Novel Subclone of Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 11 with Enhanced Virulence and Transmissibility, China

We aimed to clarify the epidemiologic and clinical importance of evolutionary events that occurred in carbapenem-resistant Klebsiella pneumoniae (CRKP). We collected 203 CRKP causing bloodstream infections in a tertiary hospital in China during 2013-2017. We detected a subclonal shift in the dominant clone sequence type (ST) 11 CRKP in which the previously prevalent capsular loci (KL) 47 had been replaced by KL64 since 2016. Patients infected with ST11-KL64 CRKP had a significantly higher 30-day mortality rate than other CRKP-infected patients. Enhanced virulence was further evidenced by phenotypic tests. Phylogenetic reconstruction demonstrated that ST11-KL64 is derived from an ST11-KL47-like ancestor through recombination. We identified a pLVPK-like virulence plasmid carrying rmpA and peg-344 in ST11-KL64 exclusively from 2016 onward. The pLVPK-like-positive ST11-KL64 isolates exhibited enhanced environmental survival. Retrospective screening of a national collection identified ST11-KL64 in multiple regions. Targeted surveillance of this high-risk CRKP clone is urgently needed.

Lateral monolayer MoS2 homojunction devices prepared by nitrogen plasma doping

Monolayer MoS₂ possesses good electron mobility, structural flexibility and a direct band gap, enabling it to be a promising candidate for flexible and wearable optoelectronic devices. In this article, the lateral monolayer MoS₂ homojunctions were prepared by a nitrogen plasma selective doping technique. The monolayer MoS₂ thin films were synthesized by chemical vapor deposition and characterized by photoluminescence, atom force microscope and Raman spectroscopy. The electronic and photoelectric properties of the lateral pn and npn homojunctions were discussed. The results showed that the rectifying ratio of the pn homojunction diode is ∼10³. As a photodetector of pn homojunction, the optical responsivity is up to 48.5 A W^-1, the external quantum efficiency is 11 301%, the detectivity is ∼10⁹ Jones and the response time is 20 ms with the laser of 532 nm and the reverse bias voltage of 10 V. As a bipolar junction transistor of npn homojunction, the amplification coefficient reached ∼10². A controllable plasma doping technique, compatible with traditional CMOS process, is utilized to realize the monolayer MoS₂ based pn and npn homojunctions, and it propels the potential applications of 2D materials in the electronic, optoelectronic devices and circuits.

Serotype Is Associated With High Rate of Colistin Resistance Among Clinical Isolates of Salmonella

To investigate the prevalence, probable mechanisms and serotype correlation of colistin resistance in clinical isolates of Salmonella from patients in China, Salmonella isolates were collected from fecal and blood samples of patients. In this study, 42.8% (136/318) clinical isolated Salmonella were resistant to colistin. MIC distribution for colistin at serotype level among the two most prevalent serotypes originating from humans in China indicated that Salmonella Enteritidis (83.9% resistance, 125/149) were significantly less susceptible than Salmonella Typhimurium (15.3% resistance, 9/59, P < 0.01). mcr genes and mutations in PmrAB confer little for rate of colistin resistant Salmonella isolated from human patients. Phylogenetic tree based on core-genome single nucleotide polymorphisms (SNPs) was separately by the serotypes and implied a diffused distribution of MICs in the same serotype isolates. Relatvie expression levels of colistin resistant related pmr genes were significantly higher in non-mcr colistin resistant S. Typhimurium than in colistin sensitive S. Typhimurium, but no discernable differences between colistin resistant and sensitive S. Enteritidis, indicating a different mechanism between colistin resistant S. Typhimurium and S. Enteritidis. In conclusion, colistin susceptibility and colistin resistant mechanism of clinical isolated Salmonella were closely associated with specific serotypes, at least in the two most prevalent serotype Enteritidis and Typhimurium. We suggest clinical microbiology laboratory interpreting Salmonella colistin MIC results in the serotype level.

Comparative Analysis of Virulence and Toxin Expression of Vancomycin-Intermediate and Vancomycin-Sensitive Staphylococcus aureus Strains

Previous studies on vancomycin-intermediate Staphylococcus aureus (VISA) have mainly focused on drug resistance, the evolution of differences in virulence between VISA and vancomycin-sensitive S. aureus (VSSA) requires further investigation. To address this issue, in this study, we compared the virulence and toxin profiles of pair groups of VISA and VSSA strains, including a series of vancomycin-resistant induced S. aureus strains—SA0534, SA0534-V8, and SA0534-V16. We established a mouse skin infection model to evaluate the invasive capacity of VISA strains, and found that although mice infected with VISA had smaller-sized abscesses than those infected with VSSA, the abscesses persisted for a longer period (up to 9 days). Infection with VISA strains was associated with a lower mortality rate in Galleria mellonella larvae compared to infection with VSSA strains (≥ 40% vs. ≤ 3% survival at 28 h). Additionally, VISA were more effective in colonizing the nasal passage of mice than VSSA, and in vitro experiments showed that while VISA strains were less virulent they showed enhanced intracellular survival compared to VSSA strains. RNA sequencing of VISA strains revealed significant differences in the expression levels of the agr, hla, cap, spa, clfB, and sbi genes and suggested that platelet activation is only weakly induced by VISA. Collectively, our findings indicate that VISA is less virulent than VSSA but has a greater capacity to colonize human hosts and evade destruction by the host innate immune system, resulting in persistent and chronic S. aureus infection.

Economic Burden of Patients with Bloodstream Infections Caused by Extended-Spectrum β-Lactamase-Producing Escherichia coli

Background

The prevalence of infections with extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) is increasing worldwide, but the economic impact of ESBL-EC bloodstream infection (BSI) has not been comprehensively evaluated.

Patients and Methods

A retrospective cohort including patients hospitalized at a tertiary hospital between January 2013 and December 2016 who were confirmed with a BSI of ESBL-EC or non-ESBL-EC was set. Clinical data and medical costs were collected by chart review of electronic and paper medical records. The economic burden was evaluated with disability-adjusted life years (DALYs).

Results

A total of 580 patients with E. coli BSI, comprising 333 patients (57.4%) with ESBL-EC BSI and 247 patients (42.6%) with non-ESBL-EC BSI, were identified. There were no significant differences in comorbidity and severity of patients between ESBL-EC and non-ESBL-EC BSI. The median length of stay (LOS) after bacteremia was 12 days for ESBL-EC (interquartile range, 7 to 21) versus 11 days for non-ESBL-EC (interquartile range, 7 to 21) (P = 0.38), and appropriate empirical antimicrobial therapy occurred in 87.4% versus 89.9% (P = 0.353). The mortalities were 20.1% versus 17.4% (P = 0.41). Patients with ESBL-EC did not have significantly different in-hospital medical costs to those with non-ESBL-EC (median, $8048.68 vs $7476.84, respectively, with a difference of $571.84, P = 0.321). In the non-ESBL-EC group, 247 patients lost 531.05 DALYs in total, with an average of 2.15 DALYs per person, while in the ESBL-EC group, 333 patients lost 692.64 DALYs in total, with an average of 2.08 DALYs per person. There is no significant difference in average DALYs (P = 0.343).

Conclusion

In conclusion, patients with BSI due to ESBL-EC did not cost more than patients with BSI due to non-ESBL-EC. This phenomenon may be attributed to timely and effective antibiotic treatment, but the initial empiric therapy with second- or third-line antibiotics in non-ESBL-EC BSI should be corrected.

Defect-Related Broadband Emission in Two-Dimensional Lead Bromide Perovskite Microsheets

Low-dimensional hybrid lead halide perovskites (LHPs) with broadband emission (BE) have been developed as promising candidates for single-source white-light-emitting diodes. However, the underlying origin of such BE is poorly understood. Herein, dual-emissive [NH₃(CH₂)₈NH₃]PbBr₄ perovskite microsheets (PMSs) with good dispersibility are successfully prepared. Besides the general narrowband emission (NE) originating from free excitons, BE (∼522 nm) is generated under a Br-poor condition, which is not observed in the single-crystal sample. Unlike self-trapped exciton emission, the BE observed in PMSs is experimentally determined to be related to bromide vacancies (V_Br), thereby exhibiting quasisaturation under high excitation intensity. Femtosecond transient absorption spectroscopy first shows that the trapping time of the photogenerated electrons by acceptor-like V_Br- is ∼15 ps, slower than that by surface defects (<1 ps). This study provides new insight into the underlying mechanism of BE and an effective approach to manipulating the optical properties of 2D perovskites.

