Current Microbiology最新文献

As multidrug-resistant bacteria continue to emerge rapidly, the demand for bioactive molecules with alternative mechanisms of action become increasingly urgent to address this global health crisis. Endophytic fungi (EFs) have emerged as promising sources of antimicrobial metabolites due to their remarkable biosynthetic potential. However, research on EF-derived antimicrobials often faces significant methodological limitations, including inadequate strain characterization, suboptimal bioassay design, limited quantitative validation, and insufficient chemical characterization of active compounds. These shortcomings hinder the translation of laboratory findings into clinically relevant solutions. This review provides a critical assessment of the current state of antimicrobial research involving EFs, highlights persistent methodological gaps, and advocates for the adoption of integrative and standardized approaches. In contrast to previous reviews, this work introduces a methodological framework that prioritizes reproducibility, cross-comparison of antimicrobial efficacy against bacterial targets, and the alignment of bioassay practices with clinical relevance. We argue that enhancing methodological rigor in endophytic fungal research is crucial to fully realizing their potential as a sustainable source of novel antimicrobial agents.

As typical urban green spaces with high human activity, hospital green soils not only serve as important microbial reservoirs but may also be associated with potential ecological impacts and public-health concerns. However, the ecological distribution patterns and potential pathogenic functional responses of keratinophilic fungi in these soils remain poorly understood. In this study, green space soils from hospitals in 30 cities across 10 provinces in southern China were examined. Using a feather enrichment treatment combined with Illumina MiSeq high-throughput sequencing, the effects of feather addition (simulating exogenous keratin inputs) on fungal community composition, diversity, and function were analyzed. The results revealed that feather enrichment significantly altered fungal community structure. The relative abundance of Ascomycota increased from 50.74% (control) to 97.19% (treatment group), with Onygenales becoming the dominant fungal order (93.72%), indicating a substantial community shift. Additionally, alpha diversity of the soil fungal community decreased. Functionally, the Pathotroph-Saprotroph trophic mode was significantly enriched, and Plant Pathogen-Undefined Saprotroph emerged as the dominant functional guild. Soil pH and carbon-to-nitrogen ratio (C/N) were identified as key environmental factors associated with community shifts, exhibiting strong negative correlations with both Onygenales and the Pathotroph-Saprotroph functional mode (P < 0.01). This study demonstrates that feather enrichment imposes keratin-based selective pressure, specifically enriching keratinophilic fungal taxa while reshaping soil fungal structure and function. These findings deepen our understanding of how keratin-rich inputs reshape fungal communities in hospital green spaces and provide important insights for the ecological risk assessment of soil microbial communities.

The swift and accurate detection of Escherichia coli O157:H7 is vital for safeguarding public health due to the serious health risks it poses. Traditional detection methods, while effective, often face challenges such as prolonged processing times, intricate sample preparation, and reliance on specialized laboratory equipment. To address these issues, significant advancements have been made in the development of nanomaterials-based biosensors over the past two decades. These innovative technologies exploit the unique properties of nanomaterials, including their high surface area, enhanced reactivity, and capacity for rapid signal transduction. This manuscript reviews the recent advancements in biosensor technologies that utilize nanomaterials for detecting E. coli O157:H7, focusing on various strategies such as electrochemical, optical, and piezoelectric biosensors. The benefits of these methods include improved sensitivity and specificity, along with the potential for real-time monitoring in clinical settings. Additionally, the pathological implications of E. coli O157:H7 infections are discussed, emphasizing the importance of timely detection for effective clinical management.

To characterize the genomic features, antimicrobial resistance mechanisms, and biological characteristics of a carbapenem-resistant Acinetobacter pittii strain co-harboring plasmid-borne bla_NDM-1 and chromosomally located bla_OXA-500. An A. pittii strain (L802) was isolated from an intestinal sample of a diarrhea outpatient in Hangzhou, Zhejiang Province, China. Whole-genome sequencing was performed using Illumina and Oxford Nanopore platforms, followed by comprehensive bioinformatics analysis. The localization of bla_NDM-1 was determined by S1-PFGE and Southern blotting. Horizontal gene transfer potential was evaluated by conjugation and electrotransformation assays. Antimicrobial susceptibility testing, biofilm formation assays, virulence evaluation using a Galleria mellonella infection model, scanning electron microscopy, phylogenetic analysis, and RT-qPCR analysis of resistance gene expression under carbapenem induction were conducted. Strain L802 was identified as A. pittii ST63 and exhibited high-level resistance to carbapenems and multiple cephalosporins, while remaining susceptible to polymyxin B and tigecycline. Whole-genome analysis revealed a 3.86 Mb circular chromosome and four plasmids. The bla_NDM-1 gene was located on a ~ 41 kb IncR-type plasmid (pL802-NDM-1) together with aph(3')-VI, sharing 99-100% sequence identity with plasmids from diverse Enterobacteriaceae species. Conjugation assays failed to yield transconjugants; however, electrotransformation confirmed that the bla_NDM-1-carrying plasmid could be introduced into Escherichia coli DH5α under laboratory conditions. Importantly, bla_OXA-500 was located on the chromosome, representing a rare genetic configuration that may contribute to enhanced stability compared with plasmid-borne resistance genes. Phenotypic assays showed weak biofilm formation and low virulence in the Galleria mellonella model. Phylogenetic analysis indicated that L802 clustered closely with other A. pittii strains isolated in China, suggesting possible regional dissemination. This study reports, for the first time in Zhejiang, China, an A. pittii strain co-harboring plasmid-borne bla_NDM-1 and chromosomally located bla_OXA-500. The coexistence of mobile and chromosomally encoded carbapenemase genes highlights a concerning resistance strategy and underscores the need for continuous surveillance and infection control measures against emerging multidrug-resistant Acinetobacter species.

