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ABSTRACT: Objectives: This study was conducted in Jilin Province to investigate the mechanism involved in the antibiotic resistance and pathogenicity of Klebsiella pneumoniae. Methods: Lung samples were collected from large-scale pig farms in Jilin Province. Antimicrobial susceptibility and mouse lethality assays were carried out. K. pneumoniae isolate JP20, with high virulence and antibiotic resistance, was chosen for whole-genome sequencing. The complete sequence of its genome was annotated, and the virulence and antibiotic resistance mechanism were analysed. Results: A total of 32 K. pneumoniae strains were isolated and tested for antibiotic resistance and pathogenicity. Among them, the JP20 strain showed high levels of resistance to all tested antimicrobial agents and strong pathogenicity in mice (lethal dose of 1.35 × 1011 CFU/mL). Sequencing of the multidrug-resistant and highly virulent K. pneumoniae JP20 strain revealed that the antibiotic resistance genes were mainly carried by an IncR plasmid. We speculate that extended-spectrum β-lactamases and loss of outer membrane porin OmpK36 play an important role in carbapenem antibiotic resistance. This plasmid contains a mosaic structure consisting of a large number of mobile elements. Conclusion: Through genome-wide analysis, we found that an lncR plasmid carried by the JP20 strain may have evolved in pig farms, possibly leading to multidrug resistance in the JP20 strain. It is speculated that the antibiotic resistance of K. pneumoniae in pig farms is mainly mediated by mobile elements (insertion sequences, transposons, and plasmids). These data provide a basis for monitoring the antibiotic resistance of K. pneumoniae and lay a foundation for an improved understanding of the genomic characteristics and antibiotic resistance mechanism of K. pneumoniae.

The yield of wheat in wheat–rice rotation cropping systems in the Yangtze River Plain, China, is adversely impacted by waterlogging. A raised bed planting (RBP) pattern may reduce waterlogging and increase the wheat yield after rice cultivation by improving the grain number per spike. However, the physiological basis for grain formation under RBP conditions remains poorly understood. The present study was performed over two growing seasons (2018/2019 and 2019/2020) to examine the effects of the planting pattern (i.e., RBP and flat planting (FP)) on the floret and grain formation features and leaf photosynthetic source characteristics of wheat. The results indicated that implementation of the RBP pattern improved the soil–plant nitrogen (N) supply during floret development, which facilitated balanced floret development, resulting in a 9.5% increase in the number of fertile florets per spike. Moreover, the RBP pattern delayed wheat leaf senescence and increased the photosynthetic source capacity by 13.9%, which produced more assimilates for grain filling. Delayed leaf senescence was attributed to the resultant high leaf N content and enhanced antioxidant metabolism. Correspondingly, under RBP conditions, 7.6–8.6% more grains per spike were recorded, and the grain yield was ultimately enhanced by 10.4–12.7%. These results demonstrate that the improvement of the spike differentiation process and the enhancement of the leaf photosynthetic capacity were the main reasons for the increased grain number per spike of wheat under the RBP pattern, and additional improvements in this technique should be achievable through further investigation.

Summary Pseudomonas sp. strain 166 was isolated from soil samples from Changbai Mountains. A novel bacteriocin PA166 from Pseudomonas sp. 166 was purified using ammonium sulfate, dextran gel chromatography column and Q‐Sepharose column chromatography successively. The molecular mass of bacteriocin PA166 was found to be 49.38 kDa by SDS‐PAGE and liquid chromatography–mass spectrometry (MS)/MS. Bacteriocin PA166 showed stability at a wide range of pH (2–10), and thermal stability (40, 60, 80 and 100°C). The bacteriocin PA166 antimicrobial activity was slightly inhibited by Ca2+, K+ and Mg2+. The minimum bactericidal concentrations of bacteriocin PA166 against five Pasteurella multocida strains ranged from 2 to 8 μg ml−1. Bacteriocin PA166 showed low cytotoxicity and a higher treatment index (TI = 82.51). Fluorescence spectroscopy indicated that bacteriocin PA166 destroyed the cell membrane to exert antimicrobial activity. In summary, bacteriocin PA166 had strong antibacterial activity, high TI and low toxicity, and hence could serve as a potential clinical therapeutic drug.