High prevalence of a globally disseminated hypervirulent clone, Staphylococcus aureus CC121, with reduced vancomycin susceptibility in community settings in China

OBJECTIVES

Most vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) are derived from hospital-associated MRSA due to treatment failure; however, the prevalence of hVISA/VISA in community settings remains unclear.

METHODS

Four hundred and seventy-six community-associated isolates were collected between 2010 and 2011 during national surveillance for antimicrobial resistance in 31 county hospitals across China. Drug susceptibility evaluation and mecA detection were performed by using broth microdilution and PCR analysis, respectively. hVISA/VISA were identified by using macro-Etest and a modified population analysis profile (PAP)-AUC method. The genetic features of all hVISA/VISA isolates were genotyped.

RESULTS

Among 476 isolates, MRSA and MSSA accounted for 19.7% (n = 94) and 80.3% (n = 382), respectively. Two VISA and 36 hVISA isolates were identified by PAP-AUC testing. The VISA isolates and 29 of the hVISA isolates were MRSA. The proportion of hVISA/VISA was significantly higher in MRSA (30.9%) than in MSSA (1.8%). The hVISA/VISA isolates were assigned to 18 STs classified into seven clonal complexes (CCs). CC121 (n = 12) followed by ST239 (n = 11) was the most prevalent hVISA/VISA clone. All ST239-hVISA/VISA were MRSA, while 12 CC121-hVISA isolates included 6 MSSA and 6 MRSA isolates. SCCmec III was predominant among MRSA-hVISA/VISA isolates. agr I and agr IV were detected in ST239 and CC121, respectively. All except two strains were positive for Panton-Valentine leucocidin genes.

CONCLUSIONS

To the best of our knowledge, this is the first report of CC121 as a prevalent hVISA clone in community settings, highlighting the necessity of surveillance and stricter infection control measures for this globally disseminated lineage.

Photoresponse-Bias Modulation of a High-Performance MoS2 Photodetector with a Unique Vertically Stacked 2H-MoS2/1T@2H-MoS2 Structure

Monolayer 2H-phase MoS₂-based photodetectors exhibit high photon absorption but suffer from low photoresponse, which severely limits their applications in optoelectronic fields. The metallic 1T phase of MoS₂, while transporting carriers faster, shows negligible response to visible light, which limits its usage in photodetectors. Herein, we propose an ultrafast-response MoS₂-based photodetector having a channel that consists of a 2H-MoS₂ sensitizing monolayer on top of 1T@2H-MoS₂. The 1T@2H-MoS₂ layer has a thickness of several nanometers and is a mixture of metallic 1T-MoS₂ and semiconducting 2H-MoS₂, imparting metal-like properties to the photodetector. Compared with the monolayer 2H-MoS₂ photodetector, we observed a drastic increase in the photoresponse of the 2H-MoS₂/1T@2H-MoS₂ vertically stacked photodetector to a value of 1917 A W^-1. Owing to the presence of metallic 1T-MoS₂ within the metal-like 1T@2H-MoS₂, the performance of the 2H-MoS₂/1T@2H-MoS₂ vertically stacked photodetector is voltage bias-modulated with an external quantum efficiency (EQE) of up to 448,384% and a specific detectivity of up to ∼10¹¹ Jones. The higher carrier density and higher mobility of the 1T@2H-MoS₂ layer explain the better bias-modulated performance. In addition, the interface between 2H-MoS₂ and 1T@2H-MoS₂ ensures fewer dangling bonds and reduced lattice mismatching. Thus, this study presents an exclusive vertically stacked MoS₂-based photodetector that lays the foundation for the development of photodetectors exhibiting higher photoresponse.

Comparative Genomic Analysis of 19 Clinical Isolates of Tigecycline-Resistant Acinetobacter baumannii

To assess the genomic profiles of tigecycline (Tgc)-resistant Acinetobacter baumannii, including antibiotic resistance (AR) genes and virulence factors (VF), whole-genome shotgun sequencing was performed on 19 Tgc-resistant (TgcR) A. baumannii strains collected in a tertiary hospital during the early phase of the clinical introduction of Tgc in China from late 2012 to mid-2014. The major sample types containing TgcR strains were sputum and drain fluid. Data from an average of 624 Mbp of sequence was generated on each bacterial genome, with Q30 quality of 90%, and an average coverage of 96.6%. TCDC-AB0715 was used as a reference genome. The genome sequences were annotated for functional elements including AR genes, VFs, genome islands, and inserted sequences before they were comparatively analyzed. The antibiotic susceptibility phenotypes of the strains were examined by a broth microdilution method to determine the minimal inhibitory concentration (MIC) of strains against major clinical antibiotics. The AR genes (ARGs) were annotated using the Comprehensive Antibiotic Resistance Database (CARD). Thirty-three ARGs were shared by all 19 TgcR strains, and 24 ARGs were distributed differently among strains. A total of 391 VFs were found to be diversely distributed in all TgcR strains. Based on ARG number distribution, the 19 TgcR strains were divided into several groups. Highly differentiated genes included gpi, mphG, armA, msrE, adec, catB8, aadA, sul1, bla_OXA–435, aph3i, and bla_TEM–1, which may represent gene markers for TgcR A. baumannii sub-types. In addition, when compared with Tgc-sensitive (TgcS) strains collected during the same period, TgcR strains featured enrichment of ARGs including aph6id, aph3ib, and teta. Compared with 26 other whole-genome sequences of A. baumannii deposited in GeneBank, TgcR strains in this study commonly lacked the EF-Tu mutation for elfamycin resistance. Previous investigation of three A. baumannii strains isolated from one patient indicated genomic exchange and a homologous recombination event associated with generation of tigecycline resistance. This study further analyzed additional TgcR strains. Phylogenetic analysis revealed a close evolutionary relationship between 19 TgcR strains and to isolates in East and Northeast China. In short, the comprehensive functional and comparative genomic analysis of 19 clinical TgcR A. baumannii strains isolated in the early stage of Tgc usage in China revealed their close phylogenetic relationship yet variable genetic background involving multiple resistance mechanisms. Using a simple ARG or VF gene number diversity method and marker genes, TgcR strain sub-types can be identified. The distinct characteristics of TgcR A. baumannii strains with versatile genomic resistance and regulation patterns raise concern regarding prediction and control of Tgc resistance in the clinic.

Effect of Short-Term Antimicrobial Therapy on the Tolerance and Antibiotic Resistance of Multidrug-Resistant Staphylococcus capitis

Background

Bacteria undergo adaptive mutation in the host. However, the specific effect of antimicrobial use on bacterial evolution and genome mutations related to bacterial survival within a patient is unclear.

Materials and Methods

Three S. capitis strains were sequentially isolated from cerebrospinal fluid of a clinical inpatient. Antimicrobial susceptibility, growth rate, biofilm formation and whole blood survival of these strains were measured. Relative fitness was calculated. The virulence was examined in the Galleria mellonella model. Whole-genome sequencing and in silico analysis were performed to explore the genetic mechanisms of the changes in antimicrobial resistance phenotype. Hypothetical proteins are cloned, expressed and characterized by detection the susceptibility to gentamycin.

Results

The first isolate was susceptible to rifampin (MIC=0.25 μg/mL), resistant to gentamicin (MIC=16 μg/mL), while the later two isolates were resistant to rifampin (MIC >64 μg/mL), susceptible to gentamicin (MIC=4 μg/mL). For the latter two strains, compared to the first, frameshift mutation in a hypothetical protein encoding gene and base substitutions (in genes saeR, moaA and rpoB) were discovered. The mutation of rpoB gene caused rifampicin resistance. Mutations in saeR, moaA and hypothetical gene are associated with changes in other biological traits. Amino acid sequence-based structure and function identification of the hypothetical protein indicated that a mutation in the encoding gene might be associated with altered aminoglycoside susceptibility. Growth curve showed that the later two isolates grew faster than the first isolate with a positive fitness advantage of 13.5%, and 14.8%, accordingly. Biofilm form ability and whole blood survival of the derivative mutants were also enhanced. No significant differences of virulence in the G. mellonella model were observed.

Conclusion

We report here for the first time that short-term clinical antibiotic use was associated with resistance mutations, collateral sensitivity, and positive in vivo fitness advantages to S. capitis during infection.

