CRISPR-Cas3 and type I restriction-modification team up against blaKPC-IncF plasmid transfer in Klebsiella pneumoniae.

OBJECTIVE: We explored whether the Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification (R-M) systems are compatible and act together to resist plasmid attacks. METHODS: 932 global whole-genome sequences from GenBank, and 459 K. pneumoniae isolates from six provinces of China, were collected to investigate the co-distribution of CRISPR-Cas, R-M systems, and blaKPC plasmid. Conjugation and transformation assays were applied to explore the anti-plasmid function of CRISPR and R-M systems. RESULTS: We found a significant inverse correlation between the presence of CRISPR and R-M systems and blaKPC plasmids in K. pneumoniae, especially when both systems cohabited in one host. The multiple matched recognition sequences of both systems in blaKPC-IncF plasmids (97%) revealed that they were good targets for both systems. Furthermore, the results of conjugation assay demonstrated that CRISPR-Cas and R-M systems in K. pneumoniae could effectively hinder blaKPC plasmid invasion. Notably, CRISPR-Cas and R-M worked together to confer a 4-log reduction in the acquisition of blaKPC plasmid in conjugative events, exhibiting robust synergistic anti-plasmid immunity. CONCLUSIONS: Our results indicate the synergistic role of CRISPR and R-M in regulating horizontal gene transfer in K. pneumoniae and rationalize the development of antimicrobial strategies that capitalize on the immunocompromised status of KPC-KP.

Association of adiposity indices with cardiometabolic multimorbidity among 101,973 chinese adults: a cross-sectional study.

BACKGROUND: Cardiometabolic multimorbidity (CMM) and obesity represent two major health problems. The relationship between adiposity indices and CMM, however, remains understudied. This study aimed to investigate the associations of body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), a body shape index (ABSI), body roundness index (BRI), and conicity index (CI) with CMM among Chinese adults. METHODS: Data of 101,973 participants were collected from a population-based screening project in Southern China. CMM was defined as having two or more of the following diseases: coronary heart disease, stroke, hypertension, and diabetes. The relationship between the six adiposity indices and CMM was investigated by multivariate logistic regression and restricted cubic splines. Receiver operator characteristic curve, C-statistic and net reclassification index were used to estimate the discriminative and incremental values of adiposity indices on CMM. RESULTS: Logistic regression models showed the six adiposity indices were all significantly associated with the odds of CMM with non-linear relationships. For per SD increment, WC (Odds ratio [OR]: 1.66; 95% confidence interval (CI): 1.62-1.70) and WHtR (OR, 1.61; 95% CI, 1.58-1.65) were more significantly associated with a higher prevalence of CMM than BMI (OR, 1.55; 95% CI, 1.52-1.58) (all P < 0.05). In addition, WC, WHtR, and BRI displayed significantly better performance in detecting CMM compared with BMI (all P < 0.05). Their respective area under the curve (AUC) values were 0.675 (95% CI: 0.670-0.680), 0.679 (95% CI: 0.675-0.684), and 0.679 (95% CI: 0.675-0.684), while BMI yielded an AUC of 0.637 (95% CI: 0.632-0.643). These findings hold true across all subgroups based on sex and age. When Adding WC, WHtR, or BRI to a base model, they all provided larger incremental values for the discrimination of CMM compared with BMI (all P < 0.05). CONCLUSIONS: Adiposity indices were closely associated with the odds of CMM, with WC and WHtR demonstrating stronger associations than BMI. WC, WHtR, and BRI were superior to BMI in discriminative ability for CMM. Avoidance of obesity (especially abdominal obesity) may be the preferred primary prevention strategy for CMM while controlling for other major CMM risk factors.

Optimal ablation index parameters for radiofrequency ablation therapy of atrial fibrillation.

