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PubMed2026

The Conundrum of Shiga Toxin-Producing Escherichia coli O157:H7 Persistence: Evidence for Locally Persistent Lineages.

Evidence suggests that Shiga toxin-producing Escherichia coli (STEC) strains do not persist at the farm level. We hypothesized that ecosystem-level STEC persistence occurs and contributes significantly to disease burden. We tested this by identifying locally persistent lineages (LPLs) of STEC O157:H7 in Minnesota. We identified 15 distinct LPLs, which were associated with 35.3% of reported cases in Minnesota and persisted for 1.3-8.6 years. Locally persistent lineages were associated with multiple outbreaks with Minnesota sources and no multi-state outbreaks, and LPL cases were spatially clustered. Our findings show long-term persistence in defined geographic areas, suggesting the importance of ecosystem-level persistence.

Minnesota↗

PubMed2026

Selective context, rather than persister cycling alone, drives resistance fixation in Escherichia coli.

Whether persister cells contribute to the evolution of antibiotic resistance and, if so, under what selective conditions this occurs, remain unresolved. Here, we examined whether repeated persister cycling itself promotes resistance evolution and how persister-associated minor variants are retained, lost, or fixed under distinct selective contexts. We compared five Escherichia coli cellular states: mutation-induced cells (M), persister-Amp cycling cells (A), persister cycling cells without selection (R), stationary-phase cells (S), and NaCl-stored persisters (P), using state-resolved whole-genome sequencing and phenotypic assays. Persister cycling without selection, stationary-phase cells, and NaCl-stored persisters maintained baseline MICs and showed no detectable high-frequency variant fixation. In contrast, mutation-induced cells fixed efflux-regulatory mutations in marR, acrR, and acrB, increasing MIC to 32 μg/mL. Persister-Amp cycling cells showed an intermediate MIC increase to 16 μg/mL without detectable quality-filtered genetic fixation, distinguishing this state from mutation-induced resistance. The stfE/stfP prophage background further shaped adaptive routes under mutation-inducing conditions. Exploratory analysis revealed sub-threshold low-frequency variant signals during persister cycling, but lineage tracking showed that these variants were not stage-specifically fixed and were instead stochastically retained or lost. These findings support a model in which persister cycling can reveal low-frequency genetic heterogeneity, but fixed resistance evolution requires selection that promotes variant retention and clonal expansion. Thus, resistance fixation was governed primarily by selective context during regrowth rather than by the persister state itself.

Journal Article↗

PubMed2026

Transgenerational continuity: Persistence as a dimension of inheritance and evolution.

Transgenerational continuity (TC) describes the persistence of inherited molecular architectures across generations. Progress in identity-by-descent (IBD) detection, recombination dynamics, and epigenetic research highlights the growing need for a more comprehensive model of inheritance. This theoretical framework synthesizes evidence from genomics, population studies, and epigenetics to outline how inherited molecular architectures, which are transmitted through IBD, together with heritable epigenetic modifications, can preserve ancestral information across generations. IBD captures genomic continuity across three nested scales, where recent familial segments link close relatives, population-level haplotypes are shared across cohorts, and archaic fragments from Neanderthal and Denisovan admixture persist as molecular fossils of ancient lineages. Although recombination and selection reshape these regions, their persistence across time scales highlights the evolutionary durability of genomic continuity. Epigenetic memory reflects regulatory persistence, whereby molecular modifications can preserve functional states across cell divisions and sometimes across generations. Together with familial and population-level IBD persistence and the long-term retention of introgressed haplotypes, these findings demonstrate that inherited molecular architectures can persist across multiple timescales. Evolutionary processes shape this persistence. Purifying selection preferentially removes deleterious inherited variants, whereas positive selection can favor the persistence of functionally relevant genomic architectures. From this perspective, evolutionary dynamics arise not only from the generation of variation, but also from the differential persistence of inherited molecular architectures through selection. Transgenerational continuity therefore provides a conceptual framework in which persistence serves as an explanatory dimension of inheritance and evolution that complements variation and explains the persistence of biological identity across generations and evolutionary time.