Multidrug-resistant Enterococcus faecalis (E. faecalis) often cause intestinal infections in cats. The aim of this study was to investigate a multidrug-resistant E. faecalis isolate for plasmidic and chromosomal antimicrobial resistance and their genetic environment. E. faecalis strain ESC1 was obtained from the feces of a cat. Antimicrobial susceptibility testing was carried out using the broth microdilution method. Conjugation experiments were performed using Escherichia coli and Staphylococcus aureus as receptors. Complete sequences of chromosomal DNA and plasmids were generated by whole genome sequencing (WGS) and bioinformatics analysis for the presence of drug resistance genes and mobile elements. Multidrug-resistant E. faecalis ESC1 contained a chromosome and three plasmids. The amino acid at position 80 of the parC gene on the chromosome was mutated from serine to isoleucine, and hence the amino acid mutation at this site led to the resistance of ESC1 strain to fluoroquinolones. Eleven antibiotic resistance genes were located on two plasmids. We identified a novel composite transposon carrying two aminoglycoside resistance genes aac(6′)-aph(2″). This study reported the coexistence of a novel 5.4 kb composite transposon and a resistance plasmid with multiple homologous recombination in an isolate of E. faecalis ESC1. This data provides a basis for understanding the genomic signature and antimicrobial resistance mechanisms of this pathogen.

IntroductionThe continued emergence and spread of multidrug-resistant (MDR) bacterial pathogens require a new strategy to improve the efficacy of existing antibiotics. Proline-rich antimicrobial peptides (PrAMPs) could also be used as antibacterial synergists due to their unique mechanism of action.MethodsUtilizing a series of experiments on membrane permeability, In vitro protein synthesis, In vitro transcription and mRNA translation, to further elucidate the synergistic mechanism of OM19r combined with gentamicin.ResultsA proline-rich antimicrobial peptide OM19r was identified in this study and its efficacy against Escherichia coli B2 (E. coli B2) was evaluated on multiple aspects. OM19r increased antibacterial activity of gentamicin against multidrug-resistance E. coli B2 by 64 folds, when used in combination with aminoglycoside antibiotics. Mechanistically, OM19r induced change of inner membrane permeability and inhibited translational elongation of protein synthesis by entering to E. coli B2 via intimal transporter SbmA. OM19r also facilitated the accumulation of intracellular reactive oxygen species (ROS). In animal models, OM19r significantly improved the efficacy of gentamicin against E. coli B2.DiscussionOur study reveals that OM19r combined with GEN had a strong synergistic inhibitory effect against multi-drug resistant E. coli B2. OM19r and GEN inhibited translation elongation and initiation, respectively, and ultimately affected the normal protein synthesis of bacteria. These findings provide a potential therapeutic option against multidrug-resistant E. coli.

Introduction: Recently, several clinical trials of immunotherapy for extensive-stage small-cell lung cancer (ES-SCLC) have shown limited benefits because of unselected patients. Thus, we aimed to explore whether YES-associated protein 1 (YAP-1) and POU domain class 2 transcription factor 3 (POU2F3) could identify SCLC patients with durable benefits from immunotherapy as potential biomarkers. Methods: We performed IHC of YAP-1 and POU2F3, and RNA-seq on tissues of ES- SCLC patients. An open-source plugin based on IHC-profiler was conducted to calculate the expression levels of YAP-1 and POU2F3. Results: Patients with ES-SCLC were retrospectively investigated in the Guangdong Provincial People's Hospital from January 2018 to July 2021, and 21 patients whoever received atezolizumab plus etoposide/carboplatin (ECT) regimen also had tissue samples reachable. The median IHC-score of YAP-1 in responders (CR/PR patients) was significantly lower than in nonresponders (SD/PD patients) at 13.97 (95% CI: 8.97–16.30) versus 23.72 (95% CI: 8.13–75.40). The IHC-score of YAP-1 and PFS showed a negative correlation by Spearman (r=-0.496). However, POU2F3 did not show a correlation with efficacy. Besides, patients with YAP-1 high expression had IL6, MYCN, and MYCT1 upregulated, while analysis of immune cell infiltration only showed that M0 macrophages were significantly higher. Conclusions: The expression of YAP-1 negatively correlated with the efficacy of ECT in ES-SCLC patients while POU2F3 did not reveal the predictive value. However, prospective investigations with a large sample size are needed.

