Epidemiological characteristics and molecular features of carbapenem-resistant Enterobacter strains in China: a multicenter genomic study

Epidemiological characteristics and molecular features of carbapenem-resistant Enterobacter (CR-Ent) species remain unclear in China. In this study, we performed a genomic study on 92 isolates from Enterobacter-caused infections from a multicenter study in China. Whole genome sequencing (WGS) was used to determine the genome sequence of 92 non-duplicated CR-Ent strains collected from multiple tertiary health centres. The precise species of Enterobacter strains were identified by average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH). Molecular features of high-risk CR-Ent sequence type (ST) lineages and carbapenemase-encoding plasmids were determined. The result revealed that the most common human-source CR-Ent species in China was E. xiangfangensis (66/92, 71.93%), and the proportion of carbapenemase-producing Enterobacter (CP-Ent) in CR-Ent was high (72/92, 78.26%) in comparison to other global regions. Furthermore, ST171 and ST116 E. xiangfangensis were the major lineages of CP-Ent strains, and ST171 E. xiangfangensis was more likely to cause infections in older patients. Genomic analysis also highlighted the likelihood of intra-hospital/inter-hospital clonal transmission of ST171 and ST116 E. xiangfangensis. In addition, the bla_NDM-harbouring IncX3-type plasmid was identified as the prevalent carbapenemase-encoding plasmid carried by CR-Ent strains, and was experimentally confirmed to be able to self-transfer with high frequency. This study detailed the genomic and clinical characteristics of CR-Ent in China in the form of multicenter for the first time. The high risk of carbapenemase-producing ST171 and ST116 E. xiangfangensis, and the bla_NDM-harbouring IncX3-type plasmid were detected and emphasized.

Emergence of colistin-heteroresistant and carbapenem-resistant hypervirulent Klebsiella pneumoniae

OBJECTIVES

To investigate the clinical emergence of colistin-heteroresistant, hypervirulent, and multidrug-resistant Klebsiella pneumoniae, and characterize the underlying molecular mechanisms.

METHODS

The population analysis profiles (PAPs) method was used to detect colistin heteroresistance. The time-killing assay was used to examine the effect of colistin on carbapenem-resistant Klebsiella pneumoniae (CRKP) in vitro. Galleria mellonella larvae infection model was used to test the potential virulence. qRT-PCR assay was conducted to compare the expression levels of efflux pump genes. Next and third-generation sequencing were conducted to analyse the genomic features.

RESULTS

Two colistin-heteroresistant isolates were detected from a multi-center carbapenem-resistant Enterobacterales (CRE) surveillance study in China, which exhibited similar survival rates as the K2 hypervirulent reference strain ATCC 43816 in a G. mellonella larvae model. The two isolates belonged to ST11, harbouring the iucABCD, iutA, iroBCD, and rpmA2 hypervirulent genes and pLVPK-like virulence plasmids. Colistin showed a weak effect on the heteroresistant strains in vitro. The efflux pump genes acrA, acrB, tolC, oqxA, and oqxB were upregulated in this subpopulation compared to the parental strains.

CONCLUSIONS

This study showed the clinical emergence of colistin-heteroresistant, hypervirulent, and multidrug-resistant Klebsiella pneumoniae. AcrAB-TolC and OqxAB efflux overexpression were involved in mediating colistin heteroresistance.

[Interpretation of expert consensus for progressive collapsing foot deformity]

Adult flatfoot is a common foot deformity, mainly manifested as medial arch collapsing, hindfoot valgus and forefoot abduction. People have a more thorough understanding of the pathological changes and pathogenesis of flatfoot with further research. There is a new expert consensus for adult flatfoot published in Foot & Ankle Inter. in 2020. The expert panel reviewed the latest literature to develop consensus recommendations for flatfoot, including its nomenclature, diagnosis, classification and operative treatment. The consensus represents a new understanding of the disease and a new concept because of the authority of its authors and the comprehensiveness of its content, and it is also a phased summary of the theoretical and clinical progress of adult flatfoot. This article gives a detailed interpretation of the content in the consensus.

Multicenter Study of Colistin Heteroresistance in Carbapenem-Resistant Klebsiella pneumoniae Strains in China

Colistin has been considered a last-line option for the treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). Heterogeneous resistance to colistin leads to unexplained clinical colistin treatment failure for CRKP. Our study aimed to investigate the extent of colistin heteroresistance among CRKP strains in China. A total of 455 colistin-susceptible strains, collected from six tertiary care hospitals in China, were characterized. The overall rate of colistin heteroresistance was 6.2%, as determined by the population analysis profiles (PAPs). Genomic analysis revealed that 60.7% of the colistin-heteroresistant isolates belonged to the epidemic sequence type 11 (ST11) clone. Single-nucleotide polymorphisms (SNPs) suggested that 6 ST5216 strains shared the same origin. Each of the subpopulations had a ≥8-fold decrease in colistin MIC in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), which indicated that heteroresistance could be suppressed by an efflux pump inhibitor. In addition, our results suggested that the PhoPQ pathway plays an important role in the mechanisms of heteroresistance. IMPORTANCE The problem of CRKP has raised alarms concerning global health. Our study enriches the epidemiological study of colistin heteroresistance among CRKP strains in China, where the prevalence of this phenomenon was previously unknown. Importantly, colistin-heteroresistant strains may cause the failure of clinical treatment with colistin, even if the clinical laboratory reports that the strains are sensitive. The commonly used broth microdilution method is unable to detect this special phenomenon. Additionally, our results indicate that efflux pumps play a major role in colistin heteroresistance, and inhibitors can effectively reverse it. Our study is the first to provide a detailed analysis of the prevalence of colistin heteroresistance in China, as well as an analysis of the genetic mechanisms of this phenomenon.

Genomic characterization of carbapenem-resistant Klebsiella oxytoca complex in China: a multi-center study

Carbapenem-resistant (CR) Klebsiella oxytoca complex can be associated with high mortality, emerging as a new threat to the public health. K. oxytoca complex is phylogenetically close to K. pneumoniae, one of most common species associated with multidrug resistance in Enterobacterale. The latest research showed that K. oxytoca is a complex of six species. Currently, the epidemiological and genomic characteristics of CR K. oxytoca complex in China are still unclear. Here, we conducted a multi-center study on 25 CR K. oxytoca complex collected from five representative regions in China. These isolates were, respectively, recovered from respiratory tract (12 cases, 48.0%), abdominal cavity (5 cases, 20.0%), blood (4 cases, 16.0%), urine tract (3 cases, 12.0%) and skin or soft tissue (1 cases, 4.0%). Among them, 32.0% (8/25) of patients infected with K. oxytoca complex had a poor prognosis. In this study, three K. oxytoca complex species were detected, namely K. michiganensis, K. oxytoca and K. pasteurii, among which K. michiganensis was the most common. Three carbapenemase genes were identified, including bla_NDM-1 (10, 38.5%), bla_KPC-2 (9, 34.6%) and bla_IMP (6 bla_IMP-4 and 1 bla_IMP-8; 7, 26.9%). Subsequent multilocus sequence typing identified various sequence types (STs), among which ST43, ST92 and ST145 were relatively common. Different from the clonal dissemination of high-risk carbapenem-resistant K. pneumoniae strains, our research revealed a polyclonal dissemination characteristic of CR K. oxytoca complex in China. S1-nuclease PFGE and Southern blot experiment showed that carbapenemase genes were encoded in plasmids of different sizes. Two bla_NDM-harboring plasmids were subsequently sequenced, and were characterized to be IncX3 and IncC incompatibility groups, respectively. This is the first multi-center study of CR K. oxytoca complex in China, which improved our understanding of the prevalence and antimicrobial resistance characteristics of CR K. oxytoca complex in China.

Acinetobacter baumannii adaptation to the host pH microenvironment is mediated by allelic variation in a single residue of BauA protein

Acinetobacter baumannii has been listed as one of the most critical pathogens in nosocomial infections; however, the key genes and mechanisms to adapt to the host microenvironment lack in-depth understanding. In this study, a total of 76 isolates (from 8 to 12 isolates per patient, spanning 128 to 188 days) were longitudinally collected from eight patients to investigate the within-host evolution of A. baumannii. A total of 70 within-host mutations were identified, 80% of which were nonsynonymous, indicating the important role of positive selection. Several evolutionary strategies of A. baumannii to increase its potential to adapt to the host microenvironment were identified, including hypermutation and recombination. Six genes were mutated in isolates from two or more patients, including two TonB-dependent receptor genes (bauA and BJAB07104_RS00665). In particular, the siderophore receptor gene bauA was mutated in multiple isolates from four patients with three MLST types, and all mutations were at amino acid 391 in ligand-binding sites. With 391T or 391A, BauA was more strongly bound to siderophores, which promoted the iron-absorption activity of A. baumannii at acidic or neutral pH, respectively. Through the A/T mutation at site 391 of BauA, A. baumannii displayed two reversible phases to adapt to distinct pH microenvironments. In conclusion, we demonstrated the comprehensive within-host evolutionary dynamics of A. baumannii, and discovered a key mutation of BauA site 391 as a genetic switch to adapt to different pH values, which may represent a model in the pathogen evolutionary adaption of the host microenvironment.

