Diagnostic value of BHI-V4 for heterogeneous and vancomycin-intermediate Staphylococcus aureus isolates: a systematic review and meta-analysis.

BACKGROUND: Brain-heart infusion agar supplemented with 4 µg/mL of vancomycin (BHI-V4) was commonly used for the detection of heterogeneous (hVISA) and vancomycin-intermediate Staphylococcus aureus (VISA). However, its diagnostic value remains unclear. This study aims to compare the diagnostic accuracy of BHI-V4 with population analysis profiling with area under the curve (PAP-AUC) in hVISA/VISA. METHODS: The protocol of this study was registered in INPLASY (INPLASY2023120069). The PubMed and Cochrane Library databases were searched from inception to October 2023. Review Manager 5.4 was used for data visualization in the quality assessment, and STATA17.0 (MP) was used for statistical analysis. RESULTS: In total, eight publications including 2153 strains were incorporated into the meta-analysis. Significant heterogeneity was evident although a threshold effect was not detected across the eight studies. The summary receiver operating characteristic (SROC) was 0.77 (95% confidence interval [CI], 0.74-0.81). The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic score and diagnostic odds ratio were 0.59 (95% CI: 0.46-0.71), 0.96 (95%CI: 0.83-0.99), 14.0 (95% CI, 3.4-57.1), 0.43 (95%CI, 0.32-0.57), 3.48(95%CI, 2.12-4.85) and 32.62 (95%CI, 8.31-128.36), respectively. CONCLUSION: Our study showed that BHI-V4 had moderate diagnostic accuracy for diagnosing hVISA/VISA. However, more high-quality studies are needed to assess the clinical utility of BHI-V4.

Implications of IFNγ SNP rs2069705 in primary Sjögren's syndrome: transcriptional activation and B cell infiltration.

Primary Sjögren's syndrome (pSS) is characterized by its autoimmune nature. This study investigates the role of the IFNγ SNP rs2069705 in modulating the susceptibility to pSS. Differential expression of IFNγ and BAFF was analyzed using the GEO database's mRNA microarray GSE84844. Genotyping of the IFNγ SNP rs2069705 was conducted via the dbSNP website. The JASPAR tool was used for predicting transcription factor bindings. Techniques such as dual-luciferase reporter assays, Chromatin immunoprecipitation, and analysis of a pSS mouse model were applied to study gene and protein interactions. A notable increase in the mutation frequency of IFNγ SNP rs2069705 was observed in MNCs from the exocrine glands of pSS mouse models. Bioinformatics analysis revealed elevated levels of IFNγ and BAFF in pSS samples. The model exhibited an increase in both CD20+ B cells and cells expressing IFNγ and BAFF. Knocking down IFNγ resulted in lowered BAFF expression and less lymphocyte infiltration, with BAFF overexpression reversing this suppression. Activation of the Janus kinase (JAK)/STAT1 pathway was found to enhance transcription in the BAFF promoter region, highlighting IFNγ's involvement in pSS. In addition, rs2069705 was shown to boost IFNγ transcription by promoting interaction between its promoter and STAT4. SNP rs2069705 in the IFNγ gene emerges as a pivotal element in pSS susceptibility, primarily by augmenting IFNγ transcription, activating the JAK/STAT1 pathway, and leading to B-lymphocyte infiltration in the exocrine glands.NEW & NOTEWORTHY The research employed a combination of bioinformatics analysis, genotyping, and experimental models, providing a multifaceted approach to understanding the complex interactions in pSS. We have uncovered that the rs2069705 SNP significantly affects the transcription of IFNγ, leading to altered immune responses and B-lymphocyte activity in pSS.

Prevalence and molecular characteristics of heterogeneous vancomycin intermediate Staphylococcus aureus in a tertiary care center of northern China.

