A multi-provincial outbreak of Salmonella Newport infections associated with red onions: A report of the largest Salmonella outbreak in Canada in over 20 years.

An investigation into an outbreak of Salmonella Newport infections in Canada was initiated in July 2020. Cases were identified across several provinces through whole-genome sequencing (WGS). Exposure data were gathered through case interviews. Traceback investigations were conducted using receipts, invoices, import documentation, and menus. A total of 515 cases were identified in seven provinces, related by 0-6 whole-genome multi-locus sequence typing (wgMLST) allele differences. The median age of cases was 40 (range 1-100), 54% were female, 19% were hospitalized, and three deaths were reported. Forty-eight location-specific case sub-clusters were identified in restaurants, grocery stores, and congregate living facilities. Of the 414 cases with exposure information available, 71% (295) had reported eating onions the week prior to becoming ill, and 80% of those cases who reported eating onions, reported red onion specifically. The traceback investigation identified red onions from Grower A in California, USA, as the likely source of the outbreak, and the first of many food recall warnings was issued on 30 July 2020. Salmonella was not detected in any tested food or environmental samples. This paper summarizes the collaborative efforts undertaken to investigate and control the largest Salmonella outbreak in Canada in over 20 years.

Everything but the kitchen sink: The use of multiple hypothesis generation methods to investigate an outbreak of Salmonella Enteritidis associated with frozen profiteroles and eclairs.

In December 2018, an outbreak of Salmonella Enteritidis infections was identified in Canada by whole-genome sequencing (WGS). An investigation was initiated to identify the source of the illnesses, which proved challenging and complex. Microbiological hypothesis generation methods included comparisons of Salmonella isolate sequence data to historical domestic outbreaks and international repositories. Epidemiological hypothesis generation methods included routine case interviews, open-ended centralized re-interviewing, thematic analysis of open-ended interview data, collection of purchase records, a grocery store site visit, analytic comparison to healthy control groups, and case-case analyses. Food safety hypothesis testing methods included food sample collection and analysis, and traceback investigations. Overall, 83 cases were identified across seven provinces, with onset dates from 6 November 2018 to 7 May 2019. Case ages ranged from 1 to 88 years; 60% (50/83) were female; 39% (22/56) were hospitalized; and three deaths were reported. Brand X profiteroles and eclairs imported from Thailand were identified as the source of the outbreak, and eggs from an unregistered facility were hypothesized as the likely cause of contamination. This study aims to describe the outbreak investigation and highlight the multiple hypothesis generation methods that were employed to identify the source.

Campylobacter assessment along the Spanish food chain: Identification of key points.

AIMS: Campylobacteriosis, caused by Campylobacter spp., is one of the most important foodborne zoonotic diseases in the world and a common cause of gastroenteritis. In the European Union, campylobacteriosis is considered the most common zoonotic disease, with over 10,000 cases in 2020 alone. This high occurrence highlights the need of more efficient surveillance methods and identification of key points. METHODS AND RESULTS: Herein, we evaluated and identified key points of Campylobacter spp. occurrence along the Spanish food chain during 2015-2020, based on the following variables: product, stage and region. We analysed a dataset provided by the Spanish Agency for Food Safety and Nutrition using a machine learning algorithm (random forests). Campylobacter presence was influenced by the three selected explanatory variables, especially by product, followed by region and stage. Among the studied products, meat, especially poultry and sheep, presented the highest probability of occurrence of Campylobacter, where the bacterium was present in the initial, intermediate and final stages (e.g., wholesale, retail) of the food chain. The presence in final stages may represent direct consumer exposure to the bacteria. CONCLUSSIONS: By using the random forest method, this study contributes to the identification of Campylobacter key points and the evaluation of control efforts in the Spanish food chain.

Vacation in Egypt associated with Shiga toxin-producing Escherichia coli infection in children and adolescents, northern Italy, 2023.