Genomic characterization of a new phage BUCT541 against Klebsiella pneumoniae K1-ST23 and efficacy assessment in mouse and Galleria mellonella larvae

Over the past decades, the spread of multi-drug-resistant Klebsiella pneumoniae (MDR-KP) is becoming a new threat and new effective therapies against this pathogen are needed. Bacteriophage (phage) therapy is considered to be a promising alternative treatment for MDR-KP infections compared with antibacterial drug usage. Here, we reported a new phage BUCT541 which can lyse MDR-KP ST23. The genome of BUCT541 is a double-stranded linear 46,100-bp long DNA molecule with 48% GC content through the Next generation sequencing (NGS) data. A total of 81 open reading frames and no virulence or antimicrobial resistance genes are annotated in the BUCT541 genome. BUCT541 was able to lyse 7 of the 30 tested MDR-KP according to the host range analysis. And the seven sensitive strains belonged to the K. pneumoniae K1-ST23. BUCT541 exhibited high thermal stability (4–70°C) and broad pH tolerance (pH 3-11) in the stability test. The in vivo results showed that BUCT541 (4 × 10⁵ plaque-forming units (PFU)/each) significantly increased the survival rate of K. pneumoniae infected Galleria mellonella from 5.3% to 83.3% within 48 h. Moreover, in the mouse lung infection model, high doses of BUCT541 (2 × 10⁷ PFU/each) cured 100% of BALB/c mice that were infected with K. pneumoniae. After 30 h of treatment with phage BUCT541 of the multiplicity of infection (MOI) = 10, the K. pneumoniae in the lungs of mice was lower than 10⁴ CFU/mL, compared to the control group 10⁹ CFU/mL. Together, these findings indicate that phage BUCT541 holds great promise as an alternative therapy with excellent stability and a wide lysis range for the treatment of MDR-KP ST23 infection.

Capsule type defines the capability of Klebsiella pneumoniae in evading Kupffer cell capture in the liver

Polysaccharide capsule is the main virulence factor of K. pneumoniae, a major pathogen of bloodstream infections in humans. While more than 80 capsular serotypes have been identified in K. pneumoniae, only several serotypes are frequently identified in invasive infections. It is documented that the capsule enhances bacterial resistance to phagocytosis, antimicrobial peptides and complement deposition under in vitro conditions. However, the precise role of the capsule in the process of K. pneumoniae bloodstream infections remains to be elucidated. Here we show that the capsule promotes K. pneumoniae survival in the bloodstream by protecting bacteria from being captured by liver resident macrophage Kupffer cells (KCs). Our real-time in vivo imaging revealed that blood-borne acapsular K. pneumoniae mutant is rapidly captured and killed by KCs in the liver sinusoids of mice, whereas, to various extents, encapsulated strains bypass the anti-bacterial machinery in a serotype-dependent manner. Using capsule switched strains, we show that certain high-virulence (HV) capsular serotypes completely block KC’s capture, whereas the low-virulence (LV) counterparts confer partial protection against KC’s capture. Moreover, KC’s capture of the LV K. pneumoniae could be in vivo neutralized by free capsular polysaccharides of homologous but not heterologous serotypes, indicating that KCs specifically recognize the LV capsules. Finally, immunization with inactivated K. pneumoniae enables KCs to capture the HV K. pneumoniae. Together, our findings have uncovered that KCs are the major target cells of K. pneumoniae capsule to promote bacterial survival and virulence, which can be reversed by vaccination.

Klebsiella pneumoniae is a major human pathogen. While capsule is the main virulence factor of the pathogen, only several of more than 80 capsule serotypes are frequently identified in invasive infections. However, it remains unclear how capsule contributes to K. pneumoniae virulence. Here we show that capsule type defines K. pneumoniae virulence by differential escape of immune surveillance in the liver. While low-virulence (LV) types are captured by Kupffer cells (KCs), high-virulence (HV) types circumvent the anti-bacterial machinery. Further, inactivated K. pneumoniae vaccine enables KCs to capture the HV K. pneumoniae and protects mice from lethal infection. Our findings explain the clinical prevalence of HV capsule types, and provide promising insights for future vaccine development.

Robust Topological Nodal-Line Semimetals from Periodic Vacancies in Two-Dimensional Materials

A nodal-line semimetal (NLSM) is suppressed in the presence of spin-orbit coupling unless it is protected by a nonsymmorphic symmetry. We show that two-dimensional (2D) materials can realize robust NLSMs when vacancies are introduced on the lattice. As a case study we investigate borophene, a boron honeycomb-like sheet. While the Dirac cones of pristine borophene are shown to be gapped out by spin-orbit coupling and by magnetic exchange, robust nodal lines (NLs) emerge in the spectrum when selected atoms are removed. We propose an effective 2D model and a symmetry analysis to demonstrate that these NLs are topological and protected by a nonsymmorphic glide plane. Our findings offer a paradigm shift to the design of NLSMs: instead of searching for nonsymmorphic materials, robust NLSMs may be realized simply by removing atoms from ordinary symmorphic crystals.

Reducing clinical review burden for insertable cardiac monitors

Funding Acknowledgements

Type of funding sources: None.

Background

The insertable cardiac monitor (ICM) is an essential tool for the ambulatory diagnosis of arrhythmias. However, definitive diagnoses still rely on time-consuming, manual adjudication of electrograms (EGMs) transmitted to the patient care network. This EGM review burden may be minimized by automatically selecting a subset of EGMs for fast review without delaying the diagnosis.

Purpose

Develop EGM selection strategies to reduce the EGM review burden without delaying diagnoses.

Methods

A retrospective analysis of 1,000 randomly selected Abbott Confirm Rx devices with 90+ days of remote transmission history was performed, regardless of transmission frequency, and all EGMs were adjudicated as either true or false positive (TP, FP). Up to 3 EGMs per day per arrhythmia type were prioritized for review based on ventricular rate and episode duration, with rules specific to each arrhythmia type: atrial fibrillation (AF), tachycardia, bradycardia, and pause. The resulting reduction in EGM review burden and TP days (patient-days with at least 1 TP EGM), as well as any diagnostic delay from the first transmitted TP, were calculated relative to reviewing all transmitted EGMs.

Results

In this population and transmission period, at least one AF, tachycardia, bradycardia, and pause EGM was transmitted by 424, 343, 190, and 325 unique devices, respectively, with a total of 35,723, 12,239, 19,752, and 28,002 EGMs, and a total of 6,163, 1,572, 1,438, and 646 TP days. For these patients with ≥1 EGM, the median [IQR] EGM transmission rate was 2.6 [0.7, 11.6], 1.1 [0.4, 4.7], 2.1 [0.6, 10.7], and 3.4 [0.6, 29.9] EGMs/patient/month, respectively. The optimal EGM selection strategy reduced this EGM review burden by 43%, 67%, 76%, and 50%, while only missing 3.4%, 2.2%, 0.3%, and 0.2% of TP days, respectively. Ultimately, 97%, 99%, 99%, and 99% of devices with a TP AF, tachycardia, bradycardia, or pause EGM exhibited no diagnostic delay vs. reviewing all transmitted EGMs.

Conclusion

EGM prioritization rules for selecting up to 3 episodes/day significantly reduced EGM burden across all patients, not just "frequent fliers," with no delay-to-diagnosis in >97% of patients who exhibited a true arrhythmia. Implementing these rules on the patient care network may improve clinical workflow and ICM patient management. Abstract Figure.

