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Bacteria employ numerous resistance mechanisms against structurally distinct drugs by the process of multidrug resistance. A study was planned to discover the antibacterial potential of a graphene oxide nanosheet (GO), a graphene oxide–zinc oxide nanocomposite (GO/ZnO), a graphene oxide-chitosan nanocomposite (GO–CS), a zinc oxide decorated graphene oxide–chitosan nanocomposite (GO–CS/ZnO), and zinc oxide nanoparticles (ZnO) alone and in a blend with antibiotics against a PS-2 isolate of Pseudomonas aeruginosa. These nanocomposites reduced the MIC of tetracycline (TET) from 16 folds to 64 folds against a multidrug-resistant clinical isolate. Efflux pumps were interfered, as evident by an ethidium bromide synergy study with nanocomposites, as well as inhibiting biofilm synthesis. These nanoparticles/nanocomposites also decreased the mutant prevention concentration (MPC) of TET. To the best of our knowledge, this is the first report on nanomaterials as a synergistic agent via inhibition of efflux and biofilm synthesis.

There are several bacteria called superbugs that are resistant to multiple antibiotics which can be life threatening specially for critically ill and hospitalized patients. This article provides up-to-date treatment strategies employed against some major superbugs, like methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, vancomycin-resistant Enterococcus, multidrug-resistant Pseudomonas aeruginosa, and multidrug-resistant Escherichia coli. The pathogen-directed therapeutics decrease the toxicity of bacteria by altering their virulence factors by specific processes. On the other hand, the host-directed therapeutics limits these superbugs by modulating immune cells, enhancing host cell functions, and modifying disease pathology. Several new antibiotics against the global priority superbugs are coming to the market or are in the clinical development phase. Medicinal plants possessing potent secondary metabolites can play a key role in the treatment against these superbugs. Nanotechnology has also emerged as a promising option for combatting them. There is urgent need to continuously figure out the best possible treatment strategy against these superbugs as resistance can also be developed against the new and upcoming antibiotics in future. Rational use of antibiotics and maintenance of proper hygiene must be practiced among patients.

BACKGROUND: The first national severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurvey in India, done in May-June, 2020, among adults aged 18 years or older from 21 states, found a SARS-CoV-2 IgG antibody seroprevalence of 0·73% (95% CI 0·34-1·13). We aimed to assess the more recent nationwide seroprevalence in the general population in India. METHODS: We did a second household serosurvey among individuals aged 10 years or older in the same 700 villages or wards within 70 districts in India that were included in the first serosurvey. Individuals aged younger than 10 years and households that did not respond at the time of survey were excluded. Participants were interviewed to collect information on sociodemographics, symptoms suggestive of COVID-19, exposure history to laboratory-confirmed COVID-19 cases, and history of COVID-19 illness. 3-5 mL of venous blood was collected from each participant and blood samples were tested using the Abbott SARS-CoV-2 IgG assay. Seroprevalence was estimated after applying the sampling weights and adjusting for clustering and assay characteristics. We randomly selected one adult serum sample from each household to compare the seroprevalence among adults between the two serosurveys. FINDINGS: Between Aug 18 and Sept 20, 2020, we enrolled and collected serum samples from 29 082 individuals from 15 613 households. The weighted and adjusted seroprevalence of SARS-CoV-2 IgG antibodies in individuals aged 10 years or older was 6·6% (95% CI 5·8-7·4). Among 15 084 randomly selected adults (one per household), the weighted and adjusted seroprevalence was 7·1% (6·2-8·2). Seroprevalence was similar across age groups, sexes, and occupations. Seroprevalence was highest in urban slum areas followed by urban non-slum and rural areas. We estimated a cumulative 74·3 million infections in the country by Aug 18, 2020, with 26-32 infections for every reported COVID-19 case. INTERPRETATION: Approximately one in 15 individuals aged 10 years or older in India had SARS-CoV-2 infection by Aug 18, 2020. The adult seroprevalence increased approximately tenfold between May and August, 2020. Lower infection-to-case ratio in August than in May reflects a substantial increase in testing across the country. FUNDING: Indian Council of Medical Research.

Background/Objectives: Globally, the COVID-19 pandemic and its prevention and control policies have impacted maternal and child health (MCH) services. This study documents the challenges faced by patients in accessing MCH services, and the experiences of health care providers in delivering those services during the COVID-19 outbreak, explicitly focusing on the lockdown period in India. Methods: A cross-sectional study (rapid survey) was conducted in 18 districts from 6 states of India during March to June, 2020. The sample size included 540 MCH patients, 18 gynaecologists, 18 paediatricians, 18 district immunisation officers and 108 frontline health workers. Bivariate analysis and multivariable analysis were used to assess the association between sociodemographic characteristics, and challenges faced by the patients. Results: More than one-third of patients (n = 212; 39%) reported that accessing MCH services was a challenge during the lockdown period, with major challenges being transportation-related difficulties (n = 99; 46%) unavailability of hospital-based services (n = 54; 23%) and interrupted outreach health services (n = 39; 18.4%). The supply-side challenges mainly included lack of infrastructural preparedness for outbreak situations, and a shortage of human resources. Conclusions/Recommendations: A holistic approach is required that focuses on both preparedness and response to the outbreak, as well reassignment and reinforcement of health care professionals to continue catering to and maintaining essential MCH services during the pandemic.

