Colonization Dynamics Research Articles

P-1003. Group B Streptococcus Colonization in Pregnant Women and Their Infants: Prevalence of Colonization, Vertical Transmission, and Serotype Dynamics

Abstract Background Group B Streptococcus (GBS) is a leading cause of neonatal mortality and morbidity worldwide. Despite historically lower colonization rates among pregnant Korean women compared to those in Western countries, recent studies indicate a rising trend in GBS colonization rates and serotype changes. This study aimed to investigate GBS colonization rates, vertical transmission, and serotype distribution among pregnant women and their infants in Korea. Methods A prospective, mother-infant paired cohort study was conducted from January 2020 to November 2023. Vaginal and rectal swabs were obtained from pregnant women, while gastric aspirate and nasopharyngeal swabs were collected from infants immediately after birth, and nasopharyngeal and rectal swabs were obtained at one and two months of age. Serotyping and multilocus sequence typing (MLST) of GBS isolates were performed. Results Among 427 pregnant women, 67 (15.7%) tested positive for GBS colonization. Serotype III (24%), followed by V (22.4%), VIII (19.0%), and Ib (17.2%), were the predominant serotypes, with the most common sequence types (ST) being ST2, ST19, and ST10. Vertical transmission was observed in one infant at birth, presenting with serotype V. GBS colonization was identified in four infants at one month of age, with serotypes Ia and VIII. Of these, serotype Ia persisted in two infants, while serotype III was newly detected in one infant at two months of age. Conclusion The increasing trend in GBS colonization among pregnant Korean women highlights the need for continuous monitoring. GBS colonization was observed in infants at birth and up to two months of age, emphasizing the importance of ongoing surveillance of GBS colonization rates and serotype distribution to establish guidelines and preventive strategies in Korea. Disclosures All Authors: No reported disclosures

315. Modeling Strain-Dependent Variability in Carbapenem-Resistant Klebsiella pneumoniae Colonization in the Malnourished Host

Abstract Background Particular strains of Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) have achieved global dominance extending to developing countries where malnutrition is a potential risk factor for infection. Bacteria and host properties that determine colonization dynamics in this context are not understood. We hypothesized that strain variability in host cell adhesion and nutrient-utilization in vitro predicts in vivo intestinal colonization by CR-Kp in malnourished hosts.Figure 1:Strain-dependent cell adhesion by carbapenem-resistant Klebsiella pneumoniae(A) Adhesion to Colo-201 cells and/or (B) Caco-2 cells as percentage of bacteria recovered after co-culturing then washing off non-adherent cells. Bacterial quantification performed by culturing on MacConkey agar + Meropenem. Strains of interest indicated with arrows and colored-bars. All experiments showing results of 3 replicates. Methods Patient-derived isolates of CR-Kp were subject to in vitro assays testing adhesion to human colon cell lines. Select isolates were further tested for in vitro growth in minimal media with limiting protein availability. These isolates were additionally inoculated via orogastric lavage into C57BL/6 mice (n=6 per group) on a nutrient replete control diet (CD) or isocaloric protein-deficient diet (PD) and intestinal colonization was quantified with selective culture of feces and intestinal specimens on MacConkey agar containing meropenem.Figure 2:Nutrient limited growth of carbapenem-resistant Klebsiella pneumoniaeGrowth in vitro determined by serial absorption measurement of bacteria culture under different nutrient conditions. M9 minimal medium (M9mm; M9 solution +0.4% glucose) was used with or without casein peptone (0.16% or 0.016%) as a protein/amino acid source. Results Across >100 screened human isolates of CR-Kp, adhesion to human colon cell lines ranged from < 1% to 30% (Figure 1). Three high-adhesion isolates (Kp175, Kp4493 and Kp4605) and one low-adhesion isolate (Kp4404) were selected for further investigation (Table 1). All three high-adhesion isolates grew to varying degrees in protein-limited conditions, while Kp4404 required a protein source for growth (Figure 2). Mice inoculated with CR-Kp were stably colonized only if they were fed a PD rather than CD diet. Kp175 and Kp4605 demonstrated the highest fecal shedding and intestinal burden (102-104 CFU per mg), which was significantly greater on a PD versus CD diet (p< 0.05 by Mann-Whitney test). In contrast, Kp4493 and Kp4404 inconsistently colonized mice regardless of diet (Figure 3).Figure 3:Diet-dependent intestinal colonization by carbapenem-resistant Klebsiella pneumoniae(A) 3-4 wk old C57BL/6 male mice initiated on nutrient-replete control diet (CD) or isocaloric protein-deficient diet (PD) and inoculated via orogastric lavage with 10^6 CFU of carbapenem-resistant Klebsiella pneumoniae (CR-Kp). (B) Weight measured over time along with bacterial burden in (C) fecal pellets and (D) intestinal tissue by culturing on MacConkey agar + Meropenem. 6 animals used per condition. * = p<0.05 by Mann Whitney Test. Conclusion Our findings suggest a wide variability in intestinal cell adhesion and nutrient utilization by clinical isolates of CR-Kp. These in vitro properties incompletely predict in vivo colonization in a mouse model. Notably, host dietary deficiency promotes intestinal colonization by certain nutritionally resilient CR-Kp isolates, with potential implications for the global spread of high-risk strains in malnourished populations.Table 1:Genotypic, clinical and phenotypic characteristics of carbapenem-resistant Klebsiella pneumoniae Adhesion percentage express as mean (standard deviation). Disclosures David van Duin, MD, PhD, Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Qpex: Advisor/Consultant|Roche: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support

