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Edoardo Carretto, Flavia Brovarone, Giuseppe Russello, Paola Nardini, Maisra El-Bouseary, Ali Aboklaish, Timothy R Walsh, Jonathan M Tyrrell
The global spread of multi-drug resistant Gram negative has led to the return of colistin for treating severe infections. Recently, different plasmid-mediated genes conferring resistance to this drug were described and reported worldwide. International committees (EUCAST/CLSI) re-evaluated inconsistencies surrounding colistin antimicrobial susceptibility testing (AST), concluding that broth microdilution (BMD) should serve as the reference method for AST. The development of an accurate, reproducible commercial test based on BMD is therefore highly desirable...
January 17, 2018: Journal of Clinical Microbiology
Agnese Lupo, Estelle Saras, Jean-Yves Madec, Marisa Haenni
Objectives: In Asian countries, blaCTX-M-55 is the second most common ESBL-encoding gene. blaCTX-M-55 frequently co-localizes with fosA and rmtB genes on epidemic plasmids, which remain sporadic outside Asia. During 2010-13, we investigated CTX-M-55-producing Escherichia coli isolates and their co-resistance to fosfomycin, aminoglycosides, fluoroquinolones and colistin as part of a global survey of ESBLs in animals in France. Methods: blaCTX-M-55, fosA, rmtB and plasmidic quinolone and colistin resistance genes were characterized by PCR, sequencing and hybridization experiments...
January 10, 2018: Journal of Antimicrobial Chemotherapy
Zhe Lyu, Chau-Wen Chou, Hao Shi, Liangliang Wang, Robel Ghebreab, Dennis Phillips, Yajun Yan, Evert C Duin, William B Whitman
Methyl-coenzyme M reductase (MCR) is a complex enzyme that catalyzes the final step in biological methanogenesis. To better understand its assembly, the recombinant MCR from the thermophile Methanothermococcus okinawensis (rMCRok) was expressed in the mesophile Methanococcus maripaludis The rMCRok was post-translationally modified correctly and contained McrD and the unique nickel tetrapyrrole coenzyme F430 Subunits of the native M. maripaludis (MCRmar) were largely absent, suggesting that the recombinant enzyme was formed by an assembly of co-transcribed subunits...
January 16, 2018: Journal of Bacteriology
Yonglin Zhou, Shui Liu, Tingting Wang, Hui Li, Shusheng Tang, Jianfeng Wang, Yang Wang, Xuming Deng
We characterized pterostilbene produced a synergistic effect with polymyxin B (FIC index=0.156 or 0.188) against MCR-producing Escherichia coli strains of both human and animal origin. The time-killing assays showed that either pterostilbene or polymyxin B failed to eradicate a mcr-1- and NDM-positive E. coli strain ZJ487, but the combination eliminated by 1-hour post-inoculation. The survival rate of mouse following the intraperitoneal infection significantly promoted from 0% to 60% in the group of combination therapy applied...
January 16, 2018: Antimicrobial Agents and Chemotherapy
Kai Zhou, Qixia Luo, Qin Wang, Chen Huang, Haifeng Lu, Rossen W A John, Yonghong Xiao, Lanjuan Li
The global dissemination of the mobile colistin resistance mcr-1 is of special concern, as colistin is one of the last-resort antibiotics for the treatment of severe infections caused by carbapenem-resistant Gram-negative bacteria. Here, we characterized an inactive form of mcr-1 in a fluoroquinolone-resistant and colistin-susceptible uropathogenic Escherichia coli isolate (ECO3347). The mcr-1 gene was deactivated by the insertion of a 1.7-Kb IS1294b element flanked by two tetramers (GTTC), and located on a 62-Kb pHNSHP45-like plasmid (p3347-mcr-1)...
January 12, 2018: International Journal of Antimicrobial Agents
Edoardo Carretto, Flavia Brovarone, Paola Nardini, Giuseppe Russello, Daniela Barbarini, Stefano Pongolini, Carlo Gagliotti, Alessandra Carattoli, Mario Sarti
In this study we report the detection of the recently described mcr-4 gene in two human isolates of Salmonella enterica serovar Typhimurium. The strains were isolated from faecal samples of two Italian patients with gastroenteritis, collected in 2016. The identified mcr-4 genes (variant mcr-4.2) differed from the mcr-4 gene originally described in a Salmonella strain of swine origin from Italy. Salmonella species could represent a hidden reservoir for mcr genes.
