Pathogen Persistence Research Articles

Use of transcriptomics and genomics to assess the effect of disinfectant exposure on the survival and resistance of Escherichia coli O157:H7, a human pathogen

Disinfectants are essential for biosecurity, preventing the persistence and spread of zoonotic pathogens on farms and subsequent human infections. In this study, transcriptomics and genomics were utilised to assess the effect of disinfectant exposure on pathogenic Escherichia coli. The exposure of E. coli O157:H7 to sub-optimal concentrations of commonly used farm disinfectants elicited changes in both the transcriptome and genome. The transcriptomics identified upregulation of >300 genes and downregulation of >100 genes with functions, which included stress response, metabolism, transcription, transportation, membrane-associated and virulence genes. The phage shock protein (psp) operon was highly upregulated in response to a quaternary ammonium compound (QAC)-containing disinfectant, which has not previously been associated with a response to chemical stress. Disinfectant-adapted isolates generated by exposure to sub-lethal disinfectants levels demonstrated resistance to several common antibiotics and decreased sensitivity to biocides. Whole genome sequencing of the mutant strains indicated that they had acquired mutations in the genes associated with the upregulation of the multiple antibiotic resistance (MAR) efflux system (lon protease and marR) and topoisomerase genes (gyrA and gyrB). The disinfectant-adapted isolates also exhibited increased expression of transcription, respiration and several pH stress response genes localised in the “acid fitness island.” This study demonstrated that sub-optimal disinfectant concentrations allow E. coli O157:H7 to adapt and survive disinfection and develop antibiotic resistance. These changes could have implications for disease treatment and elimination on farms. Although E. coli O157:H7 and farm disinfectants were the focus of this study, we believe these findings are also applicable to other settings, including hospitals.

The Staphylococcus aureus-antagonizing human nasal commensal Staphylococcus lugdunensis depends on siderophore piracy

BackgroundBacterial pathogens such as Staphylococcus aureus colonize body surfaces of part of the human population, which represents a critical risk factor for skin disorders and invasive infections. However, such pathogens do not belong to the human core microbiomes. Beneficial commensal bacteria can often prevent the invasion and persistence of such pathogens by using molecular strategies that are only superficially understood. We recently reported that the commensal bacterium Staphylococcus lugdunensis produces the novel antibiotic lugdunin, which eradicates S. aureus from the nasal microbiomes of hospitalized patients. However, it has remained unclear if S. lugdunensis may affect S. aureus carriage in the general population and which external factors might promote S. lugdunensis carriage to enhance its S. aureus-eliminating capacity.ResultsWe could cultivate S. lugdunensis from the noses of 6.3% of healthy human volunteers. In addition, S. lugdunensis DNA could be identified in metagenomes of many culture-negative nasal samples indicating that cultivation success depends on a specific bacterial threshold density. Healthy S. lugdunensis carriers had a 5.2-fold lower propensity to be colonized by S. aureus indicating that lugdunin can eliminate S. aureus also in healthy humans. S. lugdunensis-positive microbiomes were dominated by either Staphylococcus epidermidis, Corynebacterium species, or Dolosigranulum pigrum. These and further bacterial commensals, whose abundance was positively associated with S. lugdunensis, promoted S. lugdunensis growth in co-culture. Such mutualistic interactions depended on the production of iron-scavenging siderophores by supportive commensals and on the capacity of S. lugdunensis to import siderophores.EJt4aqYa_PFzdC4ihACHg3Video ConclusionsThese findings underscore the importance of microbiome homeostasis for eliminating pathogen colonization. Elucidating mechanisms that drive microbiome interactions will become crucial for microbiome-precision editing approaches.