Objectives: To explore the optimal ablation index (AI) parameters for radiofrequency catheter ablation (RA) for treating atrial fibrillation (AF). Methods: Patients with AF (186) who underwent bilateral PVAI in the Department of Cardiology, Zhuhai People's Hospital, Guangdong Province, from March 2018 to October 2019 and received catheter ablation as first-round treatment, were grouped according to the received AI. Control group included patients (95) who received the recommended AI ablation (350-400 for posterior wall, 400-450 for non-posterior wall). Patients in optimal AI group were ablated with optimal AI (300-330 for posterior wall, 350-380 for non-posterior wall). Recurrence was defined as any AF, atrial tachycardia, or atrial flutter lasting more than 30 seconds without anti-arrhythmic drugs after the 3-month blank period. Results: Of 186 patients, 66 patients had paroxysmal atrial fibrillation and a mean CHA2DS2-VASc score of 2.83±1.64. Isolation rates of bilateral PVI in both groups were 91.4% and 93.6%, for patients with paroxysmal atrial fibrillation, and 81.7% and 80% for patients with persistent atrial fibrillation (P > 0.05). Left atrial function index (LAFI) decreased under the condition of sinus rhythm at the 3rd and 6th months (P < 0.05). LAFI improvement was significantly better in the optimal AI group than in the control group (P < 0.05). Rates of pain and cough during the ablation, and postoperative gastrointestinal discomfort and use of PPIs were higher in the control group (P < 0.05). The recurrence rate was 14.7% and 14.3% after 12 months of follow-up, respectively, and the difference was not statistically significant (P > 0.05). Conclusion: Radiofrequency ablation of AF, guided by optimal AI combined with impedance, can minimize atrial injury, prevent atrial failure, promote the recovery of atrial function, reduces intraoperative cough, pain, and postoperative gastrointestinal discomfort and use of PPIs.

Preliminary Study on the Safety and Efficacy of One-Stop Treatment of Percutaneous LAAO Combined with Coronary Intervention for Higher Risk of Bleeding in Patients with AF Complicated with CHD.

AIMS: To explore the feasibility, safety, and efficacy of 1-stop treatment of percutaneous left atrial appendage occlusion (LAAO) combined with coronary intervention for patients with nonvalvular atrial fibrillation (AF) complicated with coronary heart disease (CHD). METHODS AND RESULTS: We retrospectively analyzed the clinical data of 6 patients with AF combined with CHD admitted from Zhuhai People's Hospital from April 2017 to June 2018. After the operation, all patients were treated with aspirin (100 mg qd) and clopidogrel (75 mg qd) for 1 year, which is considered long-term use of aspirin/clopidogrel. The effects of LAAO and coronary intervention were evaluated immediately. The location of the left atrial appendage occluder, thrombosis, residual leak, and clinical manifestations were observed during the 90-day follow-up. The patients were implanted with Watchman™ devices and coronary stents. After the operation, the immediate sealing effect was satisfactory. The Watchman occluder was used in accordance with the PASS principle (position, anchor, size, seal), and the coronary intervention was satisfactory. During the operation, there were no device-related thrombosis, tamponade, or vascular complications. Follow-up results showed that in the 6 patients, there were no hemorrhagic strokes, worsening heart function, residual leakage, device-related thrombosis, angina pectoris, myocardial infarction, skin ecchymosis, gastrointestinal bleeding, or cerebral hemorrhage. CONCLUSION: For patients with nonvalvular AF combined with CHD, the safety and feasibility of 1-stop treatment with left atrial appendage and coronary intervention are reliable, and the curative effects were also satisfactory at short- and medium-term follow-up.

Successfully minimal approach ViV-TAVR without angiography in a severe restenosis with renal dysfunction 17 years post-surgical aortic valve replacement: A case report.