The emerging fungal pathogen Candida auris induces IFNγ to colonize mammalian hair follicles.

Public health alarm concerning the emerging fungus Candida auris is fueled by its antifungal drug resistance and propensity to cause deadly outbreaks. Persistent skin colonization drives transmission and lethal sepsis although its basis remains mysterious. We compared the skin colonization dynamics of C. auris with its relative C. albicans , quantifying skin fungal persistence and distribution and immune composition and positioning. C. auris displayed a higher propensity to colonize hair follicles and avidly bound to human hair. While C. albicans triggered an effective sterilizing type 3/17 antifungal immune response driven by IL-17A/F-producing lymphocytes, C. auris triggered a type 1, IFNγ-driven immune response targeting hair follicles. Rather than promoting fungal clearance, IFNγ enhanced C. auris skin colonization by acting directly on keratinocytes impairing epithelial barrier integrity and repressing antifungal defense programs. C. auris exploits focal skin immune responses to create a niche for persistence in hair follicles.

Ecological and anthropogenic drivers of local extinction and colonization of giant pandas over the past 30 years.

Understanding the patterns and drivers of species range shifts is essential to disentangle mechanisms driving species' responses to global change. Here, we quantified local extinction and colonization dynamics of giant pandas (Ailuropoda melanoleuca) using occurrence data collected by harnessing the labor of >1000 workers and >60,000 worker days for each of the three periods (TP1: 1985-1988, TP2: 1998-2002, and TP3: 2011-2014), and evaluated how these patterns were associated with (1) protected area, (2) local rarity/abundance, and (3) abiotic factors (i.e., climate, land-use, and topography). We documented a decreased rate (from 0.433 during TP1-TP2 to 0.317 during TP2-TP3) of local extinction and a relatively stable rate (from 0.060 during TP1-TP2 to 0.056 during TP2-TP3) of local colonization through time. Furthermore, the occupancy gains have exceeded losses by a ratio of approximately 1.5 to 1, illustrating an expansion of panda's range at a rate of 1408.3 km2/decade. We also found that pandas were more likely to become locally extinct outside of protected areas, when locally rare in surrounding areas, and when certain biotic conditions were not met (e.g., increased forest cover). Local colonization was less likely in areas with high local rarity, challenging biotic conditions and unprotected area status. As the network of panda reserves expanded and the forest matured, the relative importance of other factors such as climate, biotic factors, and land-use became more influential in determining patterns of local extinction and colonization. Our findings provide insights into the factors governing the expansion of panda's range and illustrate how the relative influence of biotic and abiotic factors can change over time, indicating that effective conservation intervention may be able to mitigate some of the negative impacts of climate change and habitat degradation. This insight extends beyond pandas and highlights the role of conservation interventions can play in building resilience under a changing climate.