Polymyxin resistance in carbapenem-resistant Enterobacteriaceae isolates from patients without polymyxin exposure: a multicentre study in China

Polymyxins were recently approved for the clinical treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections in China. The aim of this study was to determine the prevalence and molecular mechanisms of polymyxin-resistant CRE prior to the clinical application of polymyxin and to evaluate the potential for emerging polymyxin resistance in China. A total of 504 unique CRE isolates were collected from six tertiary-care hospitals in China between October 2016 and September 2017. All isolates underwent antimicrobial susceptibility testing. Clinical, demographic, antimicrobial exposure and infection data were collected from patients' medical charts. PCR detection, Sanger sequencing and reverse transcription real-time fluorescence quantitative PCR (RT-qPCR) were used to investigate the molecular mechanism of polymyxin resistance. A total 19 (3.8%) polymyxin-resistant isolates were identified, including Klebsiella pneumoniae, Escherichia coli, Klebsiella aerogenes and Enterobacter cloacae. Genetic analysis in K. pneumoniae strains identified insertion sequence (IS) elements (n = 3), a stop codon (n = 1) and gene deletion (n = 2) in mgrB and a pmrB missense mutation (T157P) (n = 1). Two E. coli isolates contained mcr-1 and an E. cloacae strain harboured a frameshift in mgrB. Further transcriptional analysis showed that pmrA, pmrB, pmrC and pmrK were significantly upregulated in polymyxin-resistant isolates. Despite the lack of polymyxin exposure, 3.8% of CRE were resistant to polymyxin in China. Both chromosomal and plasmid-encoded mechanisms were identified. Our study suggests that clinical practice should be alert to pre-existing polymyxin resistance among CRE isolates to avoid further dissemination of polymyxin resistance.

KCNMA1-AS1 attenuates apoptosis of epithelial ovarian cancer cells and serves as a risk factor for poor prognosis of epithelial ovarian cancer

OBJECTIVE

To explore the role of KCNMA1-AS1 in epithelial ovarian cancer (EOC) and its underlying mechanism.

PATIENTS AND METHODS

We first screened out the differentially expressed lncRNAs (KCNMA1-AS1) in the GEO (gene expression omnibus) database. The relationship between KCNMA1-AS1 expression and prognosis of EOC with different pathological types was analyzed by meta-analysis. Subsequently, KCNMA1-AS1 expressions in EOC tissues and normal ovarian tissues were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between KCNMA1-AS1 level with progression-free survival (PFS) and overall survival (OS) of EOC was analyzed. Furthermore, proliferation and migration of EOC cells transfected with the corresponding plasmids were analyzed by Cell Counting Kit-8 (CCK-8) and transwell assay, respectively. Apoptosis-related genes in EOC cells were detected by Western blot.

RESULTS

KCNMA1-AS1 was a risk factor for prognosis in high-grade, advanced and serous EOC. Upregulated KCNMA1-AS1 was found in EOC tissues than that of normal tissues, showing the diagnostic potential of KCNMA1-AS1 in EOC. Statistical analysis indicated that KCNMA1-AS1 was not correlated with the DFS, OS, age, histological type, lymph node metastasis and recurrence, but related to FIGO stage of EOC patients. For in vitro experiments, the proliferation and migration of were enhanced, and apoptosis of HO8910 cells overexpressing KCNMA1-AS1 was inhibited. Furthermore, elevated expressions of Caspase-3 and Caspase-9, as well as reduced expression of Bcl-xL, were observed after KCNMA1-AS1 knockdown in EOC cells.

CONCLUSIONS

KCNMA1-AS1 is overexpressed in EOC and negatively correlated with its prognosis. KCNMA1-AS1 participates in the occurrence and development of EOC by promoting proliferation, migration and inhibiting apoptosis of ovarian cancer cells via apoptosis pathway.

Multicenter Evaluation of the Xpert Carba-R Assay for Detection and Identification of Carbapenemase Genes in Sputum Specimens

Rapid diagnosis of infections caused by carbapenem-resistant Enterobacteriaceae (CRE) is crucial for proper treatment and infection control. The Xpert Carba-R assay is a qualitative multiplex real-time PCR method that qualitatively detects and differentiates five common carbapenemase genes (blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP) directly from rectal swabs or purified colonies within approximately 1 h. We performed a multicenter evaluation of the investigational use of the Carba-R assay for detection and differentiation of carbapenemase genes from sputum specimens in patients with a clinical diagnosis of pneumonia. The intra- and interassay coefficients of variation values for the Carba-R assay were 0.2% to 2.0% and 1.4% to 2.3%, respectively. A total of 301 sputum specimens were collected and tested. Compared to bacterial culture followed by PCR identification of resistance genes from colonies, the Carba-R assay reduced turnaround time from 56 to 84 h to less than 2 h. Carbapenemase genes were detected by the Carba-R assay in Klebsiella pneumoniae (n = 236), Escherichia coli (n = 22), Enterobacter cloacae (n = 23), Klebsiella oxytoca (n = 8), Serratia marcescens (n = 6), Citrobacter freundii (n = 4), and Klebsiella aerogenes (n = 2). The Carba-R assay detected 112 blaKPC (33.5%), 70 blaNDM (21.0%), 8 blaIMP (2.4%), and 2 blaVIM (0.6%) genes, with positive percent agreement, negative percent agreement, and concordance rates of 92.9%, 86.7%, and 88.3%, respectively, for the dominant blaKPC and 85.0%, 87.8%, and 87.4%, respectively, for the blaNDM genes. Neither method detected the blaOXA-48 carbapenemase gene. The convenient, rapid, and simple characteristics of the Xpert Carba-R assay make it a potential tool for CRE detection and identification directly in sputum specimens.

Reduced Ceftazidime-Avibactam Susceptibility in KPC-Producing Klebsiella pneumoniae From Patients Without Ceftazidime-Avibactam Use History - A Multicenter Study in China

KPC-producing Klebsiella pneumoniae (KPC-KP) is the most widely spread carbapenem-resistant Enterobacteriaceae (CRE) in China. Avibactam is a novel non-β-lactam β-lactamase inhibitor which is highly active against KPC. Recently, ceftazidime-avibactam (CAZ-AVI) was approved for clinical treatment in China. Here we conducted a retrospective study to examine the antimicrobial susceptibility of CAZ-AVI prior to its usage in China, and evaluated the potential to develop resistance in KPC-KP. CAZ-AVI MICs were tested in 347 KPC-KP isolates collected from patients with no prior treatment with this combination from six medical centers in China. Almost all isolates (n = 346; 99.7%) were CAZ-AVI-susceptible, with only 12 (3.5%) which showed reduced susceptibility (MIC ≥ 4/4 μg/ml) or resistance. The 12 isolates belong to ST11 and half of them carry virulence genes. In comparison to susceptible isolates, these isolates demonstrated higher bla _KPC-2 copy numbers and expressions, and demonstrated higher frequency of developing CAZ-AVI resistance.

In vitro activity of aztreonam-avibactam against metallo-β-lactamase-producing Enterobacteriaceae-A multicenter study in China

OBJECTIVES

To study the molecular epidemiology of clinical metallo-β-lactamase (MBL)-producing Enterobacteriaceae isolates in China and to evaluate the antimicrobial susceptibility of MBL-Enterobacteriaceae isolates to aztreonam-avibactam.

METHODS

Bacterial speciation was determined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PCR was used to screen for common carbapenemase genes. Antimicrobial susceptibility testing of common clinical antibiotics and aztreonam-avibactam was performed using the standard broth microdilution method.

RESULTS

A total of 161 MBL-Enterobacteriaceae isolates were included, with Klebsiella pneumoniae (n = 73, 45.4%) and Escherichia coli (n = 53, 32.9%) being the most common species. Among the 161 isolates, bla_NDM (n = 151), bla_IMP (n = 13), and bla_VIM (n = 2) were detected, including five strains (3.1%) co-harboring two MBLs. MBL-Enterobacteriaceae isolates frequently contained two (n = 55, 34.2%) or more (n = 89, 55.3%) additional serine β-lactamase genes (bla_KPC, bla_CTX-M, bla_TEM, or bla_SHV). Antimicrobial susceptibility testing showed that 81.4% of isolates (n = 131) were resistant to aztreonam. The rates of resistance to cefazolin, ceftazidime, ceftriaxone, cefotaxime, ampicillin-sulbactam, amoxicillin-clavulanic acid, and piperacillin-tazobactam were all over 90%. The addition of avibactam (4 μg/ml) significantly reduced the minimum inhibitory concentrations (MICs) of the aztreonam-resistant isolates by more than 8-fold (range ≤0.125 to 4 μg/ml), with a MIC₅₀/MIC₉₀ of ≤0.125/1 μg/ml among the 131 isolates. Overall, 96.9% (n = 156) of the total isolates were inhibited at an aztreonam-avibactam concentration of ≤1 μg/ml. Univariate and multivariate logistic regression analysis found that in patients with MBL-Enterobacteriaceae infections, the presence of pre-existing lung disease (adjusted odds ratio 8.267, 95% confidence interval 1.925-28.297; p = 0.004) was associated with a hazard effect on worse disease outcomes.

CONCLUSIONS

The combined use of aztreonam-avibactam is highly potent against MBL-Enterobacteriaceae and may serve as a new candidate for the treatment of infections caused by MBL-Enterobacteriaceae in China.

