Effects of whole grain intake on glycemic traits: A systematic review and meta-analysis of randomized controlled trials.

Whole grains (WGs) may have various health benefits, including lowering blood glucose and improving insulin sensitivity. To conduct a meta-analysis of the effects of WGs compared with non-WGs on changes in fasting glucose, fasting insulin, glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR). A systematic literature search was performed for all published randomized controlled trials on the effects of WG intake on fasting glucose, fasting insulin, HbA1c and HOMA-IR response up to February 2021. Weighted mean differences (WMD) were calculated. Pre-specified subgroup and univariate meta-regression analyses were explored to identify the sources of heterogeneity. Sensitivity analysis and bias analysis were conducted to appraise study quality. Among 12,435 articles screened for eligibility, data were extracted from 48 articles. Meta-analysis of 4,118 participants showed that WG consumption resulted in a significant reduction in fasting glucose by -0.15 mmol/L, fasting insulin by -2.71 pmol/L, HbA1c by -0.44%, and HOMA-IR by -0.28, respectively. Compared with mixed grains, brown rice, and wheat, oats were significantly lower on marker of glycemic. Besides, multiple interventions per day consolidated effectiveness of WGs. WG consumption decreased the levels of fasting glucose, fasting insulin, HbA1c, and HOMA-IR compared with non-WG consumption.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.2001429 .

Nosocomial transmission and rearrangement of large resistance-virulence hybrid plasmids between two bacteremic ST11 carbapenem-resistant hypervirulent Klebsiella pneumoniae strains with low fitness cost.

OBJECTIVES: To characterize nosocomial transmission and rearrangement of the resistance-virulence plasmid between two ST11-K64 carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) strains (JX-CR-hvKP-10 and JX-CR-hvKP-9) with low fitness. METHODS: Phenotypic tests were used to assess the virulence of JX-CR-hvKP-10 and JX-CR-hvKP-9. Whole-genome sequencing was used to analyze JX-CR-hvKP-10 and JX-CR-hvKP-9 chromosomes and plasmids. Fitness and conjugation experiments were also conducted using these two CR-hvKP isolates. RESULTS: Phenotypic tests indicated that both JX-CR-hvKP-10 and JX-CR-hvKP-9 were multidrug-resistant and hypervirulent K. pneumoniae. Whole-genome sequencing and clinical information demonstrated that the super large resistance-virulence fusion plasmid pJX10-1 formed precisely by the fusion of pJX9-1 and pJX9-2 via the nosocomial transmission. Interestingly pJX9-1 itself was also a classic resistance-virulence fusion plasmid by way of the blaKPC-carrying resistance plasmid and pLVPK-like virulence plasmid. Compared with classic K. pneumoniae ATCC700603, fitness analysis revealed no significant difference in growth was observed between JX-CR-hvKP-10 and JX-CR-hvKP-9. CONCLUSION: Nosocomial transmission and rearrangement of a blaKPC-harboring plasmid and a pLVPK-like virulence plasmid with a low fitness cost in ST11 K. pneumoniae enhances drug resistance and virulence simultaneously. Thus, active surveillance of this hybrid plasmid is needed to prevent these efficient resistance-virulence plasmids from disseminating in hospital settings.

Quasi-continuous tunable semiconductor laser based on the gain-lever effect with full C-band coverage fabricated by standard lithography.

A quasi-continuous tunable semiconductor laser covered full C-band is demonstrated. The quasi-continuous tuning range of the tunable semiconductor laser is significantly improved by optimizing the length of the phase section using the gain-lever effect, achieving a 36 nm range that covered the whole C-band. In the tuning range, 46 channels with 100 GHz spacing are achieved, and all channels exhibit a side mode suppression ratio above 30 dB. No regrowth or high-precision lithography is involved in the fabrication process of the tunable semiconductor laser, which has the potential to provide a cost-effective light source for dense wavelength division multiplexing systems.

Approaches to tuning the exceptional point of PT-symmetric double ridge stripe lasers.

Electrically injected Parity-time (PT)-symmetric double ridge stripe semiconductor lasers lasing at 980 nm range are designed and measured. The spontaneous PT-symmetric breaking point or exceptional point (EP) of the laser is tuned below or above the lasing threshold by means of varying the coupling constant or the mirror loss. The linewidth of the optical spectrum of the PT-symmetric laser is narrowed, compared with that of traditional single ridge (SR) laser and double ridge (DR) laser. Furthermore, the far field pattern of the PT-symmetric laser with EP below the lasing threshold is compared with that of the PT-symmetric laser with EP above the lasing threshold experimentally. It is found that when the laser start to lase, the former is single-lobed while the latter is double-lobed. when the current continues to increase, the former develops into double lobe directly while the latter first develops into single lobe and then double lobe again.

