Synthesis of a Novel Boronic Acid Transition State Inhibitor, MB076: A Heterocyclic Triazole Effectively Inhibits Acinetobacter-Derived Cephalosporinase Variants with an Expanded-Substrate Spectrum

Class C Acinetobacter-derived cephalosporinases(ADCs) represent an important target for inhibition in the multidrug-resistantpathogen Acinetobacter baumannii. ManyADC variants have emerged, and characterization of their structuraland functional differences is essential. Equally as important is thedevelopment of compounds that inhibit all prevalent ADCs despite thesedifferences. The boronic acid transition state inhibitor, MB076, a novel heterocyclic triazole with improved plasma stability, wassynthesized and inhibits seven different ADC & beta;-lactamase variantswith K (i) values MB076 acted synergistically in combination with multiple cephalosporinsto restore susceptibility. ADC variants containing an alanine duplicationin the & omega;-loop, specifically ADC-33, exhibited increased activityfor larger cephalosporins, such as ceftazidime, cefiderocol, and ceftolozane.X-ray crystal structures of ADC variants in this study provide a structuralcontext for substrate profile differences and show that the inhibitoradopts a similar conformation in all ADC variants, despite small changesnear their active sites

A standard numbering scheme for class C β-lactamases

Unlike classes A and B, a standardized amino acid numbering scheme has not been proposed for the class C (AmpC) β-lactamases, which complicates communication in the field. Here, we propose a scheme developed through a collaborative approach that considers both sequence and structure, preserves traditional numbering of catalytically important residues (Ser64, Lys67, Tyr150, and Lys315), is adaptable to new variants or enzymes yet to be discovered, and includes a variation for genetic and epidemiological applications

Longitudinal Analysis of the Temporal Evolution of Acinetobacter baumannii Strains in Ohio, USA, by Using Rapid Automated Typing Methods

Genotyping methods are essential to understand the transmission dynamics of Acinetobacter baumannii. We examined the representative genotypes of A. baumannii at different time periods in select locations in Ohio, using two rapid automated typing methods: PCR coupled with electrospray ionization mass spectrometry (PCR/ESI-MS), a form of multi-locus sequence typing (MLST), and repetitive-sequence-based-PCR (rep-PCR). Our analysis included 122 isolates from 4 referral hospital systems, in 2 urban areas of Ohio. These isolates were associated with outbreaks at 3 different time periods (1996, 2000 and 2005–2007). Type assignments of PCR/ESI-MS and rep-PCR were compared to each other and to worldwide (WW) clone types. The discriminatory power of each method was determined using the Simpson's index of diversity (DI). We observed that PCR/ESI-MS sequence type (ST) 14, corresponding to WW clone 3, predominated in 1996, whereas ST 12 and 14 co-existed in the intermediate period (2000) and ST 10 and 12, belonging to WW clone 2, predominated more recently in 2007. The shift from WW clone 3 to WW clone 2 was accompanied by an increase in carbapenem resistance. The DI was approximately 0.74 for PCR/ESI-MS, 0.88 for rep-PCR and 0.90 for the combination of both typing methods. We conclude that combining rapid automated typing methods such as PCR/ESI-MS and rep-PCR serves to optimally characterize the regional molecular epidemiology of A. baumannii. Our data also sheds light on the changing sequence types in an 11 year period in Northeast Ohio

Rna

Complex cellular functions involve large networks of interactions. Pre-mRNA splicing and transcription are thought to be coupled by the C-terminal domain (CTD) of the large subunit of RNA polymerase II (Pol II). In yeast, the U1 snRNP subunit Prp40 was proposed to mediate cotranscriptional recruitment of early splicing factors through binding of its WW domains to the Pol II CTD. Here we investigate the role of Prp40 in splicing with an emphasis on the role of the WW domains, which might confer protein-protein interactions among the splicing and transcriptional machineries. Affinity purification revealed that Prp40 and Snu71 form a stable heterodimer that stably associates with the U1 snRNP only in the presence of Nam8, a known regulator of 5' splice site recognition. However, the Prp40 WW domains were dispensable for yeast viability. In their absence, no defect in splicing in vivo, U1 or U2 snRNP recruitment in vivo, or early splicing complex assembly in vitro was detected. We conclude that the WW domains of Prp40 do not mediate essential coupling between U1 snRNP and Pol II. Instead, delays in cotranscriptional U5 snRNP and Prp19 recruitment and altered spliceosome formation in vitro suggest that Prp40 WW domains assist in late steps of spliceosome assembly

ARGONAUT II study of the in vitro activity of plazomicin against carbapenemase-producing klebsiella pneumoniae

