Ultra-large library docking for discovering new chemotypes.

Despite intense interest in expanding chemical space, libraries containing hundreds-of-millions to billions of diverse molecules have remained inaccessible. Here we investigate structure-based docking of 170 million make-on-demand compounds from 130 well-characterized reactions. The resulting library is diverse, representing over 10.7 million scaffolds that are otherwise unavailable. For each compound in the library, docking against AmpC ß-lactamase (AmpC) and the D4 dopamine receptor were simulated. From the top-ranking molecules, 44 and 549 compounds were synthesized and tested for interactions with AmpC and the D4 dopamine receptor, respectively. We found a phenolate inhibitor of AmpC, which revealed a group of inhibitors without known precedent. This molecule was optimized to 77 nM, which places it among the most potent non-covalent AmpC inhibitors known. Crystal structures of this and other AmpC inhibitors confirmed the docking predictions. Against the D4 dopamine receptor, hit rates fell almost monotonically with docking score, and a hit-rate versus score curve predicted that the library contained 453,000 ligands for the D4 dopamine receptor. Of 81 new chemotypes discovered, 30 showed submicromolar activity, including a 180-pM subtype-selective agonist of the D4 dopamine receptor.

Tackling the Antibiotic Resistance Caused by Class A ß-Lactamases through the Use of ß-Lactamase Inhibitory Protein.

ß-Lactams are the most widely used and effective antibiotics for the treatment of infectious diseases. Unfortunately, bacteria have developed several mechanisms to combat these therapeutic agents. One of the major resistance mechanisms involves the production of ß-lactamase that hydrolyzes the ß-lactam ring thereby inactivating the drug. To overcome this threat, the small molecule ß-lactamase inhibitors (e.g., clavulanic acid, sulbactam and tazobactam) have been used in combination with ß-lactams for treatment. However, the bacterial resistance to this kind of combination therapy has evolved recently. Therefore, multiple attempts have been made to discover and develop novel broad-spectrum ß-lactamase inhibitors that sufficiently work against ß-lactamase producing bacteria. ß-lactamase inhibitory proteins (BLIPs) (e.g., BLIP, BLIP-I and BLIP-II) are potential inhibitors that have been found from soil bacterium Streptomyces spp. BLIPs bind and inhibit a wide range of class A ß-lactamases from a diverse set of Gram-positive and Gram-negative bacteria, including TEM-1, PC1, SME-1, SHV-1 and KPC-2. To the best of our knowledge, this article represents the first systematic review on ß-lactamase inhibitors with a particular focus on BLIPs and their inherent properties that favorably position them as a source of biologically-inspired drugs to combat antimicrobial resistance. Furthermore, an extensive compilation of binding data from ß-lactamase⁻BLIP interaction studies is presented herein. Such information help to provide key insights into the origin of interaction that may be useful for rationally guiding future drug design efforts.

Nueva Delhi metalo--ß--lactamasa en especies de Enterobacteriaceae aisladas de pacientes hospitalizados, Managua, Nicaragua / New Delhi Metallo--ß-lactamase in Enterobacteriaceae species isolated from hospitalized patients, Managua Nicaragua

Resumen Objetivo: determinar la frecuencia de metalo-β lactamasa tipo Nueva Delhi (NDM), en aislados de enterobacterias provenientes de pacientes hospitalizados con diferentes procesos infecciosos. Método: se realizó una investigación descriptiva transversal, agosto 2015 - octubre 2016, en el Hospital Alemán Nicaragüense. Se estudiaron 249 cepas en vigilancia activa a los carbapenémicos. La identificación y perfil de resistencia se efectuó en Vitek2; la sospecha de resistencia a los carbapenémicos se tomó cuando la CMI de Imipenem y Meropenem 2-4 μg/mL y Ertapenem 2 μg/mL, se determinó mediante Kirby Bauer, el test de sinergia triple disco (carbapenémicos y EDTA 10µg); se hizo la reacción en cadena de la polimerasa para metalo-β-lactamasa Nueva Delhi. Resultados: se analizaron 249 cepas, entre estas se identificó 45 cepas resistentes a los carbapenémicos, correspondiendo al 18%. De estas cepas, 43 dieron positivo para el test de sinergia con EDTA; 21 portaban el gen de Nueva Delhi. El 66% de metalo-β-lactamasa Nueva Delhi se encontró en aislamientos de Klebsiella pneumoniae, seguida de Escherichia vulneris en un 14%, Escherichia coli en un 5%, Providencia rettgeri en un 5%, Pantoea agglomerans en un 5% y Kluyvera cryocrescens en un 5%.19 Conclusiones: el hallazgo del presente estudio es una advertencia clara sobre la circulación de cepas de metalo-β-lactamasa tipo Nueva Delhi que codifican la resistencia a los carbapenémicos en el hospital analizado.