BackgroundHaemolytic uremic syndrome (HUS) is a severe complication of infection with Shiga toxin-producing Escherichia coli (STEC). Although the reservoirs of STEC are known, the source of the infection of sporadic cases is often unknown. In 2023, we observed several cases of bloody diarrhoea with STEC infection in children and adolescents returning from vacations.AimWe aimed to explore the association between travel and bloody diarrhoea with STEC infection in children and adolescents.MethodsWe included all children and adolescents with bloody diarrhoea with STEC infection identified in 2023 by the ItalKid-HUS Network surveillance system in northern Italy. We interviewed children's families and sent a questionnaire on recent travels abroad. The exposure time was between 3 days after arrival abroad and 5 days after return home. A self-controlled case series (SCCS) design was used in the analysis.ResultsOf the 43 cases, 11 developed HUS. Twenty-three cases did not travel abroad, while 20 had travelled to several destinations. The incidence rate ratio (IRR) associated with travel to Egypt was 88.6 (95% confidence interval (CI): 17.0-462). Serotype analysis excluded the possibility of a single strain causing the infections. We did not find the source of the infections.ConclusionThere is an elevated risk of acquiring STEC infection with bloody diarrhoea and HUS associated with travel to Egypt. Specific investigations to identify the source are needed to implement effective preventive measures.

Source tracking of extensively drug resistant Salmonella Typhi in food and raw vegetables using molecular approaches.

INTRODUCTION: Extensively drug resistant (XDR) strains of the Salmonella lineages have been reported to spread from Africa to South Asia. XDR strains are resistant to fluoroquinolones, chloramphenicol, co-trimoxazole, and ampicillin, resulting in treatment failure. The objectives of this study included the investigation of transmission of S. Typhi lineages and the identification of the potentially contaminated sources of the XDR typhoid outbreak from different urban areas by using molecular techniques. METHODOLOGY: Environmental samples, including food samples, were collected from different towns and the susceptibility of each isolate to the antimicrobial agents was examined. Molecular identification of different Salmonella lineages including S. Typhi, S. Paratyphi A, H58, and XDR was carried out through multiplex PCR. RESULTS AND CONCLUSIONS: A total of 328 environmental samples including raw vegetables, water, and bakery items were collected. More than half of the tested samples (64%) found harboring Salmonella spp. The Salmonella was confirmed through PCR amplification of species-specific markers that showed the presence of S. Typhi (40%), S. Paratyphi A (8%), H58 (7%), and XDR S. Typhi (6%). Raw vegetables had the highest number of Salmonella spp., indicating consumption of raw vegetables as a possible source of salmonellosis. XDR status was also affirmed through phenotypic antimicrobial susceptibility testing.

Infecciones por helmintos intestinales en Chile: Análisis retrospectivo en Santiago, años 2015-2019 / Intestinal helminth infections in Chile: a retrospective analysis in Santiago, 2015-2019

INTRODUCCIÓN: Existe escasa evidencia epidemiológica actual sobre helmintos intestinales en Chile. OBJETIVO: Describir la prevalencia de infecciones por helmintos intestinales en un centro de salud en Santiago, Chile. MÉTODOS: Análisis retrospectivo de helmintos intestinales diagnosticados en muestras parasitológicas de rutina en el Laboratorio de Microbiología de Clínica Alemana de Santiago, entre los años 2015 y 2019. Las pruebas diagnósticas se seleccionaron según la solicitud médica. Los datos se obtuvieron de los sistemas informáticos del laboratorio y se analizaron de manera anonimizada. RESULTADOS: Se detectaron 127 infecciones por helmintos en 11.809 muestras estudiadas (1,1%). Estas infecciones fueron: 78 (61,4%) Enterobius vermicularis, 25 (19,6%) Dibothriocephalus/Adenocephalus spp., 9 (7,1%) Taenia spp., 6 (4,7%) Pseudoterranova spp., 5 (3,9%) Strongyloides stercoralis y 4 (3,1%) Ascaris lumbricoides. Enterobius vermicularis predominó en niños y adolescentes; Dibothriocephalus/ Adenocephalus spp. predominó en adultos. CONCLUSIÓN: El estudio proporciona información epidemiológica actual sobre la distribución de helmintos intestinales en muestras clínicas en Santiago, Chile. Enterobius vermicularis fue prevalente, seguido de helmintos transmitidos por alimentos mientras que los transmitidos por el suelo solo se detectaron ocasionalmente. El surgimiento de difilobotriasis y anisakidosis (pseudoterranoviasis), es relevante y posiblemente se relacione con cambios en las condiciones de vida y la cultura alimentaria en Chile.

