Microbial Pathogenesis

Enteric infections caused by Salmonella enterica remain a major global health concern and are increasingly associated with antimicrobial resistance. Therefore, new strategies to combat this important pathogen are needed. The interactions between S. enterica and the human host have been the subject of intense investigation over the last several decades, yet new findings continue to emerge. We previously showed that 15-deoxy-{Delta}12,14-prostaglandin J2 (15d-PGJ2) reduces Salmonella colonization of macrophages, but the mechanisms underlying this protective effect were still unknown. Here, we demonstrate that 15d-PGJ2 limits Salmonella infection by suppressing TLR4 signaling and inflammasome activation. Treatment with 15d-PGJ2 reduced TLR4 expression, NF-{kappa}B activation, iNOS, COX-2, nitric oxide production, IL-1{beta} release, and inflammasome-related targets, including NLRP3 and caspase-1 activity, while only partially reversing macrophage polarization. Combined treatment with the TLR4 antagonist TAK-242 further reduced bacterial colonization of and IL-1{beta} release by macrophages, supporting the involvement of TLR4 signaling in the effects of 15d-PGJ2. During mouse infections, 15d-PGJ2 reduced bacterial burdens in a tissue-dependent manner. Together, these findings demonstrate that 15d-PGJ2 limits Salmonella infection through selective modulation of TLR4 signaling and inflammasome activation.

Eimeria tenella (E. tenella) preferentially invades the cecum of young chickens and causes enormous economic losses to the global poultry industry. In this study, chick infection models of virulent parent strain and precocious attenuated line were established with schizogony (2 dpi) and gametogony (6 dpi) as two critical sampling time points. Combined with pathogenicity detection, transcriptome sequencing, mucosal immune index measurement and homologous challenge protection assays, we systematically deciphered the differential molecular mechanisms underlying pathogenicity and immune regulation between the two strains. Pathogenicity results showed that increased infection dosages suppressed weight gain and aggravated bloody diarrhea and oocyst shedding in both strains. In particular, infection with 1 x 105 sporulated oocysts of the parent strain caused massive chick mortality, while the precocious line exhibited markedly lower virulence. Transcriptomic data revealed that gametogony (6 dpi) represented the peak of host immune response. The parent strain persistently overactivated the NF- {kappa}B - mediated positive feedback cascade of coagulation and complement as well as ECM remodeling, triggering steroid metabolic disorder and antioxidant exhaustion, which ultimately induced severe hemorrhagic necrosis of the cecum. By contrast, the precocious line specifically activated the PPAR - {gamma} signaling pathway to negatively restrain excessive inflammation, accompanied by enriched TLR signaling and leukocyte transendothelial migration pathways, thereby forming an immune cascade of "lipid anti - inflammation - pathogen elimination - mucosal repair". Immunoprotection trials verified that priming with 1 x 104 sporulated oocysts of the precocious line significantly alleviated cecal lesions and reduced oocyst output upon secondary challenge, conferring stable mucosal immune protection. The expression trends of seven hub genes (PPARG, PLIN1, CYP1A1, THBS1, FMO4, CYP2C18, CYP14) detected via qRT - PCR were consistent with RNA - seq data. This study identified a dual regulatory paradigm consisting of NF - {kappa}B - mediated tissue injury and PPAR - {gamma} - dependent anti - inflammatory responses, refined the mucosal immune theoretical framework for commercially available precocious attenuated strains, and provided candidate molecular targets for targeted anti - coccidial intervention in chickens.