Abstract Background Macro-reentrant atrial tachycardias (MATs) are a common complication after cardiac valve surgery. The MAT types and the effectiveness of MAT ablation might differ after different valve surgery. Data comparing the electrophysiological characteristics and the ablation results of MAT post-tricuspid or mitral valve surgery are limited. Methods Forty-eight patients (29 males, age 56.1 ± 13.3 years) with MAT after valve surgery were assigned to tricuspid valve (TV) group (n = 18) and mitral valve (MV) group (n = 30). MATs were mapped and ablated guided by a three-dimensional navigation system. The one-year clinical effectiveness was compared in two groups. Results Nineteen MATs were documented in TV group, including 16 cavo-tricuspid isthmus (CTI)-dependent AFL and 3 other MATs at right atrial (RA) free wall, RA septum and left atrial (LA) roof. Thirty-nine MATs were identified in MV group, including15 CTI-dependent AFL, 8 RA free wall scar-related, 2 RA septum scar-related, 8 peri-mitral flutter, 3 LA roof-dependent, 2 LA anterior scar-related, and 1 right pulmonary vein-related MAT. Compared with TV group, MV group had significantly lower prevalence of CTI-dependent AFL (38.5% vs. 84.2%), higher prevalence of left atrial MAT (35.9 vs.5.3%) and higher proportion of patients with left atrial MAT (40 vs. 5.6%), P = 0.02, 0.01 and 0.01, respectively. The acute success rate of MAT ablation (100 vs. 93.3%) and the one-year freedom from atrial tachy-arrhythmias (72.2 vs. 76.5%) was comparable in TV and MV group. No predictor for recurrence was identified. Conclusion Although the types of MATs differed significantly in patients with prior TV or MV surgery, the acute and mid-term effectiveness of MAT ablation was comparable in two groups. Trial registration: This study was registered as a part of EARLY-MYO-AF clinical trial at the website ClinicalTrials. gov (NCT04512222).

Antibiotic tolerance has become an increasingly serious crisis that has seriously threatened global public health. However, little is known about the exogenous factors that can trigger the development of antibiotic tolerance, both in vivo and in vitro. Herein, we found that the addition of citric acid, which is used in many fields, obviously weakened the bactericidal activity of antibiotics against various bacterial pathogens. This mechanistic study shows that citric acid activated the glyoxylate cycle by inhibiting ATP production in bacteria, reduced cell respiration levels, and inhibited the bacterial tricarboxylic acid cycle (TCA cycle). In addition, citric acid reduced the oxidative stress ability of bacteria, which led to an imbalance in the bacterial oxidation–antioxidant system. These effects together induced the bacteria to produce antibiotic tolerance. Surprisingly, the addition of succinic acid and xanthine could reverse the antibiotic tolerance induced by citric acid in vitro and in animal infection models. In conclusion, these findings provide new insights into the potential risks of citric acid usage and the relationship between antibiotic tolerance and bacterial metabolism.

Pasteurella multocida (Pm) is one of the major pathogens of bovine respiratory disease (BRD), which can develop drug resistance to many of the commonly used antibiotics. Our earlier research group found that with clinical use of enrofloxacin, Pm was more likely to develop drug resistance to enrofloxacin. In order to better understand the resistance mechanism of Pm to enrofloxacin, we isolated PmS and PmR strains with the same PFGE typing in vitro, and artificially induced PmR to obtain the highly resistant phenotype, PmHR. Then transcriptome sequencing of clinically isolated sensitive strains, resistant and highly drug-resistant strains, treated with enrofloxacin at sub-inhibitory concentrations, were performed. The satP gene, of which the expression changed significantly with the increase in drug resistance, was screened. In order to further confirm the function of this gene, we constructed a satP deletion (ΔPm) strain using suicide vector plasmid pRE112, and constructed the C-Pm strain using pBBR1-MCS, and further analyzed the function of the satP gene. Through a continuously induced resistance test, it was found that the resistance rate of ΔPm was obviously lower than that of Pm in vitro. MDK99, agar diffusion and mutation frequency experiments showed significantly lower tolerance of ΔPm than the wild-type strains. The pathogenicity of ΔPm and Pm was measured by an acute pathogenicity test in mice, and it was found that the pathogenicity of ΔPm was reduced by about 400 times. Therefore, this study found that the satP gene was related to the tolerance and pathogenicity of Pm, and may be used as a target of enrofloxacin synergistic effect.