Abstract Objective: to determine the frequency of New Delhi-type metallo-β-lactamase (NDM) in isolates of enterobacteria from patients hospitalized with different infectious processes. Method: a cross-sectional descriptive study was carried out between August 2015 and October 2016 at Alemán Nicaragüense Hospital. A total of 249 strains were studied in active surveillance of carbapenems resistance. The identification and resistance profile was carried out in Vitek2. Suspected resistance to carbapenems was considered when the MIC of Imipenem and Meropenem was 2-4 μg/mL and for Ertapenem of 2 μg/mL, determined by Kirby Bauer, the triple disc synergy test (carbapenems and EDTA 10μg). A polymerase chain reaction test was made to determinate New Delhi metallo-β lactamase. Results: a total of 249 strains were analyzed, among which 45 strains resistant to carbapenems were identified, corresponding to 18%. Of these strains, 43 were positive for the synergy test with EDTA; 21 carried the New Delhi gene. Of the New Delhi metallo-β lactamase. 66% were found in isolates of Klebsiella pneumoniae, followed by Escherichia vulneris in 6 isolates, Escherichia coli in 2, Providencia rettgeri in 2, Pantoea agglomerans in 2 and Kluyvera cryocrescens by 2. Conclusions: the results of the present study are a clear warning about the circulation of New Delhi-type metallo-β-lactamase strains that codify for the resistance to carbapenems in the hospital analyzed.

Challenges in the Development of a Thiol-Based Broad-Spectrum Inhibitor for Metallo-ß-Lactamases.

Pathogens, expressing metallo-ß-lactamases (MBLs), become resistant against most ß-lactam antibiotics. Besides the dragging search for new antibiotics, development of MBL inhibitors would be an alternative weapon against resistant bacterial pathogens. Inhibition of resistance enzymes could restore the antibacterial activity of ß-lactams. Various approaches to MBL inhibitors are described; among others, the promising motif of a zinc coordinating thiol moiety is very popular. Nevertheless, since the first report of a thiol-based MBL inhibitor (thiomandelic acid) in 2001, no steps in development of thiol based MBL inhibitors were reported that go beyond clinical isolate testing. In this study, we report on the synthesis and biochemical characterization of thiol-based MBL inhibitors and highlight the challenges behind the development of thiol-based compounds, which exhibit good in vitro activity toward a broad spectrum of MBLs, selectivity against human off-targets, and reasonable activity against clinical isolates.

Prevalencia y factores asociados a la colonización de microorganismos multirresistentes en centros de larga estancia de Gran Canaria / Prevalence and risk factors of multi-drug resistant organism colonization among long-term care facilities in Gran Canaria (Spain)

