Listeriosis

Scientists have discovered that bacterial populations remain stable on factory floor despite cleaning efforts in ready-to-eat food production facilities. Scientists from the Quadram Institute and UK Health Security Agency have discovered that bacterial populations remain stable on factory floor despite cleaning efforts in ready-to-eat food production facilities. In 2019, six people died from a listeria outbreak caused by contaminated ready-to-eat foods served in a number of hospitals across the UK. In light of this, scientists are now performing vital research which helps to understand how these pathogens can persist in ready-to-eat food preparation environments. Listeria monocytogenes is a foodborne bacterium that causes an illness called listeriosis. Symptoms for healthy individuals include a high temperature, aches and pains, feeling or being sick; but infection in those who are pregnant, elderly or immunocompromised, can lead to death. The safety of foods is therefore paramount within the food industry. However, even in the face of well-implemented strategies to disinfect facilities and control for microbial risks, microbes such as listeria can occasionally breach food safety barriers and cross-contaminate food products. This is particularly dangerous in ready-to-eat foods where consumers will not kill contaminating bacteria by heating the food before eating it. Despite this danger, very little research has been done to understand the bacteria in ready-to-eat food production environments. Researchers wanted to understand the potential sources of cross contamination and the factors that contribute to the survival of L. monocytogenes in these environments,particularly the communities of other microbes that support and protect it. They began by sampling the floor of a ready-to-eat food factory that had recurrently detected L. monocytogenes in specific non-food contact areas of the factory. They sampled different sites: a preparation area, where ingredients were kept at 4°C, and a production area where they assembled and packaged the food, kept at 10°C. They aimed to measure the changes of bacterial communities over time, so they sampled the sites over ten weeks, before and after cleaning. They then cultured and performed genetic analysis on the samples to identify which bacteria were present and in what proportions. The results showed that the populations of bacteria that coexist with L. monocytogenes were stable over time and have adapted to the conditions on the factory floor, including food safety controls. Maria Diaz from the Quadram Institute and lead of the study explains, "as L. monocytogenes is supported by a stable community of other bacteria, we may now need to develop new strategies to alter the whole bacterial population to effectively eliminate the pathogen." While the overall bacterial populations, and proportions of bacteria were stable before and after cleaning, Maria explains that we cannot assume cleaning efforts do not work. "The populations are very stable, and cleaning is not shifting the composition -- it's not letting one bacterium grow over another. After cleaning, the bacteria reduce in numbers and the bacterial load is lower, making cross contamination less likely." There was a marked difference, however, between the different areas of the factory at different temperatures; suggesting that the bacterial populations are highly adapted to the different environments within the factory. It also suggests that the bacteria present in the factory are established populations rather than bacteria introduced from outside sources -- as despite movement of personnel between them, the populations remained stable. While the factory had listeria under control at the time of sampling, this new research is important for understanding the different communities of microbes in different environments across ready-to eat-food facilities. Researchers hope that understanding how listeria survives in these environments could inform more accurate laboratory testing of cleaning methods. Maria adds, "thanks to this research, we can better understand the lifestyle of this pathogen and start to develop laboratory models that allow us to investigate new ways of killing listeria." Maria Diaz will present her data at this year's Microbiology Society Annual Conference which will take place at Edinburgh International Convention Centre. Her talk "Deciphering microbial dynamics in a Ready-to-Eat Food production facility: Insights into Listeria monocytogenes persistence" will take place on 11 April.