Although many genes are associated with leprosy, a skin and nerve infection by Mycobacterium leprae, the function of most of these genes in infection remains unknown. This is partly due to a paucity of animal models that are genetically malleable and recapitulate features of the human disease. Zebrafish, a recent leprosy model, have human-like responses to M. leprae, including macrophage-mediated inflammation and neurodegeneration. We confirm this at the transcriptional level, using RNA sequencing (RNAseq) of chronic M. leprae infection of adult zebrafish. This identified regulated zebrafish orthologs of human leprosy-associated genes, including {beta}- and {gamma}-interferon, IL-6, IL-10, IL-4, and TNF superfamily members. Other regulated genes have not been previously associated with leprosy. Genes associated with tuberculoid leprosy (T-lep) were largely downregulated, while lepromatous leprosy (L-lep) genes were upregulated. Pathways relevant to leprosy, such as phagocytosis and antiviral responses, differed between early and late stages of infection. In infected rag1 mutant zebrafish, which lack T and B cells, T-lep genes were downregulated, suggesting that adaptive immunity is required for their expression. Key pathways and genes were validated by qPCR using zebrafish infection with M. marinum:PGL-1, a model pathogen that can express M. leprae genes. This system allowed for the identification of validated M. leprae-regulated genes that alter infection outcomes, by using multiplex CRISPR to simultaneously mutate many zebrafish genes. 17 genes were screened and 2 were identified that increased mortality infection: isg15 (interferon-stimulated gene 15) and serpine1 (plasminogen activator inhibitor-1). This work confirms that, in humans and zebrafish, type I interferon and plasminogen activation are required for survival of mycobacterial disease, and demonstrates that multiplex CRISPR can identify mediators of host defense in vivo.

BackgroundEscherichia coli contamination of chicken eggs is an important food-safety concern, while antimicrobial-resistant E. coli may contribute to the dissemination of antimicrobial resistance through the food chain. However, information on egg-associated E. coli and its antimicrobial susceptibility in Natore District, Bangladesh, is limited. ObjectivesThis study aimed to determine the prevalence of E. coli in chicken eggs collected from commercial farms, markets and indigenous/backyard flocks in Natore District, identify the isolates based on cultural, morphological and biochemical characteristics, and assess their antimicrobial susceptibility. Materials and MethodsA total of 84 egg-shell swab samples, comprising 28 samples each from commercial farms, markets and indigenous chicken flocks, were collected from seven upazillas of Natore District between January and June 2023. Samples were cultured on selective and differential media, and presumptive isolates were confirmed by Gram staining, motility and biochemical tests. Antimicrobial susceptibility was determined using the Kirby-Bauer disc-diffusion method against seven antimicrobial agents. ResultsE. coli was detected in 56/84 (66.67%) egg samples. Prevalence was highest in indigenous eggs (22/28, 78.57%), followed by farm eggs (18/28, 64.28%) and market eggs (16/28, 57.14%). Among 22 confirmed isolates tested for antimicrobial susceptibility, resistance was highest to neomycin (90.91%) and erythromycin (86.36%), followed by oxytetracycline (77.27%), amoxicillin (68.18%), ciprofloxacin (63.63%), levofloxacin (59.09%) and doxycycline (36.36%). No isolate was sensitive to neomycin or erythromycin. ConclusionThe high prevalence of E. coli and substantial antimicrobial resistance among egg-associated isolates indicate an important food-safety and public-health concern. Improved hygienic egg handling, prudent antimicrobial use and continued antimicrobial-resistance surveillance are warranted throughout the poultry production and marketing chain.

BackgroundLive bird markets (LBMs) may facilitate the persistence and dissemination of Escherichia coli and antimicrobial-resistant bacteria because of intensive bird handling, environmental contamination and inadequate sanitation. However, information on E. coli contamination and antimicrobial susceptibility in LBM environments in Rajshahi District, Bangladesh, remains limited. ObjectiveThis study aimed to determine the prevalence, identify the cultural and biochemical characteristics, and assess the antimicrobial susceptibility pattern of E. coli isolated from water, soil and bird-dropping samples collected from LBMs in Rajshahi District. MethodsA total of 60 environmental samples, comprising 20 water, 20 soil and 20 bird-dropping samples, were collected from LBMs across all ten upazillas of Rajshahi District between January and June 2023. E. coli was isolated and identified using cultural characteristics, Gram staining and biochemical tests. Antimicrobial susceptibility was determined by the Kirby- Bauer disc diffusion method against seven antimicrobial agents using CLSI interpretive criteria. ResultsE. coli was detected in 33 of 60 samples, giving an overall prevalence of 55.00%. Prevalence was highest in bird-dropping samples (75.00%), followed by water (55.00%) and soil (35.00%). Among the 33 isolates, resistance was highest to oxytetracycline (78.79%) and amoxicillin (63.64%), followed by ciprofloxacin (48.48%), doxycycline (33.33%), levofloxacin (9.09%), erythromycin (9.09%) and neomycin (6.06%). Sensitivity was highest to neomycin (60.61%), followed by levofloxacin and erythromycin (51.51% each). ConclusionThe high prevalence of E. coli and substantial resistance to several commonly used antimicrobials indicate considerable microbiological and antimicrobial-resistance concerns in LBM environments. Improved sanitation, biosecurity, hygienic poultry handling and prudent antimicrobial use are warranted to reduce environmental contamination and potential transmission of resistant bacteria.