Tracing carriage, acquisition, and transmission of ESBL-producing Escherichia coli over two years in a tertiary care hospital

BackgroundThe impact of community carriage on the influx of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) into hospitals remains understudied. In this prospective 2-year single-centre study, we investigate the community ESBL-E influx and trace the colonisation, nosocomial acquisition, transmission, and infection dynamics of ESBL-producing Escherichia coli (ESBL-Ec) in non-ICU wards at a tertiary care hospital.MethodsThis study reports primary and post hoc outcomes of the clinical trial NCT01208519 in which hospitalised patients were screened for rectal carriage of ESBL-E. ESBL-Ec isolates from ≈50% of carriers, including all patients who developed infections, were sequenced and genotyped. Endogenous infection was defined as infection by the same strain (< 10 SNPs distance) as colonizing strain.ResultsOf 3703 screened patients, 456 (12.3%) were ESBL-positive-at-admission (PA-ESBL). Of the 2268 ESBL-negative-at-admission (NA-ESBL) patients with follow-up samples, 240 (10.6%) acquired ESBL-E (HA-ESBL), with an incidence density rate of 7.96 cases/1000 patient-day, notably higher in patients receiving antibiotics (P < 0.001). PA- and HA-ESBL patients developed significantly more ESBL-E infections than ESBL-free patients (P < 0.001). Sequenced ESBL-Ec showed high clonal diversity dominated by the multidrug-resistant and highly virulent ST131 clade, C2/H30-Rx. Among ESBL-Ec infections, 60% (18/30) were endogenous. Direct between-patients transmission clusters (n = 21) involved 23.9% (48/201) of patients and 23.0% (84/366) of ESBL-Ec isolates.ConclusionsOur data show a high prevalence of nosocomial acquisition of ESBL-E in a non-ICU setting. The study provides genomic evidence that the endogenous reservoir is the main driver of ESBL-Ec infections underscoring the need for wide implementation of antibiotic stewardship programmes to reduce antibiotic pressure.

Native beauveria bassiana isolates: harnessing endophytic capabilities for controlling fall armyworm infestation in maize

ABSTRACT This study investigates the establishment and colonization dynamics of Beauveria bassiana as an endophyte in maize plants using various inoculation methods. Surface sterilization and fungal isolation confirmed B. bassiana as an endophyte, with isolates ChBb and NaBb exhibiting distinct colonization patterns. Notably, foliar spray demonstrated the highest initial colonization efficiency, with ChBb achieving 93.3% in leaves at 7 days post-inoculation (DPI), decreasing to 13.3% at 35 DPI. NaBb similarly exhibited high initial colonization via foliar spray, with 93.3% in leaves at 7 DPI, declining to 33.3% at 35 DPI. Molecular analysis using nested PCR confirmed the presence of B. bassiana DNA exclusively in treated tissues, with a consistent 300 bp PCR product observed in leaf, stem, and root samples. Phylogenetic analysis highlighted genetic relationships among B. bassiana isolates, underscoring their diversity and potential for biocontrol applications. Pathogenicity tests against Spodoptera frugiperda demonstrated significant mortality rates: ChBb achieved 77.20% mortality in direct contact assays (where larvae were exposed directly to the fungal spores) and 56.82% mortality in vivo (where larvae were fed plants colonized by the fungus), while NaBb resulted in 75.86% and 51.42% mortality, respectively. These findings emphasize the efficacy of B. bassiana as a biocontrol agent, particularly through foliar application for initial colonization in maize plants.

Longitudinal prevalence and co-carriage of pathogens associated with nursing home acquired pneumonia in three long-term care facilities.

Nursing home acquired pneumonia (NHAP), and its subset - aspiration-associated pneumonia, is a leading cause of morbidity and mortality among residents in long-term care facilities (LTCFs). Understanding colonization dynamics of respiratory pathogens in LTCF residents is essential for effective infection control. This study examines the longitudinal trends in prevalence, persistence, bacterial load, and co-colonization patterns of five respiratory pathogens in three LTCFs in Phoenix, Arizona. Anterior nares and oral swabs were collected every other week and tested using qPCR for Haemophilus influenzae, Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus , and Chlamydia pneumoniae . Weekly average positivity rates were 17.75% for H. influenzae (0% - 39.39%), 9.95% for P. aeruginosa (0% - 37.74%), 31.89% for S. pneumoniae (1.79% - 41.67%), and for 28.00% for S. aureus (0% - 55.36%). C. pneumoniae was not detected. H. influenzae and S. pneumoniae predominantly colonized the oral cavity, while P. aeruginosa and S. aureus predominantly colonized the nasal cavity. S. pneumoniae and S. aureus colonizations were significantly more persistent than H. influenzae and P. aeruginosa , with persistence correlating with significantly higher bacterial loads. Co-colonization did occur in ∼20% of positive samples, but appeared to be due to random chance. This study reveals distinct colonization patterns among respiratory pathogens in LTCF residents, highlighting differences in site-specific prevalence, persistence, and bacterial load. These findings underscore the importance of longitudinal monitoring to inform targeted infection control strategies in LTCFs.

