Junwan Lu

Background: Andrographolide (Andro) and fecal microbiota transplantation (FMT) are emerging treatments for colitis. However, whether their combined administration provides superior efficacy has not been established. Methods: This study attempted to clarify the reparative effects of FMT, Andro, and their combination on colitis in mice. Research subjects were allocated to: (1) the Control (CTRL) group, (2) the dextran sulfate sodium (DSS) group, (3) the FMT group, (4) the Andro group, and (5) the Andro combined with FMT group. The experiment lasted 15 days, during which weight, colon length, and hematochezia were monitored. Colon tissues were histologically analyzed via HE staining to assess inflammatory infiltration. The concentrations of key serum inflammatory factors were measured using ELISA. WB and IHC were employed to quantify inflammatory factor levels in intestinal tissues. Finally, the taxonomic composition of colonic microbiota was examined with 16S rRNA gene sequencing. Results: All three treatments mitigated colitis, as indicated by lowered pathological body weight wasting, colon shortening, hematochezia, and inflammation. Serum and intestinal cytokine levels were significantly decreased following treatment. Mechanistic analysis indicated that Andro attenuated inflammatory responses primarily through inhibition of NF-κB. Moreover, 16S rRNA sequencing revealed a beneficial modulation of the gut microbiota by all three treatments compared with the DSS group. Integrated analysis demonstrated that Andro combined with FMT therapy produced superior therapeutic outcomes relative to either intervention alone. Conclusion: The combined administration of Andro and FMT provides enhanced protection against DSS-induced colitis in mice, highlighting a potential synergistic therapeutic strategy.

Programmed cell death is essential for maintaining cellular homeostasis, and emerging forms such as necroptosis, pyroptosis, and ferroptosis (NPF) are associated with cancer progression. However, their exact roles remain poorly characterised. In this study, we investigated the role of NPF‐related genes in cancer prognosis by analysing gene expression and clinical data from the TCGA pan‐cancer dataset. A multigene prognostic model was developed to predict patient survival. Pathway enrichment and tumour microenvironment analyses revealed significant associations between NPF‐related genes and immune cell types, particularly highlighting the link between TLR4 expression and macrophage infiltration. Elevated TLR4 expression in tumour cells was correlated with an immunosuppressive environment, positioning TLR4 as a potential therapeutic target. Moreover, treatment with the TLR4 inhibitor TAK‐242 was shown to inhibit cell proliferation and migration in PANC‐1 and SW1990 cell lines. These findings underscore the potential of NPF‐related pathways as prognostic biomarkers and support TAK‐242 as a promising therapeutic candidate for cancer treatment.

The presence and emergence of multiple species/subspecies of ECC have led to diversity and complications at the taxonomic level, which impedes our further understanding of the epidemiology and clinical significance of species/subspecies of ECC. Accurate identification of ECC species is extremely important.

Summary: The clinical and environmental infections caused by AmpC β‐lactamases have been increasingly reported recently. In this study, we characterize the novel chromosome‐encoded AmpC β‐lactamase SFDC‐1 identified in Serratia fonticola strain R28, which was isolated from a rabbit raised on a farm in southern China. SFDC‐1 shared the highest amino acid identity of 79.6% with the functionally characterized AmpC β‐lactamase gene bla _YRC‐1 , although it had highly homologous functionally uncharacterized relatives in the same species from different sources, including some of the clinical significance. The cloned bla _SFDC‐1 exhibited resistance to a broad spectrum of β‐lactam antibiotics, including most cephalosporins with the highest resistance to ampicillin, cefazolin and ceftazidime, with increased MIC levels ≥128‐fold compared with the control strains. The purified SFDC‐1 showed catalytic activities against β‐lactams with the highest catalytic activity to cefazolin. The genetic context of bla _SFDC‐1 and its relatives was conserved in the chromosome, and no mobile genetic elements were found surrounding them.