Listeria in Pregnancy—The Forgotten Culprit

Listeria monocytogenes is a Gram-positive bacterium that causes listeriosis, a severe foodborne illness that is particularly dangerous during pregnancy. It thrives in diverse environments, including refrigerated conditions and food production facilities, due to its adaptability to varying temperatures, pH levels, and salt concentrations. Its virulence stems from the ability to invade host cells, particularly macrophages and epithelial cells, and avoid, or at least postpone, immune detection by utilizing virulence factors such as internalins, listeriolysin O, and actin assembly-inducing protein. This intracellular motility and biofilm formation make LM a persistent pathogen in food safety and public health. Pregnant women are at a much higher risk of listeriosis, which can result in serious fetal complications such as miscarriage, stillbirth, and preterm labor due to LM’s affinity for placental tissues. The vertical transmission of LM from mother to fetus can lead to neonatal listeriosis, which can result in sepsis and meningitis, with high mortality rates if not promptly treated. Early diagnosis and treatment with antibiotics, such as ampicillin or gentamicin, are crucial for maternal and neonatal outcomes.

Impact of Irrigation Source on the Dissemination and Persistence of Coliforms and Foodborne Pathogens in Fresh Tomato High Tunnel-dripline System from Small Specialty Crop Farms

This study investigated the impact of irrigation sources (pond, stream, and well) in high tunnel-dripline systems on the dissemination and persistence of foodborne pathogens (Escherichia coli O157, Listeria monocytogenes, Campylobacter spp., Salmonella spp., and the ‘big six’ Shiga toxin-producing E. coli [STEC]) in small specialty crop farms (SSCFs). Ten SSCF-growing fresh tomatoes using high tunnel-dripline systems were sampled between January and November 2022. Selective enrichment combined with PCR was used to detect the selected foodborne pathogens in the irrigation water (n = 240), soil (n = 240), and tomato fruits (n = 120). Overall, surface-originated water sources (streams and ponds) having potential contact with farm animals or wildlife harbored higher pathogen burden (cumulative prevalence of all the pathogens) compared to subsurface water source (well and underground spring water). STEC O26, O45, and O103 were detected at high frequency (up to 88% per SSCF per time point) in the water source and associated dripline irrigation system of 4/6 SSCFs using stream and pond water. Other foodborne pathogens (especially, L. monocytogenes) were detected in 6/10 SSCFs, but at low frequency (<25% per SSCF per time point). The prevalence of foodborne pathogens in the 10 SSCFs over time was positively correlated with the length of high tunnel and planting date (r2 = 0.93 and 0.79, respectively; P < 0.006). Our study highlighted that dripline irrigation systems may allow the long-distance transport of foodborne pathogens from the contaminated water source to the field. Risk assessment and mitigation measures should be implemented to assure the quality of the water source used for irrigation in SSCF.

An outbreak of blaKPC−4- and blaVIM−1-producing Klebsiella pneumoniae and Klebsiella variicola at a single hospital in South Korea

BackgroundThe dissemination of Klebsiella spp. producing multiple carbapenemases has been increasingly recognized. Between July 2019 and August 2021, ten patients were found to carry Klebsiella spp. co-harboring blaKPC−4 and blaVIM−1 across multiple wards at a Korean hospital, and one isolate was recovered from a hand-washing sink, more than a year after the outbreak. This study aimed to investigate the outbreak and conduct a genomic study of these isolates.MethodsWhole-genome sequencing, including long-read sequencing, was performed to analyze plasmid structures and mobile genetic elements (MGEs). Bioinformatics analyses were performed to trace clonal transmission chains and horizontal gene transfer.ResultsThe findings suggested that the inter-ward spread of Klebsiella spp. seemed to be facilitated by healthcare worker contact or patient movement. Of the nine isolates collected (eight clinical and one environmental), seven (including the environmental isolate) were identified as K. pneumoniae (ST3680) and two were K. variicola (single-locus variant of ST5252). These isolates showed high genetic relatedness within their species and harbored the IncHI5B plasmid carrying both blaKPC−4 and blaVIM−1 (pKPCVIM.1). On this plasmid, blaVIM−1 was located in the Class 1 integron associated with IS1326::IS1353 (In2), and Tn4401b carrying blaKPC−4 was inserted into IS1326::IS1353, creating a novel MGE construct (In2_blaVIM−1-Tn4401b_blaKPC−4).ConclusionThe hospital-wide spread of blaKPC−4 and blaVIM−1 was facilitated by clonal spread and horizontal plasmid transfer. The persistence of this strain in the hospital sink suggests a potential reservoir of the strain. Understanding the transmission mechanisms of persistent pathogens is important for improving infection control strategies in hospitals.

