Background:Antibiotics, as a selection stress, could trigger specific responses in bacterial pathogens. This study aimed to investigate adaptive changes of E. coli SM10λpir (pUCP24T) under constant treatment of sub-MIC Gm (gentamicin). Methods:E. coli SM10λpir (pUCP24T) underwent continuous passage culture by serial transfer for 50 days on agar plates containing 30 μg/mL Gm to obtain E. coli SM10λpir (pUCP24T)-E. Two strains were compared for the horizontal gene transfer ability, stability of plasmid pUCP24T, fitness cost, and expression of conjugation-related genes. Based on whole genome and RNA sequencing data, functional enrichment analysis (GO and KEGG) was conducted, along with analyses of plasmid sequencing depth, SNPs, and differentially expressed genes (DEGs). Results:The conjugation frequency of E. coli SM10λpir (pUCP24T)-E with recipient PAO1 was higher, and its traI expression was significantly upregulated (p < 0.05). In the same strain, the growth rate and competition index were lower (p < 0.05); the sequencing depth of plasmid pUCP24T and the relative expression of the rep gene were much higher (p < 0.05), but the plasmid showed reduced stability. Functional enrichment analysis suggested a possible enhancement of certain physiological processes and metabolic pathways. A total of 1294 DEGs were detected, with obvious upregulation of hycB, hycD, nikE, cspA, and nanA, and obvious downregulation of gadB, gadC, yeiQ, and yjiH, transcription factors (appY, gadE), and sRNAs (arrS, isrC). Additionally, the expression of aerobic respiratory pathway genes (cyoABCDE) in E. coli SM10λpir (pUCP24T)-E increased significantly (p < 0.05). Conclusions:The enhanced conjugation frequency during adaptation may be attributed to increased expression of the transfer gene traI and an elevated copy number of plasmid pUCP24T. A heavier fitness cost was imposed on the host during this process. Aerobic respiration and metabolic efficiency were likely potentiated. sRNA isrC was hypothesized to inhibit aerobic respiration by targeting the cytochrome bo oxidase subunit cyoD.

ABSTRACT The global spread of plasmid-mediated colistin resistance gene mcr-1 poses a significant threat to public health. Although international travel is a known driver of antimicrobial resistance, the role of domestic travel in high-prevalence settings remains unclear. We conducted a prospective cohort study of 81 healthy volunteers traveling in China (June–September 2022). Fecal samples collected before and after travel were screened for mcr-1 -positive Escherichia coli (MCRPEC). Antimicrobial resistance genes (ARGs), virulence factors (VFs), plasmid replicons, and gut microbial dynamics were investigated using whole-genome sequencing and 16S rRNA sequencing. Risk factors were analyzed using logistic regression analysis. Of the 81 participants who were negative for mcr-1 at baseline, 12 (14.8%) acquired mcr-1 after travel. Acquisition was associated with residence near poultry farms (odds ratio [OR] = 5.9, P = 0.04) and diarrhea during travel (OR = 11.22, P = 0.027). MCRPEC exhibited marked genetic diversity comprising 10 sequence types and the carriage of additional 23 ARGs and nine adherence-associated VFs. mcr-1 was located on IncI2, IncX4, IncHI2, or IncP plasmids, with 91.7% ( n = 11) transferable in conjugation assays. Gut microbiome analysis showed increased α -diversity, but a stable community structure, indicating colonization without major disruption. Our study demonstrated that domestic travel in China substantially contributes to the dissemination of mcr-1 . Poultry exposure and gastrointestinal disturbances are key risk factors. Genetic diversity, plasmid transferability, and co-carriage of resistance and virulence determinants highlight the risk of onward spread. Antimicrobial resistance surveillance should extend beyond international travel and incorporate domestic mobility within a “One Health” framework.