Pharmacologic therapy to induce weight loss in women who have obesity/overweight with polycystic ovary syndrome: a systematic review and network meta-analysis

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are almost three times more likely to be obese than those without PCOS. However, we have no specific interventions to induce weight loss so far and rely on drugs used to treat other symptoms of the syndrome or obesity in the general population.

OBJECTIVE

The objective of this study is to compare the effectiveness of metformin, inositol, liraglutide and orlistat to induce weight loss in women with PCOS and overweight/obesity.

METHODS

A search was conducted using the MEDLINE, EMBASE, PubMed and CENTRAL databases. Individually randomized, parallel group trials that evaluated the effects of these pharmacological treatments among adults or adolescents with PCOS and overweight/obesity, compared with a placebo or metformin group, were considered eligible. Registration number: PROSPERO CRD 42017076625.

RESULTS

Twenty-three trials reporting on 941 women were included in the network meta-analysis. The amount of weight lost differed significantly among the drugs (in descending order): liraglutide, orlistat and metformin. Liraglutide alone, liraglutide/metformin and metformin alone significantly reduced waist circumference, but no change was found with orlistat. Data for waist-to-hip ratio were only available for metformin, which had no significant effect.

CONCLUSION

Liraglutide appears superior to the other drugs in reducing weight and waist circumference.

[Progress in the diagnosis of carbapenem-resistant Enterobacteriaceae]

Carbapenem-resistant Enterobacteriaceae (CRE) is rising rapidly all over the world, and challenges clinical diagnosis and treatment by various genotypes. This paper summarizes the characteristics and diagnostic methods of CRE. CRE can be divided into three categories and five families with various characteristics and resistant genes. The diagnosis method include the Kirby-Bauer screening test, double disc synergetic inhibition test with carbapenems collaboration (double disc EDTA and meropenem, phenylboronic acid and meropenem), modified Hodge test, chromogenic medium detection for selected test of CRE, and Carba NP colorimetric test, PCR and sequencing for CRE confirmation test. Each method has its own advantages and disadvantages, and can be applied according to the local main popular CRE genetypes and experimental conditions.

Comparison between a novel human cortical bone screw and bioabsorbable interference screw for graft fixation of ACL reconstruction

OBJECTIVE

To compare the mechanical behavior of a novel bioabsorbable cortical interference screw (BCIS) with bioabsorbable interference screw (BIS; Polylactate hydroxyapatite) used for anterior cruciate ligament (ACL) reconstruction in femoral and tibial fixation with doubled Achilles tendon graft in vitro.

PATIENTS AND METHODS

30 paired goat knee specimens were harvested from 15 male sheep aged 18 months. All soft tissues were stripped from the bones of 20 paired specimens, and the last 10 paired specimens were stripped all soft tissues besides ACL (femur-ACL-tibia complex). The Achilles tendon was harvested as graft for ACL reconstruction. The specimens were divided into several groups: BCIS femoral fixation (group A, n=10), BIS femoral fixation (group B, n=10), BCIS tibial fixation (group C, n=10), BIS tibial fixation (group D, n=10), Group E is femur-ACL-tibia complex (n=10). Cyclic loading test was performed from 50 to 250 N at 1 Hz for 1000 cycles and followed by a load-to-failure test at 25 mm/sec. A paired t-test was used to compare the biomechanical properties of group A, B, E and group C, D, E.

RESULTS

No fixation structures failed during the cyclic phase. Cyclic displacement for group B was superior to group A, and showed statistically significant difference after 30, 100, 500, 1000 cycles. Group E got minimum cyclic displacements compared with group A and group B, and showed statistically significant difference after 500, 1000 cycles compared with group A. Cyclic displacement for group D was superior to group C, and showed statistically significant difference after 100, 500, 1000 cycles. Group E got minimum cyclic displacements compared with group C and group D, and showed statistically significant difference after 500,1000 cycles compared with group C. Regarding MFL, group A was superior to group B (572.10±111.12 N vs. 413.96±34.56 N, p=0.118), group E was superior to group A (599.74±85.45N vs. 572.10±111.12 N, p=0.992), and group C was superior to group D (802.88±240.07 N vs. 415.63±51.9 N, p<0.001), group C was superior to group E (802.88±240.07 N vs. 599.74±85.45 N, p=0.024). Regarding YL, group A was superior to group B (521.57±93.96 N vs. 366.99±44.66 N, p=0.109), group E was superior to group A (565.37±66.05 N vs. 521.57±93.96 N, p=0.952), and group C was superior to group D (735.63±242.91 N vs. 394.49±31.90 N, p<0.001), group C was superior to group E (735.63±242.91 N vs. 565.37±66.05 N, p=0.063). Regarding stiffness, group A was superior to group B (157.36±34.31 N/mm vs. 91.98±25.57 N/mm, p=0.001), group E was superior to group A (181.35±25.42 N vs. 157.36±34.31 N/mm, p=0.529), and group C was superior to group D (175.28±43.19 N/mm vs. 128.24±18.92 N/mm, p=0.032), group E was superior to group C (181.35±25.42 N/mm vs. 175.28±43.19 N/mm, p=0.995).

CONCLUSIONS

In vitro, this experimental study suggested the biomechanical properties of novel bioabsorbable cortical interference screw (BCIS) were superior to bioabsorbable interference screw (BIS) used for femoral and tibial anterior cruciate ligament (ACL) reconstruction in a goat knee model.

Clinical and bacteriological features and prognosis of ascitic fluid infection in Chinese patients with cirrhosis

Background

Spontaneous bacterial peritonitis (SBP) and bacterascites (BA) represent frequent and serious complications in cirrhosis patients with ascites. However, few detailed data are available regarding the clinical and bacteriological feature of SBP or BA patients in China.

Methods

We retrospectively analyzed bacteriological and clinical characteristics of patients with SBP and BA at Beijing 302 Hospital in China from January 2012 to December 2015.

Results

A total of 600 patients with SBP (n = 408) or BA (n = 192) were enrolled. Patients with BA appeared to have a less severe clinical manifestation and lower mortality rate than patients with SBP. Gram-negative bacteria formed the majority of pathogens in SBP (73.9%) and BA (55.8%) cases. Higher ascitic fluid polymorphonuclear leucocytes (PMN) count and hepatocellular carcinoma were independent risk factors for BA episode progressing to SBP. The concentration of blood urea nitrogen (BUN) was independent risk factor for 30-day mortality of BA patients. For patients with SBP, the independent risk factors for 30-day mortality were age, Model for End-Stage Liver Disease (MELD) score, septic shock and hepatocellular carcinoma. Patients with third-generation cephalosporin or carbapenems resistant infection had a significantly lower survival probability. There were significant differences in clinical characteristics and outcome among the major bacteria. Multivariate analysis showed that patients infected with Klebsiella spp. had higher hazard ratio of 30-day mortality.

Conclusion

Our study reported the bacteriological and clinical characteristics of patients with SBP and BA. Higher ascitic fluid PMN count and hepatocellular carcinoma were found to be independent risk factors for BA episode progressed to SBP. Outcome of ascitic fluid infection in patients with cirrhosis was influenced by the type of bacteria and antimicrobial susceptibility.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3101-1) contains supplementary material, which is available to authorized users.

Revealing the nature of low-temperature photoluminescence peaks by laser treatment in van der Waals epitaxially grown WS2 monolayers

Monolayers of transition metal dichalcogenides (TMD) are promising materials for optoelectronics devices. However, one of the challenges is to fabricate large-scale growth of high quality TMD monolayers with the desired properties in order to expand their use in potential applications. Here, we demonstrate large-scale tungsten disulfide (WS₂) monolayers grown by van der Waals Epitaxy (VdWE). We show that, in addition to the large structural uniformity and homogeneity of these samples, their optical properties are very sensitive to laser irradiation. We observe a time instability in the photoluminescence (PL) emission at low temperatures in the scale of seconds to minutes. Interestingly, this change of the PL spectra with time, which is due to laser induced carrier doping, is employed to successfully distinguish the emission of two negatively charged bright excitons. Furthermore, we also detect blinking sharp bound exciton emissions which are usually attractive for single photon sources. Our findings contribute to a deeper understanding of this complex carrier dynamics induced by laser irradiation which is very important for future optoelectronic devices based on large scale TMD monolayers.