BACKGROUND: Epidemiological information on the current prevalence of intestinal helminths in Chile is scarce. AIM: To describe the prevalence of different intestinal helminth infections in a healthcare center in Santiago, Chile. METHODS: We performed a retrospective analysis of intestinal helminths diagnosed in routine parasitological samples in the microbiological laboratory of Clínica Alemana Santiago, Chile, between 2015 and 2019. Diagnostic tests were applied according to the sender's request. Data were obtained from laboratory information systems and analyzed in an anonymized manner. RESULTS: Among 11,809 samples, 127 (1.1%) helminth infections were detected, of those, 78 (61.4%) were Enterobius vermicularis, 25 (19.6%) Dibothriocephalus/Adenocephalus spp., 9 (7.1%) Taenia spp., 6 (4.7%) Pseudoterranova spp., 5 (3.9%) Strongyloides stercoralis, and 4 (3.1%) Ascaris lumbricoides. Enterobius vermicularis was predominant among children and adolescents, while Dibothriocephalus/Adenocephalus spp. was the most frequent helminth in adults. CONCLUSION: The study provides updated epidemiological information on distribution of helminth infections in clinical samples in Santiago, Chile. After E. vermicularis, food-borne helminths were second most prevalent, while soiltransmitted helminths were very rarely detected. The emergence of diphyllobothriasis and anisakidosis (pseudoterranoviasis) is noteworthy and possibly related to changes in living conditions and food culture in Chile.

Salmonella assessment along the Spanish food chain: Likelihood of Salmonella occurrence in poultry and pig products is maintained across the food chain stages.

Salmonellosis is one of the most important foodborne diseases worldwide, including the European Union. Despite the One Health approach measures for risk assessment and risk management implemented by the European Union, the occurrence of disease and disease outbreaks remains high (e.g. 694 outbreaks were reported in 2020), highlighting the need of new assessment methods. Herein we applied machine learning using the random forests method to evaluate and identify key points regarding the occurrence of Salmonella sp. along the Spanish food chain during 2015-2020, using data provided by the Spanish Agency for Food Safety and Nutrition. We compared the role of the three categorical variables [product (20 categories), region (18 categories) and stage (11 categories)]. Salmonella presence was influenced by the three explanatory variables considered: first by product, followed by region and stage. The most determinant product for Salmonella probability was 'meat', while the most important stage was 'slaughterhouse'. Specifically, the highest values were found in pig and poultry meats. In these products, the Salmonella probability was high at the early and final stages of the food chain, although not at intermediate stages. The presence of Salmonella in the final stages (retail) of the food chain is of concern, as it can cause human cases of salmonellosis, including outbreaks. This study demonstrates the utility of the random forest method to identify key points and evaluate the control efforts. We recommend improving the surveillance and control measures, especially in the product and stages pointed out by our analysis, and enhancing the data collection harmonization among the different autonomous communities.

Invasive listeriosis in Finland: surveillance and cluster investigations, 2011-2021.

Foodborne pathogen Listeria monocytogenes may cause serious, life-threatening disease in susceptible persons. We combined data from Finnish national listeriosis surveillance, patient interview responses, and laboratory data of patient samples and compared them to listeria findings from food and food production plants collected as part of outbreak investigations during 2011-2021. The incidence of invasive listeriosis in Finland (1.3/100000 in 2021) is higher than the EU average (0.5/100000 in 2021), and most cases are observed in the elderly with a predisposing condition. Many cases reported consuming high-risk foods as well as improper food storage. Since ongoing patient interviews and whole genome sequencing were introduced, several listeriosis outbreaks were detected and food sources identified. Recommendations about high-risk foods for listeriosis and proper food storage should be better communicated to susceptible people. In Finland, patient interviews and typing and comparing listeria isolates in foods and patient samples are crucial in solving outbreaks and determining measures to control invasive listeriosis.