Introducción. Los microorganismos multirresistentes (MMR) son causa importante de infección nosocomial, su manejo clínico-terapéutico es complicado y producen elevada morbimortalidad, con aumento de costes sanitarios asociados. En centros sanitarios de larga estancia (CSLE), la colonización/infección de sus residentes por MMR es cada vez mayor, pudiendo estos actuar como reservorios y vehículos para brotes de cepas resistentes en los hospitales de agudos. Los objetivos del estudio fueron determinar la prevalencia de portadores de MMR y detectar factores asociados al estado de portador. Material y métodos. Estudio de prevalencia de corte en 235 residentes de 2 CSLE en Las Palmas de Gran Canaria (Islas Canarias, España) entre octubre y noviembre del 2012. Se investigó la presencia de MMR en frotis nasal, faríngeo y rectal utilizando medios de cultivo selectivos. Se estudiaron los factores de riesgo asociados al estado de portador mediante análisis univariante y multivariante. Resultados. El 36,2% de residentes fueron portadores de al menos un MMR. El 26,6% fueron portadores de enterobacterias productoras de betalactamasa de espectro extendido y el 10,2% portadores de SARM. Los factores asociados significativamente con la colonización por MMR fueron: colonización-infección previa por MMR, ingreso hospitalario en los últimos 3 meses, infecciones de repetición del tracto urinario y enfermedad arterial periférica. Conclusiones. La prevalencia de MMR en estos CSLE es mayor que la encontrada en la bibliografía, especialmente la de enterobacterias BLEE. Debido a la alta prevalencia de infección/colonización por MMR y los factores de riesgo asociados al estado de portador, es posible que los CSLE actúen de reservorio de MMR y además su diseminación se facilite con el traslado de estos pacientes a hospitales en episodios agudos (AU)

Introduction. Multidrug resistant organisms (MDRO) are an important cause of nosocomial infections, with complicated clinical-therapeutic management and elevated morbidity-mortality, and an increase in healthcare costs. In long term care facilities (LTCFs) colonization/infection by MDRO among residents is increasing, and they may act as reservoirs and vehicles for the dissemination and production of outbreaks by resistant strains in acute hospitals. This study aimed at determining the prevalence of carriers of some common MDRO, and identifying factors associated with carrier state. Material and methods. A cross-sectional prevalence study was conducted on 235 residents in two LTCFs in the province of Las Palmas de Gran Canaria (Canary Islands, Spain) between October and November of 2012. The presence of MMR was investigated in nasal, pharyngeal and rectal swabs using selective media. Risk factors associated with carrier state were calculated using univariate and multivariate analysis. Results. More than one-third (36.2%) of residents were found to be carriers of ≥ 1 distinct MDROs. More than one-quarter (26.6%) were carriers of ESBL producing Enterobacteriaceae, and 10.2% were MRSA carriers. Factors found to be associated with colonization by any MDRO were: prior colonization or infection by MDRO, hospitalization in the past 3 months, recurrent infections of the urinary tract, and peripheral arterial disease. Conclusions. The prevalence of MDRO in the LTCFs settings studied is greater than that found in the literature, and in particular ESBL producing Enterobacteriaceae. Due to the high prevalence of infection/colonization by MDRO, it is possible that residents of LTCFs could act as important reservoirs of MDRO, and facilitate their spread into the acute care setting (AU)

N-Boc deprotection and isolation method for water-soluble zwitterionic compounds.

A highly efficient TMSI-mediated deprotection and direct isolation method to obtain zwitterionic compounds from the corresponding N-Boc derivatives has been developed. This method has been demonstrated in the final deprotection/isolation of the ß-lactamase inhibitor MK-7655 as a part of its manufacturing process. Further application of this process toward other zwitterionic compounds, such as dipeptides and tripeptides, has been successfully developed. Furthermore, a catalytic version of this transformation has been demonstrated in the presence of BSA or BSTFA.

Recent advances in the discovery of metallo-ß-lactamase inhibitors for ß-lactam antibiotic-resistant reversing agents.

The overuse of antibiotics which exerts the selective pressure for bacterial pathogens has facilitated the spread of antibiotics' resistance. Metallo-ß-lactamases (MßLs) are zinc enzymes produced by an increasing number of bacterial pathogens. They can readily cleave carbapenems and most other ß-lactams that are mainstays of therapy for bacterial infections. MßL-conferred resistance to antibiotics is most worrisome due to MßLs exhibiting very broad-spectrum resistance. Therefore, the bacteria carrying MßLs have recently become a significant clinical threat. No clinically useful MßLs inhibitor has been discovered yet. To address the serious threat to public health posed by the MßL-conferred resistance to antibiotics, novel effective MßL inhibitors are urgently needed. This review mainly describes various MßL inhibitors, giving special attention to their antibacterial activity, mechanisms of action, structure-activity relationships and synergetic effect with clinically available antibiotics.