Effects of α-linolenic acid intake on blood lipid profiles：a systematic review and meta-analysis of randomized controlled trials.

To investigate the effect of ALA intake on blood lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein (VLDL-C) and ratio of TC to HDL-C. We systematically searched randomized controlled trials of ALA intervention on PubMed, Embase, Cochrane library and related references up to March 2018. The final values were calculated as weighted mean difference (WMD) by using a random effects model. Subgroup analysis and meta-regression were used to explore the source of heterogeneity. Generalized least square was performed for dose-response analysis. Forty-seven studies with 1305 individuals in the ALA arm and 1325 individuals in the control arm were identified. Compared with control group, dietary intake of ALA significantly reduced the concentrations of TG (WMD -0.101 mmol/L; 95% CI: -0.158 to -0.044 mmol/L; P = 0.001), TC (WMD -0.140 mmol/L; 95% CI: -0.224 to -0.056 mmol/L; P = 0.001), LDL-C (WMD -0.131 mmol/L; 95% CI: -0.191 to -0.071 mmol/L; P < 0.001), VLDL-C (WMD -0.121 mmol/L; 95% CI: -0.170 to -0.073 mmol/L; P < 0.001), TC/HDL-C ratio (WMD -0.165 mmol/L; 95% CI: -0.317 to -0.013 mmol/L; P = 0.033) and LDL-C/HDL-C ratio (WMD -0.158 mmol/L; 95% CI: -0.291 to -0.025 mmol/L; P = 0.02). There is no effect of ALA intake on HDL-C (WMD 0.008 mmol/L; 95% CI: -0.018 to 0.034 mmol/L; P = 0.541). Dose-response analysis indicated that 1 g per day increment of ALA was associated with a 0.0016 mmol/L, 0.0071 mmol/L, 0.0015 and 0.0061 mmol/L reduction in TG (95% CI: -0.0029 to -0.0002 mmol/L), TC (95% CI: -0.0085 to -0.0058 mmol/L), HDL-C (95% CI: -0.0020 to -0.0011 mmol/L) and LDL-C (95% CI: -0.0073 to -0.0049 mmol/L) levels, respectively. The effects of ALA intake on TG, TC and LDL-C concentrations were more obvious among Asian participants, and also more obvious on patients with hyperlipidemia or hyperglycemia compared to healthy individuals. Dietary ALA intervention improves blood lipid profiles by decreasing levels of TG, TC, LDL and VLDL-C. Our findings add to the evidence that increasing ALA intake could potentially prevent risk of cardiovascular diseases.

Phenotypical profile and global transcriptomic profile of Hypervirulent Klebsiella pneumoniae due to carbapenemase-encoding plasmid acquisition.

BACKGROUND: Plasmids play an vital role in driving the rapid global spread of antimicrobial resistance and adaptation to changing ambient conditions. It has been suggested that the presence of plasmids can pose tremendous impacts on the host physiology. However, little is known regarding the contributions of carbapenemase-encoding plasmid carriage on the physiology and pathogenicity of hypervirulent K. pneumoniae (hvKP). RESULTS: Here we performed a transcriptomic analysis of hvKP with or without carbapenemase-encoding plasmid p24835-NDM5. The results had shown 683 genes with differential expression (false discovery rate, ≤0.001; > 2-fold change), of which 107 were up-regulated and 576 were down-regulated. Gene groups with functions relating to carbohydrate metabolism and multidrug efflux system were increased in genes with increased expression, and those relating to capsule biosynthesis and virulence factors were increased in the genes with decreased expression. In agreement with these changes, survival rate of TfpNDM-hvKP in the presence of normal human serum decreased, and competitive index (CI values) indicated significant fitness defects in the plasmid-carrying hvKP strain when co-cultured with its plasmid-free isogenic ancestor and the ATCC control. Moreover, the p24835-NDM5-containing hvKP strain retained its high neutrophil-mediated phagocytosis and murine lethality. CONCLUSION: These data indicate that hvKP responds to carbapenemase-encoding plasmid by altering the expression of genes involved in carbohydrate metabolism, antibiotic resistance, capsule biosynthesis and virulence expression. Apart from antibiotic resistance selective advantages, carbapenemase-encoding plasmid carriage may also lead to virulence change or adaption to specific habitats in hvKP strain.