Retrospective evaluation of an integrated molecular-epidemiological approach to cyclosporiasis outbreak investigations - United States, 2021.

Cyclosporiasis results from an infection of the small intestine by Cyclospora parasites after ingestion of contaminated food or water, often leading to gastrointestinal distress. Recent developments in temporally linking genetically related Cyclospora isolates demonstrated effectiveness in supporting epidemiological investigations. We used 'temporal-genetic clusters' (TGCs) to investigate reported cyclosporiasis cases in the United States during the 2021 peak-period (1 May - 31 August 2021). Our approach split 655 genotyped isolates into 55 genetic clusters and 31 TGCs. We linked two large multi-state epidemiological clusters (Epidemiologic Cluster 1 [n = 136 cases, 54 genotyped] and Epidemiologic Cluster 2 [n = 42 cases, 15 genotyped]) to consumption of lettuce varieties; however, product traceback did not identify a specific product for either cluster due to the lack of detailed product information. To evaluate the utility of TGCs, we performed a retrospective case study comparing investigation outcomes of outbreaks first detected using epidemiological methods with those of the same outbreaks had TGCs been used to first detect them. Our study results indicate that adjustments to routine epidemiological approaches could link additional cases to epidemiological clusters of cyclosporiasis. Overall, we show that CDC's integrated genotyping and epidemiological investigations provide valuable insights into cyclosporiasis outbreaks in the United States.

A scoping review of factors associated with antimicrobial-resistant Campylobacter species infections in humans.

Human infection with antimicrobial-resistant Campylobacter species is an important public health concern due to the potentially increased severity of illness and risk of death. Our objective was to synthesise the knowledge of factors associated with human infections with antimicrobial-resistant strains of Campylobacter. This scoping review followed systematic methods, including a protocol developed a priori. Comprehensive literature searches were developed in consultation with a research librarian and performed in five primary and three grey literature databases. Criteria for inclusion were analytical and English-language publications investigating human infections with an antimicrobial-resistant (macrolides, tetracyclines, fluoroquinolones, and/or quinolones) Campylobacter that reported factors potentially linked with the infection. The primary and secondary screening were completed by two independent reviewers using Distiller SR®. The search identified 8,527 unique articles and included 27 articles in the review. Factors were broadly categorised into animal contact, prior antimicrobial use, participant characteristics, food consumption and handling, travel, underlying health conditions, and water consumption/exposure. Important factors linked to an increased risk of infection with a fluoroquinolone-resistant strain included foreign travel and prior antimicrobial use. Identifying consistent risk factors was challenging due to the heterogeneity of results, inconsistent analysis, and the lack of data in low- and middle-income countries, highlighting the need for future research.

Fermenting a place in history: The first outbreak of Escherichia coli O157 associated with kimchi in Canada.

A Canadian outbreak investigation was initiated in January 2022 after a cluster of cases of Shiga-toxin-producing Escherichia coli (STEC) O157 was identified through whole genome sequencing (WGS). Exposure information was collected through case interviews. Traceback investigations were conducted, and samples from case homes, retail, and the manufacturer were tested for STEC O157. Fourteen cases were identified in two provinces in Western Canada, with isolates related by 0-5 whole genome multi-locus sequence typing allele differences. Symptom onset dates ranged from 11 December 2021 to 7 January 2022. The median age of cases was 29.5 (range 0-61); 64% were female. No hospitalisations or deaths were reported. Of 11 cases with information available on fermented vegetable exposures, 91% (10/11) reported consuming Kimchi Brand A during their exposure period. The traceback investigation identified Manufacturer A in Western Canada as the producer. One open and one closed sample of Kimchi Brand A tested positive for STEC O157, with isolates considered genetically related by WGS to the outbreak strain. Napa cabbage within the kimchi product was hypothesised as the most likely source of contamination. This paper summarises the investigation into this STEC O157 outbreak associated with kimchi, the first reported outside of East Asia.