Biological identity↗

PubMed2026

Phage vB_KpnM_NB cocktail synergizing with amikacin in inhibiting persister cells of Klebsiella pneumoniae.

UNLABELLED: The emergence of multidrug-resistant Klebsiella pneumoniae (KPN) and antibiotic-tolerant persister cells poses a significant challenge to existing anti-infection therapies. Given the urgent need for sustainable alternatives to antibiotics, phage cocktails are emerging as a promising alternative to control K. pneumoniae infections. We isolated three lytic phages vB_KpnM_NB (1-3) from Ningbo environmental samples, classified them into the Drexlerviridae family, and determined the biological characteristics of two representative phages. Genomic analysis confirmed that these phages are closely related and lack resistance and virulence genes, ensuring biosafety. Subsequently, a stable KPN persister model was established using amikacin, with a biphasic killing pattern observed during treatment. At a multiplicity of infection of 10, the phage cocktail eliminated 99.00% of persister cells, while individual phages were less effective. The phage cocktail also inhibited persister-derived biofilm formation, showing improved results when combined with amikacin. This combination significantly reduced capsule polysaccharide production in persisters, weakening the outer membrane barrier. These findings demonstrate that the phage cocktail-amikacin combination effectively targets planktonic cells, persister cells, and biofilms, providing a promising strategy against persisters and recurrent K. pneumoniae infections. IMPORTANCE: This study fills the critical gap in understanding how phage cocktails synergize with amikacin against K. pneumoniae persister cells. By constructing a highly specific phage vB_KpnM_NB cocktail, establishing a stable persister model, and performing in vitro bactericidal and biofilm assays, we demonstrate that the cocktail effectively eliminates planktonic cells, persisters, and biofilms. We clarify the core synergistic mechanism: inhibiting capsular polysaccharide synthesis, improving phage adsorption, and disrupting the bacterial outer membrane barrier. These findings provide experimental evidence for the prevention and control of multidrug-resistant and carbapenem-resistant K. pneumoniae persister infections, establishing a safe and effective phage-antibiotic combination therapy. The results are crucial for addressing antibiotic tolerance and controlling chronic, recurrent infections. They hold significant theoretical and translational value for the treatment of refractory infections in clinical settings and offer new insights into the development of novel antimicrobial strategies.

Klebsiella pneumoniae↗

PubMed2025

SARS-CoV-2 genomic diversity and within-host evolution in individuals with persistent infection in the UK: an observational, longitudinal, population-based surveillance study.

BACKGROUND: Persistent SARS-CoV-2 infections in hospitalised immunocompromised individuals are known to facilitate accelerated within-host viral evolution, potentially contributing to the emergence of highly divergent variants. However, little is known about the evolutionary dynamics and transmission risks of persistent infections in the general population. We aimed to characterise the within-host evolution of SARS-CoV-2 during persistent infections identified through a large community surveillance study. METHODS: We used data from the Office for National Statistics COVID-19 Infection Survey (ONS-CIS), a large-scale, longitudinal, population-based surveillance study conducted in the UK from April, 2020, to March, 2023. For this analysis, we focused on infections with high viral load (cycle threshold ≤30) and available genome sequences, from seven major SARS-CoV-2 lineages (alpha, delta, BA.1, BA.2, BA.4, BA.5, and XBB). ONS-CIS participants were randomly selected from the general population and tested regularly by RT-PCR, regardless of symptoms. We defined persistent infections as those with sustained or rebounding high viral RNA titres for 26 days or longer. We examined associated host characteristics and used raw sequence data to identify de novo mutations and estimate within-host synonymous and non-synonymous evolutionary rates across the SARS-CoV-2 genome. FINDINGS: Between Nov 2, 2020, and March 21, 2023, we identified 576 persistent infections with at least two sequences, including 11 alpha, 106 delta, 102 BA.1, 204 BA.2, 16 BA.4, 133 BA.5, and 4 XBB. Persistent infections were more common in males than females (p<0·0001) and individuals older than 60 years (p=0·0027). The median within-host genome-wide evolutionary rate was 7·9 × 10-4 substitutions per site per year (IQR 7·0-9·0 × 10-4), with high inter-individual variability driven largely by non-synonymous mutations, particularly in the N-terminal and receptor-binding domains of the spike protein. Longer infection duration was associated with higher evolutionary rates, while no associations were found with age, sex, vaccination status, previous infection, or virus lineage. We found no clear evidence of transmission beyond the first month of infection in any of the 84 persistent infections lasting 56 days or longer. In total, we identified 379 recurrent mutations, including many with known or predicted negative fitness effects and low prevalence at the population level, as well as de novo reversions to the Wuhan-Hu-1 reference sequence, which were likely under positive selection within those individuals. INTERPRETATION: This study highlights the heterogeneous nature of within-host SARS-CoV-2 evolution in individuals with persistent infection in the community. Notably, a small subset of persistent infections with high viral loads underwent accelerated viral evolution or recurrently acquired hallmark mutations found in novel variants. In addition, onward transmission from a persistent infection during the later stages of infection is likely to be rare. These insights have important implications for prioritising genomic surveillance and managing patients with persistent infections. FUNDING: Department of Health and Social Care.

