Microbes and Infection最新文献

This study aims to compare the clinical, laboratory, and therapeutic outcomes between acute and subacute/chronic phases of brucellosis and to identify independent predictors of a favorable treatment response. This retrospective observational and analytic study included 171 patients with brucellosis, categorized as acute (n = 146) or subacute/chronic (n = 25). A therapeutic response was defined as the complete resolution of initial symptoms with no relapse during a 12-month follow-up. A serological response was defined as a ≥4-fold decrease in the serum tube agglutination (STA) titer post-treatment. Outcomes were compared using appropriate statistical tests (p < 0.05), and logistic regression was used to identify predictors of response. Compared to the subacute/chronic group, patients with acute brucellosis had a significantly higher frequency of leukopenia (21.2 % vs. 0 %; p < 0.01), elevated C reactive protein (CRP) (76.7 % vs. 52.0 %; p = 0.01), and elevated transaminases (43.8 % vs. 20.0 %; p = 0.025). A significantly higher therapeutic response rate was observed in acute cases (93.2 %) compared to subacute/chronic cases (0.76 %) (p = 0.01). Multivariate analysis identified elevated baseline CRP (OR: 4.00; p = 0.02) and a post-treatment decrease in STA titer (OR: 5.84; p = 0.007) as independent predictors of a favorable therapeutic response. In conclusion, acute brucellosis presents with a more pronounced inflammatory profile than subacute/chronic forms. While patients with acute brucellosis demonstrated a significantly higher therapeutic response rate, the serological response was also more pronounced in this group. Elevated CRP at diagnosis and a significant decrease in STA titer post-treatment are strong, independent predictors of successful outcomes, highlighting their value in patient monitoring.

Bovine viral diarrhea virus (BVDV) is a major pathogen in cattle, causing significant economic losses and frequently contaminating cell cultures through fetal calf serum, which can compromise biological products. Gene editing technologies, such as CRISPR/Cas9, offer promising tools for developing disease-resistant models. CD46, the primary cellular receptor for BVDV, has an incompletely understood role in viral infection. This study aimed to: (i) characterize and compare CD46 between bovine cell lines resistant (CRIB) and susceptible (MDBK); (ii) edit the BVDV-binding region of MDBK-CD46; and (iii) evaluate the susceptibility of CD46-edited MDBK cells to BVDV infection. CD46 was sequenced in BVDV-sensitive MDBK cells, BVDV-resistant CRIB cells, and bovine fibroblasts. CRISPR/Cas9 was used to delete exon 1 of CD46, which encodes the viral attachment platform. Two guide RNAs were cloned into px458 plasmids expressing GFP and co-transfected into MDBK cells. Genomic DNA was PCR-amplified, cloned, and sequenced. Results showed that CRIB cells express a wild-type CD46 protein, suggesting that CD46 is not responsible for their resistance to BVDV. This resistance is likely due to the truncated ADAM17 in CRIB cells, which may alter membrane composition and endocytic pathways, affecting viral entry. Three edited MDBK cell lines were generated: two with homozygous deletions (A and B), and one with a heteroallelic edit (C). The edited lines A and B exhibited over 90 % resistance to BVDV. These findings support the use of gene editing to generate BVDV-resistant models and to further explore alternative viral receptors and entry pathways.

Influenza A virus (IAV) is a global respiratory pathogen, with macrophages playing a key role in innate immunity. We established mouse models of IAV-induced pneumonia and macrophage depletion, along with an in vitro co-culture system of lung epithelial cells (MLE-12) and macrophages (RAW264.7), to study IAV infection. HE staining, immunohistochemistry, and immunofluorescence revealed IAV-induced lung damage and macrophage recruitment. In the co-culture system, IAV infection caused morphological changes in both cell types, increased viral load, and elevated inflammatory factors. High-throughput sequencing identified miR-1260 and Sema3A-mediated PI3K/AKT/mTOR pathway involvement. Transfection with miRNA mimics, inhibitors, and Sema3A-siRNA showed that miR-1260 exacerbates cell damage by targeting Sema3A via PI3K/AKT/mTOR. Macrophage-depleted mice exhibited worse outcomes (weight loss, inflammation, viral load, pathology) than IAV-infected mice, linked to miR-1260/Sema3A/PI3K/AKT/mTOR regulation. Macrophages protect against IAV by suppressing miR-1260-mediated Sema3A/PI3K/AKT/mTOR activation.