Hypervirulence Markers Among Non-ST11 Strains of Carbapenem- and Multidrug-Resistant Klebsiella pneumoniae Isolated From Patients With Bloodstream Infections

Multidrug-resistant Klebsiella pneumoniae and hypervirulent K. pneumoniae (hvKP) have traditionally been considered two individual populations; however, strains displaying both phenotypes have emerged during the recent decade. Understanding the genotypic and phenotypic basis of the convergence could be of clinical importance. In this study, we aimed to evaluate the pathogenicity associated with different combinations of genotypes (i.e., sequence types, virulence factors, and capsular serotypes) and phenotypes (i.e., hypermucoviscosity and drug susceptibility) in K. pneumoniae. A total of 11 K. pneumoniae isolates causing bloodstream infections were included in the study, and they were assigned to seven STs (ST23, ST15, ST268, ST660, ST86, ST65, and ST1660) and carried various K-loci (KL1, KL2, KL16, KL20, and KL24). Hypermucoviscosity was observed for six isolates. bla _KPC-2 was detected in six carbapenem-resistant isolates, and the remaining ones were either multidrug-resistant or resistant to two types of antibiotics. Aerobactin- and yersiniabactin-encoding genes were detected in all isolates. Although rmpA2 was detected in all isolates, most contained frameshift mutations (82%). Genes encoding salmochelin, RmpA, and PEG344 were detected in seven isolates. Colibactin-encoding genes were carried by six isolates. Discrepancies among measured virulence in Galleria mellonella and the serum-killing assay, and genotypes and phenotypes were detected. The results illustrate the complexity and difficulty with the current knowledge of hypervirulence to predict the phenotype by using genetic and phenotypic markers. Additionally, the emergence of carbapenem resistance in two isolates of KPC-2-producing hvKP of different sequence types emphasizes the urgency with which reliable clinical diagnostics for hvKP is needed.

Epidemiology and risk factors of infective endocarditis in a tertiary hospital in China from 2007 to 2016

Background

To explore the trends in epidemiology and the risk factors related to the prognosis of infective endocarditis in a tertiary hospital over the past ten years.

Methods

A retrospective cohort study was performed. A total of 407 consecutive patients who were admitted with infective endocarditis were included. The clinical characteristics and the risk factors related to the prognosis of infective endocarditis during this period were analyzed.

Results

A total of 407 patients with infective endocarditis were included, the average age was 48 ± 16 years old with an increasing trend and in-hospital mortality rate was 10.6% and one-year mortality rate was 11.3%. Among patients with underlying heart disease, congenital heart disease was the most common (25.8%), followed by rheumatic heart disease (17.0%) which showed a decreased trend during this period (P < 0.001). There were 222(54.5%) patients with positive blood cultures results and Streptococci (24.6%) was the main pathogens with an increasing trend. There were 403 patients (99%) with surgical indications, but only 235 patients (57.7%) received surgical treatment. Hemodialysis (P = 0.041, OR = 4.697, 95% CI 1.068–20.665), pulmonary hypertension (P = 0.001, OR = 5.308, 95% CI 2.034–13.852), Pitt score ≥ 4 (P < 0.001, OR = 28.594, 95% CI 5.561–148.173) and vegetation length>30 mm (P = 0.011, OR = 13.754, 95% CI 1.832–103.250) were independent risk factors for in-hospital mortality.

Conclusions

There were no significant changes in the overall incidence of infective endocarditis, but the clinical features of infective endocarditis had slightly changed during the past ten years. Streptococci infective endocarditis was still the predominant. Patients with hemodialysis, pulmonary hypertension, Pitt score ≥ 4 and vegetation length>30 mm had an worse in-hospital outcome.

Association between the rate of fluoroquinolones-resistant gram-negative bacteria and antibiotic consumption from China based on 145 tertiary hospitals data in 2014

Background

The purpose of the study is to discuss the correlation between the resistance rate of gram negative bacteria to fluoroquinolones (FQ) and antibiotic consumption intensity of 145 China tertiary hospitals in 2014.

Methods

This retrospective study adopted national monitoring data from 2014. Each participating hospital required to report annual consumption of each antibiotic, and the resistance rate of gram negative bacteria to FQ. Then the correlation between antibiotic usage and fluoroquinolones –resistant (FQR) rate was consequently investigated.

Results

One hundred forty-five hospitals were included in the study, and the median antibiotic consumption intensity was 46.30 (23.93–115.39) defined daily dosages (DDDs) per 100 patient-days. Cephalosporins ranks first in the antibiotics consumption, followed by fluoroquinolones, penicillins, and carbapenems. Fluoroquinolones resistance rate varied from hospital to hospital. The correlation analysis showed significant relationship between the percentage of FQR Escherichia coli and the consumption of FQs (r = 0.308, p<0.01) and levofloxacin (r = 0.252, p<0.01). For FQR Klebsiella pneumoniae, not only FQs (r = 0.291, p<0.01) and levofloxacin (r = 0.260, p<0.01) use but also carbapenems (r = 0.242, p<0.01) and overall antibiotics (r = 0.247, p<0.01) use showed significant correlation. The resistant proportion of FQR Pseudomonas aeruginosa was observed to be correlated with the consumption of all antibiotics (r = 0.260, p<0.01), FQs (r = 0.319, p<0.01) and levofloxacin (r = 0.377, p<0.01). The percentage of levofloxacin-resistant Acinetobacter baumannii was significantly correlated with the consumption of all antibiotics (r = 0.282, p<0.01), third-generation cephalosporins excluding combinations with beta-lactamase inhibitors (r = 0.246, p<0.01), FQs (r = 0.254, p<0.01) and levofloxacin (r = 0.336, p<0.01). However, the correlation of the ciprofloxacin-resistant A. baumannii and the antibiotics consumption was not found.

Conclusions

A strong correlation was demonstrated between the antibiotic consumption and the rates of FQR gram-negative bacteria. As unreasonable antibiotics usage remains crucial in the proceeding of resistant bacteria selection, our study could greatly promote the avoidance of unnecessary antibiotic usage.

Association between the rate of third generation cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae and antibiotic consumption based on 143 Chinese tertiary hospitals data in 2014

This study sought to discuss the correlation between the third-generation cephalosporins (3GC)-resistant Escherichia coli and Klebsiella pneumoniae and antibiotic consumption intensity from 143 Chinese tertiary hospitals in 2014. With a retrospective design, the correlation between antibiotic consumption and 3GC-resistant E. coli and K. pneumoniae were performed. 3GC-resistant E. coli was significantly correlated with the consumption of all antibiotics (r = 0.252, p < 0.01), β-Lactams antibiotics (r = 0.313, p < 0.01), β-Lactams excluding combinations with β-lactamase inhibitors (r = 0.365, p < 0.01), cephalosporin (r = 0.398, p < 0.01), cephalosporins excluding combinations with β-lactamase inhibitors (r = 0.374, p < 0.01), 3GC (r = 0.321, p < 0.01), and 3GC excluding combinations with β-lactamase inhibitors (r = 0.343, p < 0.01). 3GC-resistant K. pneumoniae was significantly correlated with the consumption of all antibiotics (r = 0.200, p < 0.05), β-Lactams antibiotics (r = 0.232, p < 0.01), cephalosporin (r = 0.215, p < 0.05), 3GC (r = 0.383, p < 0.01), 3GC excluding combinations with β-lactamase inhibitors (r = 0.245, p < 0.01), and β-lactam-β-lactamase inhibitor combinations (r = 0.218, p < 0.05). There was a significant relationship between the antibiotic consumption and the rates of 3GC-resistant E. coli and K. pneumoniae. Clinicians should grasp the indication of antibiotics use to reduce the production of drug-resistant bacteria.

Low-damaged p-type doping of MoS2 using direct nitrogen plasma modulated by toroidal-magnetic-field

Low damaged doping of two-dimensional (2D) materials proves to be a significant obstacle in realizing fundamental devices such as p-n junction diodes and transistors due to its atom layer thickness. In this work, the defect formation energy and p-type conduction behavior of nitrogen plasma doping are investigated by first principle calculation. Low damaged substitutional p-type doping in MoS₂ using low energy nitrogen plasma composed of N⁺ and N₂ ⁺ is achieved by a novel toroidal magnetic field (TMF). The TMF helps to raise the concentration of N₂ ⁺ ions at low RF power condition. The electrical characteristics of double-layer MoS₂ field-effect transistors (FETs) clearly show an efficient p-type doping behavior. Atomic force microscope is applied to verify the slight damage in MoS₂. X-ray photoelectron spectroscopy, photoluminescence and Raman spectroscopy confirm the effective p-type doping characteristic with weak damage. These findings provide a low damage technology for efficient carrier modulation of MoS₂ and other homogeneous TMDC materials, which overcomes barriers in developing 2D electronic and optoelectronic devices.