Humans↗

PubMed2025

Strain-level differences in Gardnerella urinary tract persistence and pathogenesis are consistent with comparative phylogenomic analyses.

BACKGROUND: Gardnerella is a genus of gram variable anaerobic bacteria that is commonly present in the female urogenital tract, especially during bacterial vaginosis (BV). BV is linked with increased risk of urinary tract infections (UTI) and Gardnerella has been frequently detected in urine collected directly from the bladder. Understanding the contribution of Gardnerella to urogenital pathogenesis has been complicated by its genetic heterogeneity and a shortage of data from in vivo models. Recently, a clinical isolate of Gardnerella displayed covert pathogenesis in a mouse urinary tract inoculation model, triggering urothelial exfoliation and promoting UTI by uropathogenic E. coli. Data from clinical studies suggests differential association of Gardnerella phylogenetic clades with BV or urogenital infections. In vitro data has demonstrated heterogeneity in the presence and expression of putative virulence determinants between Gardnerella strains. This study was designed to compare diverse Gardnerella strains in vivo to identify genomic variation associated with urinary tract persistence and pathogenesis. METHODS: Eighteen Gardnerella clinical isolates from each of the four main phylogenetic clades were individually inoculated transurethrally into female C57BL/6 mice. Bacteriuria was monitored by quantitative culturing of Gardnerella in urine. Pathologic features were assessed by immunofluorescent and histological staining of bladder tissues. Pan-genome phylogenetic analyses were performed on the 18 Gardnerella isolates used for mouse infections to identify accessory genes that were associated with observable in vivo phenotypes, including long and short-term persistence, urothelial exfoliation and bladder edema. Genes that were significantly associated to phenotype were then matched against a pangenome analysis of 291 publicly available Gardnerella genomes to determine the conservation of these putative colonization and virulence factors across the genus. RESULTS: Gardnerella strains displayed clear differences in persistence and pathogenesis in the mouse bladder that were congruent with phylogeny. Clade 2 strains were more persistent in the urinary tract whereas strains from the other three clades either caused transient bacteriuria or were undetectable. Strains from clade 2 and 4 induced urothelial exfoliation while edema was triggered by strains from clades 2, 3 and 4. Pangenome analyses revealed 45 genes that were associated with in vivo persistence and pathogenicity. Among the wider 291 publicly available genomes, clade 2 strains encoded more of the genes associated with bacteriuria phenotypes compared to strains in the other three clades. Exfoliation-associated genes were present in most clade 4 strains. Clade 3 strains lack most of the in vivo-associated genes, whereas clade 1 strains were more heterogenous. CONCLUSIONS: This study provides in vivo evidence for differential urinary tract colonization and pathogenesis by strains from different clades/species within the genus Gardnerella and identifies new putative persistence and virulence factors. Utilizing the in vivo data from tested strains, pangenome analyses predicts that clade 2 Gardnerella are the most likely to persist in the urinary tract and that clades 2 and 4 have the highest uropathogenic potential. These findings inform future targeted screening and treatment approaches aimed at limiting harmful Gardnerella urinary tract exposures.