BackgroundCatheter ablation for parahisian ventricular arrhythmias (PHVA) is technically challenging and associated with increased risks of atrioventricular block (AVB). We developed a systemic mapping approach to improve the efficacy and safety of PHVA ablation.MethodsForty-three patients (29 males; average age 65.8 ± 10.5 years) with PHVAs were enrolled. A systemic mapping approach comprising differential electrocardiogram, sequential mapping, and ablation beneath/above the septal leaflet of the tricuspid valve (SLTV) and at the neighboring/contralateral regions (the aortic root and sub-aortic valve region) was applied for PHVA. The effectiveness and safety of this approach was evaluated at 1 year's follow-up.ResultsSequential ablation beneath the SLTV (B-SLTV) succeeded in 24 (66.7 %) of 36 with right PHVA and ablation above the SLTV succeeded in 6 of the remaining 12 with failed B-SLTV ablation. Target-His bundle (HB) distance > 4.5 mm significantly predicted successful right PHVA ablation (OR 1.703; 95% CI 1.084–2.676, P = 0.02). “Seeming” right PHVA by electrocardiogram in 4 and apparent left PHVA in 3 was successfully ablated at the sub-aortic parahisian region. At 1 year's follow-up, 27 (75%) of 36 patients with right PHVA and 6 (85.7%) of 7 patients with left PHVA were free of PHVA recurrence off anti-arrhythmic drugs. The total success rate was 76.7% by using the systemic mapping approach for PHVA. One patient with A-SLTV ablation underwent pacemaker implantation due to complete AVB.ConclusionsThe systemic mapping approach was effective and safe for treating PHVA. The target-HB distance was a significant predictor for right PHVA ablation.

Objectives: This research was conducted to ascertain the context and location of the antibiotic resistance determinants in a multiple antibiotic-resistant Trueperella pyogenes isolate TP1. Methods: The genome was sequenced using PacBio RS II, and the filtered data were assembled using Canu. Sequences were annotated on the basis of those in GenBank, and the genomic island (GI) of the TP1 was predicted by IslandPath-DIMOB. Results: TP1 as a multiple antibiotic-resistant isolate was recovered at Jilin Province (China) in 2017 from a dairy cow with pneumonia. TP1 exhibited resistance to aminoglycosides (gentamicin and amikacin), macrolides (erythromycin), lincosamides (clindamycin), sulfonamides (sulfamonomethoxine), tetracyclines (tetracycline and doxycycline) and chloramphenicols (chloramphenicol and florfenicol). An antibiotic resistance gene clustered together with the aadB, aadA1, cmlA5 and cmlA6 resistance genes located on a 7-kilobase (kb) multidrug-resistant (MDR) region, constituting a complex class 1 integron. The MDR region was located at one end of a 42-kb GI, and IS6100Δ1 mediated a genetic rearrangement with the complex class 1 integron-like SGI1 and formed a composite transposon. Furthermore, the tetW gene was located outside the four GIs consistent with tetracycline and doxycycline resistance. The ermD gene positioned in the front end of the 42-kb GI played an important role in mediating acquired erythromycin and clindamycin resistance. Conclusions: Multiple resistance genes are located in a complex class 1 integron within a 42-kb T. pyogenes genomic island (TGI1), leading to TP1 multiple drug resistance. In comparison with SG1 families, TGI1 possesses versatile gene distribution and specific gene context for it upstream and downstream, and it represents a new lineage of genomic resistance islands.