Plazomicin was tested against 697 recently acquired carbapenemresistant Klebsiella pneumoniae isolates from the Great Lakes region of the United States. Plazomicin MIC50 and MIC90 values were 0.25 and 1 mg/liter, respectively; 680 isolates (97.6%) were susceptible (MICs of ≤2 mg/liter), 9 (1.3%) intermediate (MICs of 4 mg/liter), and 8 (1.1%) resistant (MICs of>32 mg/liter). Resistance was associated with rmtF-, rmtB-, or armA-encoded 16S rRNA methyltransferases in all except 1 isolate

Employee Education, Information and Communication Technology, Workplace Organization and Trade: A Comparative Analysis of Greek and Swiss Enterprises

This paper aims at investigating empirically at the firm level the effect of the use of modern information and communication technologies (ICT), and also of two other factors, the adoption of new forms of workplace organization and trade (export) activities, on the demand for employees with different levels of (vocational) education. The study is based on firm-level data collected through a common questionnaire from firms' samples of similar composition (concerning firm sizes and industries) in Greece and Switzerland; from these data econometric models of similar specification have been constructed for both countries. The results of multivariate analysis show that the intensive use of ICT correlates positively with the employment shares of high-educated personnel and negatively with the ones of the loweducated personnel. These findings are consistent with the hypothesis of skill-biased technical change. Further, the intensive use of employee voice-oriented organizational practices correlates positively with the employment shares of high-educated employees in both countries, and also negatively with the employment share of low-educated ones only for the Swiss firms. The results for the work design organizational practices are more ambiguous. Thus, there is only partial confirmation of the hypothesis of skilled-biased organizational change. Finally, we found some evidence in favour of the trade effect (export activities) only for the Swiss firms. Our results show both similarities and differences in the above aspects between Greece and Switzerland and indicate that national context characteristics affect the relationship of the demand for employees with different levels of (vocational) education with ICT use, adoption of new forms of workplace organization and trade

Age and skill bias of trade liberalisation? : heterogeneous employment effects of EU Eastern Enlargement

This study analyses the 2004 Eastern Enlargement to the European Union to obtain evidence on the employment effects of an increase in trade liberalisation. The Enlargement is thought to generate a trade-induced demand shock with no (or only limited) supply effects. Besides the variation over time induced by the Enlargement, identification of the effects is based on a Melitz (2003) type productivity term to differentiate firms by the extent of exposure to the demand shock. The idea is that the effects of the demand shock should be driven by differences in firm-level productivity from the period before the new member countries actually entered the EU. German linked employer-employee data allow to observe the relation of initial establishment productivity with employment changes over a long panel from 1995 to 2009. The estimates show that the Enlargement had a negative effect on establishment-level employment growth, which is driven by increased worker separations and increased job destruction. Besides the overall employment effect, the study focuses on effect heterogeneity across age and skill groups of the workforce. These estimates point to a skill bias in the effect of the Enlargement that disadvantages low- and medium-skilled workers in terms of higher worker separation and job destruction. In addition, lowskilled workers suffer fewer accessions by firms, where against medium-skilled workers enjoy increased accessions and creation of new jobs. Besides this indication for a skill bias, there are no clear indications that point to an age bias in the employment effect of the Eastern Enlargement

The Population Structure of Acinetobacter baumannii: Expanding Multiresistant Clones from an Ancestral Susceptible Genetic Pool

Outbreaks of hospital infections caused by multidrug resistant Acinetobacter baumannii strains are of increasing concern worldwide. Although it has been reported that particular outbreak strains are geographically widespread, little is known about the diversity and phylogenetic relatedness of A. baumannii clonal groups. Sequencing of internal portions of seven housekeeping genes (total 2,976 nt) was performed in 154 A. baumannii strains covering the breadth of known diversity and including representatives of previously recognized international clones, and in 19 representatives of other Acinetobacter species. Restricted amounts of diversity and a star-like phylogeny reveal that A. baumannii is a genetically compact species that suffered a severe bottleneck in the recent past, possibly linked to a restricted ecological niche. A. baumannii is neatly demarcated from its closest relative (genomic species 13TU) and other Acinetobacter species. Multilocus sequence typing analysis demonstrated that the previously recognized international clones I to III correspond to three clonal complexes, each made of a central, predominant genotype and few single locus variants, a hallmark of recent clonal expansion. Whereas antimicrobial resistance was almost universal among isolates of these and a novel international clone (ST15), isolates of the other genotypes were mostly susceptible. This dichotomy indicates that antimicrobial resistance is a major selective advantage that drives the ongoing rapid clonal expansion of these highly problematic agents of nosocomial infections