Community dynamics during de novo colonization of the nascent peri-implant sulcus.

Dental implants have restored chewing function to over 100,000,000 individuals, yet almost 1,000,000 implants fail each year due to peri-implantitis, a disease triggered by peri-implant microbial dysbiosis. Our ability to prevent and treat peri-implantitis is hampered by a paucity of knowledge of how these biomes are acquired and the factors that engender normobiosis. Therefore, we combined a 3-month interventional study of 15 systemically and periodontally healthy adults with whole genome sequencing, fine-scale enumeration and graph theoretics to interrogate colonization dynamics in the pristine peri-implant sulcus. We discovered that colonization trajectories of implants differ substantially from adjoining teeth in acquisition of new members and development of functional synergies. Source-tracking algorithms revealed that this niche is initially seeded by bacteria trapped within the coverscrew chamber during implant placement. These pioneer species stably colonize the microbiome and exert a sustained influence on the ecosystem by serving as anchors of influential hubs and by providing functions that enable cell replication and biofilm maturation. Unlike the periodontal microbiome, recruitment of new members to the peri-implant community occurs on nepotistic principles. Maturation is accompanied by a progressive increase in anaerobiosis, however, the predominant functionalities are oxygen-dependent over the 12-weeks. The peri-implant community is easily perturbed following crown placement, but demonstrates remarkable resilience; returning to pre-perturbation states within three weeks. This study highlights important differences in the development of the periodontal and peri-implant ecosystems, and signposts the importance of placing implants in periodontally healthy individuals or following the successful resolution of periodontal disease.

The Teichichnus Ichnofacies: Its neoichnological basis and identification in the rock record

AbstractResearch on the ichnology of brackish‐water environments began in the 1930s and has led to the identification of predictable infaunal patterns. Brackish‐water deposits characteristically display low‐diversity tracefossil assemblages consisting of both vertical and horizontal structures. These salinity‐reduced ecosystems are dominated by opportunistic euryhaline‐tolerant species. Osmoregulation‐related selective pressures lead to decreased diversity and an abundance of infaunal organisms. In environments with fluctuating or low salinity, fauna adopt r‐selected strategies and are characterized by rapid colonization dynamics, high population densities, elevated mortality rates and low‐diversity assemblages. Tides in brackish‐water settings contribute a plentiful food supply with tidal currents transporting marine‐sourced and terrestrially sourced organic matter that settles on the sediment–water interface during slack‐water periods. This increased food availability favours trophic generalists using various feeding strategies to exploit both intrastratal and surficial food resources. The ichnological characteristics of modern and ancient brackish‐water strata are used to propose the Teichichnus Ichnofacies; they are temporally and spatially recurrent and reflect the biology of brackish‐water settings. The Teichichnus Ichnofacies is recognized by reduced trace‐fossil diversity, smaller trace sizes, dominance of structures reflecting trophic generalist behaviours, sporadic distributions of ichnofossils, locally high bioturbation intensities and opportunistic colonization. This ichnofacies is characterized by trace fossils interpreted to be associated with surface deposit feeding, intrastratal deposit feeding and subordinate filter feeding.

Temporal succession of marine microbes drives plastisphere community convergence in subtropical coastal waters.

Marine plastic pollution is a pervasive environmental issue, with microplastics serving as novel substrates for microbial colonization in aquatic ecosystems. This study investigates the succession of plastisphere communities on four common plastic types (polyethylene, polypropylene, polyethylene terephthalate, and polystyrene) in subtropical coastal waters of Hong Kong SAR. Over a 42-day period, we analysed the temporal development of microbial communities using a three-domain universal metabarcoding method. Our results reveal that temporal succession is a stronger driver of community structure than plastic type, with prokaryotic communities converging across different plastics as biofilms mature. Despite this convergence, plastisphere communities remain distinct from planktonic communities throughout the experiment, suggesting that plastics create unique ecological niches in marine environments. We observed differences in diversity patterns and community composition among prokaryotic, eukaryotic, and chloroplastic communities, highlighting the importance of multi-domain analyses in plastisphere research. Functional predictions suggest potential roles of prokaryotic communities in biogeochemical cycling and possible pathogenicity, highlighting the ecological and public health implications of plastisphere formation. This study provides valuable insights into the dynamics of microbial colonization across domains on marine plastics and enhances our understanding of how these anthropogenic substrates influence microbial ecology in marine ecosystems.