Abstract Bacterial enteritis is the most important disease in lamb for breeding greatly affects the growth of animals. Changes in the community of intestinal flora can cause the disorder of the colonic environment induced diarrhea. This study aimed to investigate the relationship between the incidence of bacterial enteritis and the number of intestinal microbiome, then the prevalence of drug-resistant genes was detected. Fecal samples were collected at five fattening sheep farms with different incidence of bacterial enteritis, pathogenic bacteria were isolated and identified, drug sensitivity tests were performed. Then, changes in number and structure of intestinal flora were compared by 16S rDNA V3-V4 region high-throughput sequencing, and the ARGs were detected using high-throughput real-time PCR. Our results revealed that the microbial communities were positively correlated with the incidence of bacterial enteritis in different farms. Bacterial communities were higher in YJ (with highest incidence of diarrhea) than any other farms. However, the ARGs seemed not to be more affected by the incidence of bacterial enteritis, but one of the significant findings to emerge from this study is that MCR-1 and NDM are detected in manure. This study has provided an insight of the changes occurring in intestinal flora and AGRs in fattening sheep farms with diverse incidence of bacterial enteritis.

Background: The use of direct oral anticoagulant (DOAC) off-label doses in atrial fibrillation (AF) patients may result in poor clinical outcomes. However, the true prevalence remains scarce. This study aims at estimating the prevalence of DOAC off-label doses in AF patients.Methods: Databases of MEDLINE, EMBASE, and COCHRANE were searched from inception through February 2020 for real-world studies that reported the off-label definition and prevalence data of AF patients using DOACs. The primacy outcomes were the overall prevalence of DOAC off-label doses and the corresponding underdose and overdose. The random-effects model was used for data synthesis. Variations on individual DOAC and different regions were examined by subgroup analyses.Results: A total of 23 studies involving 162,474 AF patients were finally included. The overall prevalence of DOAC off-label doses was 24% (95% CI, 19–28%), with 18% for dabigatran, 27% for rivaroxaban, 24% for apixaban, and 26% for edoxaban. The prevalence of underdosed DOACs was 20% (95% CI, 16–24%) with significant difference among individual anticoagulants (13% for dabigatran, 22% for rivaroxaban, 22% for apixaban, and 18% for edoxaban; Pinteraction=0.02). The prevalence of overdosed DOACs was 5% (95% CI, 3–7%), with the lowest prevalence observed in apixaban (2%). Subgroup analyses by regions demonstrated that the prevalence of DOAC off-label doses was higher in Asia (32%) than in North America (14%) and in Europe (22%), with underdose being predominant. Regardless of different regions, the prevalence of overdose was relatively low (4–6%).Conclusion: This study provides an estimation of DOAC off-label doses in the real-world setting. The prevalence rate of DOAC off-label doses in AF patients was relatively high, with underdose being predominant. Clinicians in Asia preferred to prescribe underdose of DOACs to AF patients. More evidence about the appropriateness of DOAC off-label doses in AF patients is urgently needed. Education programs concerning the appropriate prescription of DOACs within the drug labels and accepted guidelines are necessary to DOAC prescribers to ensure the safety and effectiveness of anticoagulation therapy for patients with AF.

Aims: This retrospective study assessed the association between sulfonylureas use and infarct size in patients with type 2 diabetes (T2DM) and ST-segment elevation myocardial infarction (STEMI) by myocardial enzymology indexes and cardiac magnetic resonance (CMR) imaging.Methods: Patients presenting STEMI between July 2013 and August 2019 were included in a retrospective database at our institution. Antidiabetic agents used before STEMI were recorded. Patients with maximum recorded troponin I (max cTNI) and creatine phosphokinase isoenzyme (CK-MB) within the first 72 h of chest pain onset were selected. Infarct size was quantified by CMR imaging, and cardiovascular outcomes were also obtained at 30 days and 6 months follow-up. Multivariable regression models explored potential risk factors associated with infarct size and clinical outcomes.Results: A total of 254 T2DM and STEMI patients were included, with 101 sulfonylurea users and 153 non-users. Sulfonylureas users were not associated with higher max cTnI and max CK-MB compared to non-users. Among 65 CMR patients, no significant differences in infarct size were detected between sulfonylureas users and non-users. Whereas, the incidence of microvascular obstruction (MVO) was higher in patients receiving sulfonylureas than those taking non-sulfonylureas (88.0 vs. 62.5%, p = 0.023). No higher cardiovascular events of sulfonylureas users vs. non-users were observed, except for heart failure events (24.0 vs. 2.5% at 30 days, p = 0.011; 28.0 vs. 2.5% at 6 months, p = 0.004). Multivariable regression analyses verified that sulfonylureas users increased the risks of MVO.Conclusions: Sulfonylureas use did not associate with larger infarct size in patients with T2DM and STEMI. A potentially higher incidence of MVO in sulfonylurea users was found. Notably, since most patients presented after a relatively long period of ischemia and glibenclamide was not used by the included patients in this observational study, the results of this study should not be extrapolated to clinical settings with short periods of ischemia or to patients using glibenclamide.