Introduction. The increasing resistance and the pathogen's complex multi-drug resistance mechanisms made the selection of effective antimicrobial treatments more challenging for Pseudomonas aeruginosa (P. aeruginosa). The study aimed to explore the effect of Scutellaria baicalensis, Prunella vulgaris and antimicrobial peptide LL-37 on the virulence factors of P. aeruginosa.Hypothesis. Previous studies have shown that extracts from traditional Chinese medicines, Scutellaria baicalensis and Prunella vulgaris, can also enhance the effects of antibiotics and reduce antibiotic resistance in P. aeruginosa. Antimicrobial peptide LL-37 shows the potential as a new-generation candidate for treating multi-drug-resistant bacteria, which has advantages over traditional antibiotics, whilst the combination role between Scutellaria baicalensis, Prunella vulgaris and LL-37 in P. aeruginosa remains unknown.Aim. We explored whether the combined use of Scutellaria baicalensis, Prunella vulgaris and LL-37 can exert antibacterial effects through the quorum sensing (QS) system.Methodology. The minimal inhibitory concentrations of Scutellaria baicalensis, Prunella vulgaris and LL-37 were determined for PAO1 and PA-ΔlasI/rhlI using micro broth dilution. The antibacterial activity of Scutellaria baicalensis combined with LL-37 and Prunella vulgaris combined with LL-37 was also assessed. The growth abilities of PAO1 were analysed after being treated with Scutellaria baicalensis, Prunella vulgaris and LL-37, respectively. Elastase secretion was measured using Congo red-elastic proteinase assays. And the expressions of QS genes (lasI, rhlR) were analysed by real-time PCR.Results. Single or combined treatments of Scutellaria baicalensis and LL-37 and Prunella vulgaris and LL-37 would significantly reduce elastase secretion. There were no significant differences in proliferation between the groups at any timepoint. All treatments downregulated lasI and rhlR gene expressions.Conclusion. Scutellaria baicalensis, Prunella vulgaris and antimicrobial peptide LL-37 all down-regulate the QS system-related genes of P. aeruginosa, inhibiting the secretion of virulence factors and reducing bacterial toxicity.

Rapid and accurate detection of antibiotic heteroresistance (HR) causing clinical bacterial infections is essential for prompt and effective treatment. However, current detection methods vary across laboratories. This study aimed to evaluate a Simplified Agar-based Population Analysis Profiling (SA-PAP) method as a practical alternative to the reference Population Analysis Profiling (PAP) for HR detection, and to describe the screening performance of a modified E-test. We collected 56 carbapenem-resistant Escherichia coli (CREC) and 305 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates. HR to tigecycline (in CREC), vancomycin, and teicoplanin (in MRSA) was assessed using the modified E-test, SA-PAP, and PAP (reference method). The screening performance of the modified E-test was evaluated descriptively, while the diagnostic agreement of SA-PAP with PAP was assessed using Cohen’s kappa. By PAP, HR prevalence was 37.5

ObjectiveCarbapenem-resistant Klebsiella pneumoniae (CRKP) has become a worldwide public health concern due to its high morbidity and mortality rate. A retrospective study was conducted to explore the molecular epidemiology of antimicrobial resistance and virulence of CRKP in South China.Methods108 CRKP isolates were collected from multiple hospitals in South China. The characteristics of the CRKP strains, including antimicrobial resistance genes, mutations and virulence factors, were analyzed using whole-genome sequencing and the software Kleborate. A phylogenetic tree was constructed to illustrate evolutionary diversification.ResultsThe main Sequence Type (ST) type, capsular serotype, and LPS serotype among CRKP isolates in South China were ST11, KL47, and OL101, respectively. KPC-2 was the most prevalent carbapenemase type. Notably, KPC-12, a recently identified and rarely reported variant of KPC-2, was discovered in four CRKP strains. All ST11 CRKP isolates harbored porin and efflux pump regulator mutations of AcrR-43%, OmpK35-17%, and OmpK36GD as well as fluoroquinolone mutations of GyrA-83I, GyrA-87G, and ParC-80I. All CRKP strains exhibited complex multi-drug resistance (MDR) phenotypes. The most common types of aerobactin (iuc) and yersiniabactin (ybt) were iuc1 and ybt9 ICEKp3, respectively. There were 17 hvCRKP (hypervirulent carbapenem-resistant Klebsiella pneumoniae) strains found in our study, which were mainly ST11-KL64 and ST413-1LV-KL112, harboring the blaKPC-2 gene and blaNDM-1 gene, respectively.ConclusionIn South China, highly virulent and MDR CRKP strains show a trend toward epidemic, underscoring the urgent need for ongoing genomic surveillance and stringent infection control measures. KPC-2 variant KPC-12 and ST413-1LV-KL112 hvCRKP, a novel type of hvCRKP carrying blaNDM-1, require particular attention and further investigation.

