Co-production of metallo-ß-lactamase and OXA-type ß-lactamases in carbapenem-resistant Acinetobacter baumannii clinical isolates in North East India.

Carbapenem-resistant Acinetobacter baumannii poses a significant threat to public health globally, especially due to its ability to produce multiple carbapenemases, leading to treatment challenges. This study aimed to investigate the antibiotic resistance pattern of carbapenem-resistant A. baumannii isolates collected from different clinical settings in North East India, focusing on their genotypic and phenotypic resistance profiles. A total of 172 multidrug-resistant A. baumannii isolates were collected and subjected to antibiotic susceptibility test using the Kirby-Bauer disk diffusion method. Various phenotypic tests were performed to detect extended-spectrum ß-lactamase (ESBL), metallo-ß-lactamase (MBL), class C AmpC ß-lactamase (AmpC), and carbapenem hydrolyzing class D ß-lactamase (CHDL) production among the isolates. Overexpression of carbapenemase and cephalosporinase genes was detected among the isolates through both phenotypic and genotypic investigation. The antibiotic resistance profile of the isolates revealed that all were multidrug-resistant; 25% were extensively drug-resistant, 9.30% were pan-drug-resistant, whereas 91.27% were resistant to carbapenems. In the genotypic investigation, 80.81% of isolates were reported harbouring at least one metallo-ß-lactamase encoding gene, with blaNDM being the most prevalent at 70.34%, followed by blaIMP at 51.16% of isolates. Regarding class D carbapenemases, blaOXA-51 and blaOXA-23 genes were detected in all the tested isolates, while blaOXA-24, blaOXA-48, and blaOXA-58 were found in 15.11%, 6.97%, and 1.74% isolates respectively. Further analysis showed that 31.97% of isolates co-harboured ESBL, MBL, AmpC, and CHDL genes, while 31.39% of isolates co-harboured ESBL, MBL, and CHDL genes with or without ISAba1 leading to extensively drug-resistant or pan drug-resistant phenotypes. This study highlights the complex genetic profile and antimicrobial-resistant pattern of the isolates circulating in North East India, emphasizing the urgent need for effective infection control measures and the development of alternative treatment strategies to combat these challenging pathogens.

Antibiotics: From Mechanism of Action to Resistance and Beyond.

Antibiotics are the super drugs that have revolutionized modern medicine by curing many infectious diseases caused by various microbes. They efficiently inhibit the growth and multiplication of the pathogenic microbes without causing adverse effects on the host. However, prescribing suboptimal antibiotic and overuse in agriculture and animal husbandry have led to the emergence of antimicrobial resistance, one of the most serious threats to global health at present. The efficacy of a new antibiotic is high when introduced; however, a small bacterial population attains resistance gradually and eventually survives. Understanding the mode of action of these miracle drugs, as well as their interaction with targets is very complex. However, it is necessary to fulfill the constant need for novel therapeutic alternatives to address the inevitable development of resistance. Therefore, considering the need of the hour, this article has been prepared to discuss the mode of action and recent advancements in the field of antibiotics. Efforts has also been made to highlight the current scenario of antimicrobial resistance and drug repurposing as a fast-track solution to combat the issue.

Prevalence and distribution pattern of AmpC ß-lactamases in ESBL producing clinical isolates of Klebsiella spp. in parts of Assam, India.

The production of extended-spectrum ß-lactamases (ESBLs) and AmpC ß-lactamases is the most common explanation of multidrug resistance in clinical isolates of Klebsiella spp. In the present study, a total of 160 isolates of Klebsiella spp. were procured from the DBT-NER project with ethical clearance no. DU/Dib/ECBHR(Human)/2021-22/02). These were collected from various health settings of Assam and identified as drug-resistant. The isolates were screened for antibiotic susceptibility and phenotypic tests were performed on multidrug resistant isolates to confirm ESBL and AmpC ß-lactamases production. The distribution pattern of ESBL and AmpC ß-lactamase genotype was investigated by polymerase chain reaction (PCR). The results showed that among 107 multidrug-resistant (MDR) isolates of Klebsiella spp., 67.28% of isolates were ESBL producers and 56.07% were potential AmpC producers. The PCR results revealed that blaCTX-M was the most prevalent ESBL genotype. Among the ESBL producers, 11.11% of isolates showed co-occurrence with plasmid-mediated AmpC ß lactamases genotype which indicated the high prevalence of ESBL and AmpC co-producers in K. pneumoniae and K. oxytoca, suggesting the possibility of serious public health concerns. Therefore, it is crucial to regularly monitor the spread of multidrug resistance among clinical isolates.