5164 Long COVID patients with menstrual symptoms: a retrospective study in Japan

Abstract Disclosure: F. Otsuka: None. Y. Sakurada: None. Y. Matsuda: None. T. Hasegawa: None. Y. Otsuka: None. Y. Nakano: None. K. Tokumasu: None. K. Yamamoto: None. N. Sunada: None. H. Honda: None. H. Hagiya: None. K. Ueda: None. It has been recognized that about one third of patients may suffer from prolonged illness after surviving from the acute phase of COVID-19. Various symptoms of the prolonged illness have been evaluated by many institutions including WHO. However, the mechanisms of the prolonged symptoms have yet to be elucidated. Long COVID is a complicated illness that develops after SARS-CoV-2 infection, independent of the severity of COVID-19. Long COVID is defined as symptoms that occur within 3 months after the initial infection and persist for at least 2 months. The major symptoms of long COVID include general fatigue, post-exertional malaise, headache, insomnia, dyspnea, cognitive dysfunction, low-grade fever, and muscle pain. Proposed pathophysiological mechanisms of long COVID include pathogen persistence and viral reactivation, immune dysregulation and autoimmunity, neurological abnormalities, tissue damage due to hypoperfusion and/or microclots, autonomic and endocrine dysfunctions, and dysregulation of microbiomes. In the present study, we aimed to elucidate the impact of long COVID on female reproductive health. In this retrospective study, medical records of patients who visited our long COVID clinic and clinical trends of their menstrual symptoms were evaluated. In our study, of 349 female patients who visited our clinic between Feb 2021 and Mar 2023, 223 patients with long COVID (18-50 years) were included. It was revealed that 44 females (19.7%) had menstrual symptoms associated with long COVID. The patients with menstrual symptoms were significantly older than those without menstrual symptoms (42.5 vs. 38 years). The percentage of patients with menstrual symptoms was higher during the Omicron phase (24%) than during the Preceding (13%) and Delta (12%) phases. Cycle irregularity (63.6%) was the most frequent menstrual symptom, followed by severe pain (25%), heavy bleeding (20.5%), perimenopausal symptoms (18.2%), and premenstrual syndrome (15.9%). Fatigue and depression were the most frequent complications with menstrual complaints. Scores indicating fatigue and QOL were significantly worse in long COVID patients with menstrual symptoms. Endocrine examinations showed significantly increased cortisol levels in patients with menstrual complaints although plasma adrenocorticotropin levels were not altered. Hence, long COVID has an impact on women’s reproductive and mental health. Presentation: 6/1/2024