Scrub typhus, caused by Orientia tsutsugamushi, is an obligate intracellular gram-negative pathogen that remains a cause of acute febrile illness in India. Culture isolation of Orientia tsutsugamushi clinical isolates is infrequent because it is technically more challenging than PCR-based molecular identification. In this report, we describe the culture isolation of Orientia from the whole blood of a 64-year-old farmer with acute febrile illness. Whole blood was inoculated onto an 80% confluent L929 cell line. Real-time PCR targeting the 47-kDa and 56-kDa genes, combined with Sanger sequencing, confirmed the isolate. Transmission electron microscopy of infected L929 cells revealed multiple oval-shaped bacteria within the host cytoplasm. Confocal microscopy demonstrated progressive accumulation of CFSE-labelled bacteria within infected cells over time. These findings support the successful isolation and visualization of a blood-derived O. tsutsugamushi isolate and provide a platform for downstream assays of host-pathogen interactions, antimicrobial susceptibility testing, and vaccine development.

Candida auris (currently Candidozyma auris) is an emerging fungal pathogen responsible for dramatic global increase in invasive candidiasis with high mortality. Most concerning, C. auris has a high propensity to colonize patients and persist and develop multidrug resistance to main classes of antifungals. In this study, we investigated the genetic and phenotypic diversity and resistance mechanisms of C. auris clinical isolates recovered from hospitalized infected patients. A total of 53 isolates from 38 unique patients were recovered from various clinical sources and evaluated for susceptibility to routine antifungal drugs. Whole genome sequencing (WGS) and single nucleotide polymorphism (SNP) analysis were performed to generate a phylogenetic network to infer population structure and identify mutations associated with drug resistance development. Isolates were also phenotypically evaluated for ability to form biofilms and aggregate, and cell wall adhesins gene expression studies were performed to provide mechanistic insights into C. auris phenotypic plasticity. Except for one clade III isolate, all isolates belonged to clade I and all were resistant to fluconazole with incidence of resistance to amphotericin B, echinocandins or both. Non-synonymous SNPs were found in genes associated with antifungal resistance including ERG11, TAC1B, CDR1 and FKS1. Phenotypically, isolates varied in their ability to form biofilm and aggregate which correlated with expression of the Scf1 and Als4112 cell wall adhesins genes highlighting C. auris phenotypic plasticity in circulating clinical strains. These findings underscore the growing clinical threat posed by C. auris and reinforce the need for optimized surveillance and treatment strategies for controlling its spread.