Identification of potential plant-based inhibitor against viral proteases of SARS-CoV-2 through molecular docking, MM-PBSA binding energy calculations and molecular dynamics simulation.

The Coronavirus disease 2019 (COVID-19), caused by the novel coronavirus, SARS-CoV-2, has recently emerged as a pandemic. Here, an attempt has been made through in-silico high throughput screening to explore the antiviral compounds from traditionally used plants for antiviral treatments in India namely, Tea, Neem and Turmeric, as potential inhibitors of two widely studied viral proteases, main protease (Mpro) and papain-like protease (PLpro) of the SARS-CoV-2. Molecular docking study using BIOVIA Discovery Studio 2018 revealed, (-)-epicatechin-3-O-gallate (ECG), a tea polyphenol has a binding affinity toward both the selected receptors, with the lowest CDocker energy - 46.22 kcal mol-1 for SARS-CoV-2 Mpro and CDocker energy - 44.72 kcal mol-1 for SARS-CoV-2 PLpro, respectively. The SARS-CoV-2 Mpro complexed with (-)-epicatechin-3-O-gallate, which had shown the best binding affinity was subjected to molecular dynamics simulations to validate its binding affinity, during which, the root-mean-square-deviation values of SARS-CoV-2 Mpro-Co-crystal ligand (N3) and SARS-CoV-2 Mpro- (-)-epicatechin-3-O-gallate systems were found to be more stable than SARS-CoV-2 Mpro system. Further, (-)-epicatechin-3-O-gallate was subjected to QSAR analysis which predicted IC50 of 0.3281 nM against SARS-CoV-2 Mpro. Overall, (-)-epicatechin-3-O-gallate showed a potential binding affinity with SARS-CoV-2 Mpro and could be proposed as a potential natural compound for COVID-19 treatment.

Klebsiella oxytoca and Emerging Nosocomial Infections.

Klebsiella oxytoca is rising as a significant opportunistic pathogen causing nosocomial infections in neonates as well as adults. This pathogen's prevalence varies from 2 to 24%, but outbreaks of infections due to multidrug-resistant strains can be fatal in immunocompromised individuals with comorbidities. Klebsiella oxytoca is responsible for a wide range of ailments from colitis to infective endocarditis, other than the common urinary and respiratory tract infections. The microbe's pathogenicity has been attributed to cytotoxins' production- Tilivalline and Tilimycin, in some intestinal disorders. Klebsiella oxytoca is reported to be resistant to a wide range of antibiotics. Here, we have tried to showcase a brief overview of the emergence of Klebsiella oxytoca in healthcare facilities and the nature of resistance in this species of Klebsiella.

RND efflux pump mediated antibiotic resistance in Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa: a major issue worldwide.

Therapeutic failures against diseases due to resistant Gram-negative bacteria have become a major threat nowadays as confirmed by surveillance reports across the world. One of the methods of development of multidrug resistance in Escherichia coli and Pseudomonas aeruginosa is by means of RND efflux pumps. Inhibition of these pumps might help to combat the antibiotic resistance problem, for which the structure and regulation of the pumps have to be known. Moreover, judicious antibiotic use is needed to control the situation. This paper focuses on the issue of antibiotic resistance as well as the structure, regulation and inhibition of the efflux pumps present in Escherichia coli and Pseudomonas aeruginosa.

NoSQL data model for semi-automatic integration of ethnomedicinal plant data from multiple sources.