Background: The publication of high-quality observational studies (OSs) has fueled reassessment of the treatment effects of direct oral anticoagulants (DOACs) in the elderly with atrial fibrillation (AF).Methods: The MEDLINE, EMBASE, and Cochrane Library databases were systematically searched (through July 1, 2019) for eligible OSs and randomized controlled trials (RCTs) that reported effectiveness outcomes [stroke or systemic embolism (SE)] or safety outcomes [intracranial hemorrhage (ICH), major bleeding, gastrointestinal bleeding (GIB), myocardial infarction (MI), and all-cause mortality] for DOACs and vitamin-K antagonists (VKAs) in elderly AF patients. A random-effects model was applied to calculate adjusted hazard ratios (HRs) for OSs and relative risks (RRs) for RCTs. Interaction analyses and the ratio of HR (RHR) were used to assess and compare OSs and RCTs.Results: A total of 32 studies involving 547,419 patients were included. No significant difference in treatment effect estimates was found between 27 OSs and 5 RCTs [Pinteraction > 0.05 for each and all 95% confidence interval (CI) of RHR crossed 1.0]. Compared with VKAs, DOACs significantly reduced risk for stroke/SE (OSs, HR: 0.87, 95% CI: 0.81–0.94; RCT, RR: 0.82, 95% CI: 0.67–0.96), and ICH (OSs: 0.47 [0.37–0.57]; RCTs: 0.47 [0.31–0.63]), without increasing risk for GIB (OSs: 1.21 [0.98–1.43]; RCTs: 1.34 [0.91–1.77]), and all-cause mortality (OSs: 1.01 [0.92–1.11]; RCTs: 0.94 [0.87–1.00]). Among OSs, DOACs significantly decreased risk for major bleeding (0.87 [0.77–0.98]) and MI (0.89 [0.79–0.99]). It was found that dabigatran, but not other DOACs, significantly increased risk for GIB (1.48 [1.23–1.72]).Conclusions: DOACs were demonstrated to be more effective and safer than VKAs in elderly AF patients, whereas dabigatran users had a 48% increase in risk for GIB.

Background: Emerging evidence shows that coronavirus disease 2019 (COVID-19) is commonly complicated by coagulopathy, and venous thromboembolism (VTE) is considered to be a potential cause of unexplained death. Information on the incidence of VTE in COVID-19 patients, however, remains unclear.Method: English-language databases (PubMed, Embase, Cochrane), Chinese-language databases (CNKI, VIP, WANFANG), and preprint platforms were searched to identify studies with data of VTE occurrence in hospitalized COVID-19 patients. Pooled incidence and relative risks (RRs) of VTE were estimated by a random-effects model. Variations were examined based on clinical manifestations of VTE (pulmonary embolism-PE and deep vein thrombosis-DVT), disease severity (severe patients and non-severe patients), and rate of pharmacologic thromboprophylaxis (≥60 and