Breaking Forbidden Transitions for Emission of Self-Trapped Excitons in Two Dimensional (F2CHCH2NH3)2CdBr4 Perovskite through Pb Alloying

In this work, a new two-dimensional Cd-based (F₂CHCH₂NH₃)₂CdBr₄ perovskite (Cd-P) with indirect bandgap and a direct Pb-based (F₂CHCH₂NH₃)₂PbBr₄ (Pb-P) are successfully synthesized with isostructural features. Compared to the blueish white light emission of Pb-P, almost no white light can be observed for Cd-P due to the forbidden transition of self-trapped exciton (STE) emission. Interestingly, the white light emission of Cd_xPb_1-x-P (x represents the feed ratio of Cd) is significantly improved with the photoluminescence (PL) quantum yield (QY) raising from <1% to 32.5% by alloying these two isostructural perovskites, which is attributed to the breaking of selection rules for forbidden transitions of STEs with Jahn-Teller like octahedral distortion, as suggested by the results from density functional theory (DFT) calculations and time-resolved spectroscopies. This study demonstrates the intriguing effect of alloying on activating STE emission as an effective approach to control and enhance the optical properties of metal halide perovskites.

On three new oonopid species from China and the discovery of the male Orchestina bialata Liu, Xiao &amp; Xu, 2016 (Araneae: Oonopidae)

Expeditions in the Jinggangshan National Nature Reserve in China yielded the discovery of some interesting goblin spiders (Oonopidae). Three new species of oonopid spiders are described and illustrated with photographs and SEMs: Ischnothyreus tergeminus sp. nov. (♂), Orchestina colubrina sp. nov. (♀), and O. zhiwui sp. nov. (♂). Both sexes of the species Orchestina bialata Liu, Xiao & Xu, 2016 were also collected and the male is described for the first time in this paper.

Antimicrobial Stewardship in China: Systems, Actions and Future Strategies

Antimicrobial resistance (AMR) has become a serious global public health crisis, and AMR control has consequently become a priority in all countries. Specifically, the incidence of various common multidrug-resistant bacteria is high, and there are multiple problems concerning the irrational use of antimicrobial drugs. In the past decade, China has established a relatively comprehensive management system and technical support framework for antimicrobial stewardship, including regulations, guidelines, networks for the surveillance of AMR and antimicrobial consumption, and professional personnel training. In addition, the Ministry of Health has carried out a special campaign to promote the proper clinical use of antibiotics in medical institutions, which significantly improved outcomes. The use of antibacterial drugs without indication and the consumption of antibiotics have been significantly reduced. In consideration of the factors that contribute to AMR, the structure of the healthcare system in China, and the need for long-term sustaining efforts to control AMR, the strategy of "two steps and two hands" must be implemented to contain AMR. The first step is to generally promote the rational use of antimicrobial agents in order to promptly curb the rising momentum of resistance with high pressure from the government. The second step requires sustainable professional work with the implementation of precise AMR control. The "first hand" refers to the government-oriented active establishment and optimization of the system and infrastructure of rational antibiotic use and AMR control. The "second hand" refers to the cultivation of professional teams to ensure the establishment and development of sustainable processes in AMR control.

The clinical features and prognosis of infective endocarditis in the elderly from 2007 to 2016 in a tertiary hospital in China

BACKGROUND

Infective endocarditis (IE) especially in the elderly is a serious disease, with a worse prognosis.

METHODS

A retrospective cohort study was conducted. A total of 405 patients with definite IE were divided into three groups: 205 patients under 50 years old, 141 patients between 50 and 64 years old and 59 patients over 65 years old.

RESULTS

For older patients, clinical symptoms such as fever, anemia, and heart murmur were as common as the younger patients. IE in old patients had more frequent nosocomial origin (P = 0.007) and tended to be more frequent with bad oral hygiene (p = 0.008). The most frequent isolated pathogens in the old groups was streptococci and coagulase-negative staphylococci. The old patients had a lower operation rate (40.7% vs 58.9% vs 62.4%, P = 0.012) and higher in-hospital mortality (20.3% vs 10.6% vs 8.8%, P = 0.044) compared with the younger patients. Surgical treatment was a significant predictor of one-year mortality even after adjusting for the confounders (HR = 2.45, 95% CI 1.027-10.598, P = 0.009). The one-year survival rate was higher for older patients with surgical intervention than those without (95.8% vs 68.6%, P = 0.007).

CONCLUSIONS

Older patients with IE presented with more comorbidities, bad oral hygiene, more nosocomial origin and a more severe prognosis than younger patients. Streptococci was the most frequent micro-organisms in this group. Surgery were underused in old patients and those with surgical treatment had better prognosis.

[Anatomical relationship between fascia propria of the rectum and visceral pelvic fascia in the view of continuity of fasciae]

Objective: To perform an anatomical observation on the extension of the mesocolon to the mesorectum and the continuity of the fasciae lining the abdomen and pelvis, in order to clarify the appropriate surgical plane of total mesorectal excision. Methods: This is an descriptive study. The operation videos of 61 cases (28 males, 33 females, median age of 61) were collected. All the patients underwent laparoscopic colorectal surgery from January 2018 to December 2018 in Yangpu Hospital, including low anterior resection for rectal cancer in 25 cases, left hemicolectomy for descending colon cancer in 15 cases, and subtotal resection of the colon for intractable constipation in 21 cases. Among these 21 constipation patients, 8 received additional modified Duhamel surgeries. Gross anatomy was performed on 24 adult cadavers provided by Department of Anatomy, Shanghai Jiaotong University School of Medicine, including 23 formalin-fixed and 1 fresh cadaver (12 males, 12 females). Sixty-one patients and 24 cadavers had no previous abdominal or pelvic surgical history. The anatomy and extension of fasciae related to descending colon, sigmoid colon and rectum, especially the morphology of Toldt fascia, and the continuities of mesocolon and mesorectum were observed carefully. The distribution characteristics of the fasciae and anatomical landmarks during laparoscopic surgery were recorded and described. Results: The anatomical study on 24 cadavers showed that visceral fascia was the densest connective tissue in the pelvic, posterolateral to the rectum, and stretched as a hammock to lift all pelvic organs. Among 61 patients undergoing laparoscopic surgery, 36 (59.0%) needed to free the left colon during operation, and Toldt fascia in the descending colon segment presented as potential, avascular and extensible loose connective tissue plane between the mesocolon and posterior Gerota fascia; 33 (54.1%) needed to free the rectum during operation, and Toldt fascia extended downward to pelvis as loose connective tissue between the fascia propria of the rectum and visceral fascia; the fascia propria of the rectum exposed completely in 32 (32/33, 97.0%) cases, which ran downward and fused with visceral fascia at the level of the fourth sacral vertebra. The anatomy of 24 cadavers also showed that fascia propria of the rectum fused with visceral fascia at the level of Waldeyer fascia. The fusion line of these two fasciae was supposed to be the extension of Waldeyer fascia. There were two avascular planes behind the rectum: one between the fascia propria of the rectum and visceral fascia, and the other between the visceral fascia and parietal fascia. In 8 constipation cases undergoing laparoscopic subtotal colon resection plus modified Duhamel operation, both mesocolon and mesorectum needed to be mobilized. It was obvious that the mesocolon of descending colon extended and became the mesocolon of sigmoid colon, and ran further into the pelvic and became the mesorectum. The colon fascia of descending colon served as the natural boundary of mesocolon extended downward as the fascia of sigmoid colon and the fascia propria of the rectum, respectively. Toldt fascia locating between mesocolon of descending colon and Gerota fascia extended to pelvis as the 'presacral space' between the fascia propria of the rectum and visceral fascia. Gerota fascia in descending colon segment extended as urogenital fascia in sigmoid colon segment and visceral fascia in the pelvis, respectively. In the cadaver anatomy study, the visceral fascia served as a corridor carrying the hypogastric nerve, and ureter was observed in 23 (23/24, 95.8%) cases. The visceral fascia passed from posterior to anterior lateral of rectum, fusing with Denonvilliers fascia in a fan shape. The pelvic plexus located exactly external to the junction of visceral fascia and Denonvilliers fascia. Pelvic splanchnic nerves went through the parietal fascia toward to the inferolateral of the pelvic plexus. Conclusion: Fascia propria of the rectum and the visceral pelvic fascia are two independent layers of fascia, and the TME surgical plane is between the fascia propria of the rectum and visceral pelvic fascia instead of between the visceral and the parietal pelvic fascia.

