OBJECTIVE: To develop and validate a predictive model for the risk of bloodstream infection (BSI) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). METHODS: A literature search was conducted in PubMed, Cochrane Library, and Embase databases from inception to July 2022 to identify studies reporting statistically significant risk factors for CRKP-BSI. Relative risks (RR) were extracted and pooled. Based on factor weights, a risk-scoring model was established. For external validation, hospitalized CRKP-infected patients from January 2016 to January 2022 at Shanghai First People's Hospital were included. Clinical data were used to calculate individual risk scores. The predictive accuracy was assessed using receiver operator characteristic curve (ROC curve). Patients were stratified into low-to-intermediate-risk and high-risk groups based on the optimal cut-off, and CRKP BSI incidence was compared between groups. RESULTS: The literatures related to the risk factors of CRKP-BSI published from database inception to July 2022 was retrieved and screened from PubMed, Cochrane Library, and Embase. Fourteen risk factors were included in the scoring model: cardiovascular disease, severe neutropenia or immunosuppression, intensive care unit (ICU) stay history, prior hospitalization, carbapenem exposure, aminoglycoside exposure, antifungal exposure, endotracheal intubation or tracheostomy, mechanical ventilation, hemodialysis, central venous catheter, indwelling urinary catheter, CRKP colonization, and Klebsiella pneumoniae positivity at non infection sites. The total score ranged from 0 to 173.5 points. In the validation cohort of 230 CRKP-infected patients, 41 developed CRKP BSI. The model yielded an area under the curve (AUC) of 0.783 (95%CI was 0.689-0.876). The optimal cut off was 81.25 points, with sensitivity of 75.6% and specificity of 81.0%. Based on this cut off, 163 patients were categorized as low-to-intermediate risk and 67 patients as high risk. The incidence of CRKP BSI in the high-risk group was significantly higher than in the low-to-intermediate-risk group [64.2% (43/67) vs. 4.9% (8/163); RR = 13.175 (95%CI was 5.920-29.319), P < 0.001]. CONCLUSIONS The model, based on 14 routinely available clinical parameters, demonstrated good performance in predicting CRKP BSI risk and may assist clinicians in early identification of high risk patients.
Humans ; Klebsiella pneumoniae/drug effects* ; Klebsiella Infections/microbiology* ; Carbapenems/pharmacology* ; Risk Factors ; Bacteremia/microbiology* ; ROC Curve ; Carbapenem-Resistant Enterobacteriaceae

Salmonellosis represents a global epidemic, and the emergence of extensively drug-resistant (XDR) Salmonella and its sustained transmission worldwide constitutes a significant public health concern. Flagellum-mediated motility serves as a crucial virulence trait of Salmonella that guides the pathogen toward the epithelial surface, enhancing gut colonization. Artemisia argyit essential oil, a traditional herb extract, demonstrates efficacy in treating inflammation-related symptoms and diseases; however, its effects on flagellum assembly and expression mechanisms in anti-Salmonella activity remain inadequately explored. This study aimed to elucidate the mechanism by which Artemisia argyit essential oil addresses Salmonella infections. Network pharmacological analysis revealed that Traditional Chinese Medicine (TCM) Artemisia argyit exhibited anti-Salmonella infection potential and inhibited flagellum-dependent motility. The application of Artemisia argyit essential oil induced notable motility defects through the downregulation of flagellar and fimbriae expression. Moreover, it significantly reduced Salmonella-infected cell damage by interfering with flagellum-mediated Salmonella colonization. In vivo studies demonstrated that Artemisia argyit essential oil administration effectively alleviated Salmonella infection symptoms by reducing bacterial loads, inhibiting interleukin-1 beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α) production, and diminishing pathological injury. Gas chromatography-mass spectrometry (GC-MS) analysis identified forty-three compounds in Artemisia argyit essential oil, with their corresponding targets and active ingredients predicted. Investigation of an in vivo model of Salmonella infection using the active ingredient demonstrated that alpha-cedrene ameliorated Salmonella infection. These findings suggest the potential application of Artemisia argyit essential oil in controlling Salmonella, the predominant food-borne pathogen.
Artemisia/chemistry* ; Oils, Volatile/chemistry* ; Animals ; Flagella/drug effects* ; Salmonella Infections/microbiology* ; Humans ; Mice ; Anti-Bacterial Agents/pharmacology* ; Salmonella/pathogenicity*