Objectives: Gram-negative bacteria (GNB) bloodstream infection (BSI) pose a significant clinical challenge in patients with haematological malignancy, further complicated by rising carbapenem-resistant GNB (CRGNB) prevalence. This study aims to investigate the prevalence and risk factors for GNB BSI and associated mortality in this population.

Methods: A retrospective study was conducted at a tertiary teaching hospital in southern China (2015-2023), including haematological malignancy patients with GNB BSI. Multivariate logistic analyses were performed to identify risk factors for CRGNB BSI and to establish a predictive model for 30-day mortality of GNB BSI.

Results: Among 351 patients with GNB BSIs, acute myeloid leukaemia (51.3 %) was the predominant underlying disease. Escherichia coli (28.8 %) and Klebsiella pneumoniae (29.7 %) were the most common GNB BSI and CRGNB BSI pathogens, respectively. Independent risk factors for CRGNB BSI included chronic liver disease, prior carbapenems therapy (≤30 days before BSI), a platelet count <30 × 10⁹/l and albumin concentration <30 g/l before BSI. The 30-day mortality prediction model of GNB BSI incorporated CRGNB infection, platelet count <30 × 10⁹/l and albumin concentration <30 g/l before BSI, demonstrating good discrimination (training cohort AUC: 0.828; validation cohort: 0.791). Calibration plots and decision curve analysis confirmed robust model performance.

Conclusions: Identified factors enable risk stratification for CRGNB BSI and poor prognosis in GNB BSI, facilitating timely interventions to improve outcomes.

Mycobacterium avium is a slow-growing non-tuberculous mycobacterium. While its medical importance is increasing, its virulence is only poorly characterized. A highly virulent M. avium strain ATTC25291 (MAA25291) has been shown to cause severe disease in mice by survival and growth in nitric oxide (NO) producing, immune suppressive monocytic-MDSC (M-MDSC). The induction and persistence of MAA25291 in M-MDSC is still unresolved. In the present study, we were interested in the role of M-MDSC in mice infected with MAA25291 at infection doses that led to the manifestation of clinical disease (high dose) or subclinical disease (low dose). Flow cytometry revealed the presence of M-MDSC in both infection groups, however, this infiltration was significantly lower after low dose infection. Histopathology showed lower infiltration of NOS2 expressing cells in spleen and liver correlated with high CD3⁺ T cell numbers after low dose infection, whereas high dose infection of mice led to T cell losses in the tissues. This study highlights that the infection dose significantly affects M-MDSC induction and their immune regulatory roles. Furthermore, it suggests that the induction and persistence of MAA25291 in M-MDSC relies on the amount of NO production.

Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening tick-borne viral infection with a high mortality rate and limited treatment options. While gastrointestinal symptoms are common, the contribution of gut microbiome disruption to disease progression remains unclear. Previous studies have noted taxonomic shifts in SFTS-associated microbiota, but their functional and metabolic consequences have not been systematically characterized. We conducted an integrated metagenomic and metabolomic analysis of fecal samples from 20 SFTS patients and 20 healthy controls. At the time of admission, patients with SFTS exhibited acute-stage infection, characterized by symptoms such as fever, thrombocytopenia, and gastrointestinal disturbances. Metagenomic sequencing was used to assess the microbial gene content, taxonomic composition, and functional potential. Untargeted metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed to profile fecal metabolites. The SFTS patients showed a significantly reduced microbial gene richness, alpha diversity, and compositional stability. Short-chain fatty acid (SCFA)-producing genera (e.g., Faecalibacterium and Roseburia) were depleted, while mucin-degrading and opportunistic taxa (e.g., Pseudomonas and Akkermansia) were enriched. Functionally, biosynthetic and homeostatic pathways were suppressed; while stress-adaptive, biofilm-forming, and virulence-associated pathways were elevated. Metabolomic profiling revealed depletion of anti-inflammatory metabolites (e.g., bile acids and curcumin sulfate) and enrichment of proinflammatory compounds (e.g., porphyrins and beta-tyvelose). Multi-omic correlation highlighted strong links between microbial disruption and altered metabolite production. In conclusion, SFTS is associated with significant alterations in the gut microbiome and its metabolic profile, which is characterized by the loss of beneficial microbial taxa and functions, alongside the emergence of virulence factors and stress-related signatures. These findings underscore the role of microbiome dysfunction in SFTS and suggest that microbiota-targeted strategies may offer supportive benefits, particularly in alleviating SFTS-associated gastrointestinal disturbances and secondary microbial imbalance.