January 2018: Euro Surveillance: Bulletin Européen sur les Maladies Transmissibles, European Communicable Disease Bulletin
Y Li, W J Yan, S Q Liu
Objective: To investigate the presence of colistin resistance gene mcr in gut bacteria from patients with acute diarrhea. Methods: Fresh stool samples were collected from 150 outpatients with acute diarrhea in the intestinal clinic of Henan Provincial People's Hospital, and were directly detected for the presence of mcr by PCR after enrichment in the broth.The mcr-producing bacteria were further isolated and identified by MALDI-TOF MS (Bruker Biotyper). Antimicrobial susceptibility of these isolates was conducted by micro-broth dilution method...
December 19, 2017: Zhonghua Yi Xue za Zhi [Chinese medical journal]
John Osei Sekyere, Jonathan Asante
Bacteria and fungi continue to develop new ways to adapt and survive the lethal or biostatic effects of antimicrobials through myriad mechanisms. Novel antibiotic resistance genes such as lsa(C), erm(44), VCC-1, mcr-1, mcr-2, mcr-3, mcr-4, bla KLUC-3 and bla KLUC-4 were discovered through comparative genomics and further functional studies. As well, mutations in genes that hitherto were unknown to confer resistance to antimicrobials, such as trm, PP2C, rpsJ, HSC82, FKS2 and Rv2887, were shown by genomics and transcomplementation assays to mediate antimicrobial resistance in Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, Saccharomyces cerevisae, Candida glabrata and Mycobacterium tuberculosis, respectively...
January 10, 2018: Future Microbiology
Rocío B Pellegrino Vidal, Franco Allegrini, Alejandro C Olivieri
Multivariate curve resolution-alternating least-squares (MCR-ALS) is the model of choice when dealing with some non-trilinear arrays, specifically when the data are of chromatographic origin. To drive the iterative procedure to chemically interpretable solutions, the use of constraints becomes essential. In this work, both simulated and experimental data have been analyzed by MCR-ALS, applying chemically reasonable constraints, and investigating the relationship between selectivity, analytical sensitivity (γ) and root mean square error of prediction (RMSEP)...
March 20, 2018: Analytica Chimica Acta
Macon Magno, Frank Hagelberg
The transport properties of zigzag graphene nanoribbons (zGNRs) were studied by density functional theory (DFT) in conjunction with Green's function analysis. In particular, spin transport through a zGNR (12,0) device was investigated under the constraint of ferromagnetic coordination of the ribbon edges. Several configurations with two vacant sites in the edge and the bulk region of the zGNR device were derived from this system. For all structures, magnetocurrent ratios (MCRs) were recorded as a function of the bias as well as the amount of strain applied longitudinally to the devices...
January 8, 2018: Journal of Molecular Modeling
Luchao Lv, Yuping Cao, Peixin Yu, Raorao Huang, Jing Wang, Qiaoling Wen, Chanping Zhi, Qianhui Zhang, Jian-Hua Liu
The presence of mcr-1 gene in Escherichia coli isolated from retailed freshwater fish was investigated. Seven (3.65%) clonal unrelated grass carp original E. coli isolates were positive for mcr-1. mcr-1 genes were encoded by either chromosomes (n = 2) or conjugative plasmids (2 IncI2, 2 IncP, 1 IncX4). The IncP plasmids were similar to other mcr-1-harboring IncP plasmids from China, though the insertion sites varied. Our report warrants further surveillance of resistance genes in aquaculture.
January 8, 2018: Antimicrobial Agents and Chemotherapy
Pak-Leung Ho, Ya Wang, Melissa Chun-Jiao Liu, Eileen Ling-Yi Lai, Pierra Ying-Tung Law, Huiluo Cao, Kin-Hung Chow
Six imported pigs originating from Guangdong, Henan, and Hunan provinces in China during October 2015-February 2017 were culture positive for meropenem-resistant Escherichia coli The samples yielded 9 E. coli isolates of diverse sequence types carrying blaNDM-5 on IncX3 (8 isolates from 5 farms) or IncFII (1 isolate from 1 farm) plasmids. The mcr-1 gene was co-harboured by four isolates. The IncX3 plasmids (∼46 kb) carrying blaNDM-5 were identical or nearly identical to each other.
January 8, 2018: Antimicrobial Agents and Chemotherapy
Jinxin Liu, Yanxian Yang, Yunxia Li, Dan Liu, Hongmei Tuo, Hongning Wang, Douglas R Call, Margaret Davis, Anyun Zhang
The plasmid-mediated colistin resistance gene mcr-1 has been found worldwide, but the diversity of organisms harboring this gene is unknown. In this study, twelve colistin-resistant Citrobacter spp. isolates were obtained from diseased or dead chickens in China, and PCR analysis indicated that five were positive for mcr-1. One Citrobacter braakii strain (SCC4) with a multidrug resistance phenotype was chosen for further analysis. SCC4 was resistant to ten tested antibiotics and the minimum inhibitory concentration (MIC) to colistin was >4 µg/mL...