Severe aortic stenosis (AS) is a major cause of morbidity and mortality in the elderly. Transcatheter aortic valve replacement (TAVR) is an approach in cardiovascular interventional therapy. As we known, most of the candidates for TAVR are suffered from advanced heart dysfunction (New York Heart Association functional class III or IV) and chronic kidney disease. However, contrast-enhanced computed tomography and coronary angiography are necessary for pre-procedures for TAVR. TAVR could have adverse effects on kidney function including contrast-induced acute kidney injury (CI-AKI), which is related to poor prognosis. In a severe recurrent valve stenosis with progressive renal dysfunction, receiving surgical aortic valve replacement (SAVR) using bioprosthetic valve (BV) 17 years ago, we successfully reversed restenosis by performing pre-procedure evaluating and valve-in-valve (ViV) TAVR without angiography. Angiography-free TAVR may be a beneficial approach for patients with aortic restenosis after SAVR complicated with renal dysfunction.

Absence of the type I-E CRISPR-Cas system in Klebsiella pneumoniae clonal complex 258 is associated with dissemination of IncF epidemic resistance plasmids in this clonal complex.

BACKGROUND: The pandemics caused by MDR Klebsiella pneumoniae are mostly due to the global dissemination of high-risk clonal complex 258 (CC258) and related IncF epidemic plasmids. However, the factors leading to the epidemiological advantages of CC258-IncF linkage remain obscure. The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) and CRISPR-associated protein (CRISPR-Cas) systems, providing adaptive immunity against invading DNA, play an important role in the interactions between plasmids and hosts. OBJECTIVES: To investigate the relationship between CRISPR-Cas systems and the high-risk linkage CC258-IncF. METHODS: CRISPR-Cas loci were detected among 381 collected K. pneumoniae clinical isolates and 207 K. pneumoniae complete genomes available in GenBank. MLST was used to determine the genetic relatedness of these isolates. Nucleotide BLAST was used to search for protospacers on K. pneumoniae plasmids. RESULTS: We observed an epidemic correlation between CRISPR-Cas loci, CC258 and IncF plasmids. Interestingly, most type I-E CRISPR-Cas systems identified carried spacers matching the backbone regions of IncF plasmids. CONCLUSIONS: Our results suggest that the absence of type I-E CRISPR-Cas systems in K. pneumoniae CC258 is strongly associated with the dissemination of IncF epidemic plasmids, contributing to the global success of the international high-risk linkage CC258-IncF. Our findings provide new information regarding the dissemination and evolution of the high-risk linkage of K. pneumoniae CC258-IncF and pave the way for new strategies to address the problem of antibiotic resistance.

Identification of hypervirulent Klebsiella pneumoniae isolates using the string test in combination with Galleria mellonella infectivity.

Distinguishing between hypervirulent Klebsiella pneumoniae (hvKp) and classical Klebsiella pneumoniae (cKp) is a challenge to clinical laboratories. The aim of this study was to determine the practicability of combining the G. mellonella killing assay with a string test to differentiate hvKp from cKp. One hundred and three clinical K. pneumoniae isolates were collected. PCR amplification and wzi sequencing were used to determine the capsular serotype. Virulence genes allS, iro, iuc, and rmpA2, used frequently to identify hvKp, were detected by PCR. The virulence of K. pneumoniae isolates was evaluated using the following assays in parallel: molecular markers detection, G. mellonella killing assay alone, G. mellonella killing assay combined with the string test, and mouse infection. The results showed that the sensitivity, specificity, positive predictive value, and negative predictive value of combining the G. mellonella killing assay with a string test were 95.56%, 94.83%, 93.48%, and 96.49%, respectively, compared with mouse infection used as a positive reference. These values were significantly greater than those obtained using the G. mellonella killing assay only. The sensitivity, specificity, positive predictive value, and negative predictive value of allS, iro, iuc, and rmpA2 were greater than 77.78%, but less than combining the G. mellonella killing assay and string test. G. mellonella killing assay used in conjugation with the string test is a relatively simple and accurate method to assess K. pneumoniae virulence and differentiate between hvKp and cKp.

Resistance reported from China antimicrobial surveillance network (CHINET) in 2018.