The use of glycopeptide medications may decline in line with the annual decline in methicillin-resistant Staphylococcus aureus (MRSA) detection rates in China. The rate of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA)detection may be impacted by this. However, there is currently a dearth of information on the incidence of hVISA in China. This study aims to analyze the recent epidemiology and molecular characteristics of hVISA strains in Beijing, China. A total of 175 non-duplicate MRSA strains from various infection sites were collected from a medical center between January 2018 and May 2023 and underwent molecular typing and susceptibility testing (Vitek2). Vancomycin and teicoplanin MICs were also evaluated by standard broth microdilution method and agar dilution method, respectively. Isolates growing on screening agar (BHIV4 and BHIT5, brain heart infusion agar containing 4 µg/ml vancomycin and 5 µg/ml teicoplanin, respectively) were characterized further by analysis of macro-Etest (MET) and population analysis profiling with area under the curve (PAP-AUC). The proportion of hVISA among MRSA isolates was 8.6 %. BHIT5 could select all hVISA strains while BHIV4 and MET only selected two hVISA strains. Compared with vancomycin- susceptible Staphylococcus aureus (VSSA), hVISA isolates were less susceptible to erythromycin and clindamycin. In addition, hVISA frequency was MIC-independent despite using different detection methods. In total, 11 types of STs, 28 types of spa typing, four types of SCCmec typing, and two types of agr typing were identified and the predominant type in both MRSA and hVISA isolates was ST239-t030-SCCmecIII-agr I. The analysis of biofilm formation, growth, and virulence genes in hVISA strains revealed sparse information. The dataset presented in this study provided the prevalence and molecular characteristics of hVISA in hospital settings and the combination of BHIT5 and PAP-AUC may identify hVISA efficiently. The result of genotyping suggested the genotype of hVISA was mainly consistent with that of local MRSA. Additional studies on the characteristics of hVISA strains were necessary.

Resistance phenotype and genetic features of a heterogeneous vancomycin intermediate-resistant Staphylococcus aureus strain from an immunocompromised patient.

Strain C1 was successfully isolated from an immunosuppressed patient with persistent bacteremia, who had not previously been exposed to glycopeptide antibiotics. This strain was found to be a heterogeneous vancomycin intermediate-resistant Staphylococcus aureus (hVISA). It is noteworthy that, following a brief period of vancomycin treatment, strains C6, C8, and C9, which were obtained from blood and other body parts, exhibited a significant reduction in heterogeneity as determined by population analysis profile-area under the curve (PAP-AUC) detection. Genotyping analysis revealed that these bacterial strains belonged to the same SCCmecIVa-ST59-t437-agrI genotype and shared the same virulome and resistome. In this study, a comparative genomics analysis was conducted between strain C1 and strain N315 to identify potential hVISA-associated mutations. Ultimately, a total of 205 mutation sites in 19 candidate genes, likely associated with the hVISA phenotype, were identified.

A non-human primate derived anti-P-selectin glycoprotein ligand-1 antibody curtails acute pancreatitis by alleviating the inflammatory responses.

Acute pancreatitis (AP) is a devastating disease characterized by an inflammatory disorder of the pancreas. P-selectin glycoprotein ligand-1 (PSGL-1) plays a crucial role in the initial steps of the adhesive at process to inflammatory sites, blockade of PSGL-1 might confer potent anti-inflammatory effects. In this study, we generated two non-human primate derived monoclonal antibodies capable of efficiently targeting human PSGL-1, RH001-6 and RH001-22, which were screened from immunized rhesus macaques. We found that RH001-6, can effectively block the binding of P-selectin to PSGL-1, and abolish the adhesion of leukocytes to endothelial cells in vitro. In vivo, we verified that RH001-6 relieved inflammatory responses and pancreatic injury in both caerulein and l-arginine induced AP models. We also evaluated the safety profile after RH001-6 treatment in mice, and verified that RH001-6 did not cause any significant pathological damages in vivo. Taken together, we developed a novel non-human primate derived PSGL-1 blocking antibody with high-specificity, named RH001-6, which can interrupt the binding of PSGL-1 and P-selectin and attenuate inflammatory responses during AP. Therefore, RH001-6 is highly potential to be further developed into therapeutics against acute inflammatory diseases, such as AP.