INTRODUCTION: Sharing traditional knowledge with the scientific community could refine scientific approaches to phytochemical investigation and conservation of ethnomedicinal plants. As such, integration of traditional knowledge with scientific data using a single platform for sharing is greatly needed. However, ethnomedicinal data are available in heterogeneous formats, which depend on cultural aspects, survey methodology and focus of the study. Phytochemical and bioassay data are also available from many open sources in various standards and customised formats. OBJECTIVE: To design a flexible data model that could integrate both primary and curated ethnomedicinal plant data from multiple sources. MATERIALS AND METHODS: The current model is based on MongoDB, one of the Not only Structured Query Language (NoSQL) databases. Although it does not contain schema, modifications were made so that the model could incorporate both standard and customised ethnomedicinal plant data format from different sources. RESULTS: The model presented can integrate both primary and secondary data related to ethnomedicinal plants. Accommodation of disparate data was accomplished by a feature of this database that supported a different set of fields for each document. It also allowed storage of similar data having different properties. CONCLUSION: The model presented is scalable to a highly complex level with continuing maturation of the database, and is applicable for storing, retrieving and sharing ethnomedicinal plant data. It can also serve as a flexible alternative to a relational and normalised database.

Identification of Potential Inhibitors of Three NDM Variants of Klebsiella Species from Natural Compounds: A Molecular Docking, Molecular Dynamics Simulation, and MM-PBSA Study.

BACKGROUND: Klebsiella species have emerged as well-known opportunistic pathogens causing nosocomial infections with ß-lactamase-mediated resistance as a prevalent antibiotic resistance mechanism. The discovery and emergence of metallo-ß-lactamases, mainly new- Delhi metallo-ß-lactamases (NDMs), have increased the threat and challenges in healthcare facilities. OBJECTIVE: A computational screening was conducted using 570 natural compounds from Dr. Duke's Phytochemical and Ethnobotanical data to discover promising inhibitors for NDM-6, NDM-9, and NDM-23 of the Klebsiella species. METHODS: Using homology modeling on the Raptor-X web server, the structures of the three NDM variants were predicted. The structures were validated using various computational tools and MD simulation for 50 ns. Lipinski - Vebers' Filter and ADMET Screening were used to screen 570 compounds, followed by docking in Biovia Discovery Studio 2019 using the CDOCKER module. GROMACS was used to simulate the compounds with the highest scores with the proteins for 50 ns. Using the MM-PBSA method and g_mmpbsa tool, binding free energies were estimated and per-residue decomposition analysis was conducted. RESULTS: The three structures predicted were found stable after the 50 ns MD Simulation run. The compounds Budmunchiamine-A and Rhamnocitrin were found to have the best binding energy towards NDM-6, NDM-9, and NDM-23, respectively. From the results of MD Simulation, MM-PBSA binding free energy calculations, and per-residue decomposition analysis, the Protein-ligand complex of NDM-6 with Budmunchiamine A and NDM-9 with Rhamnocitrin was relatively more stable than the complex of NDM-23 and Rhamnocitrin. CONCLUSION: The study suggests that Budmunchiamine-A and Rhamnocitrin are potential inhibitors of NDM-6 and NDM-9, respectively, and may pave a path for in-vivo and in-vitro studies in the future.

Anti-diabetic and anti-urease inhibition potential of Amomum dealbatum Roxb. seeds through a bioassay-guided approach.

Using HPLC-PDA and HRMS analysis, five compounds p-coumaric acid, sinapic acid, quercetin, trans-ferulic and gallic acid were identified in seeds of Amomum dealbatum Roxb. The GC-MS analysis identified 1-dodecanol, phenol, 3,5-bis(1,1-dimethylethyl), Oleic Acid and 1-Heptacosanol which possess anti-diabetic properpties. A bioassay-guided technique was used to determine the degree of inhibition that A. dealbatum seeds crude methanol extract and its most active sub-fraction had against the α-glucosidase and Helicobacter pylori urease enzymes. In the Rat L6 myoblast cell line, glucose absorption through the GLUT4 transporter of most active subfraction (EASF80) was examined. According to a molecular docking investigation, these compounds strongly interacted with the GLUT4 transporter, H pylori and α-glucosidase enzyme. Sinapic acid interacted most strongly with the H. pylori urease enzyme while gallic acid interacted with both the α-glucosidase enzyme and the GLUT4 transporter. Additionally, a molecular docking simulation study was carried out to recognise the stability of the complexes.

Arenga westerhoutii Griff.: bioactive constituents, nutraceuticals, antioxidant and anti-diabetic potential of stem extract and an insight into molecular docking analysis.