5164 Long COVID patients with menstrual symptoms: a retrospective study in Japan

Abstract Disclosure: F. Otsuka: None. Y. Sakurada: None. Y. Matsuda: None. T. Hasegawa: None. Y. Otsuka: None. Y. Nakano: None. K. Tokumasu: None. K. Yamamoto: None. N. Sunada: None. H. Honda: None. H. Hagiya: None. K. Ueda: None. It has been recognized that about one third of patients may suffer from prolonged illness after surviving from the acute phase of COVID-19. Various symptoms of the prolonged illness have been evaluated by many institutions including WHO. However, the mechanisms of the prolonged symptoms have yet to be elucidated. Long COVID is a complicated illness that develops after SARS-CoV-2 infection, independent of the severity of COVID-19. Long COVID is defined as symptoms that occur within 3 months after the initial infection and persist for at least 2 months. The major symptoms of long COVID include general fatigue, post-exertional malaise, headache, insomnia, dyspnea, cognitive dysfunction, low-grade fever, and muscle pain. Proposed pathophysiological mechanisms of long COVID include pathogen persistence and viral reactivation, immune dysregulation and autoimmunity, neurological abnormalities, tissue damage due to hypoperfusion and/or microclots, autonomic and endocrine dysfunctions, and dysregulation of microbiomes. In the present study, we aimed to elucidate the impact of long COVID on female reproductive health. In this retrospective study, medical records of patients who visited our long COVID clinic and clinical trends of their menstrual symptoms were evaluated. In our study, of 349 female patients who visited our clinic between Feb 2021 and Mar 2023, 223 patients with long COVID (18-50 years) were included. It was revealed that 44 females (19.7%) had menstrual symptoms associated with long COVID. The patients with menstrual symptoms were significantly older than those without menstrual symptoms (42.5 vs. 38 years). The percentage of patients with menstrual symptoms was higher during the Omicron phase (24%) than during the Preceding (13%) and Delta (12%) phases. Cycle irregularity (63.6%) was the most frequent menstrual symptom, followed by severe pain (25%), heavy bleeding (20.5%), perimenopausal symptoms (18.2%), and premenstrual syndrome (15.9%). Fatigue and depression were the most frequent complications with menstrual complaints. Scores indicating fatigue and QOL were significantly worse in long COVID patients with menstrual symptoms. Endocrine examinations showed significantly increased cortisol levels in patients with menstrual complaints although plasma adrenocorticotropin levels were not altered. Hence, long COVID has an impact on women’s reproductive and mental health. Presentation: 6/1/2024

Understanding the transmission of bacterial agents of sapronotic diseases using an ecosystem-based approach: A first spatially realistic metacommunity model.

Pathogens such as bacteria, fungi and viruses are important components of soil and aquatic communities, where they can benefit from decaying and living organic matter, and may opportunistically infect human and animal hosts. One-third of human infectious diseases is constituted by sapronotic disease agents that are natural inhabitants of soil or aquatic ecosystems. They are capable of existing and reproducing in the environment outside of the host for extended periods of time. However, as ecological research on sapronosis is infrequent and epidemiological models are even rarer, very little information is currently available. Their importance is overlooked in medical and veterinary research, as well as the relationships between free environmental forms and those that are pathogenic. Here, using dynamical models in realistic aquatic metacommunity systems, we analyze sapronosis transmission, using the human pathogen Mycobacterium ulcerans that is responsible for Buruli ulcer. We show that the persistence of bacilli in aquatic ecosystems is driven by a seasonal upstream supply, and that the attachment and development of cells to aquatic living forms is essential for such pathogen persistence and population dynamics. Our work constitutes the first set of metacommunity models of sapronotic disease transmission, and is highly flexible for adaptation to other types of sapronosis. The importance of sapronotic agents on animal and human disease burden needs better understanding and new models of sapronosis disease ecology to guide the management and prevention of this important group of pathogens.

Primary succession of Bifidobacteria drives pathogen resistance in neonatal microbiota assembly

Human microbiota assembly commences at birth, seeded by both maternal and environmental microorganisms. Ecological theory postulates that primary colonizers dictate microbial community assembly outcomes, yet such microbial priority effects in the human gut remain underexplored. Here using longitudinal faecal metagenomics, we characterized neonatal microbiota assembly for a cohort of 1,288 neonates from the UK. We show that the pioneering neonatal gut microbiota can be stratified into one of three distinct community states, each dominated by a single microbial species and influenced by clinical and host factors, such as maternal age, ethnicity and parity. A community state dominated by Enterococcus faecalis displayed stochastic microbiota assembly with persistent high pathogen loads into infancy. In contrast, community states dominated by Bifidobacterium, specifically B. longum and particularly B. breve, exhibited a stable assembly trajectory and long-term pathogen colonization resistance, probably due to strain-specific functional adaptions to a breast milk-rich neonatal diet. Consistent with our human cohort observation, B. breve demonstrated priority effects and conferred pathogen colonization resistance in a germ-free mouse model. Our findings solidify the crucial role of Bifidobacteria as primary colonizers in shaping the microbiota assembly and functions in early life.