Atopic dermatitis (AD) is a multifactorial, chronic relapsing disease. Staphylococcus aureus is the key microbial factor in AD, linked to disease activity. However, there is limited knowledge of genomic prevalence characteristics and phenotypic features of S. aureus in AD patients in China. We investigated 108 S. aureus of AD in China and globally publicly available genome sequences of 579 S. aureus of AD. Sequence type (ST) 7, ST15 and ST188 were the major lineages in China. Genes esaC, esxB, and sea were only detected in ST7, potentially contributing to its prevalence in AD. ST188 exhibited high virulence and adhesion, possibly due to the cna gene. Phylogenetic and population structure analysis revealed that 579 strains of global AD were classified into 15 sequence clusters (SCs), with SC5, SC2, and SC7 dominating. S. aureus of Chinese AD patients was mainly distributed in SC2, SC7, and SC12. Comparative genomic highlighted genes linked to AD, including enterotoxins (seh, selk, selq, entH), adhesion genes (fnbA, fnbB, sdrD, map, fib, narH). From China and global perspectives, we analyzed S. aureus’s genomic epidemic traits, phylogeny, and population structure in AD skin. These findings contribute to understanding S. aureus-host interactions and genomic diversity in AD.

Pseudomonas aeruginosa is a major opportunistic pathogen that causes chronic infections, particularly in patients with cystic fibrosis and chronic obstructive pulmonary disease (COPD). The type VI secretion system (T6SS) is a primary virulence factor of P. aeruginosa in chronic infections. The objective of this study was to elucidate the regulatory mechanisms and pathogenic effects of the T6SS during P. aeruginosa infection, utilizing transcriptome sequencing and functional assays. We found that T6SS expression is elevated in P. aeruginosa isolated from chronically infected patients. Deletion of the retS gene activates P. aeruginosa PAO1 T6SS while repressing T3SS in vitro. Bacterial and cellular transcriptome sequencing analyses showed that T6SS genes were upregulated, while T3SS genes were downregulated in the ΔretS mutant. Additionally, the expression levels of the fimbriae gene cupC, the histidine phosphotransfer protein hptC (PA0033), and the transcription factor PA0034 were significantly increased. Subsequent experiments revealed that adhesion mediated by cupC enhances the contact-killing activity of the T6SS. Deletion of the hptC-PA0034 operon results in the down-regulation of cupC expression. The ΔretSΔcupC and ΔretSΔhptC-PA0034 mutants exhibited reduced cytotoxicity compared to the ΔretS mutant, similar to the ΔretSΔclpV1ΔclpV2 mutant. The ΔretS infection increased cell death, inflammatory factors (IL-1β, IL-6, TNF-α), and reactive oxygen species compared to a T6SS-inactive strain. Importantly, our study demonstrates that the T6SS activates the PDE4C pathway in epithelial cells, leading to significant cellular alterations. The application of PDE inhibitors effectively mitigates cell damage and inflammatory responses. These findings highlight the critical role of T6SS in modulating host cell signaling and suggest potential therapeutic strategies for conditions associated with T6SS-mediated inflammation.