Catering of high-risk foods and potential of stored food menu data for timely outbreak investigations in healthcare facilities, Italy and Germany.

Healthcare-associated foodborne outbreaks (HA-FBOs) can cause significant morbidity and mortality, affecting particularly vulnerable hospital populations. Electronic records of food served in healthcare facilities (HCFs) could be useful for timely investigations of HA-FBOs. We explored the availability and usability of electronic food menu data to support investigations of HA-FBOs through a survey among 35 HCFs in Germany (n = 13) and in Italy (n = 22). Large variability was reported in the storage time of menu data (from no storage up to 10 years) and their formats, including paper, electronic (PDF, Word, Excel), or fully searchable databases (15/22 in Italian HCFs, 3/13 in German HCFs). Food products that may present a risk to vulnerable persons - including deli salads, raw/fermented sausage products, soft cheese, smoked fish or frozen berries - were offered on the menu of all HCFs in Germany, and one-third of the Italian HCFs. The usability of electronic food menu data for the prevention or investigation of HA-FBOs may be suboptimal in a large number of HCFs in Germany, as well as in some HCFs in Italy. Standardised collection for use of electronic food menu data might help discover the association between illnesses and food eaten during outbreak investigations. Hospital hygienists, food safety and public health authorities should collaborate to increase implementation of food safety guidelines.

Characteristics associated with successful foodborne outbreak investigations involving United States retail food establishments (2014-2016).

This study examined relationships between foodborne outbreak investigation characteristics, such as the epidemiological methods used, and the success of the investigation, as determined by whether the investigation identified an outbreak agent (i.e. pathogen), food item and contributing factor. This study used data from the Centers for Disease Control and Prevention's (CDC) National Outbreak Reporting System and National Environmental Assessment Reporting System to identify outbreak investigation characteristics associated with outbreak investigation success. We identified investigation characteristics that increase the probability of successful outbreak investigations: a rigorous epidemiology investigation method; a thorough environmental assessment, as measured by number of visits to complete the assessment; and the collection of clinical samples. This research highlights the importance of a comprehensive outbreak investigation, which includes epidemiology, environmental health and laboratory personnel working together to solve the outbreak.

Distinct epidemiological profiles of porcine circovirus 3 and fox circovirus in Canadian foxes (Vulpes spp.).

Circoviruses (genus Circovirus, family Circoviridae) are ssDNA viruses that infect mammals, and they sometimes can transmit among different species. We investigated the distribution and diversity of porcine circovirus 3 (PCV-3, species Porcine circovirus 3) and fox circovirus (species Canine circovirus 1) in different populations of foxes (Vulpes spp.) inhabiting the Canadian province of Newfoundland and Labrador to compare their epidemiological profiles. Of the 210 samples tested in this study 9 were positive for PCV-3 and 99 were positive for fox circovirus. Eight foxes were PCV-3-positive (8/128, 6.3%) and the virus was only found in the most human-populated areas. The PCV-3 positivity rate was significantly higher in stool (7/180, 8.8%) than in spleen (2/120, 1.7%: p < 0.05). Phylogenetic analyses showed that sequences from different animals were unrelated to each other. Fox circovirus was identified in 66 animals (51.6%) and positivity rates were the highest in the least human-populated areas. There were no significant differences between positivity rates in stool (32/80, 40.0%), spleen (59/120, 49.2%), or lymph nodes (8/10, 80.0%). Among 54 positive animals for which both spleen and stool samples were available, 25 (46.3%) had detectable virus in both samples. All fox circovirus sequences recovered in this study formed a monophyletic clade, and no geographic segregation of study strains was observed. The high prevalence and high genetic diversity observed for fox circovirus implies that the virus has been circulating in this population for a long time. PCV-3 cases were consistent with sporadic infections from multiple sources, possibly related to scavenging behavior and consumption of meat by-products and human waste, while fox circovirus was endemic, indicating that foxes are likely the maintenance host for this virus. To the best of our knowledge this is the first study demonstrating the presence of fox circovirus in North America and to show that PCV-3 can be detected in foxes. Future studies should evaluate the pathogenic potential of these viruses for wildlife.