PurposeElucidate the influence of glucose metabolic pathways on A. fumigatus lung and corneal infection. MethodsThe A. fumigatus acuF and creA genes were deleted in an mcherry-expressing strain. The mutants were tested for alterations in radial growth, cell wall composition by fluorescence staining assays, and antifungal sensitivity through broth microdilution assays. Hyphal penetration of the strains through explanted porcine corneas was tracked by confocal microscopy using the mCherry signal. Virulence was evaluated in established models of invasive pulmonary aspergillosis (IPA) and fungal keratitis (FK) using C57BL/6J mice. ResultsDeletion of the A. fumigatus phosphoenolpyruvate carboxykinase (acuF) resulted in a dependency on exogenous glucose to support growth in vitro, but did not impact virulence in either the IPA or FK models. Loss of the carbon catabolite repressor CreA resulted in a broad dysregulation of carbon metabolic pathways and altered cell wall homeostasis. Surprisingly, whereas the{Delta} creA remained fully virulent in the lung, the mutant was unable to establish infection in the FK model. This in vivo phenotype corresponded to an inability of{Delta} creA to physically invade porcine corneal explants, which we attributed to a marked reduction in cell wall chitin content. ConclusionsGluconeogenesis is dispensable for A. fumigatus lung and corneal infection, suggesting tissue-derived glucose supports fungal growth in both environments. Loss of CreA disrupts glucose assimilation, its synthesis into chitin and, consequently, cell rigidity and hyphal invasion into the dense corneal stroma. Thus, CreA and other cell wall regulatory proteins may serve as targets for novel FK antifungals.

The marine bacterium Vibrio alginolyticus and the food poisoning bacterium V. parahaemolyticus possess two types of flagella in one cell: proton-driven lateral flagella (Laf) extending from the periphery of the cell body, and sodium ion-driven polar flagella (Pof) extending from a cell pole. For swimming in seawater they use polar flagella, suppressing the expression of lateral flagella. When they attach to the body surface of fish or intestinal tract, lateral flagella are induced, allowing it to crawl along the surface or through mucus. The dynamometer hypothesis, which proposes that polar flagella sense rotation and control the expression of lateral flagellar genes, has been widely accepted. However, how rotation is sensed and how expression is controlled remains unclear. Although swarming has recently been analyzed by physical, biological, or biochemical perspectives, it remains unclear how this motility is controlled, or which substances and conditions are necessary for swarming ability. In this study, we discovered that adding gelatin to agar medium promotes swarming on the agar surface by the lateral flagella of Vibrio. Our data suggested that surfactants or viscous polysaccharides secreted extracellularly are important for promoting swarming on the agar surface and we identified that swarming is likely to be driven by S (social)-motility, in which bacteria move by interacting with each other, and A (adventure)-motility, in which bacteria move by interacting with the agar surface. Our study provides clues that help clarify the mechanism of bacterial swarming IMPORTANCEWe discovered that adding gelatin to hard agar medium promoted swarming on agar surfaces by the lateral flagella of Vibrio cells. The surfactants or viscous polysaccharides secreted extracellularly seem to be important for swarming ability on agar surfaces. We proposed that the swarming is thought to occur through S(social)-motility, where cells move by interacting with cell bodies each other, and A(adventure)-motility, where cells move by interacting with the agar surface and cell body. The present study should provide the clues to clarify the mechanism of bacterial swarming and how to move in a viscous environment.

Background: Pulmonary arterial hypertension (PAH) is a serious disease with poor prognosis, especially in infants or preterm babies and there is still no optimal treatment for this disease. Noradrenalin (NE) is a vasoactive mediator which is released by sympathetic ganglion. According to previous studies, NE/1-adrenoreceptors is not only in regulating normal physiologic responses, but also in the pathogenesis of PAH. However, the mechanisms of NE in PAH are not fully understood. Methods: Human PASMC (PASMC) was used in this study. Cell viability assay and Wound healing assay were used to evaluate the proliferation and migration of PASMC. Immunoprecipitation and western blots analysis were used to investigate the mechanisms which involved in NE-induced PASMC proliferation. Results: We investigated that NE could induce human PASMC proliferation and migration. Furthermore, we first find that endothelin 1 (ET-1) signaling pathway plays an important role in NE-induced PASMC proliferation. ET1 is a critical molecular which is known for regulating cell growth and migration. We investigated that NE could increase NE-1 secretion, further enhancing ET-1 bind to its receptors. For further clarifying the downstream signals in NE/ET-1 induced PASMC proliferation, we detected the phosphorylation and expression levels of ERK and JNK. Conclusions: By combining the results from ours and previous studies, we believed that JNK/c-jun pathway may play an important role in NE-induced PASMC proliferation. Key Words: Noradrenaline; Pulmonary Arterial Hypertension; Pulmonary Artery Smooth Muscle Cells; Endothelin-1; JNK/c-Jun Signaling.