Hypervirulent Klebsiella pneumoniae (hvKP) primarily colonizes the mammalian gastrointestinal tract, and it is prone to causing invasive infections under specific conditions. To establish infection, hvKP must compete with the resident gut microbiota for essential nutrients. This study focuses on the C4-dicarboxylate (C4-DC) succinate, which has been reported to accumulate in the gut under specific pathological conditions. We demonstrate that hvKP utilizes succinate as a signaling molecule to enhance virulence gene expression. Specifically, extracellular succinate activates type VI secretion system gene expression via the DcuSR two-component system (TCS), thereby increasing cytotoxicity toward intestinal epithelial cells and enhancing competitiveness against commensal Escherichia coli. Additionally, succinate facilitates the expression of type III fimbriae via the DcuSR TCS, promoting hvKP adherence to intestinal epithelial cells. Beyond its signaling role, succinate functions as a metabolic substrate and contributes to adenosine 5'-triphosphate (ATP) synthesis, potentially through C4-dicarboxylic acid transporters DctA or DcuB to boost energy synthesis. This study focuses on elucidating the impact of succinate in regulating hvKP virulence, with particular attention to the potential role of the DcuSR TCS in hvKP pathogenesis. IMPORTANCE:Succinate, a C4-DC, is produced by the host and the gut microbiota and can accumulate in the intestinal environment under various pathological conditions, such as diabetes and inflammatory bowel disease. It acts as a pivotal regulator of virulence traits and metabolic pathways in Enterobacteriaceae. Our findings highlight the significant impact of succinate on hvKP pathogenesis: (i) functioning through the DcuSR TCS to activate virulence programs and (ii) serving as a metabolic substrate that fuels bioenergetic adaptation through ATP synthesis.

Background:Porphyromonas gingivalis is a predominant pathogen in periodontitis and is closely associated with the progression of chronic obstructive pulmonary disease (COPD). Objective:This case report aims to describe a case of sepsis caused by P. gingivalis in a patient with COPD and a history of dental pain, highlighting the diagnostic challenges and clinical implications. Design:This single case report was based on clinical data collected from medical records, with the pathogen identified from blood cultures by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). A comparative analysis was performed between the present case and previously reported cases of P. gingivalis bacteremia or sepsis based on a literature review. The patient was discharged after his general condition improved as a result of the potentially effective antimicrobial agents and anti-infective treatments through literature review. Results:A 73-year-old man with COPD and a prolonged history of dental pain presented with a 30-year history of recurrent cough, expectoration, and dyspnoea, with symptoms exacerbating over the past 3 d and the recent onset of high fever for 1 d. Clinical evaluation revealed sepsis with rapid progression to septic shock. Blood cultures confirmed the presence of P. gingivalis. Conclusions:This case highlights the need to consider anaerobes like P. gingivalis in septic patients with poor oral health, especially for patients with dental pain or periodontitis, and highlights the diagnostic challenges associated with slow-growing pathogens.

BackgroundLong noncoding RNAs (lncRNAs) HIF1A-AS2 is upregulated in multiple human cancers and are associated with various aspects of tumor progression. However, the molecular mechanisms of HIF1A-AS2 in cervical cancer (CC) remain largely unknown. In this study, we aim to investigate the expression pattern and signaling pathways of HIF1A-AS2 in CC.MethodsThe study included a group of 20 CC patients, from whom tumor tissue specimens were collected. Additionally, three distinct CC cell lines (HeLa, SiHa, CaSki) were utilized. Quantitative real-time PCR (qRT-PCR) was used to assess the transcript levels of HIF1A-AS2 in these samples. Functional studies were performed by CCK-8, Transwell and Apoptosis assays. Databases including JASPAR, miRDB and Targetscan were used for the transcription factor or target miRNA prediction, subsequent dual luciferase activity assay, chromatin immunoprecipitation (ChIP) and Ago2 immunoprecipitation (RIP) were also adopted for validation.ResultsThe study demonstrated that HIF1A-AS2 expression was elevated in clinical cervical cancer specimens and cultured cell lines in comparison to normal controls. Knockdown of HIF1A-AS2 notably inhibited the proliferation and invasion of cervical cancer cells, while inducing apoptosis. In contrast, HIF1A-AS2 overexpression promoted cellular proliferation and invasion and suppressed apoptosis. It was also identified that c-Jun functions as a transcription factor, activating HIF1A-AS2 expression. Additionally, HIF1A-AS2 was found to serve as a molecular sponge for miR-34b-5p, negatively regulating its expression. Furthermore, HIF1A-AS2 controlled the expression of radixin (RDX) by sponging the miR-34b-5p pathway.ConclusionOur findings indicate that c-Jun-activated HIF1A-AS2 acts as an oncogenic factor in CC by sponging miR-34b-5p to target radixin. These findings suggest that HIF1A-AS2 might be a viable and promising therapeutic target for cervical cancer treatment.

