Frontiers in Cellular and Infection Microbiology最新文献

Background and aims: HCV genotype (GT) 3 is associated with rapid liver disease progression. However, the liver disease progression and its risk factors in patients with HCV GT 3 infection after sustained virological response (SVR) following direct-acting antivirals (DAAs) remain unclear. Therefore, we aimed to investigate the liver disease progression of patients with GT 3 after SVR.

Methods: This was a retrospective cohort study of patients with HCV infection who achieved SVR by DAAs. The clinical outcome was overall liver disease progression (OLDP), defined as newly diagnosed compensated liver cirrhosis, decompensated liver cirrhosis, or hepatocellular carcinoma. The incidence of OLDP was evaluated by Kaplan-Meier analysis. Cox regression analysis identified the risk factors for OLDP.

Results: A total of 409 patients (46.9% GT3) were followed for 43.7 (32.9, 58.7) months. The incidence of OLDP was higher in patients with GT 3 (4.63/100PY) than non-GT 3 (0.60/100PY; P < 0.001). According to Cox multivariate analysis, GT 3 was significantly associated with OLDP (HR 6.41, 95% CI 1.82 - 22.56; P=0.004). The predictors of OLDP in patients with GT 3 were HCV recurrence (HR 12.15, 95% CI 3.18 - 46.46; P < 0.001) and FIB-4 > 3.25 (HR 16.40, 95% CI 1.03 - 39.81; P = 0.046) at baseline.

Conclusion: HCV GT 3-infected patients remain at a higher risk of OLDP even after achieving SVR by DAAs, especially patients with advanced liver fibrosis and at high risk for reinfection or virological late relapse.

Background: Bloodstream infection (BSI)-induced severe sepsis is a common cause of mortality, frequently resulting in septic shock and multiple organ dysfunction syndrome (MODS). This study aimed to analyze mortality risk factors and summarize pathogen characteristics associated with BSI-induced severe sepsis in the pediatric intensive care unit (PICU).

Methods: This retrospective study was conducted at a tertiary pediatric hospital between January 2015 and December 2023, encompassing children with BSI-induced severe sepsis in the PICU. Clinical characteristics, laboratory parameters, pathogen characteristics, and drug resistance profiles of the patients were collected. Clinical and laboratory indicators along with pathogen characteristics were summarized. Logistic regression analysis was employed to identify independent risk factors associated with 28-day mortality.

Results: A total of 192 patients with bloodstream infection (BSI)-induced severe sepsis were identified, with a 28-day in-hospital mortality rate of 36.98% (71/192). The incidence of septic shock (42.1% vs. 69%, P < 0.001) and AKI (14% vs. 31%, P = 0.005) was significantly lower in the survival group compared to the non-survival group. In multivariate analysis, independent risk factors for 28-day mortality were the pediatric sequential organ failure assessment (pSOFA) score (OR 1.176; 95% CI: 1.046-1.321, p = 0.007) and the P/F value (OR 0.994; 95% CI: 0.991-0.997, P < 0.001). Double organism growth was detected in 8 cultures, and a total of 200 pathogenic bacteria were isolated from all blood cultures. Of these, 110 strains (55.0%) were Gram-negative bacteria, 88 strains (44.0%) were gram-positive bacteria, and 2 strains (1.0%) were Candida albicans. The most commonly isolated pathogens were Staphylococcus aureus, Coagulase-negative Staphylococcus, and Escherichia coli. The detection rate of carbapenem resistance (CR) in Acinetobacter baumannii (66.7%) was higher than that in Pseudomonas aeruginosa (15.4%). The detection rates of extended-spectrum cephalosporin resistance (ECR) and fluoroquinolone resistance (FQR) in Escherichia coli (E. coli) were higher than those in Klebsiella pneumoniae.

Conclusion: In the PICU, higher mortality was observed in children with BSI-induced severe sepsis who presented with elevated pSOFA scores and low P/F values. Acinetobacter baumannii exhibited the highest levels of CR and FQR, while Escherichia coli demonstrated the highest level of ECR.