Streptococcus agalactiae (Group B Streptococcus, GBS) is a Gram-positive opportunistic pathogen and the leading cause of neonatal bacterial meningitis, a life-threatening infection of the central nervous system (CNS) that occurs when bacteria cross the blood-brain barrier (BBB). GBS commonly colonizes the maternal genital tract and is a major cause of invasive neonatal disease, including bacteremia and meningitis. Despite treatment advances, GBS meningitis remains associated with substantial mortality and long-term neurological sequelae. The BBB is a highly specialized barrier formed by brain endothelial cells (BECs) that restrict microbial entry into the CNS through tightly regulated intercellular junctions. The BBB exists within the neurovascular unit, where neurons and other CNS cell types actively regulate endothelial barrier properties through intercellular signaling. However, the contribution of neuronal-endothelial interactions to BBB function during neonatal meningitis remains poorly understood. To investigate the mechanisms by which GBS disrupts and penetrates the BBB, we utilized induced pluripotent stem cell (iPSC)-derived brain-like endothelial cells. EZ-Sphere-derived neurons generated from the same iPSC source were incorporated into an isogenic BBB model to determine whether neuronal-endothelial communication influences GBS interaction with BECs. Neuronal co-culture significantly reduced GBS adherence to and invasion of BECs while preserving tight junction integrity during infection. Application of neuron-conditioned medium similarly decreased bacterial adherence and invasion, suggesting that neuron-derived soluble factors enhance barrier integrity during GBS infection. Together, these findings demonstrate that neuronal signaling enhances BBB resistance to GBS and highlight a previously underappreciated role for neurovascular crosstalk in limiting bacterial pathogenesis. ImportanceGroup B Streptococcus (GBS) is the leading cause of bacterial meningitis in newborns. GBS interacts with and crosses the blood-brain barrier (BBB) contributing to a potentially fatal infection without treatment. Understanding how the BBB interacts with bacterial pathogens is critical for developing new strategies to protect vulnerable infants. In this study, we used human stem cell-derived models to recapitulate the BBB and examine how communication between brain endothelial cells and neurons influence host response to bacterial infection. These findings identify neuronal-endothelial communication as a potential contributor to BBB protection and provide a foundation for future studies aimed at preventing GBS invasion of the central nervous system.

Clinically relevant pathogens are often tested for antimicrobial susceptibility using standard laboratory media that poorly reflect the in vivo environments in which they cause infections, leading to poor clinical outcomes. In this study, we aim to understand the impact of media on the global transcriptome, biofilm formation, and antibiotic susceptibility of methicillin-resistant Staphylococcus aureus USA300 when cultivated in a physiologically relevant wound medium, such as simulated wound fluid (SWF), compared to cation-adjusted Mueller-Hinton broth (caMHB), a general-purpose medium. The transcriptomics analysis showed upregulation of 865 genes and downregulation of 792 in SWF compared to caMHB. Upregulated genes in SWF are associated with virulence, such as genes coding for fibronectin-binding proteins (fnaAB), serine proteases (splABCDE), as well as genes involved in antimicrobial resistance, such as multidrug efflux pump genes (norB, norC). Conversely, genes associated with transmembrane ion transport, including phosphate transport (pstSCAB, phoU) and potassium intake (kdpABCF), were significantly downregulated in SWF, as further confirmed by increased membrane disruption upon exposure to a membrane-potential-sensitive dye (DiSC3). Biofilm assay showed reduced surface attached biofilm but increased cell-to-cell attachement in SWF compared to caMHB. Antimicrobial susceptibility testing revealed a 2- to 4-fold increase in tolerance to clinically relevant antibiotics in SWF compared to caMHB. Overall, our findings revealed that media affects gene expression, membrane physiology, virulence, and antibiotic tolerance in MRSA, underscoring the need to use physiologically relevant media in routine antimicrobial susceptibility testing and the drug development pipelines.