Journal Article↗

PubMed2024

Adaptation for Staphylococcus aureus to hosts via insertion mutation in the accessory gene regulator agrC gene: decreased virulence and enhanced persistence capacity.

UNLABELLED: Staphylococcus aureus is an important human pathogen due to its vast array of virulence factors regulated by multiple regulatory mechanisms, including the accessory gene regulator. In this study, two S. aureus strains were simultaneously isolated from the blood of a febrile patient, belonging to the same clone, designated as 23H with a complete hemolytic phenotype, and 23B, exhibiting an incomplete hemolytic phenotype. The genomic comparison between strains 23B and 23H revealed that 23B had a single adenine base insertion at position 923 in the agrC gene, leading to a functional loss of the encoded AgrC. Experimental findings showed that strain 23B had decreased hemolytic activity, lower cytotoxicity against human alveolar epithelial A549 cells and in the Galleria mellonella model, and a reduced ability to survive intracellularly after infecting macrophages, in comparison to 23H. Conversely, 23B exhibited enhanced biofilm formation, greater adherence to A549 cells, and increased persistence in the face of vancomycin and daptomycin treatment. Transcriptomic analysis revealed that 23B upregulated surface protein-encoding genes while simultaneously reducing the expression levels of virulence factors, highlighting the intricate regulatory adjustments facilitating its persistence and reducing pathogenic potential. ATP assay results indicated that 23B maintained elevated ATP levels during the exponential phase yet exhibited reduced levels in the stationary phase when compared with 23H. Our findings suggested that the mutation in the agrC gene of S. aureus results in diminished virulence but markedly enhances persistence. This mutated strain warrants clinical attention because it may lead to treatment failures and persist in patients. IMPORTANCE: In clinical antimicrobial therapy, bacterial strains often develop resistance to antimicrobial agents. Additionally, mutations in their gene regulatory networks can increase their persistence, especially in immunocompromised patients. This study identified an insertion mutation in the accessory gene regulator, agrC gene, carried by a Staphylococcus aureus strain isolated from the blood of a febrile patient, leading to the functional loss of AgrC. Further research revealed that despite the reduced virulence of the mutated strain, it significantly bolstered the capacity to adapt and endure within the host during prolonged infections. This was evidenced by increased adhesion and biofilm formation capabilities, development of antimicrobial tolerance, and decreased ATP levels linked to persistence. Therefore, monitoring these mutations in S. aureus is crucial clinically, as they can complicate treatment strategies.

Staphylococcus aureus↗

PubMed2023

Teicoplanin associated gene tcaA inactivation increases persister cell formation in Staphylococcus aureus.

Staphylococcus aureus is part of normal human flora and is widely associated with hospital-acquired bacteremia. S. aureus has shown a diverse array of resistance to environmental stresses and antibiotics. Methicillin-resistant S. aureus (MRSA) is on the high priority list of new antibiotics discovery and glycopeptides are considered the last drug of choice against MRSA. S. aureus has developed resistance against glycopeptides and the emergence of vancomycin-intermediate-resistant, vancomycin-resistant, and teicoplanin-resistant strains is globally reported. Teicoplanin-associated genes tcaR-tcaA-tcaB (tcaRAB) is known as the S. aureus glycopeptide resistance operon that is associated with glycopeptide resistance. Here, for the first time, the role of tcaRAB in S. aureus persister cells formation, and ΔtcaA dependent persisters' ability to resuscitate the bacterial population was explored. We recovered a clinical strain of MRSA from a COVID-19 patient which showed a high level of resistance to teicoplanin, vancomycin, and methicillin. Whole genome RNA sequencing revealed that the tcaRAB operon expression was altered followed by high expression of glyS and sgtB. The RNA-seq data revealed a significant decrease in tcaA (p = 0.008) and tcaB (p = 0.04) expression while tcaR was not significantly altered. We knocked down tcaA, tcaB, and tcaR using CRISPR-dCas9 and the results showed that when tcaA was suppressed by dCas9, a significant increase was witnessed in persister cells while tcaB suppression did not induce persistence. The results were further evaluated by creating a tcaA mutant that showed ΔtcaA formed a significant increase in persisters in comparison to the wild type. Based on our findings, we concluded that tcaA is the gene that increases persister cells and glycopeptide resistance and could be a potential therapeutic target in S. aureus.