The Bushbuckridge-East community in Mpumalanga Province, South Africa is bordered by nature reserves, including the Manyeleti Game Reserve. Murid rodents are prevalent in both Manyeleti and communal rangelands adjoining the community households. Although rodents are reservoir hosts for a broad range of viral, bacterial and parasitic pathogens, the rodent microbial diversity and transmission of zoonotic agents to humans in the community is understudied. In this study we investigated bacterial diversity in wild and commensal rodents sampled from different habitats. The 16S rRNA gene was amplified from DNA extracted from the blood of 24 wild Mastomys and one Steatomys sp. and subjected to PacBio circular consensus sequencing. As Bartonella species were dominant in the blood microbiome, gltA gene characterization was performed to delineate species. Rodents sampled from peri-urban and communal rangelands had higher proportions of Bartonella spp. [Hlalakahle (77.7%), Gottenburg (47.8%), Tlhavekisa (83.8%)] compared to those from the protected habitat (43.8%). Ehrlichia spp., Anaplasma spp., and Coxiella burnetii were detected at <1% of the sequence reads. Conventional PCR and sequencing validated the detection of Bartonella spp. with the first confirmation of Bartonella mastomydis infection in Mastomys in South Africa. Additionally, 317 mites, 90 fleas, 10 ticks and eight lice were collected from the rodents, providing evidence of possible vectors of the organisms detected. The detection of zoonotic agents in rodents in Bushbuckridge-East community, together with prior serological confirmation of Bartonella and Coxiella in non-malarial acute febrile patients from this community, highlights the possible risks that commensal rodents pose to human health.

Introduction: Vancomycin-resistant Enterococcus faecium (VRE-fm) biofilms pose a significant clinical challenge due to the limited effectiveness of traditional antibiotics. This study investigates the potential of γ-linolenic acid (GLA) as a novel antibiofilm agent.

Methods: Transcriptome analysis was performed on the V27 isolate, comparing cells in mature biofilms treated with and without GLA. The findings were further validated using qRT-PCR on six VRE-fm isolates and two E. faecalis isolates.

Results: Transcriptome analysis revealed a significant downregulation in the expression levels of genes associated with biofilm formation, including fruA, fruB, sgrA, lpxtg-cwa, tfpp, lafA, lafB, malP, fsrA, and fsrC', while a significant upregulation was observed in the expression of fsrBD. Validation by qRT-PCR in six VRE-fm isolates confirmed the significant changes in the expression levels of all genes except for lpxtg-cwa, with statistical significance. The expression of bgsB and bgsA genes, which are the homologs of lafA and lafB genes, along with the Fsr-regulated genes gelE and sprE in E. faecalis, were also found to be downregulated by GLA. In addition, KEGG analysis identified specific metabolic pathways that were significantly downregulated by GLA.

Conclusion: GLA effectively targets multiple aspects of biofilm formation in VRE-fm, including the downregulation of key biofilm-related genes, the inhibition of quorum sensing systems, and the modulation of metabolic pathways. GLA emerges as a promising candidate for eradicating Enterococcus biofilms.

Background: Ventilator-associated pneumonia (VAP) carries a high mortality rate in the intensive care units (ICUs) due to its widespread drug resistance. Traditional microbial cultures limited by speed and sensitivity, are often unable to help clinicians make effective diagnosis and treatment. Therefore, there is an urgent need for a rapid and accurate test that can identify both pathogens and their antimicrobial resistance (AMR) to improve the prognosis of patients with VAP.

Study design: We analyzed samples from ICU patients with suspected VAP using both microbial tests and targeted next-generation sequencing (tNGS), comparing the results of tNGS pathogen and AMR detection against microbial culture and antimicrobial susceptibility testing (AST).