The obscure life histories of many kickxellalean genera remain a bottleneck for comprehensive taxon sampling and phylogenetic reconstruction of the order. While Kickxellales has long been regarded as saprobes inhabiting soil or dung, the discovery of "amphibious fungi" such as Unguispora, which exhibits dimorphic growth between the animal gut and feces, suggests a cryptic gut-dwelling stage within these genera. Given its phylogenetic proximity to Unguispora, ecophysiological traits of Linderina were investigated to evaluate its potential association with the animal gut. Two isolates of L. macrospora were obtained from Japanese soil, representing the first record of this species in Japan. Physiological assays revealed that the optimal temperature for both vegetative growth and sporulation was 25-30 {degrees}C. Furthermore, comparative growth assays on different media demonstrated that sporocladium abundance per sporangiophore is sensitive to nutrient availability, and nutrient-poor media were determined to be the most suitable for evaluating morphological characterization. Under anaerobic, nutrient-rich conditions which are known to induce yeast-like growth in Unguispora, sporangiospores of L. macrospora produce arthrospores. Although marked morphological plasticity was observed during the arthrospore formation, the occurrence of yeast-like unicellular proliferation suggests a potential relationship with the animal gut. Additionally, vegetative growth and sporulation were markedly inhibited by white light exposure; notably, a lethal effect on growth was observed during incubation at 20 {degrees}C, indicating that the natural niche of the species is restricted to light-shielded environments. Our findings will help to elucidate the cryptic life cycles and evolutionary trajectories within Kickxellales.

Malaria parasite virulence will be impacted by naturally occurring variation in multiplication rates. Clinical isolates of Plasmodium falciparum exhibit a range of multiplication rates under exponential growth conditions in culture, but it needs to be discovered if relative multiplication rates under competitive conditions are principally defined by this underlying multiplication rate potential. Relative multiplication rates of P. falciparum lines were investigated in 14-day competition assays against a standard competitor clone HB3, with other long-term laboratory-adapted clones showing similar or higher mean per-48-hour rates ranging from 0.98 to 1.51 relative to HB3. In contrast, thirteen Ghanaian clinical isolates cultured for close to two months prior to assay had lower rates, ranging from 0.46 to 0.76 relative to HB3. Analysing the single-genotype clinical isolates and laboratory-adapted clones, there was a highly significant correlation between the competitive rates and previously determined exponential rates (Spearmans rho = 0.95, P = 0.0003), which accounted for most of the observed variance (Pearsons r2 = 0.77, P = 0.004). Testing the effect of alternative nutritional supplementation with human serum or Albumax showed a majority of parasites had consistent competitive rates under either condition, indicating that intrinsic differences determine most variation among parasites.

ObjectiveTo investigate the combined effects of multiple drugs and provide more therapeutic options for invasive fungal infections, this study evaluated the in vitro susceptibility of Aspergillus spp., Candida auris, Cryptococcus neoformans, and Exophiala dermatitidis to pibrentasvir (PIB) in combination with itraconazole (ITR), voriconazole (VOR), posaconazole (POS), or fluconazole (FLU). MethodsAccording to the M27-A3 and M38-A2 guidelines established by the Clinical and Laboratory Standards Institute (CLSI), the in vitro antifungal activities of PIB combined with ITR, VOR, POS, or FLU against 78 clinical isolates, including Aspergillus spp., E. dermatitidis, C. auris, and C. neoformans, were determined. The minimum inhibitory concentrations (MICs) and fractional inhibitory concentration indices (FICIs) were calculated to evaluate the synergistic effects. ResultsPIB alone exhibited no antifungal activity. Significant synergistic effects were observed when PIB was combined with azole antifungal agents. The PIB-POS combination showed synergistic effects against Aspergillus spp. (27/41, 65.90%), C. auris (9/10, 90.00%), C. neoformans (2/9, 22.20%), and E. dermatitidis (11/18, 61.11%). The PIB-ITR combination also showed synergistic effects against Aspergillus spp. (18/41, 43.9%), C. auris (9/10, 90.0%), C. neoformans (2/9, 22.2%), and E. dermatitidis (10/18, 55.5%). Synergistic effects were less frequently observed with the PIB-VOR or PIB-FLU combinations, and no antagonistic effects were observed. ConclusionThis study demonstrates that PIB acts as an azole sensitizer, with the strongest synergistic effects observed when combined with POS or ITR, providing a new research direction for combination therapy against invasive fungal infections.