Effects of plant diversity, soil microbial diversity, and network complexity on ecosystem multifunctionality in a tropical rainforest.

Introduction: Plant diversity and soil microbial diversity are important driving factors in sustaining ecosystem multifunctionality (EMF) in terrestrial ecosystems. However, little is known about the relative importance of plant diversity, soil microbial diversity, and soil microbial network complexity to EMF in tropical rainforests. Methods: This study took the tropical rainforest in Xishuangbanna, Yunnan Province, China as the research object, and quantified various ecosystem functions such as soil organic carbon stock, soil nutrient cycling, biomass production, and water regulation in the tropical rainforest to explore the relationship and effect of plant diversity, soil microbial diversity, soil microbial network complexity and EMF. Results: Our results exhibited that EMF decreased with increasing liana species richness, soil fungal diversity, and soil fungal network complexity, which followed a trend of initially increasing and then decreasing with soil bacterial diversity while increasing with soil bacterial network complexity. Soil microbial diversity and plant diversity primarily affected soil nutrient cycling. Additionally, liana species richness had a significant negative effect on soil organic carbon stocks. The random forest model suggested that liana species richness, soil bacterial network complexity, and soil fungal network complexity indicated more relative importance in sustaining EMF. The structural equation model revealed that soil bacterial network complexity and tree species richness displayed the significantly positive effects on EMF, while liana species richness significantly affected EMF via negative pathway. We also observed that soil microbial diversity indirectly affected EMF through soil microbial network complexity. Soil bulk density had a significant and negative effect on liana species richness, thus indirectly influencing EMF. Simultaneously, we further found that liana species richness was the main indicator of sustaining EMF in a tropical rainforest, while soil bacterial diversity was the primary driving factor. Discussion: Our findings provide new insight into the relationship between biodiversity and EMF in a tropical rainforest ecosystem and the relative contribution of plant and soil microibal diversity to ecosystem function with increasing global climate change.

Potential role of gut microbes in the efficacy and toxicity of immune checkpoints inhibitors.

In recent years, Immune checkpoint inhibitors have been extensively used in the treatment of a variety of cancers. However, the response rates ranging from 13% to 69% depending on the tumor type and the emergence of immune-related adverse events have posed significant challenges for clinical treatment. As a key environmental factor, gut microbes have a variety of important physiological functions such as regulating intestinal nutrient metabolism, promoting intestinal mucosal renewal, and maintaining intestinal mucosal immune activity. A growing number of studies have revealed that gut microbes further influence the anticancer effects of tumor patients through modulation of the efficacy and toxicity of immune checkpoint inhibitors. Currently, faecal microbiota transplantation (FMT) have been developed relatively mature and suggested as an important regulator in order to enhance the efficacy of treatment. This review is dedicated to exploring the impact of differences in flora composition on the efficacy and toxicity of immune checkpoint inhibitors as well as to summarizing the current progress of FMT.

Effects of Omeprazole on Recurrent Clostridioides difficile Infection Caused by ST81 Strains and Their Potential Mechanisms.

Clostridioides difficile infection (CDI) is associated with high recurrence rates that have substantial effects on patients' quality of life. To investigate the risk factors and potential mechanisms contributing to recurrent CDI (rCDI), a total of 243 cases were enrolled in this study. The history of omeprazole (OME) medication and ST81 strain infection were considered the two independent risks with the highest odds ratios in rCDI. In the presence of OME, we detected concentration-dependent increases in the MIC values of fluoroquinolone antibiotics against ST81 strains. Mechanically, OME facilitated ST81 strain sporulation and spore germination by blocking the pathway of purine metabolism and also promoted an increase in cell motility and toxin production by turning the flagellar switch to the ON state. In conclusion, OME affects several biological processes during C difficile growth, which have fundamental impacts on the development of rCDI caused by ST81 strains. Programmed OME administration and stringent surveillance of the emerging ST81 genotype are matters of considerable urgency and significance in rCDI prevention.