Whole genome assembly and functional portrait of hypervirulent extensively drug-resistant NDM-1 and KPC-2 co-producing Klebsiella pneumoniae of capsular serotype K2 and ST86.

OBJECTIVES: To characterize an emergent carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) strain, NUHL30457, which co-produces NDM-1 and KPC-2 carbapenemases. METHODS: We performed WGS analysis on a clinical carbapenemase-producing hypervirulent K. pneumoniae (CP-hvKP) strain NUHL30457. Sequence data were analysed using comparative genomics and phylogenetics. WGS was used to perform MLST, capsular genotyping and identification of virulence and antimicrobial resistance genes. The virulence of NUHL30457 was analysed by serum killing assay, neutrophil phagocytosis and mouse lethality assay. RESULTS: The NUHL30457 strain was carbapenem resistant and belonged to ST86 and serotype K2. A significant increase in resistance to serum killing and antiphagocytosis was found in the NUHL30457 strain compared with the reference strain. The murine lethality assay showed an LD50 of 2.5 × 102 cfu for the NUHL30457 strain, indicating hypervirulence. WGS revealed that NUHL30457 has a single 5.3 Mb chromosome (57.53% G + C content) and four plasmids in the range 49.2-215.7 kb. The incompatibility group (Inc)N plasmid p30457-4 carried the blaNDM-1 and qnrS1 genes. The IncFII(K) plasmid p30457-3 also carried an array of resistance elements, including blaCTX-M-65, blaTEM-1 and blaKPC-2. The IncHI1/IncFIB plasmid p30457-1, which carried virulence genes, was identical to a pLVPK plasmid reported previously. CONCLUSIONS: To the best of our knowledge, this is the first report to isolate an ST86 hvKP strain that co-produces NDM-1 and KPC-2 carbapenemase. Further investigation is required to reinforce our understanding of the epidemiology and virulence mechanisms of this clinically significant CP-hvKP.

Biological effects of trans fatty acids and their possible roles in the lipid rafts in apoptosis regulation.

A large number of recent studies are focused on evaluating the mechanism of action of trans fatty acids (TFAs) on the progression of apoptosis. A strong positive association has been reported between TFA and coronary heart disease (CHD), obesity and nonalcoholic steatohepatitis and so on. The present study reviewed the biological effects of trans fatty acids (TFA) and their possible roles in lipid rafts in regulating apoptosis. The following aspects of TFA were included: the research about TFA and diseases affecting serum lipid levels, inducing system inflammation and immune response, and the correlation between TFA and apoptosis. The primary purpose of the review article was to comprehensively evaluate the potential correlation between lipid rafts and apoptosis induced by different structures of TFA and provide some new research progress and future directions about it.

Obesity is associated with increased red blood cell folate despite lower dietary intakes and serum concentrations.

BACKGROUND: Folates are essential cofactors in metabolic pathways that facilitate biological methylation and nucleotide synthesis, and therefore have widespread effects on health and diseases. Although obesity is prevalent worldwide, few studies have investigated how obesity interacts with folate status. OBJECTIVE: Based on data from the NHANES, this study aims to examine the association between body mass index (BMI) and obesity-related metabolic factors with blood folate status. METHODS: A nationally representative sample of 3767 adults from the NHANES (2003-2006) was used as the study population. Regression analyses, with and without adjustment for demographic factors and dietary intakes, were performed to examine associations between BMI and metabolic factors with serum and RBC folate. RESULTS: The results indicate serum folate concentrations were lower in obese groups compared to the desirable BMI and overweight categories, paralleling lower intakes in this group. In contrast, RBC folate increased incrementally with BMI. Regression analyses demonstrated an inverse relation between BMI and serum folate but a positive relation for RBC folate (P < 0.01). Waist circumference, serum triglycerides, and fasting plasma glucose each displayed significant positive relations with RBC folate (P < 0.01), although relations with serum folate were not significant and consistent. CONCLUSIONS: In summary, obesity is associated with decreased serum folate, which parallels decreased folate intakes. In contrast, obesity is positively associated with RBC folate. Therefore, RBC folate, in addition to serum folate, should also be considered as a critical biomarker for folate status, especially in the obese population. Future research is needed to understand how obesity differentially alters serum and RBC folate status because they are associated with a variety of medical complications.