Fluorinated Spacers Regulate the Emission and Bandgap of Two-Dimensional Single-Layered Lead Bromide Perovskites by Hydrogen Bonding

In this work, four kinds of two-dimensional single-layered F-substituted ethylammonium lead halide perovskites (LHPs, (F_xCH_3-xCH₂NH₃)₂PbBr₄, x = 0, 1, 2, and 3) are successfully synthesized. The introduction of terminal F atoms promotes the formation of an inter- and intramolecular hydrogen bonding network, which has a great impact on the configuration of F-substituted EA, the interlayer spacing, and distortion of inorganic layers. Among these four as-prepared samples, (FCH₂CH₂NH₃)₂PbBr₄ shows the smallest bandgap (∼2.72 eV) and best photoconductivity because of the interlayer electronic coupling. Owing to the strong coupling between excitons and lattice, intense white light emission (quantum yield: 12%) is observed for (F₂CHCH₂NH₃)₂PbBr₄. Benefiting from the hydrophobic nature of F-C bonds, (CF₃CH₂NH₃)₂PbBr₄ presents a greatly improved stability toward moisture. These findings reveal that constructing inter- and intramolecular interaction can serve as an effective approach for tuning the broadband emission and the interlayer conductivity of single-layered LHPs.

Risk factors and outcomes in non-transplant patients with extended-spectrum beta-lactamase-producing Escherichia coli bacteremia: a retrospective study from 2013 to 2016

Background

Escherichia coli is one of the most common strains of extended-spectrum β-lactam (ESBL)-producing bacteria, and the prevention and treatment of ESBL-producing E. coli infections is an ongoing challenge. The clinical characteristics and outcomes of ESBL-producing E. coli bacteremia in non-transplant patients remain to be elucidated.

Methods

This retrospective study included 491 non-transplant patients with E. coli bloodstream infections (BSIs) from January 2013 to December 2016 and was conducted to investigate the risk factors, clinical features, and outcomes of these infections.

Results

Of the 491 E. coli BSI patients, 57.6% suffered from infections with ESBL-producing strains. A multivariate analysis showed that urinary tract infection, prior use of cephalosporin, and treatment with β-lactam-β-lactamase inhibitor (BLBLI) combination antibiotics were independent risk factors for the development of ESBL-producing E. coli BSIs. The overall mortality rate in E. coli BSI patients was 14.46%, and there was no significant difference in the 28 day mortality rate between ESBL-producing E. coli and non-ESBL-producing E. coli BSI patients (14.8% vs. 14.0%, respectively; P = 0.953). Similarly, there was no difference between the community-acquired infection group and the nosocomial infection group. Hepatobiliary disease, carbapenem exposure, high APACHE II score, and hypoproteinemia were independent risk factors for death in E. coli BSI patients. Multivariate analysis showed that hypoproteinemia and severe disease were independent risk factors for death from ESBL-producing E. coli BSIs. Furthermore, there was no significant difference in the 28 day mortality between patients with ESBL-producing E. coli BSIs treated with carbapenem monotherapy versus those treated with BLBLI combination antibiotics (12.8% vs. 17.9%, respectively; P = 0.384).

Conclusions

Prior use of cephalosporin or BLBLI combination antibiotics increased the risk ratio for ESBL-producing E. coli infection. Hypoproteinemia and severe disease are independent risk factors for death in patients with E. coli BSIs. There was no significant difference in the 28 day prognosis of patients with ESBL-producing E. coli and those with non-ESBL-producing E. coli BSIs. These data do not support the conclusion that carbapenems might be more effective than BLBLI antibiotics for treatment of patients with BSIs caused by ESBL-producing E. coli.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0599-y) contains supplementary material, which is available to authorized users.

In vitro reduction of colistin susceptibility and comparative genomics reveals multiple differences between MCR-positive and MCR-negative colistin-resistant Escherichia coli

Objectives: Although resistance to colistin is increasingly reported from clinical settings, the genetic mechanisms that lead to colistin resistance in Escherichia coli have not been fully characterized. Here, we assess the evolution of colistin resistance in clinical isolates of mobilized colistin resistance (MCR)-negative and MCR-positive Escherichia coli. Methods: Spontaneously mutated colistin-resistant progeny were evolved using a step-wise reduction of colistin susceptibility. Resistance phenotypes were confirmed by minimum inhibitory concentration (MIC) determination, and the probable resistance mechanisms were investigated using PCR and reverse transcription-quantitative PCR. Mutated genes of the laboratory-evolved mutants were identified by whole-genome sequencing and comparative genomics. Fitness costs and serum resistance of the mutants were also compared to the corresponding wild types. Results: MCR-negative isolates displayed higher increases in MICs than did MCR-positive isolates following colistin exposure. Upregulation of pmrAB and associated genes was evident among MCR-negative isolates but not MCR-positive isolates. Comparative genomic analysis of mutants and their corresponding wild-types (WTs) revealed numerous mutations in genes encoding membrane transporters and two-component systems. Additionally, MCR-negative mutants exhibited higher fitness costs than MCR-positive mutants compared with their corresponding WTs but displayed similar serum resistance. Conclusion: Our findings reveal multiple differences between MCR-positive and MCR-negative E. coli strains following colistin exposure, which provide reference values for clinical medication.

A new record of the spider family Caponiidae from China (Arachnida, Araneae)

The family Caponiidae Simon, 1890 is reported for the first time from China. The total number of the known spider families from China increases to 72 with the addition of this family newly recorded in the present paper. Based on male and female specimens collected from Guangxi, China, Laoponiasaetosa Platnick & Jäger, 2008 is illustrated and a global distribution map is generated.

Mutational analysis of >14,000 solid tumor NGS tests from community oncology practices: The Sarah Cannon molecular landscape

e18065

Background: Utilization of NGS-based testing for patients in community oncology settings continues to grow. A comprehensive analysis of the molecular landscape of > 14,000 patients with commercial tissue-based and plasma-based NGS (tbNGS and pbNGS) testing from Sarah Cannon’s (SC) network of community oncologists between 2012 and 2018 was performed. These data aid clinical trial design/feasibility and identify rare and actionable mutations in the community oncology setting. Methods: Medical Oncologists in the SC network ordered NGS-based molecular profiling for their patients as standard of care. Data from multiple commercial vendors starting in 2012 were harmonized and analyzed. Results: On average, tbNGS (n = 8938) and pbNGS (n = 5419) tests revealed 14 and 4 mutations/sample, respectively. The top 10 mutated genes from both tbNGS and pbNGS - tests are in the table. The most predominant mutation-types detected were SNVs in both tbNGS and pbNGS tests, and gene amplifications were detected in ~40% of tbNGS and ~22% of pbNGS tests. MET amplifications (range: 2 - 40 copies (pbNGS) and 6 - 82 copies (tbNGS)) and ERBB2 amplifications (range: 2.1 - 90.2 copies (pbNGS) and 4 - 293 copies (tbNGS)) were detected in 1.6% (MET-tbNGS) and 4.6% (MET-pbNGS) and 4.2% (ERBB2-tbNGS) and 2.69% (ERBB2-pbNGS) of patients, respectively, and informed clinical trial enrollment. Of the fusions detected, 28 NTRK rearrangements were detected (NTRK1 – 16, NTRK2 – 5, NTRK3 – 7) by tissue-based testing and 3 (NTRK1) fusions were detected by plasma-based tests. Conclusions: These data describe the mutational landscape of NGS tests ordered within community oncology practices. SC’s data infrastructure links NGS-based testing data and clinical data to support real world evidence research, and highlights the need for healthcare IT systems to marry clinical and genomic data for clinical decision support and clinical research. [Table: see text]

Simulating moxalactam dosage for extended-spectrum β-lactamase-producing Enterobacteriaceae using blood antimicrobial surveillance network data

Objectives: Monte Carlo simulation (MCS) was used to evaluate optimal dosage for cefepime (FEP), moxalactam (MOX), and cefperazone/sulbactam (CFZ/SBT) against extended-spectrum β-lactamase (ESBL) producers isolated from the Blood Bacterial Resistant Investigation Collaborative System.