Molecular epidemiology, antimicrobial susceptibility, and toxin production of clinical Clostridioides difficile isolates from a teaching hospital in Northern China.

To grasp the epidemiological trend and drug resistance mechanisms of Clostridioides difficile (C. diff) in Beijing, 302 C. diff isolates were obtained from patients with diarrhea. The sequence types (STs) from mainstream strains were all susceptible to metronidazole, vancomycin, piperacillin/tazobactam, meropenem, and tigecycline but almost resistant to ciprofloxacin and clindamycin. The missense mutation of GyrA/GyrB and RpoB resulted in fluoroquinolone and rifamycin resistance, respectively. Toxigenic strains from clade IV were likely to be missed due to the deficiency of tcdA gene. Four tcdC genotypes were first detected in strains from clade III and IV. The truncating mutation of TcdC disabled its function working as a toxin suppressor. In conclusion, the molecular epidemiology of C. diff in Beijing is different from other regions of China. The antimicrobial resistance patterns and toxin-producing abilities of strains with different STs varied greatly, which suggests that continuous surveillance and control are meaningful and urgent.

Shengjiang Xiexin Decoction ameliorates antibiotic-associated diarrhea by altering the gut microbiota and intestinal metabolic homeostasis.

BACKGROUND: Antibiotic-associated diarrhea (AAD) has had a significant increase in the last years, with limited available effective therapies. Shengjiang Xiexin Decoction (SXD), a classic traditional Chinese medicine formula for treating diarrhea, is a promising alternative for reducing the incidence of AAD. PURPOSE: This study aimed to explore the therapeutic effect of SXD on AAD and to investigate its potential therapeutic mechanism by integrated analysis of the gut microbiome and intestinal metabolic profile. METHODS: 16S rRNA sequencing analysis of the gut microbiota and untargeted-metabolomics analysis of feces were performed. The mechanism was further explored by fecal microbiota transplantation (FMT). RESULTS: SXD could effectively ameliorate AAD symptoms and restore intestinal barrier function. In addition, SXD could significantly improve the diversity of the gut microbiota and accelerate the recovery of the gut microbiota. At the genus level, SXD significantly increased the relative abundance of Bacteroides spp (p < 0.01) and decreased the relative abundance of Escherichia_Shigela spp (p < 0.001). Untargeted metabolomics showed that SXD significantly improved gut microbiota and host metabolic function, particularly bile acid metabolism and amino acid metabolism. CONCLUSION: This study demonstrated that SXD could extensively modulate the gut microbiota and intestinal metabolic homeostasis to treat AAD.

Quinolone Resistance Genes and Their Contribution to Resistance in Vibrio cholerae Serogroup O139.

BACKGROUND: Quinolones are commonly used for reducing the duration of diarrhea, infection severity, and limiting further transmission of disease related to Vibrio cholerae, but V. cholerae susceptibility to quinolone decreases over time. In addition to mutations in the quinolone-resistance determining regions (QRDRs), the presence of qnr and other acquired genes also contributes to quinolone resistance. RESULTS: We determined the prevalence of quinolone resistance related genes among V. cholerae O139 strains isolated in China. We determined that eight strains carried qnrVC, which encodes a pentapeptide repeat protein of the Qnr subfamily, the members of which protect topoisomerases from quinolone action. Four qnrVC alleles were detected: qnrVC1, qnrVC5, qnrVC12, and qnrVC9. However, the strains carrying qnrVC1, qnrVC5, and qnrVC12 were ciprofloxacin (CIP)-sensitive. Contrastingly, the strain carrying qnrVC9 demonstrated high CIP resistance. qnrVC9 was carried by a small plasmid, which was conjugative and contributed to the high CIP resistance to the receptor V. cholerae strain. The same plasmid was also detected in V. vulnificus. The qnrVC1, qnrVC5, and qnrVC12 were cloned into expression plasmids and conferred CIP resistance on the host V. cholerae O139 strain. CONCLUSIONS: Our results revealed the contribution of quinolone resistance mediated by the qnrVC9 carried on the small plasmid and its active horizontal transfer among Vibrio species. The results also suggested the different effects of qnrVC alleles in different V. cholerae strains, which is possibly due to differences in sequences of qnrVC alleles and even the genetic characteristics of the host strains.