Effect of soluble dietary fiber on soy protein isolate emulsion gel properties, stability and delivery of vitamin D3.

Emulsion gels with denser network microstructure and stronger mechanical properties have attracted increasing attentions for delivering lipophilic compounds. In this study, the effect of three distinct soluble dietary fiber (inulin (IN), resistant dextrin (RD) and stachyose (ST)) on the rheological, mechanical and microstructural properties of soy protein isolate (SPI) emulsion gel were firstly investigated. Compared with RD and IN, ST significantly accelerated water holding capacity and thermal stability, which exhibited more compact microstructure and more uniform emulsified oil droplets. Subsequently, the stability and bioavailability of vitamin D3 (VD3) in different delivery systems (medium chain triglycerides (MCT) embedding, SPI-ST emulsion embedding, SPI emulsion gel embedding and SPI-ST emulsion gel embedding) were continue evaluated. In vitro simulated digestion experiment demonstrated that the bioaccessibility of encapsulated VD3 in SPI-ST emulsion gel (69.95 %) was much higher than that of free embedding (48.99 %). In vivo pharmacokinetic experiment revealed that the bioavailability of VD3 was significantly enhanced in SPI-ST gel (p < 0.05), with the AUC0-24h value of 25-OH VD3 (the main circulating form of VD3) were 1.34-fold, 1.23-fold higher than that of free embedding, MCT embedding, respectively. These findings provide a possible approach for the development of high protein/fiber functional foods containing enhanced hydrophobic bioactives.

Virulence Characteristics and Drug Resistance of the Prevalent Capsule Types in Acinetobacter baumannii.

Acinetobacter baumannii is a highly antibiotic-resistant pathogen causing nosocomial severe life-threatening infections, especially in critically ill patients. Capsular polysaccharide is a major virulence factor of A. baumannii both in vitro and in vivo. In this study, 220 isolates were collected in the hospital. The prevalent capsular types of A. baumannii were determined using polymerase chain reaction, and the clinical characteristics of infections were analyzed. The virulence of these strains was determined by serum-killing resistance, biofilm formation, and Galleria mellonella survival assays. Twenty-eight isolates (12.7%) carried KL2, and 22 isolates (10%) carried the types KL10, KL14, KL22, and KL52. Compared with non-KL2 (KL10, KL14, KL22, and KL52) isolates, KL2 isolates had significantly higher resistance to all antimicrobials except tigecycline, cefoperazone-sulbactam, or colistin. Seventy-five percent of KL2 A. baumannii and 72.7% of non-KL2 were highly virulent using a G. mellonella model. Biofilm formation was significantly different between the KL2 and non-KL2 groups. The biofilm production of non-KL2 A. baumannii was significantly stronger than that of KL2 A. baumannii. These findings highlight the role of KL2 as a powerful factor for drug resistance and virulence of A. baumannii.

Potential use of peanut by-products in food processing: a review.

Peanut is one of the most important oil and protein producing crops in the world. Yet the amounts of peanut processing by-products containing proteins, fiber and polyphenolics are staggering. With the environmental awareness and scarcity of space for landfilling, wastes/by-product utilization has become an attractive alternative to disposal. Several peanut by-products are produced from crush peanut processes and harvested peanut, including peanut meal, peanut skin, peanut hull and peanut vine. Some of peanut by-products/waste materials could possibility be used in food processing industry, The by-products of peanut contain many functional compounds, such as protein, fiber and polyphenolics, which can be incorporated into processed foods to serve as functional ingredients. This paper briefly describes various peanut by-products produced, as well as current best recovering and recycling use options for these peanut byproducts. Materials, productions, properties, potential applications in food manufacture of emerging materials, as well as environmental impact are also briefly discussed.

Effects of oligosaccharides on the markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials.