Cincinnati Children's-led research team details how bone marrow response in mice varies by stress type and by type of bone, opening new paths for treating blood cancers, infections and more CINCINNATI, March 20, 2024 /PRNewswire/ -- Imagine being able to count the different types of blood cells being formed inside the tiny bones of a mouse and pinpointing the strings and clusters of cells within the bone marrow that are responsible for producing specific types of blood cells. Continue Reading New study in the journal Nature, led by experts at Cincinnati Children's, reveals unprecedented cell-by-cell detail of how the bone marrow's blood production process works, and how different forms of stress affect production sites. That's exactly what a team of scientists led by experts at Cincinnati Children's achieved in a far-reaching study published March 20, 2024, in the prestigious journal Nature. Their work adds unprecedented new understanding of the "elegant" and "resilient" anatomy of bone marrow while also generating evidence of unexpected variations in how the skeleton responds to stresses such as infection or blood loss. "Stunningly, we found that the response to hematopoietic insults varies across the skeleton. We speculate that certain bones have specialized to preferentially respond to some insults, and this will be the focus of future studies," the co-authors state. The research was led by co-first authors Qingqing Wu, PhD, and Jizhou Zhang, PhD, and corresponding author Daniel Lucas, PhD, all with the Division of Experimental Hematology and Cancer Biology at Cincinnati Children's. Overall, 23 researchers from five institutions contributed to this groundbreaking study. The discovery of specific blood cell production sites within the bone marrow raises new challenges and opportunities for diagnosing and treating a number of blood-related conditions. "For example, our data shows that biopsies that draw marrow from just one type of bone may not provide a full picture of how the blood production system has been affected by a disease or other insult," Lucas says. "Meanwhile, efforts to stimulate production of certain blood cell types may be dramatically improved by focusing on specific bone types." Highlights of the findings The key discoveries reported in the paper include: New tools allowing visualization of blood production inside the bone, allowing defining the basic anatomy of blood cell formation. These revealed that bone marrow functions are highly responsive and durable, but not uniform. The paper describes how strings and clusters of cells form within the marrow to act as blood cell production factories. Location matters, even during normal blood cell production. The team demonstrated that different key types of progenitor cells move through different microenvironments as they mature. These microenvironments significantly influence which types of mature blood cells get produced. Different microenvironments give rise to oxygen-carrying red blood cells versus infection-fighting white blood cells, and so on. Unexpected variations in stress responses. The researchers compared how the system responded to three acute kinds of stress: blood loss, L. monocytogenes infection, and granulocyte-colony stimulating factor (G-CSF) treatment (often given to boost white blood cell production after chemotherapy). They also measured how aging changed the process. The team meticulously measured how different bones responded to these insults. Among several examples: blood loss triggered rapid red blood cell production in the sternum, tibia, vertebrae, and humerus -- but not in the skull. Blood loss also temporarily reduced the number of B cell production sites across the skeleton. Meanwhile, when exposed to G-CSF, long bones rapidly increased formation of granulocyte progenitors and mature neutrophils. But in sharp contrast, the sternum from the same mice displayed "profound reductions" in these cell types as well as loss of neutrophil production sites. "These variations are important because until now, mouse studies of blood cell biology have depended almost entirely upon material collected from the femur and tibia," Lucas says. Innovation required just to conduct the study The research team first needed to conduct a research project-within-the-project to establish a method for imaging and counting the different cell types at work within the mouse bone marrow. Counting the cells involved a process called confocal imaging microscopy. This uses specialized microscopes relying on lasers to detect specific tags in the cells. When "tagged" properly, the cells emit different colors under the laser, which allows them to be imaged and counted. The challenge is coming up with the right tag so that the laser accurately detects the targeted cells of interest, while not counting other cells. In this study, the team started with a vast library of potential markers, then they whittled the list down to 35 promising genetic markers Ultimately, they found that detecting cells that express the gene marker ESAM, in combination with other markers, allowed distinguishing between six different types of blood progenitor cells. The marker also proved capable of showing information about the microenvironment, such as whether blood cell production was occurring within sinusoids or arterioles, two distinct types of blood channels found within bone marrow. Importantly, the process developed for this study allowed the team to analyze blood cell development in multiple parts of the skeleton. Next steps Looking ahead, Lucas says much more research will be needed to fully detail how different parts of the skeleton become specialized producers of specific blood components. Also, more studies will be needed to confirm how much of the bone marrow stress response observed in mice also occurs in humans. It will likely require several years of development, but understanding more about the mechanics of blood cell production may allow a wide range of improvements in the precision and effectiveness of treatments to support healthy blood cell production. "It might even allow to build artificial bones capable of producing red blood cells for transfusion," Lucas says. About the study Achieving these findings required significant