MRSA↗

PubMed2026

Microbiome features associated with persistent intestinal carriages of Escherichia coli ST131 in a Southeast Asian cohort study.

Escherichia coli sequence-type 131 (ST131) is the dominant global extraintestinal pathogen capable of asymptomatic intestinal carriage and sustained household transmission, challenging infection control. Despite its clinical significance, the ecological determinants of gut persistence remain poorly understood. We performed shotgun metagenomics on fecal samples to investigate gut microbiome features associated with ST131-positive samples, distinct host carrier statuses (persistent, intermittent and non-carriers) and household risks in a study of a Southeast Asian cohort. Here, we show that ST131 carriage was associated with compositional shifts without reducing species alpha-diversity. Regression analyses identified depletion of commensal taxa and the 1,5-anhydrofructose degradation pathway in ST131-positive samples. Persistent carriers exhibited highly perturbed microbiome enriched with pathobionts, aerobactin- and lipopolysaccharide (LPS)-biosynthesis pathways. Comparing household risk groups to control, revealed that biotin biosynthesis and 1,5-anhydrofructose degradation may influence ST131 co-colonization through both direct and indirect mechanisms. Machine learning analyses identified metabolic pathways as stronger discriminators of persistent carriage than taxonomic features. Genomic-resolved analysis of clinical ST131 isolates revealed conserved genes for iron-acquisition, LPS and antibiotic resistance determinants. Overall, while commensals and metabolism may influence initial ST131 colonization, persistent carriage is associated with specific microbial and metabolic adaptations, providing potential targets to limit intestinal ST131 persistence.

Humans↗

PubMed2026

CSNK1E sustains stemlike drug persistence in diffuse large B-cell lymphoma.

Relapsed or refractory (R/R) disease occurs in up to 40% of patients with diffuse large B-cell lymphoma (DLBCL) following first-line immunochemotherapy. However, the molecular mechanisms underlying drug persistence remain incompletely defined. In this study, we performed single-cell RNA and B-cell receptor sequencing on paired diagnostic and R/R samples from 8 patients who were either treatment-refractory or relapsed after remission, and validated our findings in 3 independent patient cohorts. We found that drug-persistent cells exhibited a transcriptional profile indicative of a less-differentiated state and adopted a memory B-cell-like program with enhanced stemlike properties, which correlated with unfavorable clinical outcomes across multiple DLBCL cohorts. Functionally, drug-persistent cells showed significantly increased in vitro clonogenicity and in vivo tumor-initiating capacity. Mechanistically, the WNT signaling regulator casein kinase 1ɛ (CSNK1E) was upregulated in these stemlike drug-persistent cells, in part through the activation of the A proliferation-inducing ligand (APRIL)-TNFRSF13B axis. Notably, CSNK1E inhibition impaired the growth and tumor-initiating capacity of drug-persistent cells and potentiated the efficacy of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone)-based treatment, both in vitro and in vivo. Together, our study reveals the stemlike transcriptional and functional properties of drug-persistent cells, and identifies CSNK1E as a critical mediator and therapeutic vulnerability that may improve the efficacy of standard immunochemotherapy in DLBCL.

Lymphoma, Large B-Cell, Diffuse↗

PubMed2024

Molecular Analysis of Persistent and Recurrent Barrett's Esophagus in the Setting of Endoscopic Therapy.