Objective: To investigate the effect of oligosaccharides on the markers of glycemic control, including fasting blood glucose (FBG), fasting blood insulin (FBI), glycated hemoglobin (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity index (QUICKI). Methods: PubMed, Embase, and the Cochrane Library databases were systematically searched to find randomized controlled trials (RCTs) on the effect of oligosaccharide intervention on FBG, FBI, HbA1c, HOMA-IR, and QUICKI up to 7 June 2021. Data were pooled using weighted mean difference (WMD) and 95% confidence intervals (95% CI), with a p-value ≤0.05 indicating statistical significance. Risk of bias was assessed with the Cochrane tool and the quality of the literature with the new Jadad scale. Results: A total of 46 randomized controlled trials were included. Oligosaccharides significantly reduced FBG (WMD: -0.295 mmol L-1; 95% CI: -0.396 to -0.193; p < 0.001; I2 = 90.9%; 46 trials; 2412 participants), FBI (WMD: -0.559 pmol L-1; 95% CI: -0.939 to -0.178; p < 0.01; I2 = 99.1%; 29 trials; 1462 participants), HbA1c (WMD: -0.365; 95% CI: -0.725 to -0.005; p < 0.05; I2 = 86.6%; 11 trials; 661 participants), and HOMA-IR (WMD: -0.793; 95% CI: -1.106 to -0.480; p < 0.001; I2 = 96.1%; 24 trials; 1382 participants). Oligosaccharides were more beneficial for the participants with obesity or diabetes than for healthy participants. Multiple interventions per day consolidated the effectiveness of oligosaccharides. Regardless of the processing manner (starch-modified or naturally extracted) of the oligosaccharides, their intervention was overall beneficial for the patients with diabetes. Conclusions: This study is by far the most extensive systematic review to evaluate the role of oligosaccharides on the markers of glycemic control. Oligosaccharide interventions can exert beneficial effects on FBG, FBI, HbA1c, and HOMA-IR.

Genetic characterization and passage instability of a novel hybrid virulence plasmid in a ST23 hypervirulent Klebsiella pneumoniae.

Hypervirulent variants of Klebsiella pnuemoniae (hvKP), which causes life-threatening infections, is a global priority pathogen and frequently harbours virulence plasmids. The virulence plasmids have emerged as the predominant vehicles carrying the major pathogenic determinants of hypermucoviscosity and hypervirulence phenotypes. In the present study, we characterized a novel virulence plasmid in AP8555, an ST23 hvKP strain, which induced a metastatic infection and fatal septic shock in a critically ill patient. The serum killing assay, the quantitative biofilm formation assay, the G.mellonella infection model, and the mouse lethality assay demonstrated that AP8555 was almost as virulent as the hvKP strain NUTH-K2044. The plasmid pAP855 could be conjugated to Klebsiella quasipneumoniae ATCC700603 and E. coli J53 at a frequency of 7.2× 10-5 and 8.7× 10-7, respectively. Whole-genome sequencing and bioinformatics analysis confirmed that the plasmid was novel, clustered to the incompatibility type of IncHI1B/IncFIB/IncFII and presented high similarity to the pK2044 plasmid. In contrast, a 130-kb large-fragment insertion was observed on the plasmid, which introduced a genetic hybrid zone with multiple conjugation-related genes of type IV secretion systems (T4SS) and CcdAB toxin-antitoxin systems (TAS) to the plasmid. In the transconjugants, the presence of pAP855 had a negative impact on bacterial fitness, but enhancing the virulence-associated phenotypes. In vitro evolution experiments showed that pAP855 in the transconjugants could not be stably inherited after 10 days of passage. Our study not only reports a novel hybrid plasmid but also highlights the putative pathway of conjugative virulence plasmid formation and evolution by means of genetic rearrangement through sequence insertion. These findings indicate that structural versatility could contribute to the dissemination of cointegrate virulence plasmid, although the plasmid incurred a fitness cost. Therefore, continuous monitoring the acquisition of conjugative virulence plasmids may have critical value for plasmid research and increase awareness of hvKP.

Dietary low ratio of n-6/n-3 polyunsaturated fatty acids improve type 2 diabetes mellitus via activating brown adipose tissue in male mice.