The aim of this study is to investigate the antimicrobial susceptibility of strains isolated from the major hospitals in China. A total of 44 teaching hospitals were involved. Antimicrobial susceptibility testing was conducted by Kirby-Bauer automated systems, and results were interpreted using CLSI criteria. Totally 244,843 strains were isolated in 2018, of which gram-negative bacilli and gram-positive cocci were accounting for 71.8% and 28.2%, respectively. 39.7% of isolates were cultured from lower respiratory tract, 18.8% from urine, 14.8% from blood, 1.3% from cerebrospinal fluid, respectively. Of those, the five major species were most often isolated (65.5%, 63%, 52.3%, and 30.3%). The resistance rate of MRSA to most antimicrobial agents was significantly higher than that of MSSA strains, except for to trimethoprim-sulfamethoxazole in urine specimen. E.coli was still highly susceptible to carbapenem antibiotics, and the resistance rate was less than 5%. Carbapenem resistance among Klebsiella pneumoniae, especially cultured from cerebrospinal fluid, increased significance from 18.6 to 64.1%. The resistance rates of Pseudomonas aeruginosa to carbapenems were nearly 30% in the blood, in urine, and in the lower respiratory tract, but about 60% of that in cerebrospinal fluid. About 80% of Acinetobacter baumannii strains was resistant to imipenem and meropenem, respectively. Bacterial resistance of five major clinical isolates from cerebrospinal fluid to common antibiotics (in particular Carbapenem-resistant Klebsiella pneumoniae) currently shows an increasing trend. It is worth to emphasize the importance of serious control of hospital infection and better management of clinical use of antimicrobial agents.

Oral anticoagulant prescribing in elderly patients above and below age 80 with atrial fibrillation
.

BACKGROUND: Oral anticoagulation is efficient to prevent ischemic stroke in atrial fibrillation (AF), but in very old patients, physicians always remain cautious to use anticoagulants concerning the bleeding risk. This research aims to investigate the current situation of oral anticoagulation therapy in very old (≥ 80 years) AF patients. MATERIALS AND METHODS: We carried out a cross-sectional study in an urban area in China from 2014 to 2016. Characteristics of the very old patients (age ≥ 80 years) and the younger patients (age < 80 years) were compared. Logistic analysis was used to estimate the association between oral anticoagulation therapy and CHA2DS2-VASc score. RESULTS: A total of 1,000 AF patients were enrolled; 306 were very old patients, and 694 were younger patients. In the very old group, 48.0% were women, and the average age was 84.12 ± 3.62 years. In the younger group, 35.3% were women, and the average age was 66.92 ± 9.02 years. CHA2DS2-VASc score was 2.8 ± 1.7 in the younger group and 4.5 ± 1.5 in the very old group (p < 0.001). The proportion of oral anticoagulation was low in patients with AF (31.8%) and even lower in very old patients compared to younger patients (24.5 vs. 35.0%, p = 0.004). Moreover, oral anticoagulation therapy was strongly associated with CHA2DS2-VASc scores only in the younger group, but not in the very old group, which means the very old patients were not treated with oral anticoagulation according to their elevated CHA2DS2-VASc scores. CONCLUSION: Anticoagulants were underused in AF patients, particularly in very old patients. Evidence is accumulating that the very old patients could still benefit from anticoagulants so that physicians should not exclude such patients from anticoagulation only because of their older age.

The association of metabolic syndrome components and chronic kidney disease in patients with hypertension.