Methods: Minimum inhibitory concentration (MIC) was tested by agar dilution, and ESBL producers were identified by modified Clinical and Laboratory Standards Institute tests. Pharmacokinetic parameters were derived from data on healthy individuals, and probability of target attainment (PTA) and cumulative fraction of response (CFR) %fT >MIC values were estimated by MCS.

Results: A total of 2032 Escherichia coli (875 ESBL-producing) and Klebsiella pneumoniae (157 ESBL-producing) strains, and 371 other Enterobacteriaceae strains, were isolated from patients with bloodstream infections (BSIs). MIC₉₀ values for FEP, MOX, and CFZ/SBT against ESBL-producing E. coli and K. pneumoniae were 64/64 mg/L, 2/32 mg/L, and 64/128 mg/L, respectively. Conventional MOX and CFZ/SBT doses failed to reach 90% PTA against isolates with MICs ≥8 mg/L and ≥4 mg/L, respectively. Against ESBL producers, neither FEP nor CFZ/SBT achieved ≥90% CFR, while CFRs for MOX (1 g iv q6h, 2 g iv q12h, and 2 g iv q8h) exceeded 90% against ESBL-producing E. coli. Simulated CFRs for FEP and MOX were similar (>90%) against non-ESBL-producing Enterobacteriaceae, and higher than CFRs for CFZ/SBT.

Conclusion: ESBL producers from BSIs were highly susceptible to MOX, and PTA values were generally higher for MOX than FEP or CFZ/SBT for conventional dosing regimens. This large MCS analysis shows that MOX but not FEP or CFZ/SBT can be used empirically to treat BSIs caused by ESBL-producing E. coli strains.

A retrospective analysis of Pseudomonas aeruginosa bloodstream infections: prevalence, risk factors, and outcome in carbapenem-susceptible and -non-susceptible infections

Background

Pseudomonas aeruginosa (PA) is a leading cause of nosocomial infections, and carbapenem non-susceptible strains are a major threat to patient safety.

Methods

A single center, retrospective comparative analysis of carbapenem-non-susceptible PA (CnSPA) and carbapenem-susceptible PA (CSPA) bloodstream infections (BSIs) was conducted between January 1, 2007, and December 31, 2016. Prevalence and risk factors associated with CnSPA BSIs were examined.

Results

The study enrolled 340 patients with PA BSIs; 30.0% (N = 101) of patients had CnSPA. High APACHE II scores (≥15), central venous catheterization, and delayed application of appropriate definitive therapy were independently associated with higher risk of mortality in PA BSIs. Multivariate analysis revealed that respiratory disease and exposure to carbapenems within the previous 90 days to onset of BSI were independent risk factors for acquisition of CnSPA BSIs. Overall all-cause 30-day mortality associated with PA BSIs was 26.8% (91/340). In addition, mortality was higher in patients with CnSPA than in those with CSPA (37.6% vs. 22.2%, respectively; P = 0.003). Corticosteroid therapy and delayed receipt of effective definitive therapy were independent risk factors for death from CnSPA BSIs.

Conclusion

Increased incidence of CnSPA BSIs was observed during the study period, with higher mortality seen in patients with these infections. Respiratory disease and exposure to carbapenems were independent risk factors for development of CnSPA BSIs. Appropriate definitive therapy reduced mortality rates. BLBLIs were as effective as carbapenems as a treatment for PA BSIs.

Six new species of Otacilia from southern China (Araneae: Phrurolithidae)

Six new ground sac spider species of the family Phrurolithidae were collected from southern China: Otacilia ailan sp. nov. (♀), O. daweishan sp. nov. (♂, ♀), O. fabiformis sp. nov. (♂, ♀) and O. jiandao sp. nov. (♀) from Hunan Province; and O. nonggang sp. nov. (♂, ♀) and O. yinae sp. nov. (♂) from Guangxi Zhuang Autonomous Region. All species are described and illustrated with photographs and line drawings.

Comparison of Tigecycline or Cefoperazone/Sulbactam therapy for bloodstream infection due to Carbapenem-resistant Acinetobacter baumannii

Background

We retrospectively analyzed the effect of tigecycline and cefoperazone/sulbactam therapies on the prognosis of patients with carbapenem-resistant Acinetobacter baumannii bloodstream infection (CRAB-BSI).

Methods

CRAB-BSI patients receiving tigecycline therapy or cefoperazone/sulbactam therapy between January 2012 and December 2017 was enrolled, and strict exclusion criteria were followed. The 28-day mortality of patients was analyzed. The impact of cefoperazone/sulbactam therapy on prognosis was evaluated using Cox multivariate regression analysis. The 28-day mortality of patients receiving cefoperazone/sulbactam monotherapy and cefoperazone/sulbactam-based combination therapy was also compared.

Results

Three hundred forty eight patients with CRAB-BSI were enrolled in the study. Two hundred ten patients were included after applying the exclusion criteria. Of these, 135 patients received tigecycline therapy and 75 patients received cefoperazone/sulbactam therapy. The 28-day mortality of patients in the latter group was, significantly lower than that of the tigecycline group [29.3% vs. 51.9%; P = 0.001]. Cox multivariate regression analysis revealed that cefoperazone/sulbactam therapy exerted a protective effect on the prognosis of patients [hazard ratio 0.566, 95% confidence interval (0.342–0.940); P = 0.028]. Kaplan-Meier survival curve analysis indicated that the 28-day mortality of patients receiving cefoperazone/sulbactam therapy was lower than that of patients receiving cefoperazone/sulbactam monotherapy, but the difference was not significant (22.2% vs. 40%; P = 0.074). However, the mortality of patients receiving cefoperazone/sulbactam with imipenem/cilastatin was significantly lower than that of patients receiving cefoperazone/sulbactam monotherapy (P = 0.048).

Conclusions

Patients treated with cefoperazone/sulbactam therapy had a better clinical outcome. The mortality of patients receiving cefoperazone/sulbactam with imipenem/cilastatin seems to be the lowest.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0502-x) contains supplementary material, which is available to authorized users.

Effects of calpain inhibitor on the apoptosis of hepatic stellate cells induced by calcium ionophore A23187

We previously showed that changes in calcium concentrations were related to cell apoptosis in vitro. The endoplasmic reticulum (ER) is the main component of calcium storage and signal transduction, and disrupting the balance of intracellular Ca²⁺ can cause endoplasmic reticulum stress (ERS). In this process, the ER releases stored Ca ²⁺ into the cytoplasm and activates calpain-2. To further investigate the effect of calpain in hepatic stellate cells (HSCs), in the current study, we examine the effect of N-acetyl-leu-leu-norleucinal (ALLN) on apoptosis resulting from calcium ionophore A23187-induced ERS. Our findings indicate that calpain inhibition reduces calcium ionophore A23187-induced apoptosis of HSCs and decreases the expression of ER stress proteins that may be related to the calpain/caspase signaling pathway.

A retrospective analysis of risk factors and outcomes in patients with extended-spectrum beta-lactamase-producing Escherichia coli bloodstream infections

OBJECTIVE

Risk factors and outcomes associated with extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) bloodstream infections (BSI) are not yet fully understood.

METHODS

This was a retrospective analysis of patients with E. coli BSI treated over a 4-year period. The characteristics of bacteremia caused by ESBL-producing versus non-ESBL-producing E. coli were compared. Factors influencing mortality were also assessed.

RESULTS

Of 554 eligible patients, 58.9% developed ESBL-producing E. coli. Multivariate analysis showed that urinary tract infections, stomach tube catheterization, and prior cephalosporin exposure were independent risk factors for the emergence of ESBL-producing E. coli BSI. No significant differences in 30-day mortality were seen in patients with BSI caused by ESBL-producing or non-ESBL-producing E. coli (11.1% vs. 9.2%; P=0. 642). Factors independently associated with a higher risk of mortality were previous carbapenem exposure, high APACHE II score, and respiratory tract origin.

CONCLUSIONS

This study showed that prior UTIs and previous cephalosporin exposure represent significant risk factors for the development of ESBL-producing E. coli BSI. Previous carbapenem exposure, high APACHE II score, and a respiratory tract origin were seen to be independent mortality risk factors in patients with E. coli BSI.