Disentangling the worldwide invasion process of Halyomorpha halys through approximate Bayesian computation.

Halyomorpha halys is a polyphagous insect pest, which was first found outside its native regions in 1996, and since then it has rapidly spread worldwide causing damage to agriculture. Investigating the genetic diversity among H. halys populations is essential to understand the colonization history out of its native areas. Analyses based on mtDNA indicate multiple invasions from Asia to European and American continents, as well as serial invasions within invaded countries, but the colonization dynamics are still debated. Recently, genome-wide data (ddRAD) have been published to investigate the genomic structure of H. halys, proposing China as a putative source of multiple serial invasion events to Europe and the Americas. In this study we re-analyze published ddRAD sequences from worldwide populations of H. halys to better elucidate the colonization process. We assessed the genetic diversity in native populations identifying genetic differentiation between populations in China. Furthermore, we observed a complex pattern of population structure in the invaded countries, that may have originated from the occurrence of multiple independent colonization waves through time, from sub-populations present in the native range to Europe and the Americas. We tested alternative colonization hypotheses through Approximate Bayesian Computation comparison of demographic scenarios. Our results support multiple waves of migration from East China to invaded territories and the occurrence of European and American bridgehead effects. These results underline the importance of demographic inference through genome-wide data to investigate biological invasions, whose knowledge become fundamental to establish new strategies of management and control of invasive species.

Mobile genetic elements: the hidden puppet masters underlying infant gut microbiome assembly?

The gut microbiota is important for healthy infant development. Part of the initial colonizing microbial strains originate from the maternal gut, and undergo a selective event, termed the “colonization bottleneck”. While vertical mother-to-infant inheritance and subsequent colonization of bacteria have previously been studied, the role of mobile genetic elements (MGEs) in the infant gut microbiota assembly is unclear. In this perspective article, we discuss how horizontally and vertically transmitted phages and conjugative elements potentially have important roles in infant gut microbiota assembly and colonization through parasitic and mutualistic interactions with their bacterial hosts. While some of these MGEs are likely to be detrimental to their host survival, in other contexts, they may help bacteria colonize new niches, antagonize other bacteria, or protect themselves from other parasitic MGEs in the infant gut. As a result, the horizontal transfer of MGEs likely occurs at high rates in the infant gut, contributing to gene transfer between bacteria and affecting which bacteria can pass the colonization bottleneck. We conclude by highlighting the potential in silico , in vitro , and in vivo methodological approaches that could be employed to study the transmission and colonization dynamics of MGEs and bacteria in the infant gut.

Longitudinal genomic surveillance of a UK intensive care unit shows a lack of patient colonisation by multi-drug-resistant Gram-negative bacterial pathogens.

Vulnerable patients in an intensive care unit (ICU) setting are at high risk of infection from bacteria including gut-colonising Escherichia coli and Klebsiella species. Complex ICU procedures often depend on successful antimicrobial treatment, underscoring the importance of understanding the extent of patient colonisation by multi-drug-resistant organisms (MDROs) in large UK ICUs. Previous work on ICUs globally uncovered high rates of colonisation by transmission of MDROs, but the situation in UK ICUs is less understood. Here, we investigated the diversity and antibiotic resistance gene (ARG) carriage of bacteria present in one of the largest UK ICUs at the Queen Elizabeth Hospital Birmingham (QEHB), focusing primarily on E. coli as both a widespread commensal and a globally disseminated multi-drug-resistant pathogen. Samples were taken during highly restrictive coronavirus disease 2019 (COVID-19) control measures from May to December 2021. Whole-genome and metagenomic sequencing were used to detect and report strain-level colonisation of patients, focusing on E. coli sequence types (STs), their colonisation dynamics and antimicrobial resistance gene carriage. We found a lack of multi-drug resistance (MDR) in the QEHB. Only one carbapenemase-producing organism was isolated, a Citrobacter carrying bla KPC-2. There was no evidence supporting the spread of this strain, and there was little evidence overall of nosocomial acquisition or circulation of colonising E. coli. Whilst 22 different E. coli STs were identified, only 1 strain of the pandemic ST131 lineage was isolated. This ST131 strain was non-MDR and was found to be a clade A strain, associated with low levels of antibiotic resistance. Overall, the QEHB ICU had very low levels of pandemic or MDR strains, a result that may be influenced in part by the strict COVID-19 control measures in place at the time. Employing some of these infection prevention and control measures where reasonable in all ICUs might therefore assist in maintaining low levels of nosocomial MDR.