The influence of social and spatial processes on the epidemiology of environmentally transmitted pathogens in wildlife: implications for management.

Social and spatial structures of host populations play important roles in pathogen transmission. For environmentally transmitted pathogens, the host space use interacts with both the host social structure and the pathogen's environmental persistence (which determines the time-lag across which two hosts can transmit). Together, these factors shape the epidemiological dynamics of environmentally transmitted pathogens. While the importance of both social and spatial structures and environmental pathogen persistence has long been recognized in epidemiology, they are often considered separately. A better understanding of how these factors interact to determine disease dynamics is required for developing robust surveillance and management strategies. Here, we use a simple agent-based model where we vary host mobility (spatial), host gregariousness (social) and pathogen decay (environmental persistence), each from low to high levels to uncover how they affect epidemiological dynamics. By comparing epidemic peak, time to epidemic peak and final epidemic size, we show that longer infectious periods, higher group mobility, larger group size and longer pathogen persistence lead to larger, faster growing outbreaks, and explore how these processes interact to determine epidemiological outcomes such as the epidemic peak and the final epidemic size. We identify general principles that can be used for planning surveillance and control for wildlife host-pathogen systems with environmental transmission across a range of spatial behaviour, social structure and pathogen decay rates. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.

Comprehensive analysis of a peripheral blood transcriptome signature in piglets infected with Salmonella Typhimurium: insight into immune responses

Salmonella Typhimurium (ST) infection in pigs poses a significant threat to animal health and food safety; the intricate mechanisms underlying host–immune responses and pathogen persistence remain poorly understood. To address this knowledge gap, we comprehensively analyzed the peripheral blood transcriptome in piglets infected with ST. We performed histopathological evaluation, blood parameter analysis, advanced RNA-sequencing techniques, and quantitative reverse transcription PCR (RT-qPCR)-based validation. The increasement in the monocyte counts at 2 days post-infection suggested its potential to serve as a hematological marker for ST infection in piglets. Functional and pathway enrichment analyses of the differentially expressed genes highlighted the pivotal roles of innate and adaptive immune responses, notably in pathways associated with Toll-like receptors, NIK/NF-κB signaling, cytokine signaling, and T cell proliferation. RT-qPCR-based validation using peripheral blood mononuclear cells provided additional insights into the immune system dynamics in response to ST infection, revealing the marked elevation of the interleukin (IL)-15, IL-27, and CXCL10 levels being significantly elevated in ST-infected piglets. Our comprehensive analysis underscores the multifaceted impact of ST infection on piglets and offers valuable insights into the host–pathogen interactions and the role of host immune system during ST infection.

Abiotic and biotic factors jointly influence the contact and environmental transmission of a generalist pathogen.

The joint influence of abiotic and biotic factors is important for understanding the transmission of generalist pathogens. Abiotic factors such as temperature can directly influence pathogen persistence in the environment and will also affect biotic factors, such as host community composition and abundance. At intermediate spatial scales, the effects of temperature, community composition, and host abundance are expected to contribute to generalist pathogen transmission. We use a simple transmission model to explain and predict how host community composition, host abundance, and environmental pathogen persistence times can independently and jointly influence transmission. Our transmission model clarifies how abiotic and biotic factors can synergistically support the transmission of a pathogen. The empirical data show that high community competence, high abundance, and low temperatures correlate with high levels of transmission of ranavirus in larval amphibian communities. Discrete wetlands inhabited by larval amphibians in the presence of ranavirus provide a compelling case study comprising distinct host communities at a spatial scale anticipated to demonstrate abiotic and biotic influence on transmission. We use these host communities to observe phenomena demonstrated in our theoretical model. These findings emphasize the importance of considering both abiotic and biotic factors, and concomitant direct and indirect mechanisms, in the study of pathogen transmission and should extend to other generalist pathogens with the capacity for environmental transmission.