BACKGROUND: Hypertension is a highly prevalent disease and the leading cause of chronic kidney disease (CKD). Metabolic syndrome could also be the risk factor for CKD. We sought to study the association between metabolic syndrome components and the prevalence of CKD in patients with hypertension. METHODS: We carried out a multi-center cross-sectional study from Apr. 2017- Apr. 2018 in 15 cities in China. RESULTS: A total of 2484 patients with hypertension were enrolled. Among them, 56% were male and the average age was 65.12 ± 12.71 years. The systolic BP/diastolic BP was 142 ± 18/83 ± 12 mmHg. Metabolic syndrome components turned out to be highly prevalent in patients with hypertension, ranging from 40 to 58%. The prevalence of chronic kidney disease reached 22.0%. Multi-variate logistic analysis revealed that elevated triglyceride (TG) (OR = 1.81, 95% CI 1.28-2.57, p < 0.01), elevated fasting blood glucose (FBG) (OR = 1.43, 95% CI 1.00-2.07, p = 0.05) and hypertension grades (OR = 1.20, 95% CI 1.00-1.44, p = 0.05) were associated with the prevalence of CKD. In sub-group analysis, elevated TG remained strongly associated with CKD in both diabetes (OR = 2.10, 95%CI 1.22-3.61, p < 0.01) and non-diabetes (OR = 1.53, 95% CI 1.09-2.16, p = 0.01). In sub-group analysis of hypertension grades, there was also a graded trend between elevated TG and CKD from controlled blood pressure (BP) to hypertension grade 2 (OR = 1.81, 95%CI 1.06-3.11, p = 0.03; OR = 1.85, 95%CI 1.00-3.43, p = 0.05; OR = 2.81, 95% CI 1.09-7.28, p = 0.03, respectively). CONCLUSION: Elevated TG, elevated FBG and hypertension grades were significantly associated with the prevalence of CKD in patients with hypertension. Particularly, elevated TG was strongly associated with CKD, independent of diabetes and hypertension grades.

MicroRNA-31 promotes adverse cardiac remodeling and dysfunction in ischemic heart disease.

RATIONALE: Myocardial infarction (MI) triggers a dynamic microRNA response with the potential of yielding therapeutic targets. OBJECTIVE: We aimed to identify novel aberrantly expressed cardiac microRNAs post-MI with potential roles in adverse remodeling in a rat model, and to provide post-ischemic therapeutic inhibition of a candidate pathological microRNA in vivo. METHODS AND RESULTS: Following microRNA array profiling in rat hearts 2 and 14days post-MI, we identified a time-dependent up-regulation of miR-31 compared to sham-operated rats. A progressive increase of miR-31 (up to 91.4±11.3 fold) was detected in the infarcted myocardium by quantitative real-time PCR. Following target prediction analysis, reporter gene assays confirmed that miR-31 targets the 3´UTR of cardiac troponin-T (Tnnt2), E2F transcription factor 6 (E2f6), mineralocorticoid receptor (Nr3c2) and metalloproteinase inhibitor 4 (Timp4) mRNAs. In vitro, hypoxia and oxidative stress up-regulated miR-31 and suppressed target genes in cardiac cell cultures, whereas LNA-based oligonucleotide inhibition of miR-31 (miR-31i) reversed its repressive effect on target mRNAs. Therapeutic post-ischemic administration of miR-31i in rats silenced cardiac miR-31 and enhanced expression of target genes, while preserving cardiac structure and function at 2 and 4weeks post-MI. Left ventricular ejection fraction (EF) improved by 10% (from day 2 to 30 post-MI) in miR-31i-treated rats, whereas controls receiving scrambled LNA inhibitor or placebo incurred a 17% deterioration in EF. miR-31i decreased end-diastolic pressure and infarct size; attenuated interstitial fibrosis in the remote myocardium and enhanced cardiac output. CONCLUSION: miR-31 induction after MI is deleterious to cardiac function while its therapeutic inhibition in vivo ameliorates cardiac dysfunction and prevents the development of post-ischemic adverse remodeling.

Translocation of Carbapenemase Gene blaKPC-2 both Internal and External to Transposons Occurs via Novel Structures of Tn1721 and Exhibits Distinct Movement Patterns.