The ratio n-6/n-3 polyunsaturated fatty acids (PUFA) has been caused widespread discussion. However, the best ratio and mechanism of n-6/n-3 PUFA in type 2 diabetes mellitus (T2DM) are largely unknown. This study investigated the effects of different ratio of n-6/n-3 PUFA diets on brown adipose tissue (BAT) and T2DM in mice. Results showed that compared with high ratio of n-6/n-3 PUFA (50:1) diet, lower ratio of n-6/n-3 PUFA (1:1 and 5:1) diets significantly increased BAT mass by 67.55% and 60.49%, decreased the fasting blood glucose (24.87% and 20.64%), total cholesterol (32.9% and 23.84%), triglyceride (33.51% and 29.62%), low-density lipoprotein cholesterol (19.23% and 17.38%), and increased glucose tolerance by 21.99% and 15.52%. Further, qRT-PCR analyses indicated that lower ratio of n-6/n-3 PUFA diets activated BAT, increased the expression of Ucp1, ß-3AR, PPAR-γ, cAMP, GLU1, HSL, LPL, and PGC-1α, further improved lipid and glucose metabolism in T2DM mice. In conclusion, this study substantiated that the lower ratio of n-6/n-3 PUFA (1:1 and 5:1) improve symptoms associated with T2DM via activating BAT. PRACTICAL APPLICATION: Dietary ratio of n-6/n-3 polyunsaturated fatty acids is essential for the improvement of chronic diseases. Our current study showed that 1:1 or 5:1 ratio of n-6/n-3 polyunsaturated fatty acids had better efficiency for type 2 diabetes mellitus via activating brown adipose tissue when compared with 1:50. This finding provided useful guidance for the daily diet of patients with diabetes.

High Prevalence of 16s rRNA Methylase Genes Among Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae Isolates in a Chinese Tertiary Hospital.

Thirty-nine carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) isolates collected from a Chinese tertiary hospital were used in the characterization of the prevalence of 16S rRNA methylase genes. In total, 66.7% (26/39) of the CR-hvKP isolates were found to carry 16S rRNA methylase genes. The most frequently detected 16S rRNA methylase gene was armA (11/26, 42.3%), followed by rmtB (8/26, 30.8%), and coexistence of both armA and rmtB (7/26, 26.9%). All the clinical isolates were found to carry at least one carbapenemase gene, with blaKPC-2 (79.5%, 31/39), blaNDM-1 (10.3%, 4/39), and cocarrying blaKPC-2 and blaNDM-1 (10.3%, 4/39). A total of 89.7% (35/39) isolates carried extended-spectrum ß-lactamase (ESBL) genes, including 61.5% (24/39) blaSHV-1, 71.8% (28/39) blaTEM-1, and 89.7% (35/39) blaCTX-M-14. All except four isolates (89.7%, 35/39) harbored quinolone resistance genes, with qnrS (82.1%, 32/39), aac(6')-Ib-cr (79.5%, 31/39), and qnrB (2.6%, 1/39). Twenty-six hvKP strains in this study were first reported to cocarry carbapenemase genes, ESBL genes, quinolone resistance genes, and 16S rRNA methylase genes simultaneously. Multilocus sequence typing (MLST) analysis assigned the 39 CR-hvKP isolates into 4 sequence types (STs), with ST11 encompassing 79.5% of the strains. Pulsed field gel electrophoresis (PFGE) typing showed that strains closely related by MLST clustered in major PFGE clusters, of which cluster A accounts for 31 ST11 isolates. Cumulatively, 16S rRNA methylase genes are highly prevalent in CR-hvKP clinical isolates especially for ST11; it is, therefore, critical to continuously monitor the epidemiology of these 16S rRNA methylase-producing CR-hvKP while simultaneously minimizing potential risks from aminoglycoside-resistant CR-hvKP.

Microbiological and Clinical Characteristics of Klebsiella pneumoniae Isolates of K57 Capsular Serotype in China.

Background: K57 Klebsiella pneumoniae (K57-KP) is associated with hypervirulence, but the basis and systematic data of K57-KP are limited. Materials and Methods: A retrospective study was conducted in 156 patients between January 2013 and January 2016. The clinical and molecular data, including antimicrobial susceptibility testing, multilocus sequence typing, antimicrobial resistance genes, and virulence determinants were assessed. Results: Among the 39 K57-KP isolates, 14 isolates (35.9%) were associated with various types of invasive infections. Diabetes, drainage, use of carbapenems and quinolone antibiotics were dependent risk factors for K57-KP infections. Sequence type (ST)412 was the most prevalent among K57-KP isolates. K57-KP isolates were more resistant to clinically often used antimicrobial agents than hvKP (K1/K2) strains, and 12.8% (5/39) of the strains were resistant to carbapenems, which all harbored blaKPC-2. The prevalence of hypermucoviscosity phenotype, aerobactin, rmpA, rmpA2, and ybts revealed 66.7%, 100%, 89.7%, 89.7%, and 30.8%, whereas wcaG, allS, magA and kfu revealed 0%, 0%, 0%, and 5.1%, which were significantly lower than that of hvKP (K1/K2). The serum sensitivity, neutrophil phagocytic rate, and biofilm formation capacity of K57-KP strains were higher than that of K1/K2. Conclusion: There were no significant differences in the prevalence of hypermucoviscosity phenotype, carriage of rmpA and aerobactin genes between K57 and K1/K2 isolates, but the composition and production of capsule polysaccharide of K57-KP may be different from that of K1/K2 strains. K57-KP isolates exhibited distinctive virulence-associated traits, most of which belonged to ST412. Physicians should enhance the management of K57-KP infections because of the emergence of more and more carbapenem-resistant K57-KP isolates.