Deformed wings in the bumblebee Bombus terrestris (Linnaeus, 1758) in Luxembourg

Deformed wing virus (DWV), a persistent pathogen in European honeybees contributing to colony losses, also affects wild bees, including bumblebees, and a wide range of other insects. Bumblebees play a crucial role in crop production in temperate and cold ecosystems. A case of wild buff-tailed bumblebee workers Bombus terrestris (Linnaeus, 1758) showing visible clinical symptoms associated with overt, acute DWV infection is documented in Luxembourg, the first report for this bumblebee species widely distributed in the country. Further investigation is needed in Luxembourg to understand the impact of infectious diseases on wild pollinators and the role of managed pollinators in pathogen spillover.

Impact of Biotic and Abiotic Factors on Listeria monocytogenes, Salmonella enterica, and Enterohemorrhagic Escherichia coli in Agricultural Soil Extracts.

Outbreaks of Enterohemorrhagic Escherichia coli (EHEC), Salmonella enterica, and Listeria monocytogenes linked to fresh produce consumption pose significant food safety concerns. These pathogens can contaminate pre-harvest produce through various routes, including contaminated water. Soil physicochemical properties and flooding can influence pathogen survival in soils. We investigated survival of EHEC, S. enterica, and L. monocytogenes in soil extracts designed to represent soils with stagnant water. We hypothesized pathogen survival would be influenced by soil extract nutrient levels and the presence of native microbes. A chemical analysis revealed higher levels of total nitrogen, phosphorus, and carbon in high-nutrient soil extracts compared to low-nutrient extracts. Pathogen survival was enhanced in high-nutrient, sterile soil extracts, while the presence of native microbes reduced pathogen numbers. A microbiome analysis showed greater diversity in low-nutrient soil extracts, with distinct microbial compositions between extract types. Our findings highlight the importance of soil nutrient composition and microbial dynamics in influencing pathogen behavior. Given key soil parameters, a long short-term memory model (LSTM) effectively predicted pathogen survival. Integrating these factors can aid in developing predictive models for pathogen persistence in agricultural systems. Overall, our study contributes to understanding the complex interplay in agricultural ecosystems, facilitating informed decision-making for crop production and food safety enhancement.

Effect of Palmitoylethanolamide Compared to a Placebo on the Gut Microbiome and Biochemistry in an Overweight Adult Population: A Randomised, Placebo Controlled, Double-Blind Study.

This study investigates the effects of palmitoylethanolamide (PEA) on the gut microbiome of overweight adults. Fifty-eight participants (twenty males, thirty-eight females) aged 18-65 years with a BMI range of 30-40 kg/m2 were recruited. Participants were randomised to receive PEA (n = 36) or a placebo (n = 22) for 12 weeks. Microbiota composition, richness, diversity, and metabolic functions, faecal short chain fatty acids and calprotectin, pathology markers, and health-related questionnaires were analysed throughout the 12 weeks of supplementation. PEA supplementation significantly reduced triglyceride levels and IL-2 concentrations. No significant differences were found in the overall microbiota composition between the groups, and microbiota richness and diversity remained consistent for both groups. Functional analysis demonstrated no differences in functional richness and diversity, but specific pathways were modified. PEA supplementation resulted in a decrease in the abundance of pathways related to aromatic compound degradation, NAD interconversion, and L-glutamate degradation, while pathways associated with molybdopterin biosynthesis and O-antigen building blocks exhibited increased abundance. Increased production of O-antigen results in smooth LPS associated with reduced pathogenic stealth and persistence. PEA supplementation may influence specific microbial species, metabolic pathways, and reduce serum triglyceride and IL-2 concentration, shedding light on the intricate relationship between PEA, the microbiome, and host health.