OBJECTIVE: Pseudomonas aeruginosa( P. aeruginosa) is a prevalent pathogenic bacterium involved in meningitis; however, the virulence factors contributing to this disease remain poorly understood. METHODS: The virulence of the P. aeruginosa A584, isolated from meningitis samples, was evaluated by constructing in vitro blood-brain barrier and in vivo systemic infection models. qPCR, whole-genome sequencing, and drug efflux assays of A584 were performed to analyze the virulence factors. RESULTS: Genomic sequencing showed that A584 formed a phylogenetic cluster with the reference strains NY7610, DDRC3, Pa58, and Pa124. Its genome includes abundant virulence factors, such as hemolysin, the Type IV secretion system, and pyoverdine. A584 is a multidrug-resistant strain, and its wide-spectrum resistance is associated with enhanced drug efflux. Moreover, this strain caused significantly more severe damage to the blood-brain barrier than the standard strain, PAO1. qPCR assays further revealed the downregulation of the blood-brain barrier-associated proteins Claudin-5 and Occludin by A584. During systemic infection, A584 exhibited a higher capacity of brain colonization than PAO1 (37.1 × 10 ⁶ CFU/g brain versus 2.5 × 10 ⁶ CFU/g brain), leading to higher levels of the pro-inflammatory factors IL-1β and TNF-α. CONCLUSION This study sheds light on the virulence factors of P. aeruginosa involved in meningitis.
Pseudomonas aeruginosa/genetics* ; Virulence Factors/metabolism* ; Animals ; Virulence ; Mice ; Pseudomonas Infections/microbiology* ; Blood-Brain Barrier/microbiology* ; Humans ; Female

OBJECTIVES: This study aimed to observe the effects of initial periodontal therapy on the level of neutrophil extracellular traps (NETs) in gingival crevicular fluid (GCF) of patients with severe periodontitis and to analyze the factors related to the formation of NETs. METHODS: Thirty-one patients with stage Ⅲ-Ⅳ periodontitis were recruited. Clinical periodontal parameters, including plaque index (PLI), gingival index (GI), probing depth (PD), and clinical atta-chment loss (CAL), were recorded before and 6-8 weeks after initial periodontal therapy. Levels of NETs in GCF were detected by immunofluorescence staining. Quantities of total bacteria, Porphyromonas gingivalis (P. gingivalis), Aggregatibacter actinomycetemcomitans (A. actionomycetemcomitans) and Prevotella intermedia (P. intermedia)in unattached subgingival plaque were determined by real-time quantitative PCR, and levels of tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) in GCF were explored by enzyme-linked immunosorbent assay. In addition, the correlations between the level of NETs and the above indicators were analyzed. RESULTS: After initial periodontal therapy, the level of NETs in GCF, PLI, GI, PD, and CAL; quantities of total bacteria, P. gingivalis, A. actinomycetemcomitans, and P. itermedia; and levels of IL-8 and TNF-α significantly decreased (P<0.05). We observed strong positive correlations between the level of NETs and PLI, GI, PD, CAL, the amount of total bacteria, P. gingivalis, TNF-α, and IL-8 (P<0.05). CONCLUSIONS Initial periodontal therapy might decrease the level of NETs in GCF from patients with severe periodontitis, which might be positively correlated with the quantities of P. gingivalis andthe levels of TNF-α and IL-8 in GCF.
Humans ; Gingival Crevicular Fluid ; Extracellular Traps/metabolism* ; Porphyromonas gingivalis/isolation & purification* ; Aggregatibacter actinomycetemcomitans/isolation & purification* ; Periodontitis/metabolism* ; Tumor Necrosis Factor-alpha/analysis* ; Prevotella intermedia/isolation & purification* ; Interleukin-8/analysis* ; Male ; Female ; Middle Aged ; Periodontal Index ; Adult

2-substituted quinolines are the building blocks for the synthesis of natural products and pharmaceuticals. In comparison with classical methods, dehydroaromatization of 2-substituted-1,2,3,4-tetrahydroquinolines has emerged in recent years as an efficient and straightforward method to synthesize quinolines due to its high atom economy and sustainability. However, existing chemical methods need transition metal catalysts and harsh reaction conditions. Biocatalysis with high efficiency, high selectivity, and mild reaction conditions has become an important method of organic synthesis. We mined a strain Pseudomonas monteilii ZMU-T06 capable of producing monoamine oxidase for the dehydroaromatization of 2-substituted-1,2,3,4-tetrahydroquinolines to synthesize 2-substituted quinolines (8 substrates, yields of 45.7%-48.4%) and then hypothesized the catalytic mechanism, providing a new method for green synthesis of 2-substituted quinolines.
Quinolines/chemistry* ; Pseudomonas/classification* ; Oxidation-Reduction ; Monoamine Oxidase/biosynthesis* ; Biocatalysis