Clonorchiasis, a foodborne parasitic disease caused by Clonorchis sinensis (C. sinensis), is prevalent in certain regions of Asia and can result in severe hepatobiliary complications, including cholangiocarcinoma, peribiliary fibrosis, and hepatic fibrosis. In certain regions of China, the concurrent consumption of raw freshwater fish and alcohol, which are components of the local dietary culture, has contributed to the high prevalence of this disease. Infected individuals often endure the dual burden of clonorchiasis and alcoholic liver disease (ALD). While both C. sinensis infection and alcohol abuse can disrupt the gut microbiota, the synergistic mechanisms of these two factors in patients with alcoholic cirrhosis (ALC) remain poorly understood. This study aims to elucidate the impact of C. sinensis infection on the gut microbiota of patients with ALC, with the objective of identifying potential diagnostic or therapeutic targets. A total of 64 patients diagnosed with ALC were recruited for this study, with half of the participants infected with C. sinensis and the other half remaining uninfected. Fresh fecal samples were collected from all participants. Alterations in the gut microbiota were analyzed using high-throughput sequencing of the 16S ribosomal RNA gene derived from the fecal samples. Our results showed that analysis of β-diversity revealed significant differences in gut microbial communities between C. sinensis-infected and non-infected groups (P < 0.05). The Linear discriminant analysis effect size (LEfSe) identified the phylum Firmicutes (highest LDA score at the phylum level) and the genus Prevotella (dominant at the genus level) as key taxa driving gut microbial composition differences in patients with ALC and C. sinensis infection (P < 0.05). Correlation analysis at the genus level demonstrated significant negative associations between Enterococcus and multiple bacterial genera in the C. sinensis-infected group. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis further highlighted divergent metabolic pathways between groups, with the vancomycin resistance pathway showing the most pronounced disparity. In conclusion, patients with ALC and C. sinensis infection show alterations in gut microbiota compared to non-infected counterparts. Notably, specific bacteria such as Prevotella and Enterococcus may represent potential targets for the development of novel diagnostic and therapeutic strategies for ALC patients afflicted by C. sinensis infection.