Prevalence of Helicobacter pylori Virulence Genes and Their Association with Chronic Gastritis in Beijing, China.

Helicobacter pylori is closely related to chronic gastritis. The aim of the study was to investigate the correlation between H. pylori virulence genes and chronic gastritis in order to determine the pathogenic role of H. pylori virulence genes in chronic gastritis. Gastric mucosal tissues were obtained from 142 patients with chronic gastritis at three Beijing hospitals. The presence of virulence genes was determined by polymerase chain reaction (PCR) from H. pylori DNA. Multilocus sequence typing (MLST) and a phylogenetic tree were performed to characterize the overall genetic diversity. 91 new sequence types were identified by MLST in this study, and all strains showed high genetic diversity. The H. pylori isolates were divided into three types: hspEAsia strains (61 strains), hpEurope strains (15 strains), and mixed strains (16 strains). Some virulence genes were found to be significantly different between strains. The highest positive rates were found for dupA in chronic atrophic gastritis (AG), iceA1 in chronic non-atrophic gastritis with erosions, and iceA2 in chronic non-atrophic gastritis. The presence of dupA was found to be inversely related to the risk of AG. The H. pylori strains display high genetic diversity. Some virulence genes were found to be significantly different between diseases. The detection of various virulence genes is critical for screening high-risk populations for precancerous lesions and for the early prevention and control of gastric cancer.

An Ultrasensitive PCR-Based CRISPR-Cas13a Method for the Detection of Helicobacter pylori.

The rapid and simple detection of Helicobacter pylori (H. pylori) is essential for its clinical eradication. Although various methods for detecting H. pylori have been well established, such as endoscopy in combination with histology or culture, rapid urease test (RUT) and molecular tests using clinical specimens, it is of great importance to develop an ultrasensitive and accurate nucleic acid detection platform and apply it to identify H. pylori. To meet these demands, a novel method based on PCR and CRISPR-Cas13a, called PCR-Cas13a, was developed and validated using the DNA of 84 clinical strains and 71 clinical specimens. PCR primers for the pre-amplification of conservative sequence and CRISPR RNA (crRNA) for the detection of specific sequence were designed according to the principle. The designed primers and crRNA were specific to H. pylori, and the assay showed a high degree of specificity compared with other common pathogens. Our detection system can screen H. pylori with a limit of 2.2 copies/µL within 30 mins after PCR amplification. Using a coincidence analysis with traditional methods, our method exhibited 100% accuracy for the detection of H. pylori. Furthermore, its diagnostic performance was compared, in parallel with a q-PCR. The PCR-Cas13a demonstrates 98% sensitivity and 100% specificity. Moreover, our approach had a lower limit of detection (LOD) than q-PCR. Herein, we present a diagnostic system for the highly sensitive screening of H. pylori and distinguish it from other pathogens. All the results demonstrated that this PCR-based CRISPR assay has wide application prospects for the detection of H. pylori and other slow-growth pathogens.

An Overview of Analytical Methodologies for Determination of Vancomycin in Human Plasma.

Vancomycin is regarded as the last resort of defense for a wide range of infections due to drug resistance and toxicity. The detection of vancomycin in plasma has always aroused particular concern because the performance of the assay affects the clinical treatment outcome. This article reviews various methods for vancomycin detection in human plasma and analyzes the advantages and disadvantages of each technique. Immunoassay has been the first choice for vancomycin concentration monitoring due to its simplicity and practicality, occasionally interfered with by other substances. Chromatographic methods have mainly been used for scientific research due to operational complexity and the particular requirement of the instrument. However, the advantages of a small amount of sample needed, high sensitivity, and specificity makes chromatography irreplaceable. Other methods are less commonly used in clinical applications because of the operational feasibility, clinical application, contamination, etc. Simplicity, good performance, economy, and environmental friendliness have been points of laboratory methodological concern. Unfortunately, no one method has met all of the elements so far.

