and multifactorial process, expressed by gene absence or presence and allele variations of core genes. Several host-specific allelic variants from different phylogenetic backgrounds, including dnaE, rpoB, ftsX or pycB play important roles for genome maintenance and metabolic pathways. Thus, variants of genes important for C. jejuni to cope with specific ecological niches or hosts may be useful markers for both surveillance and future pathogen intervention strategies.Peer Reviewe

Listeriose-Ausbrüche in Deutschland – Hinweise auf geräucherte oder gebeizte Lachsprodukte als Ursache von Infektionen, Fortschreibung des Berichts aus 2021

Listeriose, verursacht durch das Bakterium Listeria (L.) monocytogenes, tritt in verschiedenen Formen auf und wird vor allem durch Konsum kontaminierter Lebensmittel übertragen. Die Krankheit ist mit teilweise schweren Verläufen und einer hohen Sterblichkeit assoziiert. Im Epidemiologischen Bulletin 3/2021 wurde ein Artikel zu 22 Listeriose-Ausbrüchen in Deutschland mit Hinweisen auf geräucherte oder gebeizte Lachsprodukte als Ursache von Infektionen publiziert. Im vorliegenden Bericht wird nun ein Update zur aktuellen Situation gegeben: Es konnten insgesamt 24 bundeslandübergreifende Listeriose-Ausbrüche mit Hinweisen auf geräucherte oder gebeizte Lachsprodukte als Ursache seit 2010 identifiziert werden. Dies sind zwei Ausbrüche mehr als im vorherigen Bericht. In den Jahren 2021 und 2022 gab es 66 Listeriose-Fälle in 15 Ausbrüchen. Die Daten bestätigen, dass geräucherte oder gebeizte Lachsprodukte in Deutschland weiterhin ein relevantes Risiko für Listeriose darstellen. Zudem ist insgesamt bei allen Listeriose-Ausbrüchen mit einer starken Untererfassung zu rechnen. Es ist deshalb davon auszugehen, dass die Erkrankungszahlen in der Bevölkerung in Deutschland deutlich höher sind.Peer Reviewe

Molecular Tracing to Find Source of Protracted Invasive Listeriosis Outbreak, Southern Germany, 2012–2016

We investigated 543 Listeria monocytogenes isolates from food having a temporal and spatial distribution compatible with that of the invasive listeriosis outbreak occurring 2012–2016 in southern Germany. Using forensic microbiology, we identified several products from 1 manufacturer contaminated with the outbreak genotype. Continuous molecular surveillance of food isolates could prevent such outbreaks

Outbreaks of virulent diarrheagenic Escherichia coli - are we in control?

Shiga toxin-producing Escherichia coli (STEC) are the most virulent diarrheagenic E. coli known to date. They can be spread with alarming ease via food as exemplified by a large sprout-borne outbreak of STEC O104:H4 in 2011 that was centered in northern Germany and affected several countries. Effective control of such outbreaks is an important public health task and necessitates early outbreak detection, fast identification of the outbreak vehicle and immediate removal of the suspected food from the market, flanked by consumer advice and measures to prevent secondary spread

Characterisation of Legionella pneumophila phospholipases and their impact on host cells

Phospholipases are a diverse class of enzymes produced both by eukaryotic hosts and their pathogens. Major insights into action pathways of bacterial phospholipases have been provided during the last years. On the one hand bacterial phospholipases act as potent membrane destructors and on the other hand they manipulate and initiate host signalling paths, such as chemokine expression or the inflammatory cascade. Reaction products of bacterial phospholipases may potentially influence many more host cell processes, such as cell respreading, lamellopodia formation, cell migration and membrane traffic. Phospholipases play a dominant role in the biology of the lung pathogen Legionella pneumophila. So far, 15 different phospholipase A-encoding genes have been identified in the L. pneumophila genome. These phospholipases can be divided into three major groups, the GDSL, the patatin-like and the PlaB-like enzymes. The first two lipase families are also found in higher plants (such as flowering plants) and the second family shows similarities to eukaryotic cytosolic phospholipases A. Therefore, when those enzymes are injected or secreted by the bacterium into the host cell they may mimic eukaryotic phospholipases. The current knowledge on L. pneumophila phospholipases is summarised here with emphasis on their activity, mode of secretion, localisation, expression and importance for host cell infections

Disulfide loop cleavage of Legionella pneumophila PlaA boosts lysophospholipase A activity

L. pneumophila, an important facultative intracellular bacterium, infects the human lung and environmental protozoa. At least fifteen phospholipases A (PLA) are encoded in its genome. Three of which, namely PlaA, PlaC, and PlaD, belong to the GDSL lipase family abundant in bacteria and higher plants. PlaA is a lysophospholipase A (LPLA) that destabilizes the phagosomal membrane in absence of a protective factor. PlaC shows PLA and glycerophospholipid: cholesterol acyltransferase (GCAT) activities which are activated by zinc metalloproteinase ProA via cleavage of a disulphide loop. In this work, we compared GDSL enzyme activities, their secretion, and activation of PlaA. We found that PlaA majorly contributed to LPLA, PlaC to PLA, and both substrate-dependently to GCAT activity. Western blotting revealed that PlaA and PlaC are type II-secreted and both processed by ProA. Interestingly, ProA steeply increased LPLA but diminished GCAT activity of PlaA. Deletion of 20 amino acids within a predicted disulfide loop of PlaA had the same effect. In summary, we propose a model by which ProA processes PlaA via disulfide loop cleavage leading to a steep increase in LPLA activity. Our results help to further characterize the L. pneumophila GDSL hydrolases, particularly PlaA, an enzyme acting in the Legionella-containing phagosome

Phospholipases during membrane dynamics in malaria parasites

Plasmodium parasites, the causative agents of malaria, display a well-regulated lipid metabolism required to ensure their survival in the human host as well as in the mosquito vector. The fine-tuning of lipid metabolic pathways is particularly important for the parasites during the rapid erythrocytic infection cycles, and thus enzymes involved in lipid metabolic processes represent prime targets for malaria chemotherapeutics. While plasmodial enzymes involved in lipid synthesis and acquisition have been studied in the past, to date not much is known about the roles of phospholipases for proliferation and transmission of the malaria parasite. These phospholipid-hydrolyzing esterases are crucial for membrane dynamics during host cell infection and egress by the parasite as well as for replication and cell signaling, and thus they are considered important virulence factors. In this review, we provide a comprehensive bioinformatic analysis of plasmodial phospholipases identified to date. We further summarize previous findings on the lipid metabolism of Plasmodium, highlight the roles of phospholipases during parasite life-cycle progression, and discuss the plasmodial phospholipases as potential targets for malaria therapy

Closed Genome Sequences of Clinical Listeria monocytogenes PCR Serogroup IVb Isolates Associated with Two Recent Large Listeriosis Outbreaks in Germany

Here, we report the closed genome sequences of two representative Listeria monocytogenes strains belonging to PCR serogroup IVb, which are related to two large outbreaks of human listeriosis that affected Germany in 2015 (Eta1) and 2018 to 2019 (Epsilon1a).Peer Reviewe