BACKGROUND:The emerging ST80 vancomycin-resistant Enterococcus faecium (VREfm) lineage, linked to the increases of clinical infections in China and Japan, raises concerns about environmental transmission. Hospital wastewater systems are recognized reservoirs for antimicrobial-resistant bacteria, but their role in disseminating ST80 VREfm remains unclear. This study investigates VREfm prevalence in hospital wastewater and genomic links between patients and hospital wastewater. METHODS:From December 2023 to May 2024, a total of 262 wastewater samples were collected from three hospitals in Guangzhou, China. VREfm was identified using vancomycin-supplemented media. Antimicrobial susceptibility was assessed using the broth dilution method. Ninety-five patient-derived VREfm genomes in the same hospitals were included. Whole-genome sequencing and bioinformatic analysis were performed to reveal genomic characterizations and genetic transmission links. RESULTS:VREfm was detected in 54.6 % (143/262) of samples. All isolates carried vanA, with 25.9 % (37/143) co-harboring vanA and vanM. The dominant ST80 lineage (43.4 %, n = 62) was linked to recent regional prevalence. A novel sequence type ST2460, belonging to CC17, emerged as the second most prevalent (27.2 %, n = 39). ST80 isolates exhibited enriched antimicrobial resistance genes, correlating with multidrug resistance phenotypes and high resistance rates. Genomic analysis revealed that 95.7 % (132/138) of ST80 isolates from wastewater and patients exhibited close genetic relatedness (median of SNP = 19, IQR: 14-23) and were linked within cross-source transmission networks, supported by the high similarity of a shared p23VRE019-like plasmid. CONCLUSIONS:Hospital wastewater is a critical reservoir for high-risk VREfm clones, particularly the outbreak-associated ST80 lineage. The persistence of VREfm in effluents and evidence of cross-source transmission underscores the urgent need for enhanced environmental surveillance. Integrated strategies addressing environmental reservoirs are essential to combat the growing threat of VREfm.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a significant public health challenge. This study evaluated the Pluslife SARS-CoV-2 assay employing proprietary RNase Hybridization-Assisted amplification (RHAM) isothermal amplification technology, with comparative performance assessment against the EasyNAT Rapid SARS-CoV-2 assay and the Wondfo 2019-nCoV antigen assay. Analytical testing determined the Pluslife assay’s limit of detection to be 400 copies/mL, with no cross-reactivity against common respiratory viruses and no interference from tested substances. Using RT-qPCR as the reference standard on 197 nasopharyngeal swabs, the Pluslife assay showed a positive percentage agreement (PPA) of 96.30% and a negative percentage agreement (NPA) of 99.30% (κ = 0.962, P < 0.001). The EasyNAT assay demonstrated a PPA of 96.30% and NPA of 98.60% (κ = 0.949, P < 0.001). The Wondfo antigen assay showed a PPA of 81.48% and NPA of 100% (κ = 0.865, P < 0.001). The Pluslife assay demonstrates comparable diagnostic accuracy to EasyNAT for SARS-CoV-2 detection, while offering advantages in portability, speed, and cost. Its performance significantly exceeded that of the Wondfo antigen assay, particularly in reducing false negatives. The Pluslife Mini Dock platform shows potential for rapid SARS-CoV-2 screening in diverse settings.IMPORTANCEThe newly developed Pluslife Rapid severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay is a next-generation molecular point-of-care testing (POCT) method, based on RNase Hybridization-Assisted amplification (RHAM), a self-developed isothermal amplification molecular detection technology of Pluslife Biotech. The purpose of this study is to evaluate the analytical and clinical performance of this new SARS-CoV-2 POCT method and compare the clinical performance with the EasyNAT Rapid SARS-CoV-2 assay and the Wondfo 2019-nCoV antigen assay. The results of this study are of great significance to clinical practice.

Background: Surveillance systems revealed that the prevalence of vancomycin-resistant Enterococcus faecium (VREfm) has increased. We aim to investigate the epidemiological and genomic characteristics of VREfm in China. Methods: We collected 20,747 non-redundant E. faecium isolates from inpatients across 19 hospitals in six provinces between January 2018 and June 2023. VREfm was confirmed by antimicrobial susceptibility testing. The prevalence was analyzed using changepoint package in R. Genomic characteristics were explored by whole-genome sequencing. Results: 5.59% (1159/20,747) of E. faecium isolates were resistant to vancomycin. The prevalence of VREfm increased in Guangdong province from 5% before 2021 to 20-50% in 2023 (p < 0.0001), but not in the other five provinces. Two predominant clones before 2021, ST17 and ST78, were substituted by an emerging clone, ST80, from 2021 to 2023 (88.63%, 195/220). All ST80 VREfm from Guangdong formed a single lineage (SC11) and were genetically distant from the ST80 VREfm from other countries, suggesting a regional outbreak. All ST80 VREfm in SC11 carried a new type of plasmid harbouring a vanA cassette, which was embedded in a Tn1546-like structure flanked by IS1678 and ISL3. However, no conjugation-related gene was detected and no transconjugant was obtained in conjugation experiment, indicating that the outbreak of ST80 VREfm could be attributed to clonal transmission. Conclusions: We revealed an ongoing outbreak of ST80 VREfm with a new vanA-harbouring plasmid in Guangdong, China. This clone has also been identified in other provinces and countries, foreboding a risk of wider spreading shortly. Continuous surveillance is needed to inform public health interventions.