Results: Involving 199 patients with suspected VAP, tNGS showed a sensitivity rate of 98.98% for pathogen identification. While the sensitivity rate of microbial culture was just 66.84%. Additionally, tNGS performed almost half the turnaround time of microbial culture (1.66 days vs 3.00 days). For AMR, the overall consistency between AST and tNGS was 79.31%. The great performance particularly exhibited for Acinetobacter baumannii carbapenem-penicillin-cephamycin resistance.

Conclusion: tNGS excels in identifying pathogens and AMR. Its rapid workflow makes it ideal for managing critically ill patients, enhancing treatment precision, and reducing antibiotic misuse.

Bacterial infections pose significant threats to human health, and prudent antibiotic use remains a key strategy for disease treatment and control. However, a global escalation of drug resistance among pathogenic bacteria presents a formidable challenge. Probiotics have emerged as a promising approach to combating pathogenic bacterial infections. In this study, we investigated the antibacterial activity of BTS1-knockout (BTS1-KO) Saccharomyces cerevisiae. Our findings demonstrate its effective inhibition of pathogen growth as evidenced by Minimum inhibitory concentration (MIC) assays, growth curves, bacteriostatic spectrum analyses and co-culture experiments. Additionally, it significantly impedes Escherichia coli and Staphylococcus aureus biofilm formation. Moreover, BTS1-KO S. cerevisiae exhibits low haemolytic activity, acid resistance, resistance to high bile salt concentrations, high auto-aggregation capacity and high co-aggregation capacities with pathogenic bacteria. Moreover, infected larvae treated with BTS1-KO S. cerevisiae in Galleria mellonella-E. coli (in vivo) and G. mellonella-S. aureus (in vivo) infection models showed significantly prolonged survival times. Mechanistic investigations revealed that BTS1-KO S. cerevisiae primarily produced lactic acid via metabolism, thereby lowering the environmental pH and inhibiting pathogenic bacterial growth. In summary, our study underscores the probiotic potential of BTS1-KO S. cerevisiae, offering broad-spectrum antibacterial activity in vitro and in vivo with low toxicity. This highlights BTS1-KO S. cerevisiae as a promising probiotic candidate for clinical prevention and control of bacterial infection.

Morganella morganii is a Gram-negative, opportunistic pathogen that is often associated with nosocomial infections. Here, the genomic characteristics and antimicrobial resistance (AMR) of Morganella clinical isolates between 2016 and 2023 were determined. A total of 218 clinical isolates were mainly identified from urinary tract (48.2%) and respiratory tract (16.5%), with 105 isolates randomly selected for whole genome sequencing. The highest rates of antibiotic resistance were observed with SAM (68.3%), followed by CIP (39.9%), and SXT (37.2%). Distance analysis suggested that the 105 newly sequenced isolates could be divided into two groups: M. morganii subsp. morganii and M. morganii subsp. sibonii. While, the average nucleotide identity between these groups showed only 91.5-92.2% similarity, raising the possibility that they may be distinct species. Phylogenomic analysis revealed that the 102 M. morganii isolates fell into six clades, with clades 4-6 making up the majority. Core genome multi-locus sequence type analysis indicted high genomic diversity among different hosts and relatively stability (< 10 SNPs accumulated over three years) within the same host. Together with epidemiological data, isolates of four genetic clusters could be possible nosocomial transmissions. The identified 80 AMR genes belonged to 15 drug-related classes, with tet(B) gene being the most prevalent, followed by sul1, catA2, and sul2 genes. This study provided comprehensive genomic insights and AMR patterns of Morganella isolates in China, highlighting the necessity for continuous monitoring through whole genome sequencing.