Abstract Background Bacterial infections have become more challenging to treat due to the emergence of multidrug-resistant pathogenic bacteria. Combined antibiotics prove to be a relatively effective method to control such resistant strains. This study aim to investigate synergistic activity of eugenol combined with colistin against a collection of clinical isolated Escherichia coli (E.coli) strains, and to evaluate potential interaction. Methods Antimicrobial susceptibility, minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) of the bacteria were determined by disk diffusion assay, broth microdilution method and checkerboard assay, respectively. The mcr-1 mRNA expression was measured by Real-time PCR. To predict possible interactions between eugenol and MCR-1, molecular docking assay was taken. Results For total fourteen strains including eight colistin-resistant strains, eugenol was determined with MIC values of 4 to 8 μg/mL. Checkerboard dilution test suggested that eugenol exhibited synergistic activity when combined with colistin (FICI ranging from 0.375 to 0.625). Comparison analysis of Real-time PCR showed that synergy could significantly down-regulate expression of mcr-1 gene. A metal ion coordination bond with catalytic zinc atom and a hydrogen bond with crucial amino acid residue Ser284 of MCR-1 were observed after molecular docking, indicating antibacterial activity and direct molecular interactions of eugenol with MCR-1 protein. Conclusions Our results demonstrated that eugenol exhibited synergistic effect with colistin and enhanced its antimicrobial activity. This might further contribute to the antibacterial actions against colistin-resistant E.coli strains. Graphical abstract Synergistic effect of eugenol with colistin against colistin-resistant Escherichia coli isolates.

Abstract Background In recent years, highly frequent swine respiratory diseases have been caused by extraintestinal pathogenic Escherichia coli (ExPEC) in China. Due to this increase in ExPECs, this bacterial pathogen has become a threat to the development of the Chinese swine industry. To investigate ExPEC pathogenesis, we isolated a strain (named SLPE) from lesioned porcine lungs from Changchun in China, reported the draft genome and performed comparative genomic analyses. Results Based on the gross post-mortem examination, bacterial isolation, animal regression test and 16S rRNA gene sequence analysis, the pathogenic bacteria was identified as an ExPEC. The SLPE draft genome was 4.9 Mb with a G + C content of 51.7%. The phylogenomic comparison indicated that the SLPE strain belongs to the B1 monophyletic phylogroups and that its closest relative is Avian Pathogenic Escherichia coli (APEC) O78. However, the distribution diagram of the pan-genome virulence genes demonstrated significant differences between SLPE and APEC078. We also identified a capsular polysaccharide synthesis gene cluster (CPS) in the SLPE strain genomes using blastp. Conclusions We isolated the ExPEC (SLPE) from swine lungs in China, performed the whole genome sequencing and compared the sequence with other Escherichia coli (E. coli). The comparative genomic analysis revealed several genes including several virulence factors that are ExPEC strain-specific, such as fimbrial adhesins (papG II), ireA, pgtP, hlyF, the pix gene cluster and fecR for their further study. We found a CPS in the SLPE strain genomes for the first time, and this CPS is closely related to the CPS from Klebsiella pneumoniae.

Eugenol, the major active essential oil component of clove, was reported to possess QS (quorum sensing) inhibitory activity. A previous study found that eugenol could bind to quorum sensing receptors of Pseudomonas aeruginosa and down-regulate the expression of Streptococcus mutans virulence genes at sub-MIC (minimum inhibitory concentration) without affecting the bacterial growth. However, the alterations of QS signal molecules at transcription levels was not well understood. To better understand interactions of Klebsiella pneumoniae in response to eugenol and explore molecular regulations, transcriptome sequencing was performed. A total of 5779 differentially expressed genes (DEGs) enriched in a variety of biological processes and pathways were identified. The transcriptional data was validated by qPCR and the results showed that the expression profiles of 4 major genes involved in autoinducers-2 (AI-2) synthesis, including luxS, pfs, and lsrK were consistent with transcriptome analysis except for lsrR, a transcriptional repressor gene of lsr operon, which may repress the expression of following genes responsible for AI-2 signal transmission in vivo. In vitro AI-2 synthesis assay also revealed that eugenol could inhibit AI-2 generation. The results of our study offer insights into the mechanisms of QS inhibitory activity and K. pneumoniae AI-2 alterations after eugenol treatment.