The blaKPC-2 gene encodes a carbapenemase that hydrolyzes almost all ß-lactams, including carbapenems. The rapid emergence and international spread of this gene in Enterobacteriaceae seriously limit clinical treatment, posing an alarming threat for public health. Transposable elements, such as Tn4401, a proven transposon in Europe, the United States, and elsewhere, often play a role in the dissemination of the blaKPC-2 gene. In eastern China, the blaKPC-2 gene is frequently associated with several novel structures of Tn1721, but their transposition ability and mechanism of movement remain unclear. Here, we experimentally demonstrate that Tn1721-like transposons are capable of transferring blaKPC-2 both internal and external to the Tn1721 element from one strain to another and that distinct transposon structures exhibit different movement patterns and transposition frequencies. This process did not involve homologous recombination. Moreover, a 5-bp duplication of the target site, a characterized signature of transposition events in the Tn3 family, was confirmed. Tn1721-like transposons were found to insert preferentially into a 5-bp region that gradually exhibits a degenerated degree of AT-rich regions from both sides to the middle and that is immediately flanked by GC-rich regions. The observation in clinical isolates of diverse sequences flanking the transposons and a 5-bp duplication of the target site, as well as the prevalence of Tn1721-like transposons, also sustained our experimental results. This study first gives evidence about the functional role of Tn1721-like transposons in transferring the blaKPC-2 gene and provides new sight into the transposable element and the dissemination of antibiotic resistance in Enterobacteriaceae.

Dynamin-related protein inhibitor downregulates reactive oxygen species levels to indirectly suppress high glucose-induced hyperproliferation of vascular smooth muscle cells.

Hyperproliferation of vascular smooth muscle cells is a pathogenic mechanism common in diabetic vascular complications and is a putatively important therapeutic target. This study investigated multiple levels of biology, including cellular and organellar changes, as well as perturbations in protein synthesis and morphology. Quantitative and qualitative analysis was utilized to assess the effect of mitochondrial dynamic changes and reactive oxygen species(ROS) levels on high-glucose-induced hyperproliferation of vascular smooth muscle cells. The data demonstrated that the mitochondrial fission inhibitor Mdivi-1 and downregulation of ROS levels both effectively inhibited the high-glucose-induced hyperproliferation of vascular smooth muscle cells. Downregulation of ROS levels played a more direct role and ROS levels were also regulated by mitochondrial dynamics. Increased ROS levels induced excessive mitochondrial fission through dynamin-related protein (Drp 1), while Mdivi-1 suppressed the sensitivity of Drp1 to ROS levels, thus inhibiting excessive mitochondrial fission under high-glucose conditions. This study is the first to propose that mitochondrial dynamic changes and ROS levels interact with each other and regulate high-glucose-induced hyperproliferation of vascular smooth muscle cells. This finding provides novel ideas in understanding the pathogenesis of diabetic vascular remodeling and intervention.

First report of a clinical, multidrug-resistant Enterobacteriaceae isolate coharboring fosfomycin resistance gene fosA3 and carbapenemase gene blaKPC-2 on the same transposon, Tn1721.

In order to understand the genetic background and dissemination mechanism of carbapenem resistance and fosfomycin resistance in Enterobacteriaceae isolates, we studied a clinical Escherichia coli strain HS102707 isolate and an Enterobacter aerogenes strain HS112625 isolate, both of which were resistant to carbapenem and fosfomycin and positive for the bla(KPC-2) and fosA3 genes. In addition, a clinical Klebsiella pneumoniae strain HS092839 isolate which was resistant to carbapenem was also studied. A 70-kb plasmid was successfully transferred to recipient E. coli J53 by a conjugation test. PCR and Southern blot analysis showed that bla(KPC-2) was located on this plasmid. The complete sequence of pHS102707 showed that this plasmid belongs to the P11 subfamily (IncP1) and has a replication gene, several plasmid-stable genes, an intact type IV secretion system gene cluster, and a composite transposon Tn1721-Tn3 that harbored bla(KPC-2). Interestingly, a composite IS26 transposon carrying fosA3 was inserted in the Tn1721-tnpA gene in pHS102707 and pHS112625, leading to the disruption of Tn1721-tnpA and the deletion of Tn1721-tnpR. However, only IS26 with a truncated Tn21-tnpR was inserted in pHS092839 at the same position. To our knowledge, this is the first report of fosA3 and bla(KPC-2) colocated in the same Tn1721-Tn3-like composite transposon on a novel IncP group plasmid.