In recent years, polymyxin has been used as a last-resort therapy for carbapenem-resistant bacterial infections. The emergence of heteroresistance (HR) to polymyxin hampers the efficacy of polymyxin treatment by amplifying resistant subpopulation. However, the mechanisms behind polymyxin HR remain unclear. Small noncoding RNAs (sRNAs) play an important role in regulating drug resistance. The purpose of this study was to investigate the effects and mechanisms of sRNA on polymyxin B (PB)-HR in carbapenem-resistant Klebsiella pneumoniae. In this study, a novel sRNA PhaS was identified by transcriptome sequencing. PhaS expression was elevated in the PB heteroresistant subpopulation. Overexpression and deletion of PhaS were constructed in three carbapenem-resistant K. pneumoniae strains. Population analysis profiling, growth curve, and time-killing curve analysis showed that PhaS enhanced PB-HR. In addition, we verified that PhaS directly targeted phoP through the green fluorescent protein reporter system. PhaS promoted the expression of phoP, thereby encouraging the expression of downstream genes pmrD and arnT. This upregulation of arnT promoted the 4-amino-4-deoxyL-arabinosaccharide (L-Ara4N) modification of lipid A in PhaS overexpressing strains, thus enhancing PB-HR. Further, within the promoter region of PhaS, specific PhoP recognition sites were identified. ONPG assays and RT-qPCR analysis confirmed that PhaS expression was positively modulated by PhoP and thus up-regulated by PB stimulation. To sum up, a novel sRNA enhancing PB-HR was identified and a positive feedback regulatory pathway of sRNA-PhoP/Q was demonstrated in the study. This helps to provide a more comprehensive and clear understanding of the underlying mechanisms behind polymyxin HR in carbapenem-resistant K. pneumoniae.

We read with interest an Article published in The Lancet Microbe by Colin J Worby and colleagues.1 They examined the changes in gut microbiome and antimicrobial resistant organisms in a cohort of US travellers before and after international travel. They found that the travellers frequently acquired Enterobacteriaceae and antimicrobial resistance genes (ARGs), aligning with our findings and those of other studies.2–5 Nevertheless, they were unable to determine the persistence of acquired antimicrobial resistant organisms, as they obtained only pre-travel and post-travel samples.

This study investigated resistance evolution mechanisms of conjugated plasmids and bacterial hosts under different concentrations of antibiotic pressure. Ancestral strain ECNX52 was constructed by introducing the blaNDM-5-carrying IncX3 plasmid into E. coli C600, and was subjected to laboratory evolution under different concentrations of meropenem pressure. Minimal inhibitory concentrations and conjugation frequency were determined. Fitness of these strains was assessed. Whole genome sequencing and transcriptional changes were performed. Ancestral host or plasmids were recombined with evolved hosts or plasmids to verify plasmid or host factors in resistance evolution. Role of the repA mutation on plasmid copy number was determined. Two out of the four clones (EM2N1 and EM2N3) exhibited four-fold increase in MIC when exposed to a continuous pressure of 2 μg/mL MEM (1/32 MIC), by down regulating expression of outer membrane protein ompF. Besides, all four clones displayed four-fold increase in MIC and higher conjugation frequency when subjected to a continuous pressure of 4 μg/mL MEM (1/16 MIC), attributing to increasing plasmid copy number generated by repA D140Y (GAT→TAT) mutation. Bacterial hosts and conjugative plasmids can undergo resistance evolution under certain concentrations of antimicrobial pressure by reducing the expression of outer membrane proteins or increasing plasmid copy numbers.