The catheterized bladder environment induces dysregulation of macrophage polarization exacerbating bacterial UTI.

Urinary catheterization causes bladder damage, predisposing hosts to catheter-associated urinary tract infections (CAUTIs). CAUTI pathogenesis is mediated by bladder damage-induced inflammation, resulting in accumulation and deposition of the blood-clotting protein fibrinogen (Fg) and its matrix form fibrin, which are exploited by uropathogens as biofilm platforms to establish infection. Catheter-induced inflammation also results in robust immune cell recruitment, including macrophages (Mϕs). A fundamental knowledge gap is understanding the mechanisms by which the catheterized-bladder environment suppresses the Mϕ antimicrobial response, allowing uropathogen persistence. Here, we found that Fg and fibrin differentially modulate M1 and M2 Mϕ polarization, respectively. We unveiled that fibrin accumulation in catheterized mice induced an anti-inflammatory M2-like Mϕ phenotype, correlating with pathogen persistence. Even GM-CSF treatment of wildtype mice to promote M1 polarization was not sufficient to reduce bacterial burden and dissemination, indicating that the catheterized-bladder environment provides mixed signals, dysregulating Mϕ polarization, hindering its antimicrobial response against uropathogens.

Eosinophils as drivers of bacterial immunomodulation and persistence.

Traditionally, eosinophils have been linked to parasitic infections and pathological disease states. However, emerging literature has unveiled a more nuanced and intricate role for these cells, demonstrating their key functions in maintaining mucosal homeostasis. Eosinophils exhibit diverse phenotypes and exert multifaceted effects during infections, ranging from promoting pathogen persistence to triggering allergic reactions. Our investigations primarily focus on Bordetella spp., with particular emphasis on Bordetella bronchiseptica, a natural murine pathogen that induces diseases in mice akin to pertussis in humans. Recent findings from our published work have unveiled a striking interaction between B. bronchiseptica and eosinophils, facilitated by the btrS-mediated mechanism. This interaction serves to enhance pathogen persistence while concurrently delaying adaptive immune responses. Notably, this role of eosinophils is only noted in the absence of a functional btrS signaling pathway, indicating that wild-type B. bronchiseptica, and possibly other Bordetella spp., possess such adeptness in manipulating eosinophils that the true function of these cells remains obscured during infection. In this review, we present the mounting evidence pointing toward eosinophils as targets of bacterial exploitation, facilitating pathogen persistence and fostering chronic infections in diverse mucosal sites, including the lungs, gut, and skin. We underscore the pivotal role of the master regulator of Bordetella pathogenesis, the sigma factor BtrS, in orchestrating eosinophil-dependent immunomodulation within the context of pulmonary infection. These putative convergent strategies of targeting eosinophils offer promising avenues for the development of novel therapeutics targeting respiratory and other mucosal pathogens.

The plastisphere can protect Salmonella Typhimurium from UV stress under simulated environmental conditions

Plastic waste is found with increasing frequency in the environment, in low- and middle-income countries. Plastic pollution has increased concurrently with both economic development and rapid urbanisation, amplifying the effects of inadequate waste management. Distinct microbial communities can quickly colonise plastic surfaces in what is collectively known as the ‘plastisphere’. The plastisphere can act as a reservoir for human pathogenic bacteria, including Salmonella enterica sp. (such as S. Typhimurium), which can persist for long periods, retain pathogenicity, and pose an increased public health risk. Through employing a novel mesocosm setup, we have shown here that the plastisphere provides enhanced protection against environmental pressures such as ultraviolet (UV) radiation and allows S. Typhimurium to persist at concentrations (>1 × 103 CFU/ml) capable of causing human infection, for up to 28 days. Additionally, using a Galleria Mellonella model of infection, S. Typhimurium exhibits greater pathogenicity following recovery from the UV-exposed plastisphere, suggesting that the plastisphere may select for more virulent variants. This study demonstrates the protection afforded by the plastisphere and provides further evidence of environmental plastic waste acting as a reservoir for dangerous clinical pathogens. Quantifying the role of plastic pollution in facilitating the survival, persistence, and dissemination of human pathogens is critical for a more holistic understanding of the potential public health risks associated with plastic waste.