In vitro Studies of Non-Diphtheriae Corynebacterium Isolates on Antimicrobial Susceptibilities, Drug Resistance Mechanisms, and Biofilm Formation Capabilities.

Objective: This study aimed to investigate the antimicrobial susceptibilities, drug resistance mechanisms, and biofilm formation capacities of non-diphtheriae Corynebacterium strains isolated from sterile midstream urine of hospitalized patients with clinical urinary tract infections (UTIs). Methods: A total of 45 non-diphtheriae Corynebacterium isolates were recovered from sterile midstream urine. The available data of 45 patients were collected. Minimum inhibitory concentrations (MICs) of 10 commonly used antibiotics were determined. Meanwhile, the molecular resistance mechanisms of each agent were performed through PCR with specific primers. Moreover, the biofilm formation capability of each isolate on abiotic surfaces was detected with the MTT method. Results: In this study, the most prevalent three species were C. striatum (15/45, 33.3%), C. glucuronolyticum (9/45, 20.0%) and C. urealyticum (8/45, 17.8%). These three species also accounted for most renal and ureteral calculi cases. Male patients older than 50 years, especially those with underlying diseases, were more susceptible to non-diphtheriae Corynebacterium infection. All the 45 isolates were 100% susceptible to vancomycin and linezolid, but highly resistant to macrolide-lincosamide-streptogramin B (MLSB), fluoroquinolones, tetracyclines and ß-lactams with corresponding mechanisms. The detection rate of multidrug-resistant (MDR) non-diphtheriae Corynebacterium is 91.1%. All isolates are able to form biofilm on abiotic surfaces, except those of C. urealyticum, C. tuberculostearicum and C. jeikeium. Isolates of C. glucuronolyticum and C. Striatum possessed the strongest biofilm formation capacity. C. amycolatum could form biofilm, but varied greatly among different isolates. Conclusion: C. striatum, C. glucuronolyticum and C. urealyticum were the most prevalent species relevant to UTIs. The high occurrence of MDR isolates and high diversities in resistance profiles, and the distinctive abilities of biofilm formation highlighted the urgency for identification to species level. We should pay more attention to the drug resistance profiles of non-diphtheriae Corynebacterium, which would help improve empirical antibiotic therapy and reduce drug resistance transmission.

Host and microbial-derived metabolites for Clostridioides difficile infection: Contributions, mechanisms and potential applications.

Clostridioides difficile infection (CDI), which mostly occurs in hospitalized patients, is the most common and costly health care-associated disease. However, the biology of C. difficile remains incompletely understood. Current therapeutics are still challenged by the frequent recurrence of CDI. Advances in metabolomics facilitate our understanding of the etiology of CDI, which is not merely an alteration in the structure of the gut microbial community but also a dysbiosis metabolic setting promoting the germination, expansion and virulence of C. difficile. Therefore, we summarized the gut microbial and metabolic profiles for CDI under different conditions, such as those of postantibiotic treatment and postfecal microbiota transplantation. The current understanding of the role of host and gut microbial-derived metabolites as well as other nutrients in preventing or alleviating the disease symptoms of CDI will also be provided in this review. We hope that a specific nutrient-centric dietary strategy or the administration of certain nutrients to the colon could serve as an alternate line of investigation for the prophylaxis and mitigation of CDI in the future. Nevertheless, rigorously designed basic studies and randomized controlled trials need to be conducted to assess the functional mechanisms and effects of such therapeutics.

Soil moisture regulates warming responses of autumn photosynthetic transition dates in subtropical forests.