January 3, 2018: International Journal of Antimicrobial Agents
Husamettin Aygun, Murat Karamese, Cem Ozic, Fikret Uyar
AIM: Adherent-invasive Escherichia coli (AIEC) pathovar has been identified in intestinal mucosa of patients with Crohn's disease. Our aim was to compare the impact of sterile mucosal media (Muc-M) originated from different parts of the intestine on some pathogenic traits of AIEC LF82 strain. MATERIALS & METHODS: Muc-M composed of certain rates of cell culture medium or M63 minimal medium and mucosal contents obtained from different part of intestine were designed for cell-infection experiments and biofilm-formation assays...
January 5, 2018: Future Microbiology
Sarah M Matt, Dor Ben-Amotz
Raman multivariate curve resolution (Raman-MCR) spectra obtained from pure and isotopically dilute water are used to probe the influence of intermolecular resonance couplings on water OH and OD stretch band shapes and intensities, in the absence of intramolecular coupling. Intermolecular resonant coupling is found to broaden and red-shift the stretch band of water, in qualitative agreement with the predictions of Yang and Skinner. The influence of intermolecular coupling is found to increase with decreasing temperature, and to increase the Raman scattering cross section of the OH stretch, but decrease the OD stretch cross section...
January 3, 2018: Journal of Physical Chemistry. B
Haifang Zhang, Minhui Miao, Jieting Yan, Min Wang, Yi-Wei Tang, Barry N Kreiswirth, Xia Zhang, Liang Chen, Hong Du
The plasmid-encoded colistin resistance gene (mcr-1) has recently been reported in various Gram-negative species. However, the expression profile of mcr-1 remains unknown. Here, we investigated the expression of mcr-1 in various plasmids and bacteria. The mcr-1 expression levels in pMCR1_IncX4 varied from 1.81 × 10-5 to 1.05 × 10-4 (pmol per μg total RNA) in the two K. pneumoniae strains SZ03 and SZ04 (ST25) and the two E. coli strains SZ01 and CDA6 (ST2448 and ST167, respectively). The mcr-1 expression levels of pMCR1_IncI2 in E...
December 8, 2017: Oncotarget
Wenjie Wang, Qingyun Cai, Fang Zhou, Jiali Liu, Xiaoliang Jin, Ping Ni, Meng Lu, Guangji Wang, Jingwei Zhang
Although metabolic reprogramming and redox imbalance are widely reported to be involved in chemo-resistance in cancer treatment, much more attention was paid to anti-cancer drug induced effect. Our previous studies showed that cancer cells can develop P-gp overexpression-mediated intrinsic drug resistance in the formation of 3D MCF-7 multi-cellular layers (MCLs) without any drug induction. However, whether metabolic reprogramming and redox imbalance functioned during this progress remained unrevealed. In our present study, LC-Q/TOF-MS and GC-MS were used in combination for analysing intracellular metabolites...
December 21, 2017: Redox Biology
Yannick Casamayou-Boucau, Alan G Ryder
Anisotropy resolved multidimensional emission spectroscopy (ARMES) provides valuable insights into multi-fluorophore systems like proteins that have complex overlapping emission bands. The method combines multidimensional fluorescence, anisotropy, and chemometrics to facilitate the differentiation of fluorophores with very similar emission properties. Here, we address the critical issue of standardizing the chemometric methods required to accurately extract spectral and anisotropy information from fluorophore mixtures using two standard sample sets: perylene in glycerol, and a mixture of Erythrosin B and Phloxine B with overlapping emission but different anisotropies...
February 13, 2018: Analytica Chimica Acta
Ludovic Duponchel
Analytical chemistry is rapidly changing. Indeed we acquire always more data in order to go ever further in the exploration of complex samples. Hyperspectral imaging has not escaped this trend. It quickly became a tool of choice for molecular characterisation of complex samples in many scientific domains. The main reason is that it simultaneously provides spectral and spatial information. As a result, chemometrics has provided many exploration tools (PCA, clustering, MCR-ALS …) well-suited for such data structure at early stage...
February 13, 2018: Analytica Chimica Acta
Siewert Hugelier, Sara Piqueras, Carmen Bedia, Anna de Juan, Cyril Ruckebusch
The use of sparseness in chemometrics is a concept that has increased in popularity. The advantage is, above all, a better interpretability of the results obtained. In this work, sparseness is implemented as a constraint in multivariate curve resolution - alternating least squares (MCR-ALS), which aims at reproducing raw (mixed) data by a bilinear model of chemically meaningful profiles. In many cases, the mixed raw data analyzed are not sparse by nature, but their decomposition profiles can be, as it is the case in some instrumental responses, such as mass spectra, or in concentration profiles linked to scattered distribution maps of powdered samples in hyperspectral images...
February 13, 2018: Analytica Chimica Acta
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