Herein, we reported a systematic scientific study of Arenga westerhoutii Griff. by evaluating its bioactive components, nutraceuticals, antioxidant and anti-diabetic properties. Three major bioactive compounds were identified using HPLC and HRMS. Quantification of the components through HPLC yielded the presence of 75.67 ± 0.05, 38.19 ± 0.10 and 13.11 ± 0.02 µg/mL of chlorogenic acid, ferulic acid and epicatechin respectively in 1 mg/ml of the extract. 50% MeOH hydro-alcoholic extract was found to show lowest IC50 value in both in-vitro antioxidant (IC50 = 2.925 ± 0.12 µg/mL, DPPH assay) and anti-diabetic assays (IC50 = 18.03 ± 0.18 µg/mL, α-glucosidase assay). Further analysis by molecular docking study suggested the interaction of components towards α-glucosidase enzyme.

Phenolic compounds of Zanthoxylum armatum DC as potential inhibitors of urease and SARS-CoV2 using molecular docking approach and with simulation study.

The anti-urease effects of active extract and three isolated phenolic compounds viz., chlorogenic acid, trans-ferulic acid, and gallic acid of leaves of Zanthoxylum armatum DC were evaluated. The compounds were identified based on HPLC-PDA, HR-MS, and NMR analysis. Molecular docking analysis revealed that these compounds significantly interacted with Helicobacter pylori urease and SARS-CoV2 vital proteins. Chlorogenic acid was found to show the strongest interaction with the H. pylori urease and coronavirus main protease (Mpro, also called 3CLpro), while gallic acid with five spike proteins (Cathepsin L) of SARS-CoV2. The compounds were checked for their drug-likeliness character and were found to pass the Lipinski filter and abide by Veber's rule and passed through ADMET. Chlorogenic acid was simulated for 50 ns using GROMACS. The study shows that chlorogenic acid isolated from Z. armatum could be a significant antagonist of the H. pylori urease.

Anti-diabetic and anti-urease potential of Osbeckia nutans Wall. leaves.

A study was conducted to investigate the anti-diabetic and anti-urease potential of Osbeckia nutans leaves (ONL). Six compounds, i.e. quercetin-3-O-glucoside, myricetin, shikimic acid, catechin, trans-ferulic acid and luteolin were identified from the butanol sub-fraction, BE2 and the ethyl acetate sub-fraction, EA5 of ONL. BE2 inhibited α-glucosidase and Jack bean urease with IC50 values of 0.036 µg/mL (437.46 µg/mL for acarbose) and 0.327 mg/mL (0.039 mg/mL for thiourea), respectively. In the glucose uptake experiment, BE2 (0.05 mg/mL) treatment resulted in a substantial increase in glucose uptake in free fatty acid (FFA)-treated cells at a concentration 10 times lower than that seen in EA5 (0.5 mg/mL) treated cells. The binding energies of quercetin-3-O-glucoside with α-glucosidase, glucose transporter GLUT4 and H. pylori urease were found to be -94.2585, -219.8271 and -254.391 kcal/mol, respectively. This study revealed that ONL has anti-diabetic and anti-urease abilities and further in-depth research may unveil its full potential.

Antidiabetic potential of Amomum dealbatum Roxb. flower and isolation of three bioactive compounds with molecular docking and in vivo study.

Amomum dealbatum Roxb. parts have been traditionally used as remedies for joint pain, diabetes, muscular rheumatism, antiseptic, and abscesses in Arunachal Pradesh, Assam, and Tripura. Ethyl acetate sub-fraction E3 had significantly inhibited the α-glucosidase (IC50 5.385 µg/mL). The molecular docking revealed quercetin-3-O-galactoside to be the most potent α-glucosidase inhibitor (binding energy -43.214 kcal/mol). Using the QSAR model, the pIC50 values of myricetin, gallic acid, quercetin-3-O-galactoside, and acarbose were predicted to be 5.65235, 4.39858, 5.65235, and 6.03058, respectively. For the first time, quercetin-3-O-galactoside, myricetin, and gallic acid have been isolated from the flowers of A. dealbatum (ADF). E3 decreased blood glucose level to a near-normal concentration (100.60 ± 2.94 mg/dL) in comparison to diabetic control rats (575.20 ± 24.80 mg/dL). The results have strongly suggested the potential of ADF in treating diabetes. This lesser-known plant has the potential to uncover its full medicinal properties through further in-depth research.