Improved apple latent spherical virus-induced gene silencing in multiple soybean genotypes through direct inoculation of agro-infiltrated Nicotiana benthamiana extract

BACKGROUND

Virus induced gene silencing (VIGS) is a powerful genomics tool for interrogating the function of plant genes. Unfortunately, VIGS vectors often produce disease symptoms that interfere with the silencing phenotypes of target genes, or are frequently ineffective in certain plant genotypes or tissue types. This is especially true in crop plants like soybean [Glycine max (L.) Merr]. To address these shortcomings, we modified the inoculation procedure of a VIGS vector based on Apple latent spherical virus (ALSV). The efficacy of this new procedure was assessed in 19 soybean genotypes using a soybean Phytoene desaturase (GmPDS1) gene as the VIGS target. Silencing of GmPDS1 was easily scored as photo-bleached leaves and/or stems.

RESULTS

In this report, the ALSV VIGS vector was modified by mobilizing ALSV cDNAs into a binary vector compatible with Agrobacterium tumefaciens-mediated delivery, so that VIGS-triggering ALSV variants could be propagated in agro-infiltrated Nicotiana benthamiana leaves. Homogenate of these N. benthamiana leaves was then applied directly onto the unifoliate of young soybean seedlings to initiate systemic gene silencing. This rapid inoculation method bypassed the need for a particle bombardment apparatus. Among the 19 soybean genotypes evaluated with this new method, photo-bleaching indicative of GmPDS1 silencing was observed in nine, with two exhibiting photo-bleaching in 100% of the inoculated individuals. ALSV RNA was detected in pods, embryos, stems, leaves, and roots in symptomatic plants of four genotypes.

CONCLUSIONS

This modified protocol allowed for inoculation of soybean plants via simple mechanical rubbing with the homogenate of N. benthamiana leaves agro-infiltrated with ALSV VIGS constructs. More importantly, inoculated plants showed no apparent virus disease symptoms which could otherwise interfere with VIGS phenotypes. This streamlined procedure expanded this functional genomics tool to nine soybean genotypes.

The use and discontinuation of hormone replacement therapy in women in South China

OBJECTIVE

The use of hormone replacement therapy (HRT) started later in China than in European countries. The purpose of the present study was to investigate HRT patterns and reasons for the initiation and discontinuation of HRT among women in South China.

METHODS

A telephone survey about menopausal status, the use of HRT, reasons for HRT discontinuation and duration of HRT treatment was conducted in 2014.

RESULTS

A total of 825 telephone surveys were carried out, and 217 previous HRT users and 390 current users were recruited for this study. Among these 607 subjects, 50.7% of the women sought out HRT for hot flushes, 41.6% for fatigue and 41.5% for sleeplessness. Approximately one-third (35.9%) of the patients abandoned HRT during the following year. The reasons for stopping HRT were mainly fear of breast and uterine cancer (28.4%), reduced menopausal symptoms (22.9%) and the inconvenience of taking pills or seeing a doctor (17.9%). The factors related to HRT discontinuation were the age when HRT was initiated (odds ratio 1.59, 95% confidence interval 1.19-2.13) and education level (odds ratio 0.78, 95% confidence interval 0.62-0.98).

CONCLUSIONS

The duration of HRT use in women in south China was short, and a high proportion of the women discontinued HRT. Given the high discontinuation rate and the low medical compliance, Chinese health-care providers still have much to do to let women know about the advantages and disadvantages of HRT and to encourage the use of HRT appropriately.

Decreased γ-aminobutyric acid levels in the brainstem in patients with possible sleep bruxism: A pilot study

BACKGROUND

An increasing number of studies have indicated that the central and autonomic nervous systems play roles in the genesis of sleep bruxism (SB). The role of specific neurochemicals in SB has been a subject of interest.

OBJECTIVE

In this study, we use proton magnetic resonance spectroscopy (¹ H-MRS) to determine whether the levels of γ-aminobutyric acid (GABA) and glutamate (Glu) are different in the brainstem and bilateral cortical masticatory area (CMA) between possible sleep bruxism (SB) patients and controls, and discuss whether the brainstem or cortical networks which may affect the central masticatory pathways are under the genesis of SB.

METHODS

Twelve possible SB patients and twelve age- and gender-matched controls underwent ¹ H-MRS using the "MEGA-Point Resolved Spectroscopy Sequence" (MEGA-PRESS) technique in the brainstem and bilateral CMA. Proton magnetic resonance spectroscopy data were processed using LCModel. Because the signal detected by MEGA-PRESS includes contributions from GABA, macromolecules (primarily proteins) and homocarnosine, the GABA signal is referred to as "GABA+". The glutamate complex (Glx) signal contains both glutamate (Glu) and glutamine (Gln), which mainly reflect glutamatergic metabolism.

RESULTS

Edited spectra were successfully obtained from the bilateral CMA in all subjects. There were no significant differences in neurochemical levels between the left and right CMA in possible SB patients and controls. In the brainstem, significantly lower GABA+ levels were found in possible SB patients than in controls (P = .011), whereas there was no significant difference (P = .307) in Glx levels between the 2 groups.

CONCLUSIONS

SB patients may possess abnormalities in the GABAergic system of brainstem networks.

Correlation of insulin-like growth factor 1 and osteoarthritic cartilage degradation: a spontaneous osteoarthritis in guinea-pig

OBJECTIVE

The pathogenesis of osteoarthritis centers on the imbalance between catabolic and anabolic processes in cartilage metabolism. Insulin growth factor 1 (IGF-1) has been shown to have anabolic effects in cartilage in vitro. This study aim to determine whether IGF-1 on cartilage is associated with loss of chondrocyte and extracellular matrix breakdown using the Hartley guinea pig model.

MATERIALS AND METHODS

Cartilage from the medial and lateral tibial plateau of 6-month and 12-month old Hartley guinea pigs were used for this study. Histological analysis was performed with hematoxylin-eosin (HE) and toluidine blue staining. Safranin-O staining was used to quantify proteoglycan (PG) loss and the extent of cartilage damage by Modified Mankin score. Distribution of IGF-1 was demonstrated with in situ hybridization techniques. IGF-1 mRNA levels were assessed using Real-time PCR.

RESULTS

Histological loss of chondrocytes, and cartilage matrix and decreased IGF-1 distribution were demonstrated in a temporal and spatial manner. Compared to the 6-month old samples, the 12-month specimens had significantly cartilage degeneration and less cartilage matrix and PGs staining. Decreased level of IGF-1 was also observed in the 12-month samples. These observations were more pronounced in the medial tibial plateau when compared to the lateral plateau.

CONCLUSIONS

The decreased level of IGF-1 may play a critical role for maintaining the balance between catabolic and anabolic processes in cartilage metabolism during the development of osteoarthritis. Thus, the increase of IGF-1 may be applicable to developing OA therapy.

Epidemiology and antifungal susceptibilities of yeast isolates causing invasive infections across urban Beijing, China

AIM

To investigate the species distribution and antifungal susceptibility profiles of yeast isolates causing invasive infections across Beijing.

MATERIALS & METHODS

A total of 1201 yeast isolates recovered from blood and other sterile body fluids were correctly identified by matrix-assisted laser desorption/ionization TOF MS supplemented by DNA sequencing. Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute broth microdilution method.

RESULTS

Candida (95.5%) remained the most common yeast species isolated; Candida albicans (38.8%) and Candida parapsilosis (22.6%) were the leading species of candidemia. Azole resistances were mainly observed in Candida glabrata and Candida tropicalis isolates.

CONCLUSION

This study outlined the epidemiologic data of invasive yeast infections and highlighted the need for continuous monitoring of azole resistances among C. glabrata and C. tropicalis isolates in Beijing.

Molecular epidemiology of bla OXA-23 -producing carbapenem-resistant Acinetobacter baumannii in a single institution over a 65-month period in north China

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii poses a significant threat to hospitalized patients, as few therapeutic options remain. Thus, we investigated the molecular epidemiology and mechanism of resistance of carbapenem-resistant A.baumannii isolates in Beijing, China.

METHODS

Carbapenem-resistant A.baumannii isolates (n = 101) obtained between June 2009 and November 2014 were used. Multilocus sequence typing (MLST) and PCR assays for class C and D β-lactamase were performed on all isolates. S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization were performed to identify the resistance gene location.

RESULTS

All 101 A.baumannii isolates were highly resistant to frequently used antimicrobials, and were considered multidrug resistant. A total of 12 sequence types (STs) were identified, including 10 reported STs and 2 novel STs. Eighty-seven isolates were classified to clonal complex 92 (CC92), among which ST191 and ST195 were the most common STs. The bla _OXA-23 gene was positive in most (n = 95) of the A.baumannii isolates. Using S1-nuclease digestion PFGE and Southern blot hybridization, 3 patterns of plasmids carrying bla _OXA-23 were confirmed. ST191 and ST195 (both harboring bla _OXA-23 ) caused outbreaks during the study period, and this is the first report of outbreaks caused by ST191 and ST195 in north China.