Acinetobacter baumannii is a Gram-negative opportunistic pathogen widely distributed in hospital settings. It can survive for a long time and cause a variety of infections, including pneumonia, septicemia, urinary tract infections, and meningitis. The bacterium demonstrates extensive resistance, particularly to critical antibiotics like carbapenems and polymyxins, posing a serious threat to the recovery of severely ill patients. Carbapenem-resistant A. baumannii has been designated as a pathogen of critical priority on the World Health Organization (WHO) Bacterial Pathogen Priority List, requiring urgent development of new therapeutic agents. Phages, as a novel biological control approach, exhibit substantial potential in combating A. baumannii infections due to their specific ability to infect and lyse bacteria. This review highlights the application and potential of phages and phage-derived enzymes against multidrug-resistant A. baumannii, considering the epidemiological trends of A. baumannii in China, with the aim of providing innovative insights and strategies for phage therapy of drug-resistant bacterial infections.
Acinetobacter baumannii/drug effects* ; Drug Resistance, Multiple, Bacterial ; Phage Therapy/methods* ; Acinetobacter Infections/microbiology* ; Humans ; Bacteriophages/physiology* ; Anti-Bacterial Agents/pharmacology*

Chlorobenzene contaminants (CBs) pose a threat to the eco-environment, and functional strains hold considerable potential for the remediation of CB-contaminated sites. To deeply explore the application potential of functional bacteria in the in-situ bioremediation of CBs, this study focused on the biodegradation characteristics and degradation kinetics of CB and 1, 2-dichlorobenzene (1, 2-DCB) in soil by the isolated strain Serratia marcescens TF-1. Additionally, an in-situ remediation trial was conducted with this strain at a chemical industrial site. Batch serum bottle experiments showed that the degradation rate of CB at the concentrations ranging from 20 to 200 mg/L by TF-1 was 0.22-0.66 mol/(g_cell·h), following the Haldane model, with the optimal concentration at 23.12 mg/L. The results from simulated soil degradation experiments indicated that the combined use of TF-1 and sodium succinate (SS) significantly enhanced the degradation of CBs, with the maximum degradation rate of CB reaching 0.104 d^-1 and a half-life of 6.66 d. For 1, 2-DCB, the maximum degradation rate constant was 0.068 7 d^-1, with a half-life of 10.087 d. The in-situ remediation results at the chemically contaminated site demonstrated that the introduction of bacterial inoculant and SS significantly improved the removal of CBs, achieving the removal rates of 84.2%-100% after 10 d. CB, 1, 4-dichlorobenzene (1, 4-DCB), and benzo[a]pyrene were completely removed. Microbial diversity analysis revealed that the in-situ remediation facilitated the colonization of TF-1 and the enrichment of indigenous nitrogen-fixing Azoarcus, which may have played a key role in the degradation process. This study provides a theoretical basis and practical experience for the in situ bioremediation of CBs-contaminated sites.
Chlorobenzenes/isolation & purification* ; Biodegradation, Environmental ; Soil Pollutants/isolation & purification* ; Serratia marcescens/metabolism* ; Industrial Waste ; Soil Microbiology