Bi-national outbreak of Salmonella Newport infections linked to onions: the United States experience.

From 2016-2019, dry bulb onions were the suspected cause of three multistate outbreaks in the United States. We investigated a large multistate outbreak of Salmonella Newport infections that caused illnesses in both the United States and Canada in 2020. Epidemiologic, laboratory and traceback investigations were conducted to determine the source of the infections, and data were shared among U.S. and Canadian public health officials. We identified 1127 U.S. illnesses from 48 states with illness onset dates ranging from 19 June to 11 September 2020. Sixty-six per cent of ill people reported consuming red onions in the week before illness onset. Thirty-five illness sub-clusters were identified during the investigation and seventy-four per cent of sub-clusters served red onions to customers during the exposure period. Traceback for the source of onions in illness sub-clusters identified a common onion grower in Bakersfield, CA as the source of red onions, and onions were recalled at this time. Although other strains of Salmonella Newport were identified in environmental samples collected at the Bakersfield, CA grower, extensive environmental and product testing did not yield the outbreak strain. This was the third largest U.S. foodborne Salmonella outbreak in the last 30 years. It is the first U.S. multistate outbreak with a confirmed link to dry bulb onions, and it was nearly 10-fold larger than prior outbreaks with a suspected link to onions. This outbreak is notable for its size and scope, as well as the international data sharing that led to implication of red onions as the primary cause of the outbreak. Although an environmental assessment at the grower identified several factors that likely contributed to the outbreak, no main reason was identified. The expedient identification of the outbreak vehicle and response of multiple public health agencies allowed for recall and removal of product from the marketplace, and rapid messaging to both the public and industry on actions to protect consumers; these features contributed to a decrease in cases and expeditious conclusion of the outbreak.

Multistate outbreak of Salmonella Mbandaka infections linked to sweetened puffed wheat cereal - United States, 2018.

In May of 2018, PulseNet, the national molecular subtyping network for enteric pathogens, detected a multistate cluster of illnesses caused by an uncommon molecular subtype of Salmonella serovar Mbandaka. A case was defined as an illness in a person infected with the outbreak strain of Salmonella Mbandaka with illness onset on or after 3 March 2018 and before 1 September 2018. One-hundred thirty-six cases from 36 states were identified; 35 hospitalisations and no deaths were reported. Ill people ranged in age from <1 year to 95 years (median: 57 years). When standardised questionnaires did not generate a strong hypothesis, opened-ended interviews were performed. Sixty-three of 84 (75%) ultimately reported consuming or possibly consuming a specific sweetened puffed wheat cereal in the week before illness onset. Environmental sampling performed at the cereal manufacturing facility yielded the outbreak strain. The outbreak strain was also isolated from open cereal samples from ill people's homes and from a sealed retail sample. Due to these findings, the brand owner of the product issued a voluntary recall of the cereal on 14 June 2018. Additional investigation of the manufacturing facility identified persistent environmental contamination with Salmonella Mbandaka that was closely genetically related to other isolates in the outbreak. This investigation highlights the ability of Salmonella to survive in low-moisture environments, and the potential for prolonged outbreaks linked to products with long shelf lives and large distribution areas.

One Health Genomic Analysis of Extended-Spectrum ß-Lactamase‒Producing Salmonella enterica, Canada, 2012‒2016.