The pathogenic fungus Trichosporon asahii causes severe mycoses in immunocompromised hosts, such as neutropenic patients. In Cryptococcus neoformans, the unfolded protein response (UPR) sensor Ire1 induces hxl1 mRNA splicing and contributes to stress responses and virulence. The function of Ire1-triggered hxl1 mRNA splicing in stress tolerance and virulence of T. asahii, however, remains unclear. Here, we demonstrated that ire1- and hxl1 gene-deficient T. asahii mutants are sensitive to dithiothreitol (DTT), an inducer of endoplasmic reticulum stress, and exhibit reduced virulence in a silkworm infection model. DTT treatment induced hxl1 mRNA splicing in the wild-type strain, whereas ire1 gene-deficient mutants did not undergo hxl1 mRNA splicing. The ire1 gene-deficient mutants were more sensitive than the parent strain to DTT, H2O2, Congo red, and SDS, and showed reduced virulence in silkworms. Similarly, hxl1 gene-deficient mutants exhibited increased sensitivity to these stressors and reduced virulence. Both the ire1 gene-deficient and hxl1 gene-deficient mutants showed decreased expression of reactive oxygen species-detoxifying related genes CAT2, SOD1, and SOD2, compared with the parent strain. Together, these findings suggest that Ire1-triggered hxl1 mRNA splicing contributes to stress resistance and virulence in T. asahii.

Coxiella burnetii alternates morphologies to survive in two niches: the external environment and a degradative intracellular compartment. The small cell variant (SCV) is adapted for environmental persistence and transmission of Q fever to ruminants and humans. The large cell variant (LCV) is intracellular, and despite not being a major source of transmission, is infectious in vitro. When modeling infection, researchers typically apply a mixed population of these cell types as inocula. As this practice does not mimic natural infection, it may confound our understanding of early Q fever infection events. We separated SCV and LCV by density gradient centrifugation and compared their replication in primary murine macrophages and a fibroblast cell line. SCV inocula replicated more efficiently than LCVs in both host cell types. LCV replication was delayed for four days in macrophages compared with SCV inocula, which had completed logarithmic growth by that time point. We found no difference in pathogenic vacuole size, but there was a modest difference in their respective bacterial burdens. Interestingly, IL-6 and CXCL2 secretion was significantly elevated in LCV-infected macrophages as compared to SCV at 24 hours, suggesting a difference in the host response to each. This is the first study to demonstrate that C. burnetii developmental status influences the progression of infection.

With the rise of antimicrobial resistance, anti-virulence therapeutics are a viable alternative to circumvent resistance pressures. Hypothetical genes and proteins are an under-studied source of potential virulence factor targets. We performed bioinformatic analyses to identify conserved hypothetical genes enriched in pathogenic Pseudomonas aeruginosa but not in non-pathogenic strains. This analysis identified an atypical BlaIR system, which we named pvmSR, that regulated P. aeruginosa virulence in a Caenorhabditis elegans infection model. This is in contrast with the typical BlaIR system from Staphylococcus aureus, which regulates resistance to {beta}-lac-tam antibiotics. The{Delta} pvmSR mutant showed reduced virulence in a C. elegans slow-killing assay. To understand how PvmSR regulated virulence in vivo, we performed dual RNA-seq to analyze transcriptomic changes in both C. elegans and P. aeruginosa. We found that C. elegans responded to P. aeruginosa {Delta}pvmSR infection by decreasing expression of lysosome and phagocytosis pathways. In P. aeruginosa {Delta}pvmSR, we observed decreased gene expression of several known virulence factors including the hydrogen cyanide synthase, hcnC, and heparinase, hepP. Additionally, we observed dysregulation in genes important for quorum sensing and biofilm formation. Collectively, our findings indicated that PvmSR contributed to virulence regulation and may serve as a potential anti-virulence target.