Virtual high-throughput screening and simulation studies of compounds from selected traditionally important medicinal plants for the identification of potential inhibitors of AcrB.

One of the significant human health concerns today is the emergence of drug-resistant bacteria and their propagation worldwide, rendering all available treatment options useless. One of the molecular mechanisms behind the evolution and dissemination of multidrug-resistant species is the overexpression of efflux pumps. AcrB is a major component of the AcrAB-TolC efflux pump belonging to the RND division and responsible for the extrusion of antibiotics from the bacterial cell leading to resistance. In this study, we applied the reverse chemogenomics technique to find inhibitors of AcrB to combat the issue of drug resistance. A total of 102 compounds from five different plants having medicinal properties were passed through Lipinski filter and ADMET screening was done to check their drug likeliness before docking against the AcrB protein and based on the -cDocker energy scores and toxicity analysis report, the compounds with best values were analyzed. A comparison was made between them and known inhibitors as well as antibiotics. Heat maps, frequency histograms, 2 D diagrams were generated, and the molecules were simulated for 60 ns using GROMACS. From the study, we have found Dihydrocapsaicin and Garcinexanthone-A to be a potential efflux pump inhibitors having all the characters of a promising drug candidate.Communicated by Ramaswamy H. Sarma.

Bioassay-guided isolation of potent α-glucosidase inhibitory compounds from the fruit of Piper mullesua Buch-Ham ex D Don. and their in silico screening.

Two bioactive compounds caffeic and sinapic acid were isolated from the fruit of the Piper mullesua Buch-Ham ex D Don using bioassay guided approach. These compounds were isolated from water fraction using column chromatography followed by semi preparative HPLC. These compounds showed very potent anti-diabetic and antioxidant activities. The molecular docking was carried out to predict the mode of interaction of the isolated compounds with α-glucosidase. The in vitro α-glucosidase inhibitory activity of caffeic and sinapic acid was determined, and their IC50 values were found 0.67 and 0.82 µg/ml, respectively. A QSAR equation was generated with an R2 value of 84.81%, which is suitable enough for predicting the IC50 values of test molecules. The aforementioned finding confirms the isolated compounds show very significant anti-diabetic potential which is supported by the molecular docking and QSAR study. So, it has ample scope for drug development with further in vivo and clinical study.

Design and Synthesis of Quinazolinone-Triazole Hybrids as Potent Anti-Tubercular Agents.

A straightforward and convenient methodology has been developed for the reaction of 2-aminobenzamide and carbonyls affording 2,3-dihydroquinazolin-4(1H)-ones using aqueous solution of [C12Py][FeCl3Br]. The developed methodology was applied for the synthesis of 25 quinazolinone-triazole hybrids followed by evaluation of their in vitro anti-tubercular (TB) activity. The results revealed that 8 quinazolinone-triazole hybrids displayed promising activity having MIC values of 0.78-12.5 µg/mL. The compound 3if with MIC 0.78 µg/mL was found to be the lead nominee among the series, better than Ethambutol, a first line anti-TB drug and comparable with Rifampicin. The active compounds with MIC values ≤ 6.25 µg/mL were subjected to in vitro cytotoxicity and found nontoxic. In drug-drug interaction, compounds 3ia and 3ii interacted synergistically with all the three anti-TB drugs, INH, RFM, and EMB. Other 3 compounds interacted either in synergistic or additive manners. Important information on the binding interaction of the target compounds with the active sites of 1DQY Antigen 85C from Mycobacterium tuberculosis and Enoyl acyl carrier protein reductase (InhA) enzymes was obtained from molecular docking studies. Screening of the drug-likeness properties and bioactivity score indicates that synthesized molecules could be projected as potential drug candidates. Based on the current study, quinazolinone-triazole hybrids framework can be useful in drug development for TB.

Prevalence and molecular characterization of ß-lactamase producers and fluoroquinolone resistant clinical isolates from North East India.