This study characterizes the alterations in peripheral blood lymphocyte subsets and cytokine levels in patients with respiratory syncytial virus (RSV) infection and evaluates their clinical relevance. We collected clinical data from 215 RSV-positive inpatients. Patients were stratified into distinct groups according to different criteria; within-group comparisons were performed. In the RSV-infected group, absolute counts of all peripheral blood lymphocyte subsets were significantly lower than in controls and showed a negative correlation with disease severity. Conversely, all measured cytokines were markedly elevated in the infected group and positively correlated with the severity of RSV infection. Within the infected group, elderly patients (≥65 years) showed significantly different lymphocyte-subset counts and cytokine profiles compared with non-elderly patients. Similarly, individuals with high-risk diseases exhibited significant differences in these parameters relative to those without such diseases. RSV infection induces abnormalities in peripheral blood lymphocyte subsets and cytokine levels. The magnitude of these immune changes is linked to disease severity, patient age, and selected comorbidities, suggesting their potential utility as adjunct biomarkers for clinical assessment.

Co-infections involving Pseudomonas aeruginosa and Candida auris are becoming increasingly common in hospitals and represent an emerging clinical challenge, as these pathogens can form mixed biofilms during catheter-associated infections, which complicates treatment, prolongs the disease and poses a significant threat to public health. In this study, we formed individual- and dual-species biofilms with Pseudomonas aeruginosa and Candida auris, and then treated mature biofilms with or without meropenem to determine the number of viable cells (colony-forming units). Moreover, Pseudomonas aeruginosa biofilms plus total or fractionated Candida auris supernatant were exposed to meropenem to calculate biofilm-associated viable cells. The results showed that Pseudomonas aeruginosa exhibits increased survival to meropenem in dual-species biofilms compared to individual-species biofilms. Furthermore, we demonstrated that the molecule that promotes meropenem tolerance is present in the supernatant of Candida auris biofilms with a molecular mass <10 kDa. In conclusion, Candida auris induces meropenem tolerance in Pseudomonas aeruginosa during mixed biofilms.

Pathogenic Leptospira spp. evade the complement system by capturing soluble regulators of the alternative, classical, and lectin pathways - such as factor H, C4BP, and vitronectin - via proteins on their surface. By capturing these regulators, Leptospira can disrupt the complement activation cascade, thereby preventing opsonization by C3b/iC3b and lysis by the membrane attack complex (MAC). The ability of low-passage pathogenic Leptospira strains - LOCaS46 (L. interrogans sv Canicola), LOVe30 (L. interrogans sv Icterohaemorrhagiae), and MOCA45 (L. santarosai sv Tarassovi) - to bind C4BP was evaluated and compared to their corresponding culture-attenuated (LOCaS46, LOVe30, and MOCA45) and to the saprophytic Patoc I strain of Leptospira biflexa sv Patoc. Binding to C4BP was assessed by ELISA and confirmed by Western blot, the expression level of the genes for C4BP-binding proteins was evaluated by RT-qPCR, and the survival of the Leptospira spp. strains in normal human serum (NHS) was estimated to assess complement resistance. Results showed that culture attenuated (CA) strains had a lower capacity for binding to C4BP, and surviving to NHS as compared to low-passage (LP) strains. Also, transcription level of the genes for the C4BP-binding proteins LigA, LigB, LcpA, enolase and Lsa23, was lower in the CA strains than in their corresponding LP strains. This suggest that reduction of the ability to capture C4BP in culture attenuated (CA) strains is due at least in part to lower expression of C4BP-binding proteins, affecting the evasion of classical and lectin pathways of the complement system and therefore the capability of survival in NHS.