Extended-spectrum ß-lactamases (ESBLs) confer resistance to extended-spectrum cephalosporins, a major class of clinical antimicrobial drugs. We used genomic analysis to investigate whether domestic food animals, retail meat, and pets were reservoirs of ESBL-producing Salmonella for human infection in Canada. Of 30,303 Salmonella isolates tested during 2012-2016, we detected 95 ESBL producers. ESBL serotypes and alleles were mostly different between humans (n = 54) and animals/meat (n = 41). Two exceptions were blaSHV-2 and blaCTX-M-1 IncI1 plasmids, which were found in both sources. A subclade of S. enterica serovar Heidelberg isolates carrying the same IncI1-blaSHV-2 plasmid differed by only 1-7 single nucleotide variants. The most common ESBL producer in humans was Salmonella Infantis carrying blaCTX-M-65, which has since emerged in poultry in other countries. There were few instances of similar isolates and plasmids, suggesting that domestic animals and retail meat might have been minor reservoirs of ESBL-producing Salmonella for human infection.

Phylogenetic and Phenotypic Analyses of a Collection of Food and Clinical Listeria monocytogenes Isolates Reveal Loss of Function of Sigma B from Several Clonal Complexes.

To understand the molecular mechanisms that contribute to the stress responses of the important foodborne pathogen Listeria monocytogenes, we collected 139 strains (meat, n = 25; dairy, n = 10; vegetable, n = 8; seafood, n = 14; mixed food, n = 4; and food processing environments, n = 78), mostly isolated in Ireland, and subjected them to whole-genome sequencing. These strains were compared to 25 Irish clinical isolates and 4 well-studied reference strains. Core genome and pan-genome analysis confirmed a highly clonal and deeply branched population structure. Multilocus sequence typing showed that this collection contained a diverse range of strains from L. monocytogenes lineages I and II. Several groups of isolates with highly similar genome content were traced to single or multiple food business operators, providing evidence of strain persistence or prevalence, respectively. Phenotypic screening assays for tolerance to salt stress and resistance to acid stress revealed variants within several clonal complexes that were phenotypically distinct. Five of these phenotypic outliers were found to carry mutations in the sigB operon, which encodes the stress-inducible sigma factor sigma B. Transcriptional analysis confirmed that three of the strains that carried mutations in sigB, rsbV, or rsbU had reduced SigB activity, as predicted. These strains exhibited increased tolerance to salt stress and displayed decreased resistance to low pH stress. Overall, this study shows that loss-of-function mutations in the sigB operon are comparatively common in field isolates, probably reflecting the cost of the general stress response to reproductive fitness in this pathogen. IMPORTANCE The bacterial foodborne pathogen Listeria monocytogenes frequently contaminates various categories of food products and is able to cause life-threatening infections when ingested by humans. Thus, it is important to control the growth of this bacterium in food by understanding the mechanisms that allow its proliferation under suboptimal conditions. In this study, intraspecies heterogeneity in stress response was observed across a collection consisting of mainly Irish L. monocytogenes isolates. Through comparisons of genome sequence and phenotypes observed, we identified three strains with impairment of the general stress response regulator SigB. Two of these strains are used widely in food challenge studies for evaluating the growth potential of L. monocytogenes. Given that loss of SigB function is associated with atypical phenotypic properties, the use of these strains in food challenge studies should be re-evaluated.

[Raw meat, lots of problems: rare infection in a patient after mechanical valve replacement and liver transplantation]. / Rohes Fleisch, viele Probleme: seltene Infektion bei einem Patienten nach mechanischem Klappenersatz und Lebertransplantation.

We report about a 43-year-old man who presented to the emergency department in septic shock with nonspecific gastrointestinal symptoms. Sonography and computed tomography (CT) could not identify the location of the infection in the patient who had undergone liver transplantation and has a mechanical mitral valve. Blood cultures were positive for Listeria monocytogenes. Transesophageal echocardiography showed prosthetic endocarditis. The findings regressed markedly under ampicillin.

Ongoing High Incidence and Case-Fatality Rates for Invasive Listeriosis, Germany, 2010-2019.

We used 10 years of surveillance data to describe listeriosis frequency in Germany. Altogether, 5,576 cases were reported, 91% not pregnancy associated; case counts increased over time. Case-fatality rate was 13% in non-pregnancy-associated cases, most in adults ≥65 years of age. Detecting, investigating, and ending outbreaks might have the greatest effect on incidence.