Mapping the resistance-associated mobilome of a carbapenem-resistant Klebsiella pneumoniae strain reveals insights into factors shaping these regions and facilitates generation of a 'resistance-disarmed' model organism.

OBJECTIVES: This study aims to investigate the landscape of the mobile genome, with a focus on antibiotic resistance-associated factors in carbapenem-resistant Klebsiella pneumoniae. METHODS: The mobile genome of the completely sequenced K. pneumoniae HS11286 strain (an ST11, carbapenem-resistant, near-pan-resistant, clinical isolate) was annotated in fine detail. The identified mobile genetic elements were mapped to the genetic contexts of resistance genes. The blaKPC-2 gene and a 26 kb region containing 12 clustered antibiotic resistance genes and one biocide resistance gene were deleted, and the MICs were determined again to ensure that antibiotic resistance had been lost. RESULTS: HS11286 contains six plasmids, 49 ISs, nine transposons, two separate In2-related integron remnants, two integrative and conjugative elements (ICEs) and seven prophages. Sixteen plasmid-borne resistance genes were identified, 14 of which were found to be directly associated with Tn1721-, Tn3-, Tn5393-, In2-, ISCR2- and ISCR3-derived elements. IS26 appears to have actively moulded several of these genetic regions. The deletion of blaKPC-2, followed by the deletion of a 26 kb region containing 12 clustered antibiotic resistance genes, progressively decreased the spectrum and level of resistance exhibited by the resultant mutant strains. CONCLUSIONS: This study has reiterated the role of plasmids as bearers of the vast majority of resistance genes in this species and has provided valuable insights into the vital role played by ISs, transposons and integrons in shaping the resistance-coding regions in this important strain. The 'resistance-disarmed' K. pneumoniae ST11 strain generated in this study will offer a more benign and readily genetically modifiable model organism for future extensive functional studies.

Optimization of the degumming process for camellia oil by the use of phospholipase C in pilot-scale system.

In present study, phospholipase C (PLC) was applied in camellia oil degumming and the response surface method (RSM) was used to determine the optimum degumming conditions (reaction time, reaction temperature and enzyme dosage) for this enzyme. The optimum conditions for the minimum residual phosphorus content (15.14 mg/kg) and maximum yield of camellia oil (98.2 %) were obtained at reaction temperature 53 ºC, reaction time 2.2 h, PLC dosage 400 mg/kg and pH 5.4. The application of phospholipase A (PLA) - assisted degumming process could further reduce the residual phosphorus content of camellia oil (6.84 mg/kg) to make the oil suitable for physical refining while maintaining the maximal oil yield (98.2 %). These results indicate that PLC degumming process in combination with PLA treatment can be a commercially viable alternative for traditional degumming process. Study on the quality changes of degummed oils showed that the oxidative stability of camellia oil was slightly deceased after the enzymatic treatment, thus more attention should be paid to the oxidative stability in the further application.

Contribution of ß-lactamases and porin proteins OmpK35 and OmpK36 to carbapenem resistance in clinical isolates of KPC-2-producing Klebsiella pneumoniae.

Fifty-seven carbapenem-resistant Klebsiella pneumoniae isolates belonging to ST11 (50 isolates), ST423 (5 isolates), and two other sequence types were studied. All were positive for blaKPC-2, blaTEM-1, and blaCTX-M-14. SDS-PAGE analysis of six representative isolates demonstrated varied porin expression. Nevertheless, when blaKPC-2 was deleted, carbapenem resistance was markedly reduced. Additionally, SHV-12, DHA-1, and/or VIM-1 appeared to contribute to accessory carbapenemase activity. In contrast, OmpK35 and/or OmpK36 deficiency seemed to serve only as a minor cooperative factor.

Insights from metagenomics into gut microbiome associated with acute coronary syndrome therapy.