Prevalence of the NTEKPC-I on IncF Plasmids Among Hypervirulent Klebsiella pneumoniae Isolates in Jiangxi Province, South China.

Infection caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) has become a tricky health care threat in China and KPC-2 enzyme is a main factor mediating resistance to carbapenems of K. pneumoniae. Here, we report the characterization of the genetic environment of the blaKPC-2 gene in CR-hvKP clinical isolates from South China. Forty-five non-duplicated CR-hvKP isolates collected in Jiangxi Province from 2018 to 2019 were analyzed. Each of them were multidrug-resistant due to the presence not only of blaKPC-2 gene but also of other resistance determinants, including Metallo-ß-lactamases (NDM-1), extended-spectrum ß-lactamases (TEM-1, CTX-M-14, SHV-1), and plasmid-mediated quinolone resistance determinants (qnrS, aac(6')-Ib-cr). After plasmid analyses of PCR-based replicon typing (PBRT), mapping PCR, amplicon sequencing, and whole-genome sequencing (WGS) were used to analyze the genetic environment of the blaKPC-2 gene. PCR analysis of pLVPK-like plasmids, Southern Blot, and mouse lethality assay were used to characterize the virulence phenotype of K. pneumoniae. Multilocus sequence typing (MLST) analysis showed ST11 CR-hvKP was the predominant clone. In conclusion, this is the first analysis of diverse genetic structures blaKPC-2 gene in CR-hvKP isolates from south China. Both the NTEKPC-I on the IncF plasmids and pLVPK-like virulence plasmids make contributions to the formation of CR-hvKP especially ST11 which need more attention.

[Biosynthesis mechanisms of bacterial polysaccharide--a review].

Bacterial polysaccharides play important roles both in medicine and industry. Due to the development of bacterial genome sequencing, many gene clusters related to the biosynthesis of bacterial polysaccharide have been found, aligned and analyzed. Despite of their complex composition and structures, different bacterial polysaccharides are biosynthesized via similar pathways. This review discussed the research development of the biosynthetic mechanism of different bacterial polysaccharides, with emphasis on the glycosyltransferases and polymerases involved in the biosynthetic pathway.

Distribution of CRISPR-Cas Systems in Clinical Carbapenem-Resistant Klebsiella pneumoniae Strains in a Chinese Tertiary Hospital and Its Potential Relationship with Virulence.

Aim: In this study, we aimed to characterize the CRISPR-Cas systems in clinical carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates and to investigate the potential association of CRISPR-Cas systems with bacterial virulence. Methods: A total of 168 CRKP strains were collected from inpatients in a teaching hospital in Jiangxi Province. Five common carbapenemase genes, subtype genes of the CRISPR-Cas system, and 13 virulence genes were amplified by PCR using specific primers. The potential virulence of all the clinical CRKP strains was tested in a Galleria mellonella infection model. Results: PCR analysis of five common carbapenemase genes revealed the frequency of carbapenemase gene KPC-2 was the highest in the CRISPR-negative strains, compared to CRISPR type I-E* strains or CRISPR type I-E strains (p < 0.01). Isolates having the subtype I-E* CRISPR-Cas system tended to have more virulence genes such as magA, kfu, wcaG, and allS, compared to CRISPR-negative isolates and type I-E CRISPR-Cas isolates (p < 0.01). The average survival time of the larvae infected with the isolates having the subtype I-E* CRISPR-Cas system was significantly shorter than the other two group isolates (p < 0.05). Conclusion: The CRKP strains, which had the subtype I-E CRISPR-Cas system or the subtype I-E* CRISPR-Cas system, showed reduced acquisition of carbapenemase genes compared to CRISPR-negative isolates. Importantly, we first found that a small portion of "CR-hvKP" strains were selected from the CRKP clones, which had the type I-E* CRISPR-Cas systems.