CONCLUSION

bla _OXA-23 -producing A.baumannii ST191 and ST 195 isolates can disseminate in a hospital and are potential nosocomial outbreak strains. Surveillance of imipenem-resistant A.baumannii and antimicrobial stewardship should be strengthened.

Allelic Variation of the Capsule Promoter Diversifies Encapsulation and Virulence In Streptococcus pneumoniae

The polysaccharide capsule is the major virulence factor of Streptococcus pneumoniae (pneumococcus), a major human pathogen. The sequences in the promoter and coding regions of the capsule gene locus undergo extensive variations through the natural transformation-mediated horizontal gene transfer. The sequence variations in the coding region have led to at least 97 capsular serotypes. However, it remains unclear whether the sequence polymorphisms in the promoter region have any biological significance. In this study, we determined the sequences of the cps promoter region from 225 invasive pneumococcal isolates, and identified modular composition and remarkable inter-strain sequence variations in this region. The strain-to strain variations in the cps promoter are characterized by diversity in sequence and size, mosaic combinations of nucleotide polymorphisms and sequence modules, selective preservation of the sequence combinations, and promiscuous assortments of the sequences between the promoter and coding regions. Isogenic pneumococci carrying allelic variants of the cps promoter displayed significant differences in the transcription of the capsule genes, capsule production, adhesion to host epithelial cells, anti-phagocytosis and virulence in mouse bacteremia model. This study has thus indicated that the sequence polymorphisms in the cps promoter represent a novel mechanism for fine-tuning the level of encapsulation and virulence among S. pneumoniae strains.

Bone turnover alterations across the menopausal transition in south-eastern Chinese women [corrected]

OBJECTIVES

To explore the serum levels of bone resorption marker C-terminal telopeptide of type I collagen (CTX) and bone formation marker N-amino terminal propeptide of type I collagen (PINP) in Chinese women across the menopausal transition and the correlation between follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol with the bone turnover markers.

METHODS

A cross-sectional study was conducted on 464 healthy Chinese women, separated into pre-, peri- and postmenopausal groups based on their menstruation changes. The serum levels of CTX, PINP, FSH, LH, and estradiol were measured.

RESULTS

The serum levels of CTX and PINP were significantly higher in women in the peri- and postmenopausal groups. The serum levels of FSH were significantly correlated with the serum levels of PINP in premenopausal women. Both serum FSH and LH were positively correlated with serum CTX in perimenopausal women and postmenopausal women. Estradiol was inversely correlated with CTX in the perimenopausal group. Multiple linear regression models show the serum FSH levels were independently related to the bone turnover markers CTX and PINP.

CONCLUSIONS

The elevated serum levels of FSH were independent risk factors for bone loss in peri- and postmenopausal women, and measurement of the serum FSH levels in mid-age women with irregular menses could be used in early diagnosis of postmenopausal osteoporosis.

A fluorometric assay for tyrosinase activity and its inhibitor screening based on graphene quantum dots

Pristine graphene quantum dots (GQDs) without any functionalization were used as probes to develop a sensitive and selective fluorescence sensing platform for the detection of tyrosinase (TYR) activity and its inhibitor screening for the first time.

Plasmid-encoding extended-spectrum β-lactamase CTX-M-55 in a clinical Shigella sonnei strain, China

AIMS

To characterize a clinical Shigella sonnei strain harboring a conjugatable blaCTX-M-55-borne plasmid.

MATERIALS & METHODS

S. sonnei strain #1081 was isolated from a dysentery patient in China. A CTX-M-55-encoding plasmid harbored in this strain was transformed to Escherichia coli, and then its complete nucleotide sequence was determined by next generation sequencing. The MIC values of bacterial strains were tested by using Vitec(®) 2 (Biomerieux, Marcy l'Etoile, France).

RESULTS

Strain #1081 conferred the resistance to multiple beta-lactam antibiotics. blaCTX-M-55 was the only known antibiotic resistance gene and located in a 3090-bp ISEcp1-blaCTX-M-55-orf477 transposition unit carried by a conjugatable plasmid p1081-CTXM in #1081. The ISEcp1-mediated transposition provided a sole promoter, which was located adjacently upstream of the inverted repeat right element of ISEcp1, to drive the expression of CTX-M-55.

CONCLUSION

Plasmid p1081-CTXM was a close variant of the IncI2-type plasmid pHN1122-1 that was harbored in a faecal E. coli strain recovered from a dog in China, indicating the potential transfer of CTX-M-55-encoding plasmids from faecal flora E. coli to human pathogen S. sonnei.

Matrix-assisted laser desorption ionization: time of flight mass spectrometry-identified models for detection of ESBL-producing bacterial strains

Background

The increase in the amount of extended spectrum beta-lactamases (ESBL)-producing gram-negative bacteria is seriously threatening human health in recent years. Therefore, it is necessary to develop a rapid and reliable method for identification of ESBLs. The purpose of this study was to establish a novel method to discriminate between ESBL-producing and non- ESBL-producing bacteria by using the matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) technique.

Material/Methods

We detected hydrolyzed production of cefotaxime after incubation with 69 gram-negative bacteria by using MALDI-TOF-MS. Then we established genetic algorithm (GA), supervised neural networks (SNN), and quick classifier (QC) models using several peaks to identify ESBL-producing strains. To confirm the clinical applicability of the models established, a blinded validation test was performed in 34 clinical isolated strains.

Results

Using ClinPro Tools software, we identified 4 peaks (456 Da, 396 Da, 370 Da, and 371 Da) in mass spectra of cefotaxime solution that have high enough specificity to discriminate ESBL-producing from non- ESBL-producing strains. Recognition capability of models established were 97.5% (GA), 92.5% (SNN), and 92.5% (QC), and cross validation rates were 90.15% (GA), 97.62 (SNN), and 97.62% (QC). The accuracy rates of the blinded validation test were 82.4% (GA), 88.2% (SNN), and 82.4% (QC).

Conclusions

Our results demonstrate that identification of ESBLs strains by MALDI-TOF-MS has potential clinical value and could be widely used in the future as a routine test in clinical microbiology laboratories.

Elevated plasma sphingomyelin (d18:1/22:0) is closely related to hepatic steatosis in patients with chronic hepatitis C virus infection

Hepatic steatosis affects disease progression in patients with chronic hepatitis C virus (HCV) infection. We investigated the plasma sphingolipid profile in patients with chronic hepatitis C (CHC) and whether there was an association between HCV-related steatosis and plasma sphingolipids. We used high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to analyze plasma sphingolipids in 120 interferon-naïve, non-diabetic, and non-obese CHC patients. Hepatic steatosis was defined as ≥5 % hepatocytes with fat based on histopathological analysis. Blood biochemical indicators and HCV load and genotype were also determined. Thirty-six (30.0 %) of 120 patients presented with hepatic steatosis Grades 1-3. Forty-four plasma sphingolipids were detected. Plasma sphingomyelin (SM) (d18:1/22:0) and ceramide (Cer) (d18:1/24:0)-1-P correlated with steatosis grade (r = 0.22, p = 0.015; r = -0.23, p = 0.012, respectively). SM (d18:1/22:0) [odds ratio (OR) = 1.12] and Cer (d18:1/24:0)-1-P (OR = 0.88) were independent factors for the presence of hepatic steatosis in CHC patients. The area under the curve (AUC) of SM (d18:1/22:0) and Cer (d18:1/24:0)-1-P was 0.637 and 0.638, respectively, to identify the presence of steatosis. Further analysis for genotype 2 CHC showed that only SM (d18:1/22:0) was independently linked to steatosis (OR = 1.21). The AUC of SM (d18:1/22:0) to identify hepatic steatosis in genotype 2 CHC was 0.726. Its sensitivity and negative predictive value reached 0.813 and 0.886, respectively. This study suggested that altered plasma SM (d18:1/22:0) was closely related to hepatic steatosis in chronic HCV infection, especially with genotype 2. Experimental studies are needed to determine further the underlying mechanisms responsible for these associations.

Short leukocyte telomere length predicts poor prognosis and indicates altered immune functions in colorectal cancer patients

BACKGROUND

Numerous studies indicate that the leukocyte telomere length is associated with the risk of cancers, including colorectal cancer (CRC). However, the prognostic value of leukocyte telomere length in CRC patients has not been investigated.

PATIENTS AND METHODS

Relative telomere length (RTL) of peripheral blood leukocytes (PBLs) from 571 CRC patients receiving surgical resection was measured using a polymerase chain reaction-based method. The Cox proportional hazards ratio model and the Kaplan-Meier curve were used to estimate the association between RTL and the clinical outcome of CRC patients in the training set (90 patients) and the testing set (86 patients). Finally, an independent cohort of 395 patients was used as an external validation set. The immunophenotype of PBLs and the plasma concentration of several immune-related cytokines were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively.