Reflecting their tropism for keratinocytes, most poxviruses that infect vertebrates replicate to high titers and cause pathology in the skin. Keratinocytes, the main cells of the epidermis, are found in different stages of a differentiation program that produces the critical barrier against environmental damage. While systemic poxviruses (e.g. smallpox virus, sheeppox virus) also infect other cell types, the parapoxvirus orf virus (ORFV), which causes localized infections in sheep and goats, has not been shown to replicate in cells other than keratinocytes. Notably, ORFV infection only occurs after or concomitant with epidermal damage and the subsequent healing response and shows unexplained delayed virus replication in an uncharacterized keratinocyte subpopulation. Using in situ hybridization, immunohistochemistry, confocal microscopy, qPCR, and a full-thickness wound/infection model in sheep, the natural host, we show that during an initial 2-day eclipse phase viral transcription and viral DNA replication are not detected. Between days 2 and 3 pi, viral transcription is first detected in keratinocytes of the stratum granulosum and upper stratum spinosum in the proliferative zone at the wound margin. These cells are positive for cytokeratin 10, a suprabasal marker; cytokeratin 6, a protein induced during early repair responses; stratum granulosum markers filaggrin and loricrin; and negative for the nuclear proliferation marker Ki-67 and cytokeratin 14, a basal cell marker. This marker profile suggests that keratinocytes supportive of viral replication are engaged in advanced keratinocyte differentiation rather than proliferation.

Introduction: Infections with coagulase negative staphylococcal species (CoNS) are a major cause of mortality and morbidity in joint and heart valve replacement procedures, largely due to biofilm formation. Cells within biofilms have higher rates of antibiotic resistance than their planktonic counterparts; consequently, novel mechanisms are needed to combat these infections.

Methods: To enhance antibiotic delivery and penetration, this innovative study involved treating CoNS biofilms with murine blood clots impregnated with antibiotics. We then investigated the impact of this treatment on biofilm density, metabolism, and architecture.

Results: Our pilot study demonstrates that this method of antibiotic delivery results in improved biofilm clearance, relative to conventional exposure methods.

Discussion: Our results demonstrate that blood clot exposure has an intrinsic impact on biofilm density and potentially reduces colonization, warrenting further investigation into the mechanism.

Objectives: The goal of this study is to evaluate the analytical and clinical performance of a new human immunodeficiency virus antigen and antibody (HIV Ag/Ab) test using light-initiated chemiluminescent assay (LiCA^®) and compare it with the well-established Architect^® HIV Ag/Ab combo assay in a clinical setting.

Methods: We used banked samples and national reference controls to identify the ability to detect HIV Ag/Ab and different viral subtypes. Thirteen seroconversion panels were tested to evaluate early detection of HIV. A total of 21,042 patient samples were collected to compare the diagnostic performance of LiCA^® with Architect^®. Screening-reactive results were confirmed by Western blotting and nucleic acid testing.

Results: Total imprecision was within 2.49%-6.56%. The C₅-C₉₅ interval was within -10.20%-7.67% away from C₅₀. The limit of detection for p24 antigen was <1.00 IU/mL. Using national reference panels and banked sample pools, LiCA^® successfully detected all negative and positive controls in line with the criteria, and all HIV-positive specimens containing different viral subtypes. In 13 seroconversion panels, LiCA^® detected reactive results on average 5.73 days (95% CI: 3.42-8.04) after the initial RNA test results were confirmed positive, which was 1.27 days earlier (-3.75 to 1.21) compared to Architect^®. Paired comparisons in 21,042 clinical patient samples demonstrated that LiCA^® detected HIV Ag/Ab with a slightly better performance in sensitivity (100.00% vs. 99.65%), specificity (99.85% vs. 99.81%), negative predictive value (NPV, 100.00% vs. 99.99%), and positive predictive value (PPV, 89.84% vs. 87.85%) than Architect^®. Total agreement between two assays was 99.67% with a kappa value of 0.89.

Conclusion: LiCA^® HIV Ag/Ab is a precise and highly sensitive assay for measuring HIV-1 p24 antigen and HIV-1/2 antibodies with differentiated S/Co values of Ag/Ab. The assay is appropriate for use in the clinical routine test for the early detection of HIV.