Ursolic acid (UA), a natural triterpene, demonstrated promising activity against visceral leishmaniasis (VL); however, its clinical use is limited by poor aqueous solubility (< 5.64 µg/mL), low permeability, hindered oral bioavailability (< 3%), and extensive first-pass metabolism. Hence, hyaluronic acid-coated ursolic acid-bearing liposomes (HA-UA-Lips) were formulated using the thin-film hydration method integrated with Box-Behnken Design (BBD). HA-UA-Lips displayed a vesicle size of 200.2 ± 5.2 nm, PDI of 0.164 ± 0.041, and zeta potential of -21.39 ± 0.27 mV. The surface topography analysis confirmed spherical shape and uniform dispersion of vesicles. Additionally, HA-UA-Lips indicated a significant (P < 0.0001) sustained release of drug after 72 h (70.4 ± 1.68%) as compared to ursolic acid-loaded liposomes (UA-Lips; 87.4 ± 2.61%). The IC₅₀ of HA-UA-Lips was calculated to be 0.6316 ± 0.0004 µg/mL, which was notably declined (P < 0.0001) as compared to UA (22.0 ± 0.35 µg/mL) and blank liposomes (Blk-Lips; 36.205 ± 0.745-µg/mL), respectively, in L. donovani-infected murine macrophage cell line J774A.1. The C6-HA-UA-Lips (Coumarin-6-dye-loaded hyaluronic acid-coated ursolic acid bearing liposomes) further demonstrated augmented uptake in RAW264.7 cells compared to C6-UA-Lips (Coumarin-6-dye-loaded ursolic acid bearing liposomes), which probably followed the receptor-mediated endocytosis pathway through extracellular CD44 receptors, enhancing site-specific accumulation. HA-UA-Lips showed significantly improved pharmacokinetics over UA, with 2.6, 4.27, 4.75, and 2.85 fold increases in t_1/2 (P < 0.01), AUC_0-∞ (P < 0.0001), AUC_0-t (P < 0.0001), and MRT (P < 0.05), respectively, compared to UA. In conclusion, HA-UA-Lips are a novel vesicular drug delivery cargo that should be further tested in a validated preclinical model of VL under stringent in vitro and in vivo parameters for translational research.

Extrauterine growth restriction (EUGR) is a pervasive clinical issue in preterm infants, affecting neonatal development and their long-term health. This study aimed to characterize the gut microbiome and its derived genes in preterm neonates with EUGR using metagenomic sequencing. Sixty-two preterm infants hospitalized in the neonatal intensive care unit at Guangdong Women and Children Hospital were enrolled in this study. Participants were divided into two groups: the EUGR group (n = 34) and the normal growth group (AGA, n = 28). Fecal samples were collected at one month postnatally. Total bacterial DNA was extracted and sequenced using the Illumina HiSeq X Ten system. Significant differences in the gut microbial community between the EUGR and AGA groups were observed, as evidenced by the Bray-Curtis dissimilarity index. The EUGR group exhibited a notable increase in Klebsiella pneumoniae and Enterococcus faecalis, along with a significant decrease in Streptococcus raffinosi, Rothia mucilaginosa, Parabacteroides merdae and Eggerthella lenta compared to the AGA group. Functional annotation of metagenomic genes identified 415 genes with significantly different relative abundances between the groups. A classification model incorporating five discriminatory genes achieved effective separation of EUGR from AGA infants. Additionally, the EUGR group exhibited a higher relative abundance of antibiotic resistance genes. This study elucidates the alterations in the gut microbiome and its derived genes in preterm neonates with EUGR. These findings provide new insights into the potential microbial signatures associated with impaired growth, although further mechanistic studies are needed to clarify causal relationships.

Nosocomial infections, those acquired during receiving healthcare services, represent a significant public health challenge, particularly when caused by multidrug-resistant (MDR) bacteria. While natural products have been widely investigated for their antibacterial properties, many show limited efficacy against nosocomial pathogens and fail to adequately address the escalating problem of antimicrobial resistance. Moreover, research on the antibacterial effects of natural product combinations remains scarce. This study investigates the antibacterial activity of black cumin (Nigella sativa) essential oil (NSE) combined with clove (Syzygium aromaticum) essential oil (SAE) against key nosocomial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, Escherichia coli, and Bacillus sp. A descriptive, observational, and experimental approach was employed, incorporating FTIR spectroscopy, the checkerboard microdilution assays, and isobologram methods. Antibacterial interactions were also assessed using the fractional inhibitory concentration index (FICI), which quantifies the nature of the combined effect. The results revealed synergistic interactions between NSE and SAE against MRSA, A. baumannii, and Bacillus sp., highlighting their potential as a natural alternative in the management of nosocomial infections. While, NSE exhibited no inhibitory activity against E.coli. These findings underscore the value of essential oil combinations in enhancing antibacterial efficacy and offer a promising strategy to help curb the emergence of antibiotic resistance driven by overuse.