Natural colonization as a means to upscale restoration of subarctic woodlands in Iceland

The global climate and biodiversity crisis has led to extensive restoration initiatives, calling for cost‐effective strategies harnessing the potential of natural processes. Natural colonization of target species is a key process in the scaling up of woodland restoration, and effective planning and implementation of restoration strategies requires a mechanistic understanding of colonization processes. In this study, we investigated patterns and processes of natural colonization of mountain birch (Betula pubescens ssp. tortuosa), the only native woodland‐forming tree species in Iceland, into adjacent treeless lands under diverse conditions, and its implications for low‐intensity restoration strategies. Accordingly, we assessed spatial patterns of seedling densities on transects extending from 10 birch woodlands in Iceland and analyzed the impact of local environments on colonization dynamics. Seedling densities generally decreased rapidly with distance from the seed source to around 40 m. In many study areas, however, birch seedlings were registered at high enough densities to potentially form woodlands, up to 140 m from a standing seed source. We identified a range of biotic and abiotic determinants of colonization, with the largest number affecting the early‐establishment phase of birch colonization, including safe site availability, wind speed and dominant direction, and grazing. Our results demonstrate a good potential for natural colonization as a restoration strategy for birch woodlands in subarctic environments, and they can furthermore be used to identify areas where birch colonization is likely to occur naturally and determine appropriate interventions that can facilitate birch colonization in areas where it is less likely.

Reconstruction and Prediction of Invasive Cydia pomonella Population Dynamics: A Laboratory Study

ABSTRACTInvasive species pose a significant threat to global biodiversity and ecological services. The specific threshold of the initial population size necessary for the successful establishment of an invasive species remains uncertain. This research delves into the effects of different initial population sizes on the colonisation and population dynamics of the globally recognised invasive pest, Cydia pomonella, within a controlled laboratory setting. The results revealed that even a single pair of C. pomonella displayed notable eggs laid (fecundity) and hatched (fertility) by producing offspring upon mating. Larger initial population size exhibited increased mating rates, leading to enhanced fecundity and subsequently more offspring, indicating that the development of C. pomonella population is directly impacted by the mating rate of the initial individuals. Projections based on F1 data indicate that the C. pomonella population size could persistently increase over a span of 150 days, with varying growth rates influenced by the initial population size. These findings indicate the importance of heightened monitoring and management in non‐invaded regions to avert early colonisation of C. pomonella, thus mitigating the threat of invasion and subsequent population expansion.

Rapid colonisation of environmental plastic waste by pathogenic bacteria drives adaptive phenotypic changes

Microbial biofilms on environmental plastic pollution can serve as a reservoir for both pathogenic and commensal bacteria. Associating with this ‘plastisphere’, provides a mechanism for the wider dissemination of pathogens within the environment and a greater potential for human exposure. For pathogens to bind to environmental plastic waste they need to be in close contact with it; therefore, understanding how rapidly pathogens can bind to plastics and the temporal colonisation dynamics of the continual cycling between the plastisphere and the environment are important factors for quantifying the persistence of human pathogens. Using simulated environmental conditions, we demonstrate that pathogenic E. coli O157 can rapidly colonise plastics (within 30 min) and persist for extended periods (at least 21 days), at concentrations sufficient to cause human infection. Importantly, repeated colonisation and dissociation cycles of E. coli O157 from the plastisphere leads to an enhanced capacity for persistence and the emergence of variants with increased virulence traits, including improved biofilm formation and antibiotic tolerance. This phenotypic adaptation to repeated colonisation of environmental plastic surfaces could be selecting for more persistent and virulent strains of pathogens, and hence increase the co-pollutant risks associated with plastic pollution.