Delftia tsuruhatensis has become an emerging pathogen in humans. There is scant information on the genomic characteristics of this microorganism. In this study, we determined the complete genome sequence of a clinical D. tsuruhatensis strain, TR1180, isolated from a sputum specimen of a female patient in China in 2019. Phylogenetic and average nucleotide identity analysis demonstrated that TR1180 is a member of D. tsuruhatensis. TR1180 exhibited resistance to β-lactam, aminoglycoside, tetracycline and sulphonamide antibiotics, but was susceptible to phenicols, fluoroquinolones and macrolides. Its genome is a single, circular chromosome measuring 6,711,018 bp in size. Whole-genome analysis identified 17 antibiotic resistance-related genes, which match the antimicrobial susceptibility profile of this strain, as well as 24 potential virulence factors and a number of metal resistance genes. Our data showed that Delftia possessed an open pan-genome and the genes in the core genome contributed to the pathogenicity and resistance of Delftia strains. Comparative genomics analysis of TR1180 with other publicly available genomes of Delftia showed diverse genomic features among these strains. D. tsuruhatensis TR1180 harbored a unique 38-kb genomic island flanked by a pair of 29-bp direct repeats with the insertion of a novel In4-like integron containing most of the specific antibiotic resistance genes within the genome. This study reports the findings of a fully sequenced genome from clinical D. tsuruhatensis, which provide researchers and clinicians with valuable insights into this uncommon species.

To characterize the molecular structure of IncR plasmid-related sequences, comparative genomic analysis was conducted using 261 IncR plasmid backbone-related sequences. Among the sequences, 257 were IncR plasmids including the multidrug-resistance IncR plasmid pR50-74 from Klebsiella pneumoniae strain R50 of this work, and the other four were from bacterial chromosomes. The IncR plasmids were derived from different bacterial genera or species, mainly Klebsiella pneumoniae (70.82, 182/257), Escherichia coli (11.28, 29/257), Enterobacter cloacae (7.00, 18/257), and Citrobacter freundii (3.50, 9/257). The bacterial chromosomes carrying IncR plasmid backbone sequences were derived from Proteus mirabilis AOUC-001 and Klebsiella pneumoniae KPN1344, among others. The IncR backbone sequence of P. mirabilis AOUC-001 chromosome shows the highest identity with that of pR50-74. Complex class 1 integrons carrying various copies of ISCR1-sdr-qnrB6-△qacE/sul1 (ISCR1-linked qnrB6 unit) were identified in IncR plasmids. In addition to two consecutive copies of qnrB6-qacE-sul1, the other resistance genes encoded on pR50-74 are all related to mobile genetic elements, such as IS1006, IS26, and the class 1 integron. This study provides a clear understanding of the mobility and plasticity of the IncR plasmid backbone sequence and emphasizes the important role of ISCR in the recruitment of multicopy resistance genes.

The diversity of class D β-lactamases mediating resistance to β-lactams has been increasingly reported recently. In this study, a novel class D oxacillinase named OXA-830 was identified in a fully sequenced Aeromonas simiae strain, which was isolated from sewage discharged from a farm in southern China. OXA-830 shares the highest amino acid identity of 79.3% with an OXA-12-like variant named OXA-725. When expressed in E. coli DH5α, OXA-830 conferred resistance to penicillins and selected β-lactamase inhibitors but not to cephalosporins and carbapenems. Kinetic analysis of OXA-830 revealed a broad substrate profile including penicillins, cefazolin, cefoxitin, and ceftazidime but not carbapenems. The hydrolytic activity was significantly inhibited by sulbactam, followed by tazobactam, but was less effectively inhibited by clavulanic acid. The bla_OXA–830 gene was located on the A. simiae A6 chromosome and the bla_OXA–830-related region was bracketed by a pair of perfect inverted repeats.