[The reliability of using impenem, meropenem, cefoperazone-sulbactam and piperacillin-tazobactam to treat nosocomial Gram-negative bacterial infections with Monte Carlo simulation]

Objective: To evaluate the reliability of using imipenem, meropenem, cefoperazone-sulbactam, piperacillin-tazobactam in the treatment of hospital-acquired Gram-negative bacterial infections with Monte Carlo simulation(MCS). Methods: The MIC of the four agents collected from hospital-acquired infections were detected in accordance with broth dilution method of Clinical and Laboratory Standard Institute (CLSI). MCS were conducted with MICs and the pharmacokinetics parameters of the four agents based on conventional dose regimens.The cumulative fraction of response (CFR) of time over MIC target attainment in different dosing regimen were generated. Results: A total of 2 541 strains, including 2 093 strains of Enterobacteriaceae and 448 strains of glucose non-fermentative bacilli were collected.The MIC(90) of imipenem and meropenem against Enterobacteriaceae were less than 1 mg/L in general, whereas MIC(90) of two agents with β-lactamase inhibitors was around 64 mg/L.As to glucose non-fermenting bacteria, MICs of all the four agents were very high, especially to Acinetobacter baumannii, which indicated MIC(50) more than 32 mg/L.MCS revealed that carbapenems had significantly higher CFR than those with β-lactamase inhibitors.Imipenem and meropenem (1 g, q8 h) obtained CFRs of 74.69% and 81.42%, respectively.The CFR of cefoperazone-sulbactam (2 g, q8 h) and piperacillin-tazobactam (4 g, q6 h) (both excluding β-lactamase inhibitors) were just 49.59% and 27.66% respectively, which increased after excluding A. baumannii in piperacillin-tazobactam. Conclusions: The conventional dose regimens of imipenem and meropenem are reliable for the empiric therapy of Gram-negative hospital-acquired bacterial infections.Piperacillin-tazobactam is suggested to use with higher doses or prolonged infusion time to satisfy the time of drug concentration exceeded the MIC(T>MIC)requirement.More clinical studies of cefoperazone-sulbactam should be conducted to optimize its regimen and guarantee its efficacy.

Plasmon enhanced photocatalytic and antimicrobial activities of Ag-TiO2 nanocomposites under visible light irradiation prepared by DBD cold plasma treatment

Silver nanoparticles (Ag NPs) have been deposited on powder P25 by a novel two-step method involving a precipitation reaction and atmospheric pressure dielectric barrier discharge (DBD) cold plasma treatment without the use of any environmentally and biologically hazardous reducing agents. The silver precursor is formed in the processing of precipitation reaction and then completely reduced to the metallic state by atmospheric pressure DBD cold plasma treatment as proved by X-ray photoelectron spectroscopy, UV-Visible absorption spectra and HRTEM analyses. TEM images indicate that the Ag NPs with average diameter of 3.7 nm were deposited on powder P25 with high dispersion although no reducing agents, stabilizers or surfactants were used. The prepared products show remarkable improvement for methylene blue (MB) photodegradation and effective inhibition of bacterias against Escherichia coli and Staphylococcus aureus.

Retrospective comparative analysis of risk factors and outcomes in patients with carbapenem-resistant Acinetobacter baumannii bloodstream infections: cefoperazone-sulbactam associated with resistance and tigecycline increased the mortality

Background

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a rapidly emerging, life-threatening nosocomial infection. This study aimed to explore the risk factors, clinical features, antimicrobial therapy, and outcomes of CRAB bloodstream infections (BSIs).

Methods

This is a retrospective, comparative analysis of data from patients with A. baumannii BSI, treated from 2012 to 2015 at a tertiary teaching hospital. Risk factors associated with CRAB BSI and factors associated with the 28-day mortality were evaluated using logistic analyses.

Results

Data from 293 patients with confirmed A. baumannii BSI were included; 242 (82.6%) patients had CRAB BSI and 51 (17.4%) patients had non-CRAB BSI. Risk factors significantly associated with CRAB BSI were a previous intensive care unit (ICU) stay (P=0.029), cefoperazone–sulbactam use (P=0.030), and carbapenem use (P=0.004). Among 236 patients with A. baumannii BSI who were evaluable at 28 days after receiving antibacterial therapy, there were 86 deaths. Factors associated with the 28-day mortality were ICU stay after BSI (P=0.040), readmission within 90 days (P=0.029), Acute Physiology and Chronic Health Evaluation II (APACHE II) score at diagnosis >19 (P=0.012), tigecycline therapy (P=0.021), presence of septic shock (P=0.029), and multiple organ failure (P=0.016). Death rates in patients treated with tigecycline were 53.5% vs 24.1% in patients treated with other agents. Among 186 patients with CRAB BSI evaluable at 28 days, 84 patients died. The associated risk factors were an ICU stay after BSI (P=0.036), APACHE II score >19 at diagnosis (P = 0.002), presence of septic shock (P=0.030), and multiple organ failure (P=0.007).

Conclusion

This study demonstrated that an ICU stay and cefoperazone–sulbactam or carbapenem use were seen to be the risk factors associated with the development of CRAB BSI. Critical illness and tigecycline therapy were significantly associated with higher mortality of patients with A. baumannii BSI.

Five new Lathys species (Araneae: Dictynidae) from South China and the first description of the male of Lathys spiralis Zhang, Hu Zhang, 2012

Dictynidae spiders were collected from Jinggang Mountain National Nature Reserve, Jiangxi Province, China in the past four years. Five new species are described and illustrated with photographs, SEMs and line drawings: Lathys adunca Liu spec. nov. (male), L. deltoidea Liu spec. nov. (female), L. fibulata Liu spec. nov. (female), L. huangyangjieensis Liu spec. nov. (male, female) and L. zhanfengi Liu spec. nov. (female). Both sexes of the species L. spiralis Zhang, Hu Zhang, 2012 were collected from leaf litter in Jinggangshan University and the male is described for the first time. All specimens are deposited in the Animal Specimen Museum, Life Science College, at the Jinggangshan University (ASM-JGSU).

Characterization of lasR-deficient clinical isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a prevalent opportunistic pathogen that causes fatal infections in immunocompromised individuals. Quorum sensing (QS) is a cell-to-cell communication process that controls virulence gene expression and biofilm formation in P. aeruginosa. Here, the QS systems and the relevant virulence traits in clinical P. aeruginosa isolates were characterized. Eleven out of the ninety-four P. aeruginosa isolates exhibited a biofilm-deficient phenotype. Two biofilm-deficient isolates, one from blood and the one from pleural effusion, appeared to carry a same mutation in lasR. These two isolates differed in the ability to produce QS-regulated virulence factors, but contained the same functionally deficient LasR with the truncated C-terminal domains and belonged to the same multilocus sequence type (ST227). Chromosomal lasR complementation in these lasR mutants verified that lasR inactivation was the sole cause of las deficiency. LasR was not absolutely required for rhl signal in these lasR mutants, suggesting the presence of lasR-independent QS systems. We provided evidence that the virulence gene expression are not regulated in the same manner in these isolates. These results support the hypothesis that conventional QS hierarchy can be smashed by naturally occurring lasR mutation in clinical P. aeruginosa isolates and that complex QS hierarchy may play a role in maintaining infection of this opportunistic pathogen.

Characterization of the population structure, drug resistance mechanisms and plasmids of the community-associated Enterobacter cloacae complex in China

Objectives

To investigate the population structure, drug resistance mechanisms and plasmids of community-associated Enterobacter cloacae complex (CA-ECC) isolates in China.

Methods

Sixty-two CA-ECC isolates collected from 31 hospitals across China were typed by hsp60 typing and MLST. ESBL and AmpC-overexpression phenotype was determined by double-disc synergy test. Replicon typing and conjugation were performed for plasmid analysis. All ESBL-positive isolates and representative conjugants were subjected to detailed characterization by WGS.

Results

Enterobacter hormaechei and Enterobacter kobei were predominant in our collections. MLST distinguished 46 STs with a polyclonal structure. ST591 was the most prevalent clone detected in northern China. Twenty-two isolates (35.5%) were ESBL positive and half of them were E. kobei. ESBL positivity was related to ESBL production (15/22) and to AmpC overexpression (18/22). Core-genome phylogenetic analysis identified intra- and inter-regional dissemination of ESBL-producing E. kobei clones. ESBL producers were exclusively classified as E. hormaechei and E. kobei, and blaCTX-M-3 was the most prevalent ESBL genotype (10/15) detected in four different environments. In the ESBL-positive population, the ESBL producers encoded more drug resistance genes (8-24 genes) by carrying more plasmids (1-3 plasmids) than the non-ESBL-producing isolates, resulting in an inter-group difference in drug susceptibilities. IncHI-type plasmids were prevalent in the ESBL producers (12/15). All IncHI2-type plasmids (n = 11) carried ESBL genes and shared a similar backbone to p09-036813-1A_261 recovered from Salmonella enterica in Canada.