RESULTS

Patients with shorter RTL had significantly poorer overall survival and relapse-free survival than those with longer RTL in the training, testing and validation sets. Furthermore, leukocyte RTL and Tumor-Node-Metastasis (TNM) stage exhibited a significant joint effect in the prognosis prediction of combined CRC patients, indicating that patients with both short RTL and advanced stages had the worst prognosis, when compared with other subgroups. In addition, patients with short RTL showed the higher percentage of CD4(+) T cell and the lower percentage of B cell in peripheral blood mononuclear cells, as well as the lower concentration of plasma transforming growth factor-β1, suggesting a possibility that the immune functions changed with RTL alteration.

CONCLUSIONS

Our study for the first time demonstrates that leukocyte RTL is an independent prognostic marker complementing TNM stage and associated with the immune functions in CRC patients.

First Report of Grapevine leaf roll-associated virus-2 and -3 in Ohio Vineyards

Grapevine leaf roll-associated viruses (GLRaVs) are a group of nine closely related viruses belonging to the Closteroviridae family that cause grapevine leaf roll disease in vineyards across the world (3). Within the continental United States, GLRaVs have been reported in the states of California, Michigan, Missouri, New York, Oregon, Washington, and Wisconsin, but not in Ohio (2,3). During 2012, grapevines with typical leaf roll symptoms were reported by owners of several Ohio vineyards. The symptoms included small, red leaves and downwardly rolled leaf margins, accompanied by tiny grape clusters with few fruits. A total of 20 symptomatic leaf samples were collected from two sites about 300 miles apart within Ohio, namely Valley Vineyards (cultivars Vidal Blanc and Fronterac) and South River Winery (cultivar Cabernet Franc). Total RNA was extracted from the samples using a previously reported procedure (1) and subjected to reverse transcription (RT)-PCR using specific primers for five known grapevine viruses including GLRaV-1 (1F: 5'-ACCTGGTTGAACGAGATCGCTT and 1R: 5'-GTAAACGGGTGTTCTTCAATTCTCT), GLRaV-2 [2F(FQ): 5'-GCTCCTAACGAGGGTATAGAAG and 2R(FQ): 5'-AGAGCGTACATACTCGCGAACAT], GLRaV-3 [3F(FQ): CAAGTGCTCTAGTTAAGGTCAG and 3R(FQ): 5'-CGGAACGTCGGTTCATTTAGA], Grapevine fan leaf virus (GFLVR1-F: 5'-TGAGATTAGTCATGGAGCAGCTT and GFLVR1-R: 5'-GGATAGACGTCTGGTTGATTTTG), and Tobacco ring spot virus (TRSVR1-1255F: 5'-GAGTGTTGTGCAATTATCT-GCATA and TRSVR1-1844R: 5'-CAAAGATGCCAAGAAAAGTTGCAAG). A 295-bp fragment of a grapevine actin cDNA (primers VvACT-F: 5'-ATCTCCATGTCAACCAAACTGAG and VvACT-R: 5'-GACAGAATGAGCAAGGAAATCAC) was used as a positive control for RT-PCR. The samples tested negative for GFLV, TRSV, or GLRaV-1 with our primer sets. However, four of the samples were positive for GLRaV-2, and 12 positive for GLRaV-3, as evidenced by the detection of PCR fragments of expected sizes (404 and 344 bp, respectively). All samples positive for GLRaV-2 were from a single field, whereas samples positive for GLRaV-3 were from both vineyards examined. The identities of GLRaV-2 and -3 were further confirmed by directly sequencing one GLRaV-2 and two GLRaV-3 (one from each location) PCR fragments from both ends. The 404 bp GLRaV-2-specific fragment shared 95 to 98% sequence identity with various GLRaV-2 isolates whose sequences were deposited at the GenBank. Similarly, the two 344-bp GLRaV-3 fragments share a 95 to 97% identity with known GLRaV-3 isolates. Notably, the sequences of the two GLRaV-3-specific fragments derived from two vineyards are not identical (97% identity), suggesting these two isolates might have different origins. As these viruses are known to be recalcitrant to mechanical transmission, we did not attempt to transmit these viruses to healthy plants. In summary, our results report for the first time the detection of GLRaV-2 and -3 in Ohio, suggesting that these two viruses are associated with the observed leaf roll symptoms, hence should be part of an effective management plan for grapevine viral diseases in the state. References: (1) C. Louime et al. Eur. J. Sci. Res. 22:232, 2008. (2) S. Lunden and W. Qiu. Plant Dis. 96:462, 2012. (3) A. M. Sharma et al. PLoS One 6:e26227, 2011.

[Distribution of genotypes in ESBLs producing E. coli strains isolated from posthepatitic cirrhosis' patients with bloodstream infection]

OBJECTIVE

To study the genotype distribution of extended-spectrum beta-lactamases (ESBLs) in ESBLs-producing Escherichia coli (E. coli) isolates from posthepatitic cirrhosis' patients with bloodstream infection.

METHODS

E. coli were isolated in bloodstream from patients with posthepatitic cirrhosis between January and December in 2011. The strains were identified by VITEK-II. The antibiol susceptibility tests were performed with K-B method. beta-lactamases genes were detected multi-PCR, PCR, sequence and blast.

RESULTS

A total of 79 non-duplicate clinical isolates of E coli were consecutively collected from liver cirrhosis' patients with bloodstream infection. There were 20 isolates produced TEM-1 type beta-lactamases and 1 isolate produced SHV-1 typebeta-lactamases. 40 clinical isolates were detected to produce CTX-M type ESBLs, there were 20 CTX-M-1 group and 26 CTX-M-9 group, including 6 stains habouring both CTX-M-1 and CTX-M-9 group. Eight CTX-M genotypes were confirmed by sequencing of the PCR products, including CTX-M-3, CTX-M-14, CTX-M-15, CTX-M-24, CTX-M-28, CTX-M-31, CTX-M-65 and CTX-M-79.

CONCLUSION

CTX-M genotype ESBLs was the most popular extended-spectrum beta-lactamases in E. coli isolated from liver cirrhosis' patients with bloodstream infection. The CTX-M-14 is the dominant epidemic type.

Changing trends and serotype distribution of Shigella species in Beijing from 1994 to 2010

Shigella species are a common cause of acute diarrheal disease in China. In this study, we characterized the changing trends and serotype distribution of Shigella species in Beijing from 1994 to 2010. A total of 5999 Shigella strains were isolated and serotyped from the 302nd Hospital in Beijing. The annual number of Shigella isolates reached a peak (n = 1192; 19.84%) in 1996 and then decreased annually, reaching the lowest point (n = 24; 0.41%) in 2010. S. flexneri 2a and S. sonnei were the most frequently isolated Shigella, with their respective isolates making up 53.3% and 27.6% of the total. Isolates of S. flexneri 4c, 4a, and x made up 3% respectively of the total isolates. Significant decreases in percentage of S. flexneri over time were observed. S. sonnei surpassed S. flexneri 2a as the predominant serotype in 2000. Most isolates were recovered from July to September; 13.6% of the isolates were recovered from children aged 0 to 5 years, and 16% were recovered from those aged 21 to 25 years. S. flexneri 2a and 5 were recovered mostly from males (33.41%, p < 0.001; and 0.46%, p < 0.001%; respectively), whereas S. flexneri 2b and 6, and S. sonnei were most often isolated from females. Continuous monitoring of Shigella showed that all 4 species and 27 serotypes were present in Beijing, China, during the study period. The emergence of S. sonnei and the overall decreasing isolation rate of Shigella in Beijing can potentially aid in the development of vaccine and control strategies for shigellosis in the city.