In recent years, aerosols have been recognized as a prominent medium for the transmission of antibiotic-resistant bacteria and genes. Among these, particles with a particle size of 2 μm (PM2.5) can directly penetrate the alveoli. However, the presence of antibiotic-resistant genes in aerosols from pet hospitals and the potential risks posed by antibiotic-resistant bacteria in these aerosols to humans and animals need to be investigated. In this study, cefotaxime-resistant bacteria were collected from 5 representative pet hospitals in Changchun using a Six-Stage Andersen Cascade Impactor. The distribution of bacteria in each stage was analyzed, and bacteria from stage 5 and 6 were isolated and identified. Minimal inhibitory concentrations of isolates against 12 antimicrobials were determined using broth microdilution method. Quantitative Polymerase Chain Reaction was employed to detect resistance genes and mobile genetic elements that could facilitate resistance spread. The results indicated that ARBs were enriched in stage 5 (1.1–2.1 μm) and stage 3 (3.3–4.7 μm) of the sampler. A total of 159 isolates were collected from stage 5 and 6. Among these isolates, the genera Enterococcus spp. (51%), Staphylococcus spp. (19%), and Bacillus spp. (14%) were the most prevalent. The isolates exhibited the highest resistance to tetracycline and the lowest resistance to cefquinome. Furthermore, 56 (73%) isolates were multidrug-resistant. Quantitative PCR revealed the expression of 165 genes in these isolates, with mobile genetic elements showing the highest expression levels. In conclusion, PM2.5 from pet hospitals harbor a significant number of antibiotic-resistant bacteria and carry mobile genetic elements, posing a potential risk for alveolar infections and the dissemination of antibiotic resistance genes.

Abstract Background Multidrug resistance in Enterobacteriaceae including resistance to quinolones is rising worldwide. The development of resistance may lead to the emergence of new transmission mechanisms. In this study, the collection of different E. coli was performed from animals and subjected to subsequent procedures including pulsed-field gel electrophoresis, micro-broth dilution method, polymerase chain reaction. Whole genome sequencing of E. coli C3 was performed to detect the affinity, antimicrobial resistance and major carriers of the isolates. Results A total of 66 E. coli were isolated and their antibiotic resistance genes, frequency of horizontal transfer and genetic environment of E. coli C3 were determined. The results showed there were both different and same types in PFGE typing, indicating clonal transmission of E. coli among different animals. The detection of antimicrobial resistance and major antibiotic resistance genes and the plasmid transfer results showed that strains from different sources had high levels of resistance to commonly used clinical antibiotics and could be spread horizontally. Whole-genome sequencing discovered a novel ICE mobile element. Conclusion In summary, the antimicrobial resistance of E. coli in northeast China is a serious issue and there is a risk of antimicrobial resistance transmission. Meanwhile, a novel ICE mobile element appeared in the process of antimicrobial resistance formation.

Aims The prognostic implication of left ventricular (LV) torsion on ST-elevation myocardial infarction (STEMI) is unclear. Methods and results We analysed cardiovascular magnetic resonance (CMR) findings of 420 patients from a registry study (NCT03768453). These patients received CMR examination within 1 week after timely primary percutaneous coronary intervention. LV torsion and other CMR indexes were measured. Compared with healthy control subjects, STEMI significantly decreased patients' LV torsion (1.04 vs. 1.63°/cm, P < 0.001). During follow-up (median, 52 months), the reduction of LV torsion was greater in patients with than without composite major adverse cardiac and cerebrovascular events (MACCEs, 0.79 vs. 1.08°/cm, P < 0.001). The risk of MACCEs would increase to 1.125- or 1.092-fold, and the risk of 1-year LV remodelling would increase to 1.110- or 1.082-fold for every 0.1°/cm reduction in LV torsion after adjustment for clinical or CMR parameters respectively. When divided dichotomously, patients with LV torsion≤ 0.802°/cm had significantly higher risk of MACCEs (40.2 vs. 12.3%, P < 0.001) and more remarkable LV remodelling (46.1 vs. 11.9%, P < 0.001) than patients with better LV torsion. The addition of LV torsion to conventional prognostic factors such as the LV ejection fraction and infarction size led to a better risk classification model of patients for both MACCEs and LV remodelling. Finally, tobacco use, worse post-PCI flow, and greater microvascular obstruction size were presumptive risk factors for reduced LV torsion. Conclusion LV torsion measured by CMR is closely associated with the prognosis of STEMI and would be a promising indicator to improve patients' risk stratification. Clinical Trial Registration Clinicaltrials.gov, NCT03768453 [ABSTRACT FROM AUTHOR]