Conclusions

The species-specific distribution, species-dependent ESBL mechanism and endemic plasmids identified in our study highlight the necessity for tailored surveillance of CA-ECC in the future.

Abstract 1724: Evaluation of niraparib in combination with anti-PD1/anti-PD-L1 in preclinical models

Niraparib is an orally available and selective poly(ADP-ribose) polymerase (PARP)-1/-2 inhibitor approved for maintenance treatment of adult patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in complete or partial response to platinum-based chemotherapy. PARP inhibition may enhance the immune response in tumors treated with anti-PD-1 therapy via generation of cytosolic DNA that activates T cells through the stimulator of interferon gene (STING) pathway, rendering tumors immunologically “hot” with an increase in infiltrating lymphocytes.

In this study, we explored the responses and mechanism of action of niraparib and anti-PD-1/anti-PD-L1 combination therapy in preclinical models. Out of a cohort of 14 immune-competent mouse tumor models, the combination treatment demonstrated enhanced anti-tumor activity in eight tumor models derived from BRCA-proficient and BRCA-deficient genetic backgrounds. Substantial increases compared to monotherapies in anti-tumor activity was observed in 5 models, indicative of synergy between niraparib and anti-PD-1/anti-PD-L1 therapy. The combination triggered durable responses that were coincident with induction of immune memories in a BRCA-deficient ovarian syngeneic model. Mechanistically, niraparib treatment increased the number of infiltrating CD8+ and CD4+ cells within the intratumoral region. The enhanced immune cell infiltration was accompanied by elevated interferon-stimulated gene expression. Pathway analyses using transcriptome profiling identified interferon response gene signatures as the significantly differentially-upregulated gene sets following niraparib treatment. Consistently, niraparib treatment activated the STING pathway in vitro in BRCA-deficient MDA-MB-436 human triple negative breast cancer cells. STING pathway markers including p-STING(Ser366), p-TBK1(Ser172) and p-NFκB p65 were elevated following niraparib treatment and was accompanied by an increase in IFNB mRNA expression. In summary, our data suggested that niraparib treatment in combination with anti-PD-1/anti-PD-L1 therapy enhanced immune cell infiltration, interferon-stimulated gene expression and tumor responses.

Citation Format: Sarah Wang, Kaiming Sun, Yonghong Xiao, Bin Feng, Keith Mikule, Sridhar Ramaswamy, Jeffrey Hanke, Jing Wang. Evaluation of niraparib in combination with anti-PD1/anti-PD-L1 in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1724.

In vitro antibacterial effect of fosfomycin combination therapy against colistin-resistant Klebsiella pneumoniae

Objectives

Colistin is still a “last-resort” antibiotic used to manage human infections due to multidrug-resistant (MDR) Klebsiella pneumoniae. However, colistin-resistant K. pneumoniae (CR-Kp) isolates emerged a decade ago and had a worldwide distribution. The purpose of this study was to evaluate the genetic data of CR-Kp and identify the antibacterial activity of fosfomycin (FM) alone and in combination with amikacin (AMK) or colistin (COL) against CR-Kp in vitro.

Methods

Three clinical CR-Kp isolates from three patients were collected. Whole-genome sequencing and bioinformatics analysis were performed. The Pharmacokinetics Auto Simulation System 400, by simulating human pharmacokinetics in vitro, was employed to simulate FM, AMK, and COL alone and in combination. Different pharmacodynamic parameters were calculated for determining the antimicrobial effect.

Results

Whole-genome sequencing revealed that none of the three isolates contain mcr gene and that no insertion was found in pmrAB, phoPQ, or mgrB genes. We found the antibacterial activity of AMK alone was more efficient than FM or COL against CR-Kp. The area between the control growth and antibacterial killing curves of FM (8 g every 8 hours) combined with AMK (15 mg/kg once daily) was higher than 170 LogCFU/mL·h⁻¹. In addition, the area between the control growth and antibacterial killing curves of FM (8 g every 8 hours) combined with COL (75,000 IU/kg every12 hours) was higher than that of monotherapies (>100 LogCFU/mL·h⁻¹ vs <80 LogCFU/mL·h⁻¹).

Conclusion

FM (8 g every 8 hours) combined with AMK (15 mg/kg once daily) was effective at maximizing bacterial killing against CR-Kp.

A retrospective, comparative analysis of risk factors and outcomes in carbapenem-susceptible and carbapenem-nonsusceptible Klebsiella pneumoniae bloodstream infections: tigecycline significantly increases the mortality

Background

Carbapenem-nonsusceptible Klebsiella pneumoniae (CnSKP) is rapidly emerging as a life-threatening nosocomial infection. The efficacy of tigecycline in the treatment of bloodstream infections (BSIs) remains controversial.

Methods

Data from a total of 428 patients with carbapenem-susceptible Klebsiella pneumoniae (CSKP) and CnSKP BSIs were collected at a single center between January 2013 and December 2015. A three-part analysis was conducted to identify the risk factors associated with CnSKP, explore prognosis, and evaluate treatments.

Results

Data from 428 patients with Klebsiella pneumoniae (KP) BSIs were included, 31.5% (n=135) of them with CnSKP. Multivariate analysis showed that prior hospitalization, urinary catheterization, the use of immunosuppressive agents, prior use of antibiotics, pulmonary disease, and high Acute Physiology and Chronic Health Evaluation (APACHE) II scores were independent risk factors for CnSKP-BSIs. The 30-day mortality was higher in patients with CnSKP than in those with CSKP (58.5% vs 15.4%; P<0.001). In patients with KP-BSIs, neutropenia, multiple organ dysfunction, respiratory failure, CnSKP infection, high APACHE II score, and tigecycline therapy were independently associated with higher mortality risk. Among patients whose APACHE II score was <15, higher mortality rates were observed in patients treated with tigecycline than in those treated with other antibiotics (45.3% vs 7.7%; P<0.001). Central venous catheterization, multiple organ dysfunction, and high APACHE II scores were independent risk factors for death from CnSKP.

Conclusion

A significant increase in the incidence of CnSKP-BSIs was observed during the study period, with a higher mortality rate found in these patients. Exposure to carbapenems and severe illness were independent risk factors for the development of CnSKP-BSIs, and tigecycline therapy resulted in a significant increase in mortality.

Oncogenic Signaling Pathways in The Cancer Genome Atlas

Genetic alterations in signaling pathways that control cell-cycle progression, apoptosis, and cell growth are common hallmarks of cancer, but the extent, mechanisms, and co-occurrence of alterations in these pathways differ between individual tumors and tumor types. Using mutations, copy-number changes, mRNA expression, gene fusions and DNA methylation in 9,125 tumors profiled by The Cancer Genome Atlas (TCGA), we analyzed the mechanisms and patterns of somatic alterations in ten canonical pathways: cell cycle, Hippo, Myc, Notch, Nrf2, PI-3-Kinase/Akt, RTK-RAS, TGFβ signaling, p53 and β-catenin/Wnt. We charted the detailed landscape of pathway alterations in 33 cancer types, stratified into 64 subtypes, and identified patterns of co-occurrence and mutual exclusivity. Eighty-nine percent of tumors had at least one driver alteration in these pathways, and 57% percent of tumors had at least one alteration potentially targetable by currently available drugs. Thirty percent of tumors had multiple targetable alterations, indicating opportunities for combination therapy.

Genomic and Molecular Landscape of DNA Damage Repair Deficiency across The Cancer Genome Atlas

DNA damage repair (DDR) pathways modulate cancer risk, progression, and therapeutic response. We systematically analyzed somatic alterations to provide a comprehensive view of DDR deficiency across 33 cancer types. Mutations with accompanying loss of heterozygosity were observed in over 1/3 of DDR genes, including TP53 and BRCA1/2. Other prevalent alterations included epigenetic silencing of the direct repair genes EXO5, MGMT, and ALKBH3 in ∼20% of samples. Homologous recombination deficiency (HRD) was present at varying frequency in many cancer types, most notably ovarian cancer. However, in contrast to ovarian cancer, HRD was associated with worse outcomes in several other cancers. Protein structure-based analyses allowed us to predict functional consequences of rare, recurrent DDR mutations. A new machine-learning-based classifier developed from gene expression data allowed us to identify alterations that phenocopy deleterious TP53 mutations. These frequent DDR gene alterations in many human cancers have functional consequences that may determine cancer progression and guide therapy.