INTRODUCTION: Early neoplastic progression of Barrett's esophagus (BE) is often treated with endoscopic therapy. Although effective, some patients are refractory to therapy or recur after apparent eradication of the BE. The goal of this study was to determine whether genomic alterations within the treated BE may be associated with persistent or recurrent disease. METHODS: We performed DNA sequencing on pre-treatment esophageal samples from 45 patients who were successfully treated by endoscopic therapy and did not recur as well as pre-treatment and post-treatment samples from 40 patients who had persistent neoplasia and 21 patients who had recurrent neoplasia. The genomic alterations were compared between groups. RESULTS: The genomic landscape was similar between all groups. Patients with persistent disease were more likely to have pre-treatment alterations involving the receptor tyrosine kinase pathway ( P = 0.01), amplifications of oncogenes ( P = 0.01), and deletions of tumor suppressor genes ( P = 0.02). These associations were no longer significant after adjusting for patient age and BE length. More than half of patients with persistent (52.5%) or recurrent (57.2%) disease showed pre-treatment and post-treatment samples that shared at least 50% of their driver mutations. DISCUSSION: Pre-treatment samples were genomically similar between those who responded to endoscopic therapy and those who had persistent or recurrent disease, suggesting there is not a strong genomic component to treatment response. Although it was expected to find shared driver mutations in pre-treatment and post-treatment samples in patients with persistent disease, the finding that an equal number of patients with recurrent disease also showed this relation suggests that many recurrences represent undetected minimal residual disease.

Humans↗

PubMedDate not supplied

[Persistent infection in murine L cells infected with the parainfluenza virus SV5].

Persistent infection of mouse L cells was achieved by serial passages of undiluted parainfluenza SV5 virus. At the level of the 10--12th passage a stationary noncytocidal type of persistent infection was established. A low level of the infectious virus produced by the persistently infected cells was observed; the number of cells synthesizing the virus-specific antigen detectable by immunofluorescence was high. Persistently infected cells were resistant to the infection with the homologous virus and sensitive to superinfection with heterologous viruses. The persisting virus had marked interfering activity. The possibility of participation of defective interfering particles and endogenous oncornavirus in the maintenance of the persistent infection is discussed.

Animals↗

PubMed2026

Durable burden suppression and recurrence patterns after cryoablation in early persistent AF: 3-year results of COOL-PER trial.

BACKGROUND: Long-term rhythm outcomes following cryoballoon ablation (CBA) in early persistent atrial fibrillation (AF) remain incompletely characterized. OBJECTIVE: To evaluate 3-year atrial fibrillation (AF) burden trajectories, subsequent recurrence patterns detected by implantable loop recorder (ILR), and their association with healthcare resource utilization (HCRU). METHODS: The COOL-PER trial was a prospective, multicenter, single-arm study that enrolled patients with early persistent AF (duration ≤ 3 years). An ILR was implanted 7-90 days before CBA for continuous rhythm monitoring. RESULTS: Among 130 enrolled patients, 123 completed the 3-year follow-up (mean age, 60.5 ± 8.4 years; 25.2% women). Median AF burden decreased from 99.9% (interquartile range, 53.1-100.0) at baseline to 0.1% (0.0-4.2), 0.5% (0.0-9.1), and 0.7% (0.0-9.5) at 1, 2, and 3 years (all P < .001). Of 47 patients who were recurrence-free at 1 year, 25 (53.2%) developed subsequent recurrence, and 20 (80.0%) were detected by ILR alone. Compared with first-year recurrence, subsequent recurrence was less often persistent (4.0% vs 28.9%; P = .001) and was associated with a lower AF burden (0.1% [0.0-1.6] vs 2.8% [0.4-18.7]; P = .010). Both persistent-type recurrence and AF burden ≥ 10% were associated with more additional rhythm control interventions (78.3% vs 30.8% vs 0%; 78.6% vs 39.1% vs 0%; both P < .001) and cardiovascular hospitalization (17.4% vs 3.8% vs 0%, P = .045; 14.3% vs 4.3% vs 0%, P = .029). CONCLUSION: CBA achieved durable AF burden suppression over 3 years in early persistent AF. Subsequent recurrence after the first year was common and was predominantly detectable by ILR only. Subsequent recurrences were often paroxysmal, with a lower AF burden and associated with lower HCRU, supporting the value of continuous long-term rhythm monitoring for characterizing rhythm status beyond the first post-ablation year.