Plasmid-mediated conjugation is a common mechanism for most bacteria to transfer antibiotic resistance genes (ARGs). The conjugative transfer of ARGs is emerging as a major threat to human beings. Although several transfer-related factors are known to regulate this process, small RNAs (sRNAs)-based regulatory roles remain to be clarified. Here, the Hfq-binding sRNA GadY in donor strain Escherichia coli (E. coli) SM10λπ was identified as a new regulator for bacterial conjugation. Two conjugation models established in our previous studies were used, which SM10λπ carrying a chromosomally integrated IncP-1α plasmid RP4 and a mobilizable plasmid pUCP24T served as donor cells, and P. aeruginosa PAO1 or E. coli EC600 as the recipients. GadY was found to promote SM10λπ-PAO1 conjugation by base-pairing with its target mRNA SdiA, an orphan LuxR-type receptor that responds to exogenous N-acylated homoserine lactones (AHLs). However, SM10λπ-EC600 conjugation was not affected due to EC600 lacking AHLs synthase. It indicates that the effects of GadY on conjugation depended on AHLs-SdiA signalling. Further study found GadY bound SdiA to negatively regulate the global RP4 repressors KorA and KorB. When under ciprofloxacin or levofloxacin treatment, GadY expression in donor strain was enhanced, and it positively regulated quinolone-induced SM10λπ-PAO1 conjugation. Thus, our study provides a novel role for sRNA GadY in regulating plasmid-mediated conjugation, which helps us better understand bacterial conjugation to counter antibiotic resistance.

Background and purpose Whether symptomatic unruptured intracranial aneurysms (UIAs) lead to change in circulating inflammation remains unclear. This study aims to evaluate the role of hematological inflammatory indicators in predicting symptomatic UIA. Methods Adult patients diagnosed with saccular intracranial aneurysm from March 2019 to September 2023 were recruited retrospectively. Clinical and laboratory data, including the white blood cells (WBC), neutral counts (NEUT), lymphocyte counts (LYM), and monocyte counts (MONO) of each patient, were collected. The neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) were calculated as NLR = NEUT/LYM, LMR = LYM/MONO, SII = PLT*NEUT/LYM. The hematological inflammatory indicators were compared in symptomatic saccular and asymptomatic UIA patients. Multivariable logistic regression analyses were performed to explore the factors predicting symptomatic UIA. Results One hundred and fifty UIA patients with a mean age of 58.5 ± 12.4 were included, of which 68% were females. The NLR and LMR were significantly associated with symptomatic UIA, and the association remained in small UIAs (< 7 mm). The multiple logistic regression analysis showed that NLR was independently associated with symptomatic UIA. On ROC curve analysis, the optimal cutoff value of NLR to differentiate symptomatic from asymptomatic was 2.38. In addition, LMR was significantly associated with symptomatic UIA smaller than 7 mm. Conclusion There was a significant correlation between NLR and symptomatic UIA. The NLR was independently associated with symptomatic UIA.

The 2019 novel coronavirus (2019-nCoV) is a newly discovered pathogen in 2019. The coronavirus disease (COVID-19) has spread around the world and has greatly affected global health and the world economy. It is a positive-sense single-stranded RNA virus, which generates subgenomic RNA from discontinuous transcription of the replication-transcription complex (RTC). This discontinuous transcription is regulated by transcriptional regulatory sequences/elements, produced by switching templates on genomic RNA. At present, the detection methods of subgenomic RNA include the next generation sequencing, nanopore sequencing, reverse transcription dropletdigital polymerase chain reaction, reverse transcription real-time quantitative polymerase chain reaction, etc. Subgenomic RNA is produced only when the virus infects cell, so it may be a novel marker for viral replication.