Autumn phenology plays a key role in regulating the terrestrial carbon and water balance and their feedbacks to the climate. However, the mechanisms underlying autumn phenology are still poorly understood, especially in subtropical forests. In this study, we extracted the autumn photosynthetic transition dates (APTD) in subtropical China over the period 2003-2017 based on a global, fine-resolution solar-induced chlorophyll fluorescence (SIF) dataset (GOSIF) using four fitting methods, and then explored the temporal-spatial variations of APTD and its underlying mechanisms using partial correlation analysis and machine learning methods. We further predicted the APTD shifts under future climate warming conditions by applying process-based and machine learning-based models. We found that the APTD was significantly delayed, with an average rate of 7.7 days per decade, in subtropical China during 2003-2017. Both partial correlation analysis and machine learning methods revealed that soil moisture was the primary driver responsible for the APTD changes in southern subtropical monsoon evergreen forest (SEF) and middle subtropical evergreen forest (MEF), whereas solar radiation controlled the APTD variations in the northern evergreen-broadleaf deciduous mixed forest (NMF). Combining the effects of temperature, soil moisture and radiation, we found a significantly delayed trend in APTD during the 2030-2100 period, but the trend amplitude (0.8 days per decade) was much weaker than that over 2003-2017. In addition, we found that machine learning methods outperformed process-based models in projecting APTD. Our findings generate from different methods highlight that soil moisture is one of the key players in determining autumn photosynthetic phenological processes in subtropical forests. To comprehensively understand autumn phenological processes, in-situ manipulative experiments are urgently needed to quantify the contributions of different environmental and physiological factors in regulating plants' response to ongoing climate change.

In vitro Antimicrobial Activity and the Mechanism of Berberine Against Methicillin-Resistant Staphylococcus aureus Isolated from Bloodstream Infection Patients.

Purpose: To investigate the antimicrobial activity of berberine and the mechanism by which it combats methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from patients with bloodstream infections. Methods: Fifteen clinical MRSA isolates were collected, and their Multi-locus Sequence Types (MLST) were examined. The minimum inhibitory concentration (MIC) and combined antibacterial activity of berberine alone, and when combined with clindamycin and rifampicin separately, were determined. Additionally, two MRSA strains (ST239 and ST5) were selected to perform the time-killing assay and biofilm formation test. Cell wall alterations and cell membrane integrity were measured by confocal laser scanning microscopy (CLSM) and electron microscopy to assess the influence on cell morphology. Results: Our data showed berberine was effective against MRSA at MIC values varying from 256 to 64 mg*L-1 for different MLST types. Berberine alone, and when combined with clindamycin and rifampicin separately, displayed excellent antibacterial activity which reduced the bacterial counts by 2lgCFU*mL within 24h and significantly weakened biofilm formation compared with control strain. Additionally, bacterial cytological profiling indicates that berberine destroyed the structure of the cell walls, membrane integrity and further changed the cell morphology with concentration increased. Conclusion: In our study, berberine has excellent anti-MRSA activities and has synergistic antibacterial property when combined with clindamycin and rifamycin separately, and the mechanism of activities involves the destruction of cell wall and membrane.

Rapid detection of cagA-positive Helicobacter pylori based on duplex recombinase aided amplification combined with lateral flow dipstick assay.

Infection with cytotoxin-associated gene A (cagA)-positive Helicobacter pylori (H. pylori) is associated with severe gastrointestinal disease. A rapid, simple, and convenient detection method for cagA-positive H. pylori was an urgent need. We have developed and evaluated a duplex recombinase aided amplification combined with lateral flow dipstick (Duplex RAA-LFD) assay for detection of cagA-positive H. pylori strains. The Duplex RAA-LFD successfully detected DNA extracts in 25 min at 39°C, with visual detection limits of 1.2 × 102 CFU/mL and 10 pg, respectively. No positive amplification was observed in 6 non-H. pylori strains, indicating higher specificity. When testing 56 clinical isolates, the sensitivity and specificity of the Duplex RAA-LFD assay were 96% and 100%, respectively, with Duplex PCR serving as the reference method. Therefore, the Duplex RAA-LFD assay is a potential rapid and effective alternative to detect cagA-positive H. pylori strains in fresh gastric mucosal tissue.