Shewanella oneidensis MR-1, a Gram-negative bacterium with a significant role in the adsorption and reduction of uranium in wastewater and a quorum-sensing effect, can be used to remove uranium from wastewater. Exogenous signaling molecules (acyl-homoserine lactones, AHLs) can be added to induce the quorum sensing behavior for rapid biofilm formation, thereby improving the removal efficiency of this bacterium for uranium. Extracellular polymeric substances (EPS), as the significant components of biofilm, play a key role in biofilm formation. To investigate the quorum sensing behavior induced by AHLs, we systematically investigated the effects of AHLs on the EPS secretion and biofilm properties of S. oneidensis MR-1 by regulating parameters such as AHL species, concentration, addition time point, and contact time. The results showed that the addition of 10 μmol/L N-butyryl-l-homoserine lactone (C4-HSL) after 6 h of culture and continued incubation to reach the time point of 72 h significantly promoted the secretion of EPSs, in which the content of extracellular proteins and extracellular polysaccharides was increased by 15.2% and 28.2%, respectively, compared with that of the control group. The biofilm electrodes induced by signaling molecules showed superior properties, which were evidenced by an increase of exceeding 20 μm in biofilm thickness, an increase of 33.9% in the proportion of living cells, enhanced electroactivity, and an increase of 10.7% in the uranium removal rate. The biofilm electrode was confirmed to immobilize uranium in wastewater mainly by electrosorption, physicochemical adsorption, and electro-reduction through characterization means such as X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). This study provides a new technical idea for the efficient recovery of uranium in wastewater and enriches the theoretical system of quorum sensing regulation of electroactive biofilms.
Biofilms/drug effects* ; Acyl-Butyrolactones/pharmacology* ; Quorum Sensing/drug effects* ; Uranium/metabolism* ; Shewanella/metabolism* ; Adsorption ; Uranium Compounds/metabolism* ; Wastewater/chemistry* ; Biodegradation, Environmental ; Extracellular Polymeric Substance Matrix/metabolism*

Hydroxyectoine, a vital compatible solute, is widely utilized in cosmetics, food, pharmaceutical industries, and biologics. However, the current microbial fermentation methods for hydroxyectoine production face challenges including insufficient precursor supply and low yields. Therefore, developing engineering microbial strains capable of efficiently synthesizing hydroxyectoine is of great significance. In this study, we first constructed a high-yield ectoine-producing strain ECT04 by multi-copy integration of the ectoine synthesis genes ectABC into the pseudogene loci of Escherichia coli MG1655(DE3), achieving an ectoine titer of 6.03 g/L. Subsequently, we employed plasmids with varying copy numbers to express ectD from Chromohalobacter salexigens to enable the conversion for hydroxyectoine production. We further investigated the effects of promoter, co-substrate ɑ-ketoglutarate, Fe²⁺ concentration, and dissolved oxygen on hydroxyectoine synthesis. Through fed-batch fermentation in a 7-L bioreactor, we significantly enhanced the hydroxyectoine production efficiency, attaining a final titer of 8.58 g/L and a productivity of 0.24 g/(L·h). This work successfully achieved the de novo synthesis of hydroxyectoine in E. coli, laying a foundation for the efficient bioproduction of this compound.
Escherichia coli/genetics* ; Fermentation ; Amino Acids, Diamino/biosynthesis* ; Bioreactors/microbiology* ; Metabolic Engineering/methods* ; Chromohalobacter/genetics* ; Plasmids/genetics*

To develop biocontrol agents for the control of kiwifruit bacterial canker, we isolated a strain CXG2-5 with inhibitory activity against Pseudomonas syringae pv. actinidiae (Psa), the pathogen of kiwifruit bacterial canker, from the rhizosphere soil of kiwifruit by the plate confrontation test. The strain was identified by morphological observation, physiological and biochemical tests, and molecular biological methods. The indoor control efficacy of the strain was determined by the inoculation of the strain into detached branches with wounds and into leaf discs by vacuum infiltration. The ability of the strain to expand and colonize leaf veins was determined by fluorescent labeling and scanning electron microscopy. Subsequently, the strain was prepared into microcapsules, the field control efficacy of which was evaluated. The strain CXG2-5 was identified as Pseudomonas benzenivorans. It demonstrated good antagonistic activity against Psa, with an inhibition zone diameter of 22 mm and an inhibition rate of 72.7%. The preventive effects of the strain on kiwifruit bacterial canker were better than the therapeutic effects on both detached branches and leaves, with the preventive effects reaching 65% and 92.4%, respectively. The control effect of microcapsules of this strain in the field reached 60.89%, which was slightly lower than that of 20% kasugamycin and higher than that of Bacillus subtilis wettable powder. In conclusion, strain CXG2-5 serves as a candidate for the control of kiwifruit bacterial canker, and the prepared microcapsules have good value for development and application.
Actinidia/microbiology* ; Plant Diseases/prevention & control* ; Pseudomonas syringae ; Pseudomonas/isolation & purification* ; Capsules ; Antibiosis ; Biological Control Agents ; Pest Control, Biological/methods*