The genusCitrobacteris an opportunistic pathogen causing infections in animals, and the published data for its resistance to florfenicol are scarce. In this study, we investigated the antimicrobial susceptibility and molecular characteristics of florfenicol resistance genes amongCitrobacterisolates from animal and relevant environmental samples and conducted a comparative analysis of a multidrug-resistantCitrobacter freundiistrain isolated from a rabbit. Among 20Citrobacterstrains isolated from animal samples, resistance was most commonly observed to ampicillin (100%), tetracycline (75%), streptomycin (65%), florfenicol (60%), chloramphenicol (60%), and aztreonam (50%), while all the strains found in environmental samples were resistant to few antibiotics. The florfenicol resistance genefloRwas detected in 12 isolates (48%, 12/25) from animal samples, and all of thefloR-positive isolates were resistant to florfenicol with minimum inhibitory concentration (MIC) values ≥256 μg/mL. Sequencing and comparative analysis of the plasmids from a multidrug-resistantC. freundiiisolate named R47 showed that thefloR-containing region in the plasmid pR47-54 was a truncated transposon-like structure and could be found on both plasmids and chromosomes of bacteria of either animal or human origin. Furthermore, a range of antimicrobial and metal resistance genes associated with mobile genetic elements could be identified in pR47-54 and the other plasmid pR47-309 ofC. freundiiR47. These results provide in-depth views into the phenotypic and molecular characteristics ofCitrobacterisolates recovered from animal and relevant environmental samples, as well as highlight the role horizontal gene transfer plays in the dissemination of plasmid-encoded resistance genes.

Due to inappropriate use, florfenicol resistance is becoming increasingly serious among animal respiratory tract and gut bacteria. To detect the florfenicol resistance mechanism among Enterobacteriaceae bacteria, 292 isolates from animal feces were examined. The agar dilution method was conducted to determine the minimum inhibitory concentration (MIC) for florfenicol, and polymerase chain reaction (PCR) was performed to detect florfenicol resistance genes. To further explore the molecular mechanism of florfenicol resistance, the whole-genome Leclercia adecarboxylata R25 was sequenced. Of the strains tested, 61.6% (180/292) were resistant to florfenicol, 64.4% (188/292) were positive for floR, and 1.0% (3/292) for cfr. The whole-genome sequence analysis of L. adecarboxylata R25 revealed that the floR gene is carried by a transposon and located on a plasmid (pLA-64). Seven other resistance genes are also encoded on pLA-64, all of which were found to be related to mobile genetic elements. The sequences sharing the greatest similarities to pLA-64 are the plasmids p02085-tetA of Citrobacter freundii and p234 and p388, both from Enterobacter cloacae. The resistance gene-related mobile genetic elements also share homologous sequences from different species or genera of bacteria. These findings indicate that floR mainly contributes to the high rate of florfenicol resistance among Enterobacteriaceae. The resistance gene-related mobile genetic elements encoded by pLA-64 may be transferred among bacteria of different species or genera, resulting in resistance dissemination.

To investigate the mechanisms of multiple resistance and the horizontal transfer of resistance genes in animal pathogens, we characterized the molecular structures of the resistance gene-related sequences in a multidrug-resistant Klebsiella pneumoniae strain R46 isolated from a rabbit. Molecular cloning was performed to clone the resistance genes, and minimum inhibitory concentrations (MICs) were measured to determine the resistance characteristics of the cloned genes and related strains. A conjugation experiment was conducted to assess the transferability of the resistance plasmids. Sequencing and comparative genomic methods were used to analyze the structures of the resistance gene-related sequences. The K. pneumoniae R46 genome consisted of a chromosome and three resistance plasmids named pR46-27, pR46-42, and pR46-270, respectively. The whole genome encoded 34 antibiotic resistance genes including a newly identified chromosome-encoded florfenicol resistance gene named mdfA2. pR46-270, besides encoding 26 antibiotic resistance genes, carried four clusters of heavy metal resistance genes and several virulence-related genes or gene clusters. The plasmid-encoded resistance genes were mostly associated with mobile genetic elements. The plasmid with the most similarity to the floR gene-harboring plasmid pR46-27 was pCTXM-2271, a plasmid from Escherichia coli. The results of this work demonstrated that the plasmids with multidrug resistance genes were present in animal-derived bacteria and more florfenicol resistance genes such as mdfA2 could be present in bacterial populations. The resistance genes encoded on the plasmids may spread between the bacteria of different species or genera and cause the resistance dissemination.