Acute coronary syndrome (ACS) is a predominant cause of mortality, and the prompt and precise identification of this condition is crucial to minimize its impact. Recent research indicates that gut microbiota is associated with the onset, progression, and treatment of ACS. To investigate its role, we sequenced the gut microbiota of 38 ACS patients before and after percutaneous coronary intervention and statin therapy at three time points, examining differential species and metabolic pathways. We observed a decrease in the abundance of Parabacteroides, Escherichia, and Blautia in patients after treatment and an increase in the abundance of Gemalla, Klebsiella variicola, Klebsiella pneumoniae, and others. Two pathways related to sugar degradation were more abundant in patients before treatment, possibly correlated with disorders of sugar metabolism and risk factors, such as hyperglycemia, insulin resistance, and insufficient insulin secretion. Additionally, seven pathways related to the biosynthesis of vitamin K2 and its homolog were reduced after treatment, suggesting that ACS patients may gradually recover after therapy. The gut microbiota of patients treated with different statins exhibited notable differences after treatment. Rosuvastatin appeared to promote the growth of anti-inflammatory bacteria while reducing pro-inflammatory bacteria, whereas atorvastatin may have mixed effects on pro-inflammatory and anti-inflammatory bacteria while increasing the abundance of Bacteroides. Our research will provide valuable insights and enhance comprehension of ACS, leading to better patient diagnosis and therapy.

Diversity of gene cassette promoter variants of class 1 integrons in uropathogenic Escherichia coli.

Class 1 integrons play important roles in the emergence and horizontal transfer of antibiotic resistance genes among bacteria. The gene cassette promoter variants Pc or Pc-P2 of class 1 integrons not only drive the transcription of downstream gene cassettes, they also correlate with the excision and integration efficiency of the capture exogenous gene cassettes. In this study, the diversity of Pc or Pc-P2 variants of class 1 integrons and their association with antibiotic resistance phenotypes were analyzed in 132 uropathogenic Escherichia coli strains. Class 1 integrons were detected in 95 (72 %) strains. Sixteen different gene cassettes, 11 different gene cassette arrays and six different Pc or Pc-P2 variants were detected. The most prevalent gene cassettes were those that conferred resistance to trimethoprim, aminoglycosides, and chloramphenicol. The most prevalent promoter was PcH1, a relatively weak promoter. Certain gene cassette arrays or gene cassettes were mainly associated with the same Pc or Pc-P2 in different strains. Strains harboring class 1 integrons with relatively strong promoters had higher resistance rates to, or higher MIC(50) for, amikacin, chloramphenicol and tobramycin than those with relatively weak promoters. To the best of our knowledge, this is the first report of the diversity of class 1 integron Pc or Pc-P2 variants in uropathogenic E. coli strains.

Influence of roasted flaxseed marc flour on rheological, structural, fermentation, water distribution, and migration properties of wheat dough.

Roasted flaxseed (RF) marc, which is a by-product obtained from RF oil extraction, has high nutritional value. This study evaluated the impact of RF marc flour on rheological, structural, fermentation, water distribution, and migration properties of the wheat dough. Results showed that adding RF into wheat flour (WF) could effectively increase the water absorption in the dough and retard the retrogradation of starch. The fermentation results revealed that adding RF could improve the gas retention coefficient of dough. Compared to the dough prepared with WF, the doughs enriched with RF had higher tan Î´ values (ratio of loss modulus G″ to storage modulus G'), indicating a more liquid-like property. The mobility of tightly bound and free water in dough was decreased by adding RF, whereas the distribution of free water was increased. On the one hand, adding RF would dilute the gluten content in dough, resulting in a weaker protein network. On the other hand, the dietary fiber and proteins in RF could offset the gluten dilution effect to some extent. Overall, the results suggested that the substitution level of RF in WF should be below 25% to avoid serious dough quality deterioration, and the RF-WF blended flour could be a potential ingredient to produce wheat products with moist taste. These findings could be useful for guiding the future usage of RF marc in wheat-based products.