Fractional-Order Mathematical Modeling of Methicillin- Resistant Staphylococcus aureus Transmission in Hospitals

This article investigates the environmental contamination and antibiotic exposure effect on the transmission dynamics of the Methicillin-Resistant Staphylococcus aureus (MRSA) model in hospitals using the fractional Adams–Bashforth–Moulton Method (ABMM). This epidemic model simulates the dynamics of patient populations, bacterial contamination, and healthcare worker safety under varying conditions. This model provides critical insights into the interactions between hospital practices, environmental factors, and infection dynamics, demonstrating the importance of symmetry in balancing hospital admission and discharge rates to manage infection spread effectively. The analysis extends to the impact of environmental bacterial density and hospital admission rates on patient colonization. Increasing admission rates introduce more susceptible patients, exacerbating infection spread when bacterial density is high. Conversely, lower admission rates and bacterial density result in a more controlled infection environment. The model further investigates how varying discharge rates influence colonization dynamics, highlighting that effective discharge practices can mitigate infection spread, especially in high-bacterial density scenarios. It must be noted that this model is studied fractionally for the first time. Overall, this model provides critical insights into the interactions between hospital practices, environmental factors, and infection dynamics, offering valuable guidance for infection control strategies and hospital policy formulation. By adjusting fractional order constant (σ) values and analyzing different scenarios, this research aids in understanding and managing bacterial infections in healthcare settings. The proposed method is able to provide the results presented in the figures within this study considering the influence of many factors.

Early-life Upper Airway Microbiota are Associated with Decreased Lower Respiratory Tract Infections

Microbial interactions mediating colonization resistance play key roles within the human microbiome, shaping susceptibility to infection from birth. To gain insight into microbiome-mediated defenses and respiratory pathogen colonization dynamics, we sequenced and analyzed nasal (n=229) and oral (n=210) microbiomes with associated health/environmental data from our Wisconsin Infant Study Cohort at age 24-months. Participants with early-life lower respiratory tract infection (LRTI) were more likely to be formula-fed, attend daycare, and experience wheezing. Shotgun metagenomic sequencing with detection of viral and bacterial respiratory pathogens revealed nasal microbiome composition to associate with prior LRTI – namely lower alpha diversity, depletion of Prevotella, and enrichment of Moraxella catarrhalis including drug-resistant strains. Prevotella originating from healthy microbiomes had higher biosynthetic gene cluster abundance and exhibited contact-independent inhibition of M. catarrhalis, suggesting interbacterial competition impacts nasal pathogen colonization. This work advances understanding of protective host-microbial interactions occurring in airway microbiomes that alter infection susceptibility in early-life.

The role of the microbiota in respiratory virus-bacterial pathobiont relationships in the upper respiratory tract.

The mechanisms by which respiratory viruses predispose to secondary bacterial infections remain poorly characterized. Using 2,409 nasopharyngeal swabs from 300 infants in Botswana, we performed a detailed analysis of factors that influence the dynamics of bacterial pathobiont colonization during infancy. We quantify the extent to which viruses increase the acquisition of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. We provide evidence of cooperative interactions between these pathobionts while identifying host characteristics and environmental exposures that influence the odds of pathobiont colonization during early life. Using 16S rRNA gene sequencing, we demonstrate that respiratory viruses result in losses of putatively beneficial Corynebacterium and Streptococcus species that are associated with a lower odds of pathobiont acquisition. These findings provide novel insights into viral-bacterial relationships in the URT of direct relevance to respiratory infections and suggest that the URT bacterial microbiota is a potentially modifiable mechanism by which viruses promote bacterial respiratory infections.

Can microplastics variability drive the colonization dynamics of periphytic protozoan fauna in marine environments?

In recent years, microplastics have become a global environmental hot topic of concern. To explore the effects of different concentrations of microplastics on colonization dynamics of periphytic protozoan fauna, a 21-day study was conducted in temperature-controlled circulation systems. Periphytic protozoan communities were used as test organisms and exposed to five concentrations of MPs: 0, 1, 5, 25, and 125 mg l−1, identification and enumeration were conducted on days 3, 5, 7, 10, 14 and 21. The results showed that the colonization dynamics were driven by MPs and significantly shifted at concentrations over 5 mg l−1. However, a notable decline in maximum species richness and abundance was observed in the high concentrations of microplastic, along with significant deviations in colonization patterns from the control group (0 mg l−1). Therefore, it is suggested that the colonization dynamics of periphytic protozoa can serve as a bioindicator for assessing microplastic concentrations in marine environments.