Cryoballoon ablation↗

PubMed2024

Transcriptional profiles of Microcystis reveal gene expression shifts that promote bloom persistence in in situ mesocosms.

Harmful algal blooms caused by cyanobacteria threaten aquatic ecosystems, the economy, and human health. Previous work has tried to identify the mechanisms that allow blooms to form, focusing on the role of nutrients. However, little is known about how introduced nutrients influence gene expression in situ. To address this knowledge gap, we used in situ mesocosms initiated with water experiencing a Microcystis bloom. We added pulses of nutrients that are commonly associated with anthropogenic sources to the mesocosms for 72 hours and collected samples for metatranscriptomics to examine how the physiological function of Microcystis and bloom status changed. The addition of nitrogen (N) as urea, but not the addition of PO4, resulted in conspicuous bloom persistence for at least 9 days after the final introduction of nutrients. The addition of urea initially resulted in the upregulation of photosynthesis machinery, as well as phosphate, carbon, and N transport and metabolism. Once Microcystis presumably became N-replete, upregulation of amino acid metabolism, microcystin biosynthesis, and other processes associated with biomass generation occurred. These capacities coincided with the upregulation of toxin-antitoxin systems, CRISPR-cas genes, and transposases suggesting that phage defense and genome rearrangement are critical in bloom persistence. Overall, our results show the stepwise transcriptional response of a Microcystis bloom to the introduction of nutrients, specifically urea, as it is sustained in a natural setting. The transcriptomic shifts observed herein may serve as markers of the longevity of blooms while providing insight into why Microcystis blooms over other cyanobacteria.IMPORTANCEHarmful algal blooms represent a threat to human health and ecosystems. Understanding why blooms persist may help us develop warning indicators of bloom persistence and create novel mitigation strategies. Using mesocosm experiments initiated with water with an active bloom, we measured the stepwise transcription changes of the toxin-producing cyanobacterium Microcystis in response to the addition of nutrients that are important in causing blooms. We found that nitrogen (N), but not phosphorus, promoted bloom longevity. The initial introduction of N resulted in the upregulation of genes involved in photosynthesis and N import. At later times in the bloom, upregulation of genes involved in biomass generation, phage protection, genomic rearrangement, and toxin production was observed. Our results suggest that Microcystis first fulfills nutritional requirements before investing energy in pathways associated with growth and protection against competitors, which allowed bloom persistence more than a week after the final addition of nutrients.

Microcystis↗

PubMed1978

[A peculiar type of chronic persisting hepatitis (author's transl)].

Six cases of persisting hepatitis with a duration of 3 to 9 years are reported. During this time 2--3 acute inflammatory episodes occurred with transaminase levels raised to more than 500 U/l. Icterus did not occur during these attacks. The remaining laboratory parameters which are usually normal in persisting hepatitis (gamma-GT, bromsulfalein) were pathological during the acute attack and later became normal. As the disease progressed after overcoming the attack, the transaminases were only slightly raised in all cases. Laparoscopy and histological examinations of between three and nine punctates gave an unchanged picture of chronic persisting hepatitis. During the acute attack the inflammatory activities in the liver punctates increased, there were also increased single cell necroses. It is suggested that this peculiar type of chronic persisting hepatitis shall be called "acute recurrent persistent hepatitis.".

Adrenocorticotropic Hormone↗

PubMed1976

Persistent infection of BHK cells with herpes simplex virus types 1 and 2 in the absence of specific anti-herpetic antibody.