Weather-related changes in the dehydration of respiratory droplets on surfaces bolster bacterial endurance

HypothesisThe study shows for the first time a fivefold difference in the survivability of the bacterium Pseudomonas Aeruginosa (PA) in a realistic respiratory fluid droplet on fomites undergoing drying at different environmental conditions. For instance, in 2023, the annual average outdoor relative humidity (RH) and temperature in London (UK) is 71 % and 11 °C, whereas in New Delhi (India), it is 45 % and 26 °C, showing that disease spread from fomites could have a demographic dependence. Respiratory fluid droplet ejections containing pathogens on inanimate surfaces are crucial in disease spread, especially in nosocomial settings. However, the interplay between evaporation dynamics, internal fluid flow and precipitation and their collective influence on the distribution and survivability of pathogens at different environmental conditions are less known. ExperimentsShadowgraphy imaging is employed to study evaporation, and optical microscopy imaging is used for precipitation dynamics. Micro-particle image velocimetry (MicroPIV) measurements reveal the internal flow dynamics. Confocal imaging of fluorescently labelled PA elucidates the bacterial distribution within the deposits. FindingsThe study finds that the evaporation rate is drastically impeded during drying at elevated solutal concentrations, particularly at high RH and low temperature conditions. MicroPIV shows reduced internal flow under high RH and low temperature (low evaporation rate) conditions. Evaporation rate influences crystal growth, with delayed efflorescence and extending crystallization times. PA forms denser peripheral arrangements under high evaporation rates and shows a fivefold increase in survivability under low evaporation rates. These findings highlight the critical impact of environmental conditions on pathogen persistence and disease spread from inanimate surfaces.

Exploring the Antimicrobial Efficacy of Low-Cost Commercial Disinfectants Utilized in the Agro-Food Industry Wash Tanks: Towards Enhanced Hygiene Practices.

The increase in vegetable consumption has underlined the importance of minimizing the risks associated with microbiological contamination of fresh produce. The critical stage of the vegetable washing process has proven to be a key point for cross-contamination and the persistence of pathogens. In this context, the agri-food industry has widely adopted the use of disinfectants to reduce the bacterial load in the wash water. Therefore, we conducted laboratory-scale experiments in order to demonstrate the antimicrobial activity of disinfectants used in the wash tank of agro-food industries. Different wash water matrices of shredded lettuce, shredded cabbage, diced onion, and baby spinach were treated with sodium hypochlorite (NaClO), chlorine dioxide (ClO2), and per-oxyacetic acid (PAA) at recommended concentrations. To simulate the presence of pathogenic bacteria, a cocktail of E. coli O157:H7 was inoculated into the process water samples (PWW) to determine whether concentrations of disinfectants inhibit the pathogen or bring it to a viable non-culturable state (VBNC). Hereby, we used quantitative qPCR combined with different photo-reactive dyes such as ethidium monoazide (EMA) and propidium monoazide (PMA). The results indicated that concentrations superior to 20 ppm NaClO inhibit the pathogen E. coli O157:H7 artificially inoculated in the process water. Concentrations between 10-20 ppm ClO2 fail to induce the pathogen to the VBNC state. At concentrations of 80 ppm PAA, levels of culturable bacteria and VBNC of E. coli O157:H7 were detected in all PWWs regardless of the matrix. Subsequently, this indicates that the recommended concentrations of ClO2 and PAA for use in the fresh produce industry wash tank do not inhibit the levels of E. coli O157:H7 present in the wash water.