support from the Bio-Imaging Analysis Facility and the Research Flow Cytometry Core at Cincinnati Children's. In addition to Wu, Zhang and Lucas, Cincinnati Children's co-authors included: Sumit Kumar, Siyu Shen, Morgan Kincaid, Courtney B. Johnson, Yanan Sophia Zhang, and Shelli Homan, Marie Dominique Filippi, PhD, and H. Leighton Grimes, PhD, all with Experimental Hematology and Cancer Biology; Anastasiya Slaughter, Benjamin Weinhaus, and Baobao Song from the Immunology Graduate Program; Bryan Sherman, Tzu-Yu Shao, and Sing Sing Way, MD, PhD, from Infectious Diseases; and Matt Kofron, PhD, a member of Developmental Biology and director of the Bio-Imaging and Analysis Facility. The study also included contributions from researchers with the Charles P. Lin lab at Massachusetts General Hospital, Harvard Medical School, and Keisuke Ito at the Albert Einstein College of Medicine in Bronx, NY. The study was supported with funds from several grants from the National Institutes of Health. Individual co-authors also receive support from the Leukemia and Lymphoma Society, the Edward P. Evans Foundation, the HHMI Faculty Scholar's Program, the Burroughs Wellcome Fund, and the March of Dimes Foundation Ohio Collaborative. SOURCE Cincinnati Children's Hospital Medical Center

Maternal-fetal listeriosis is a severe disease that can lead to miscarriage, premature birth or serious neonatal infection. But what are the long-term consequences of neonatal listeriosis on the health of surviving infants? A team of scientists and physicians monitored the development of children infected with the bacterium Listeria monocytogenes up to the age of 5, and compared their development with that of uninfected gestational age-matched children. The study showed that the long-term outcomes of neonatal listeriosis were mainly due to prematurity. Maternal-fetal listeriosis is a severe disease that can lead to miscarriage, premature birth or serious neonatal infection. But what are the long-term consequences of neonatal listeriosis on the health of surviving infants? For the first time, a team of scientists and physicians from the Institut Pasteur, Université Paris Cité, the Paris Public Hospital Network (AP-HP) and Inserm monitored the development of children infected with the bacterium Listeria monocytogenes up to the age of 5, and compared their development with that of uninfected gestational age-matched children. The study showed that the long-term outcomes of neonatal listeriosis were mainly due to prematurity. The results, published in the journal The Lancet Child and Adolescent Health on October 20, 2023, will allow parents to be better informed about how the health of their children may develop and help anticipate the potential onset of neurodevelopmental sequelae. Pregnant women today are all too aware of the risk of acquiring listeriosis, a foodborne infection, during pregnancy, and they are advised to avoid unpasteurized cheeses, cold meats and ready-to-eat foods that have not been thoroughly reheated. And with good reason, as the consequences can be severe: the bacterium Listeria monocytogenes can lead to miscarriage, premature birth and/or serious infection in newborn babies (septicemia or lung/neurological infection). In France, around 40 newborn babies are affected each year. "Since 2009 we have been studying all the strains of Listeria and all listeriosis patients in France -- since listeriosis is a notifiable disease -- to elucidate the characteristics of the disease. One of our questions was how infants with neonatal listeriosis, who have recovered after antibiotic treatment, go on to grow and develop," explains Marc Lecuit, Head of the National Reference Center for Listeria and the Biology of Infection Unit (Institut Pasteur/Université Paris Cité/Inserm), Professor of Infectious Diseases at Université Paris Cité and Necker-Enfants Malades Hospital, and co-last author of the study. The team of scientists and physicians used the French MONALISA cohort, which recruits all confirmed cases of listeriosis, to study the long-term neurological and neurodevelopmental consequences of infection in surviving children. This in-depth follow-up, made possible thanks to the active participation of the children's families, provided an unprecedented picture of the consequences of neonatal listeriosis on the neurocognitive development of children at a key age, when they are entering primary school. The multidisciplinary team, consisting in infectious disease experts, pediatricians, neuropsychologists and epidemiologists, followed about 50 children born to mothers who had contracted listeriosis at different stages of pregnancy, and conducted a comprehensive health assessment at age 5. Cognitive development was assessed using the French version of the Wechsler Preschool and Primary Scale of Intelligence, and motor and visual development was assessed using a physical examination designed to screen for cerebral palsy and developmental coordination disorder. Parental interviews and clinical tests were also used to assess hearing, functional communication and socialization. The results obtained were compared with those of uninfected gestational age-matched children from two large contemporary national cohorts: EPIPAGE-2 (preterm infants) and ELFE (term infants). This comparative approach revealed that two-thirds of infants born with listeriosis had sequelae (cognitive dysfunction, motor coordination problems, visual or hearing impairment) at age 5, mainly attributable to their prematurity. "We can now confirm that the long-term outcomes of neonatal listeriosis are mainly a result of prematurity rather than infection. These results will enable clinicians to provide science-based guidance to parents of newborns with listeriosis and to inform them about the development of their child's health. They also support the implementation of systematic long-term screening for possible sequelae so that appropriate early treatment can be offered, together with tailored educational support," concludes Caroline Charlier, a scientist at the Biology of Infection Unit (Institut Pasteur/Université Paris Cité/Inserm), Professor of Infectious Diseases at Université Paris Cité and Cochin Hospital, and first author and coordinator of the study.