INTRODUCTION: The rapid emergence and variations of antibiotic resistance among common gram negative bacteria cause a significant concern specially in India and all over the world because of high mortality and morbidity rates. METHODS: In our study, we screened 189 bacterial isolates from Assam Medical College & Hospital, Dibrugarh for antibiotic resistance pattern and tried to identify the resistant genes causing responsible for ß-lactam and fluoroquinolones resistance. RESULTS: More than 80% and 45% strains were resistant to all the 3rd generation cephalosporins, fluoroquinolones respectively. Among the 3rd generation cephalosporin resistant strains, 38% and 24% isolates were only ESBL and MBL producers respectively and 11% were reported to have both ESBL and MBL genes. The ESBL positive isolates have shown the dominance of CTX-M3 gene. VIM-1 gene was mostly reported in MBL producers. Our study probably for the first time reporting SIM-1 and SPM-1 MBL gene from India. Mutations in QRDR is found to be the primary cause of fluoroquinolone resistance along with efflux pump and PMQR presence. CONCLUSION: The study represents the first detailed study on antibiotic resistance from NE India this could help to take control measures for the emerging antibiotic resistance in hospital and community based infections in North East India.

A novel phytochemical from Dipteris wallichii inhibits human ß-secretase 1: Implications for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is the most prevalent progressive neurodegenerative disease, and the most common cause of dementia. One of the histopathological hallmarks of AD is the accumulation of extracellular amyloid-ß (Aß) oligomers as neuritic plaques in brain. The Aß oligomers are produced from amyloid precursor protein by the action of secretase enzymes, among which ß-secretase 1 (BACE1) catalyses the rate-limiting step. Thus, BACE1 is one of the most important therapeutic targets in preventing deposition of the plaques, progression of the disease, and thus as a disease-modifying therapeutic strategy. The present study was undertaken to isolate and identify novel phytochemicals from the pteridophyte Dipteris wallichii, and to determine their pharmacological properties. A novel compound was eventually detected and named Dip-1, and its pharmacological properties were predicted using computational modelling. The compound was found to have pharmacophores similar to those of known BACE1 inhibitors. Thus, further studies were performed to determine its drug likeness, blood-brain barrier (BBB) permeability, inhibitory potential and IC50 value. The results were promising, and the compound was found to have high drug likeness and BBB permeability, and a potent inhibitor of BACE1, with IC50 value of 0.0372 nM. Thus, the present study reports a novel BACE1 inhibitor from the plant D. wallichii, and is significant owing to its therapeutic implication as a disease-modifying therapy for AD.

Morpho-taxonomic, genetic, and biochemical characterization of freshwater microalgae as potential biodiesel feedstock.

In the present study, seven axenic fresh water microchlorophytes were isolated and identified as Tetradesmus dimorphus (NEIST BT-1), Chlorella sorokiniana (NEIST BT-2), Desmodesmus sp. (NEIST BT-10), Selenastrum sp. (NEIST BT-A6), Tetradesmus obliquus (NEIST BT-A1), Tetradesmus sp. (NEIST BT-A10), and Asterarcys sp. (NEIST BT-A15) based on morphological and molecular characterization. Their potential to be used as biodiesel feedstock was evaluated depending on their growth characteristics and lipid profiles. Among the seven isolates, NEIST BT-2 was found to be the most promising candidate owing to its high biomass yield (2.09 ± 0.037 g L-1) and lipid productivity (107.60 ± 10.175 mg L-1 day-1). The gas chromatography analysis confirmed the presence of significant amounts of palmitic acid, linoleic acid, linolenic acid, and oleic acid in the isolate which are some of the major constituents of any biodiesel. The predictive models showed that the biodiesel from this isolate has ideal fuel properties which comply with the ASTM D6751 and EN 14214 specifications. These findings demonstrate that NEIST BT-2 can be used as a prospective candidate for consideration of large-scale biodiesel production.

Emergence of antibiotic resistant Shigella species: A matter of concern.

A major threat to the world is the emergence of antibiotic resistant bacteria, which has rendered previously susceptible drugs useless and increased the rate of therapeutic failures. Shigella species, which are the causative organism of Shigellosis, were earlier susceptible to ampicillin, chloramphenicol, co-trimoxazole and nalidixic acid but now they have developed resistance against fluoroquinolones, cephalosporins and azithromycin. Many shigellosis outbreaks have been reported by resistant strains of Shigella species. This review attempts to provide a brief overview about the scenario of shigellosis and the emergence as well as ubiquitous nature of multidrug resistant (MDR) Shigella species.