Wheat mosaic virus (WMoV), the Causal Agent of High Plains Disease, is Present in Ohio Wheat Fields

High Plains disease was first described in wheat (Triticum aestivum) in Nebraska, Idaho, Texas, and other High Plains states in 1993 to 1994 (1). The causal agent is a negative sense RNA virus in the genus Emaravirus with at least three genome segments, which is transmitted by the wheat curl mite (Aceria tosichella Keifer) (2). This virus is variously referred to as High Plains virus (HPV), Maize red stripe virus (MRSV/MRStV), or Wheat mosaic virus (WMoV) in the literature. We adopt the name WMoV based on the latest recommendation (3). The presence of WMoV in Ohio was revealed through a comprehensive survey conducted in early spring 2012. Specifically, wheat plants exhibiting virus-like symptoms including chlorosis, reddening, stunting, spotting, or striping were collected from 27 wheat fields in 14 counties throughout Ohio, between March 20 and April 15, 2012. Total RNA was extracted from individual leaf samples, then pooled prior to ribosomal RNA removal and high throughput RNA-sequencing (RNA-Seq) using the Illumina HiSeq2000 platform (University of Illinois Biotechnology Center, Champaign-Urbana, IL). The resulting sequences were assembled and analyzed using CLC Genomics Workbench 5.5 software (CLC Bio, Cambridge, MA). One 983-nt contig was 99% identical to the nucleocapsid protein (NP)-coding RNA segment of WMoV (GenBank Accession DQ324466). We used reverse transcription (RT)-PCR to determine the distribution of WMoV in individual samples using WMoV-specific primers: WMoV NPf1 (TGCTATGTCATTGTTCAGGTGGTC), and WMoV NPr1 (TTAGGCAGTCCTTGATTGTGCTG). WMoV was identified in one sample each from Miami, Auglaize, and Paulding Counties, which are all in western Ohio. The WMoV-positive plants were chlorotic, with varying degrees of stunting and leaf striping. The presence of WMoV in the three samples was confirmed using protein A sandwich (PAS)-ELISA with WMoV-specific antiserum. Vascular puncture inoculation (VPI) (4) was used to inoculate germinating maize seed (cv. Spirit) with the extracts from the WMoV-positive samples. WMoV was detected in two of 378 surviving inoculated plants by RT-PCR and PAS-ELISA. These two WMoV-positive maize plants developed flecking mosaic symptoms on upper uninoculated leaves, consistent with reported WMoV symptoms. The WMoV-positive sample from Auglaize County also contained Wheat streak mosaic virus (WSMV), and 60 of the 120 surviving plants inoculated with this sample were positive for WSMV. This result suggests that, even with VPI, mechanical transmission of WMoV remains a great challenge. To our knowledge, this is the first report of WMoV in Ohio, and demonstrates that WMoV is more widespread than previously thought, reaching at least the eastern edge of the Midwest wheat production region. The expanding distribution of this emerging virus is significant because of its potential to cause additional yield losses in wheat. References: (1) S. G. Jensen et al. Plant Dis. 80:1387, 1996. (2) N. Mielke-Ehred and H.-P. Muhlbach. Viruses 4:1515, 2012. (3) J. M. Skare et al. Virology 347:343, 2006. (4) R. Louie et al. J. Virol. Methods 135:214, 2006.

Quorum sensing modulates transcription of cpsQ-mfpABC and mfpABC in Vibrio parahaemolyticus

Vibrio parahaemolyticus AphA and OpaR are the two master regulators of quorum sensing (QS) that are abundantly produced and operate at low cell density (LCD) and high cell density (HCD), respectively, with an outcome of reciprocally gradient production of these two proteins with transition between LCD and HCD. The cpsQ-mfpABC gene cluster is transcribed as two operons cpsQ-mfpABC and mfpABC in V. parahaemolyticus. MfpABC is a putative membrane fusion transporter that contributes to biofilm development. CpsQ is a c-di-GMP-binding regulator that activates the expression of capsular polysaccharide genes and mfpABC and, thus, induces biofilm development. As shown in this study, OpaR and AphA bind to the promoter region of mfpABC to enhance and repress its transcription, respectively. In contrast, the positive and negative regulation of cpsQ-mfpABC by AphA and OpaR, respectively, achieves probably through acting of AphA or OpaR on additional unknown regulator(s) of cpsQ-mfpABC. The transcriptional levels of cpsQ-mfpABC and mfpABC enhance gradually with transition from LCD to HCD due to the above reciprocal regulatory action of OpaR and AphA. Data presented here present a novel paradigm of combined action of the two master QS regulators in controlling expression of the QS regulon members.

[Dynamic analysis of the lymphocyte subsets in HCV children with different genotypes during treatment]

OBJECTIVE

To discuss the changes of lymphocyte subsets in HCV children with different genotypes during treatment with pegylated interferon alfa-2b and ribavirin.

METHODS

The genotype of 45 HCV infected children were identified by real time PCR. The lymphocyte subsets were dynamically detected by BD FACSCalibur flow cytometer with four color MultiTEST IMK Kit during the treatment.

RESULTS

For the children with 1b genotype, after 24 weeks, the CD4+ T cells were higher than pre-treatment (P < 0.05). For the children with 2a genotype, after 12 weeks and after 24 weeks, the CD3+ T cells and CD4+ T cells significantly increased while the NK cells decreased than pre-treatment (P < 0.05).

CONCLUSIONS

The lymphocyte subsets of HCV children with 2a genotype were different from 1b genotype during trentment with pegylated interferon alfa-2b and ribavirin.

First Report of Soybean vein necrosis-associated virus in Ohio Soybean Fields

Soybean vein necrosis-associated virus (SVNaV), a newly discovered tospovirus that infects soybean, was first described as widespread in a number of southern and midwestern states, but so far has not been reported in Ohio (1). Here we describe its occurrence in six different soybean leaf samples collected from five Ohio counties: Champaign, Hardin, Sandusky, Seneca, and Wyandot. Specifically, SVNaV was initially identified through a comprehensive survey during the summer of 2011 that used high throughput sequencing to detect genome sequences of viruses present in a pool of 110 field samples collected from 24 Ohio counties. Three assembled contigs, with sizes of 7,551, 4,937, and 1,554 nucleotides (nt) respectively, share 99% nt identity with the three SVNaV genomic RNAs (L, M, and S), and thus constitute partial sequences of the SVNaV Ohio (OH) isolate. The distribution of this virus was further delineated using reverse transcription (RT)-PCR with primers SVNaV-1734F (5' CCATCTTTCTTTCCAGGCATTTCA 3') and SVNaV-S-2421R (5' GATTCAAGTTCAGCGAGTTCTACAA 3'). All plants from which the SVNaV-positive samples were collected showed typical virus symptoms, including systemic mosaic accompanied by leaf deformation, chlorosis, vein necrosis, and rusty spots on mature leaves. These symptoms are largely consistent with the previous report by Zhou and colleagues (1). Intriguingly, further analysis with RT-PCR revealed that five out of the six SVNaV-positive samples also contained a second virus, with Bean pod mottle virus found in four of the samples, and Tobacco ringspot virus in the fifth. Since it is not yet possible to initiate SVNaV infection mechanically, it is difficult to determine whether the co-infecting viruses contribute to the disease symptoms and yield losses. It should be noted that SVNaV may have been in Ohio for some time since symptoms similar to those reported by Zhou and colleagues (1) have been observed in soybean fields of this state since at least 2009. Furthermore, while in 2011 these symptoms were observed in only a few fields, as reflected by the detection of SVNaV in six of the 110 samples, the 2012 growing season has seen a big jump of symptomatic plants and fields. The current report confirms its presence with molecular evidence and lays the groundwork for further assessment of its impact on soybean production. Reference: (1) J. Zhou et al. Virus Genes 43:289, 2011.

Genotypes and antimicrobial profiles of Shigella sonnei isolates from diarrheal patients circulating in Beijing between 2002 and 2007

Shigella sonnei has become the dominant serotype causing shigellosis in Asian countries in recent years. In this study, we characterize the increasing trend of antibiotic resistance profiles and genotypes of S. sonnei isolates in the Beijing area. From January 2002 to December 2007, a total of 1108 Shigella isolates including 362 S. sonnei were recovered from diarrhea patients at the 302nd Hospital in Beijing. While the frequency of S. flexneri gradually decreased, S. sonnei gradually increased and became the dominant species. A total of 362 S. sonnei isolates were further analyzed for their antimicrobial profiles and 272 revived isolates were selected for genotyping analysis, respectively. High-level antimicrobial resistances were observed in sulfamethoxazole/trimethoprim (94.5%), ampicillin (40.3%), piperacillin (36.5%), and ceftriaxone (12.8%) with significant single- and multiple-drug resistance increase trends from 2002 to 2007 (P = 0.0000). Pulsed-field gel electrophoresis analysis indicated that 263 (96.7%) S. sonnei belonged to 1 clonal genotype A, which were further divided into A1–A6 subtypes. While subtype A2 was dominant in the early stage of study years, subtype A4 started to emerge and increased significantly in later years. Antimicrobial resistance rates are statistically different among the 6 subtypes (P = 0.0000), and A4 possessed the highest resistance rates to ampicillin (83.7%) and piperacillin (81.4%). Subtype A3 was highly clustered in inpatients compared to other subtypes (P = 0.0145). This study indicates that a clonal S. sonnei strain has become dominant in the Beijing area, and subtype A4 is responsible for increased antibiotic resistance.