BackgroundHair tools such as hairbrushes and combs allow for various styling options to produce desired hairstyles among various people. However, there is the risk of they serving as fomites for infection and contamination especially among people in close habitation. ObjectivesThis study therefore decided to investigate the trend of microbial populations on these hair grooming tools in universities such as KNUST to inform student hygiene practices and disease prevention strategies. Methods30 students were randomly selected for the study, and swab samples from different hairbrushes and combs were taken for microbial investigation. Microbial isolates were identified based on their morphological and biochemical characteristics. Determination of efficacy of different cleaning methods for hair tools was also done. ResultsThe study found an average bacterial and fungal count of 7.4x102 CFU/ml and 4.6x103 CFU/ml, respectively. The bacterial isolates suspected included Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus sp., Bacillus subtilis, and Corynebacterium sp. The fungal isolates included Aspergillus species, Penicillium sp., Rhizopus sp., Neurospora sp., Colletotrichum gloeosporioides and Curlvularia sp. Correlation analysis showed higher bacterial numbers significantly associated with the presence of hair diseases such as dandruff (p=0.046). Water and detergent were found to be the most effective method of eliminating microbial content from hairbrushes and combs. ConclusionThis study uncovered a variety of microbes on KNUST students combs and hairbrushes, which is evident of microbial contamination. While these numbers are relatively low, this study highlights the need for students to still follow good hygiene procedures and implement efficient cleaning techniques of hair tools, as they may still serve as an ideal environment to harbor and transfer microbes

BackgroundEscherichia coli is a common environmental and zoonotic bacterium that serves as an important indicator of fecal contamination and antimicrobial resistance (AMR) in poultry production systems. The emergence of multidrug-resistant (MDR) E. coli in poultry farm environments poses a significant One Health threat to animal, human, and environmental health. ObjectiveThis study aimed to isolate, identify, determine the prevalence, assess the antibiotic susceptibility pattern, and molecularly confirm Escherichia coli isolated from poultry farm environments in Lalmonirhat district, Bangladesh. Materials and MethodsA cross-sectional study was conducted from January to June 2024 using 60 environmental samples comprising water (n = 20), soil (n = 20), and bird-dropping (n = 20) samples collected from poultry farms in five upazilas of Lalmonirhat district. Isolation and identification of E. coli were performed using standard cultural, morphological, and biochemical techniques. Antimicrobial susceptibility was determined by the Kirby-Bauer disc diffusion method following CLSI guidelines. Ten randomly selected isolates were confirmed by polymerase chain reaction (PCR) targeting the species-specific uidA gene. ResultsThe overall prevalence of E. coli was 50% (30/60). Source-wise prevalence was highest in bird-dropping samples (75%), followed by water (45%) and soil (30%). Area-wise prevalence ranged from 33.33% in Patgram to 66.67% in Hatibandha. The isolates exhibited the highest resistance to oxytetracycline (66.67%) and ciprofloxacin (60%), while the highest susceptibility was observed to erythromycin (63.33%), neomycin (56.67%), and amoxicillin (56.67%). All ten isolates subjected to PCR produced the expected 486 bp uidA gene amplicon, confirming their identity as E. coli. ConclusionThe findings demonstrate a considerable prevalence of antimicrobial-resistant E. coli in poultry farm environments of Lalmonirhat district. Strengthening farm biosecurity, improving hygiene and waste management, implementing antimicrobial stewardship, and maintaining continuous molecular surveillance are essential to minimize the dissemination of resistant E. coli within a One Health framework.