Persistent infection of BHK-21 cells with 5 strains of herpes simplex virus (HSV) type 1 and a 1 strain of HSV type 2 is described. Acute infection only was obtained with two strains of type 1 and one strain of type 2. Persistent infection could not be established in HeLa and rabbit lung cells. Persistent infection of BHK cells proceeded in the absence of specific antibody. Persistently infected cells were more resistant to superinfection with homologous or heterologous HSV as compared to infection of normal BHK cells. No interferon activity was demonstrated in persistently infected cell cultures. The results of virus titration were in accordance with the demonstration of fluorescent antigen of HSV.

Animals↗

PubMed2025

Fe-S cluster deficiency drives small colony variant formation in persistent infections.

INTRODUCTION: Small colony variants (SCVs) of Staphylococcus aureus (S. aureus) are associated with persistent infections and poor clinical outcomes. The mechanisms driving stable SCV formation remain poorly understood, particularly concerning metabolic adaptations. This study explores the in-host evolutionary dynamics of S. aureus and identifies a novel genetic determinant linked to SCV formation. OBJECTIVES: To investigate the genetic mutations and phenotypic adaptations underlying SCV formation, with a focus on the role of a novel mutation in the sufB gene, which is critical for Fe-S cluster biosynthesis. METHODS: Sequential isolates from a patient with recurrent infections were analyzed using whole-genome sequencing, antimicrobial susceptibility testing, and functional assays. The phylogenetic relationship of the isolates was determined, and specific mutations were identified. Functional assays included aconitase and glutamate synthase activity measurements, ATP level quantification, reactive oxygen species (ROS) production, and biofilm formation assays. In vivo pathogenesis was assessed using a murine catheter infection model. RESULTS: A novel frameshift mutation in sufB was identified, disrupting Fe-S cluster biosynthesis and impairing the TCA cycle and electron transport chain, leading to reduced ATP and ROS production. This metabolic reprogramming promoted stable SCV formation, characterized by slow growth, enhanced tolerance to antibiotics and neutrophil-mediated killing, and persistent inflammation in vivo. Restoration of sufB reversed these phenotypes, confirming its pivotal role in SCV-associated persistence. CONCLUSION: sufB is a novel genetic determinant of stable SCV formation through Fe-S cluster deficiency, driving metabolic shifts that enhance immune evasion and chronic infection. Our findings highlight antibiotic stewardship and suggest potential therapeutic strategies for managing persistent SCV-associated infections.

Staphylococcus aureus↗

PubMed2026

Prevalence and risk factors for persistent faecal carriage of extended spectrum beta-lactamase producing Escherichia coli in a paediatric community population.

OBJECTIVE: To investigate clinical and microbiological factors associated with persistent faecal carriage of extended spectrum beta-lactamase (ESBL) producing Escherichia coli in infants. METHODS: Between 2010 and 2022, children aged 3 months to 2 years old were sampled in a community setting in France, at two visits, V1 and V2, 3-24 months apart, to screen for prolonged faecal carriage of ESBL-producing E. coli. Patient clinical information and whole genome sequence of each isolate were used for association studies. RESULTS: A total of 4641 children were sampled. 375 (8%) carried an ESBL-producing Enterobacterales, among which 142 of ESBL-producing E. coli carriers were once again sampled at V2 and included in this study. 21.8% (n = 31/142) and 18.4% (n = 16/99) carried the same ESBL-producing E. coli clone for at least 3 and 6 months, respectively. B2 phylogroup, and among which ST131 clones were associated with an increased risk of persistent carriage. Multivariate analysis identified virulence associated genes involved in adhesion (papC/papGII allele and a tia-like gene) and encoding toxin (senB) as major risk factors for persistence. A genome wide association study highlighted the potential role of the frz metabolic operon, known to be involved in enterocytes adhesion/internalisation. CONCLUSION: Main extraintestinal pathogenic E. coli genomic features (phylogenetic background, adhesion properties) are associated with ESBL-producing E. coli gut colonisation persistence in infants, which could potentially lead to an increased risk of febrile urinary tract infection in these patients.

Child↗