The compound 4-hydroxy-α-tetralone (1) has been reported to possess potent anti-tubercular, anti-diabetic and anti-leishmanial activities. In our earlier studies the compound 1 and its various semi-synthetic derivatives showed potent bioenhancing activity in combination with nalidixic acid (NAL) and tetracycline (TET) reducing the minimum inhibitory concentration (MIC) of antibiotics up to 8 folds by inhibition of ABC efflux pump. However, in gram negative bacteria, resistance nodulation division (RND) family are considered as major efflux pump responsible for multidrug resistance (MDR). Hence, the current study was carried out to access the in-silico docking potential of compound 1 and its cinnamoyl (1a), 3, 4, 5-trimethoxybenzoyl (1b) derivatives against RND efflux pump target proteins AcrA, AcrB, TolC of E. coli. The docking study showed that the test compounds have good binding affinity with target proteins. The derivative 1a showed highest interaction with AcrA followed by AcrB showing binding energies -8.7 and -8.2 kcal/mol respectively. The low molecular weight ≤500, high hydrogen bonding, high log p value (>1) with hydroxy, methoxy and aromatic group of ligands make these compounds as effective efflux pump inhibitor. In drug likeliness studies, these compounds pass the safety criteria with enhanced bioavailability and absorption, less acute oral toxicity, less hepatotoxicity. This study promises that the compound 1 and its derivatives (1a & 1b) might be RND efflux pump inhibitors providing the initial platform for development of safer and cost-effective antibacterial drug to manage MDR infections.

We explored the antibacterial potential (alone and combination) against multidrug resistant (MDR) Pseudomonas aeruginosa isolates KG-P2 using synthesized thieno[3,2-c]pyran-2-ones in combination with different antibiotics. Out of 14 compounds, two compounds (3g and 3l) abridged the MIC of tetracycline (TET) by 16 folds. Compounds was killing the KG-P2 cells, in time dependent manner, lengthened post-antibiotic effect (PAE) of TET and found decreased the mutant prevention concentration (MPC) of TET. In ethidium bromide efflux experiment, two compounds repressed the drug transporter (efflux pumps) which is further supported by molecular docking of these compounds with efflux complex MexAB-OprM. In another study, these compounds inhibited the synthesis of biofilm.

Uttar Pradesh is the densely populated state of India and is the sixth highest COVID-19 affected state with 22,904 deaths recorded on November 12, 2021. Whole-genome sequencing (WGS) is being used as a potential approach to investigate genomic evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. In this study, a total of 87 SARS-CoV-2 genomes−49 genomes from the first wave (March 2020 to February 2021) and 38 genomes from the second wave (March 2021 to July 2021) from Eastern Uttar Pradesh (E-UP) were sequenced and analyzed to understand its evolutionary pattern and variants against publicaly available sequences. The complete genome analysis of SARS-CoV-2 during the first wave in E-UP largely reported transmission of G, GR, and GH clades with specific mutations. In contrast, variants of concerns (VOCs) such as Delta (71.0%) followed by Delta AY.1 (21.05%) and Kappa (7.9%) lineages belong to G clade with prominent signature amino acids were introduced in the second wave. Signature substitution at positions S:L452R, S:P681R, and S:D614G were commonly detected in the Delta, Delta AY.1, and Kappa variants whereas S:T19R and S:T478K were confined to Delta and Delta AY.1 variants only. Vaccine breakthrough infections showed unique mutational changes at position S:D574Y in the case of the Delta variant, whereas position S:T95 was conserved among Kappa variants compared to the Wuhan isolate. During the transition from the first to second waves, a shift in the predominant clade from GH to G clade was observed. The identified spike protein mutations in the SARS-CoV-2 genome could be used as the potential target for vaccine and drug development to combat the effects of the COVID-19 disease.

From the discovery to the golden age of antibiotics (miracle), millions of lives have been saved. The era of negligence towards chemotherapeutic agents gave birth to drug resistance. Among all the regulators of drug resistance, drug transporters are considered to be the key regulators for multidrug resistance. These transporters are prevalent from prokaryotes to eukaryotes. Endophytes are one of the unexplored wealths of nature. Endophytes are a model mutualistic partner of plants. They are the reservoir of novel therapeutics. The present review deals with endophytes as novel drug resistance reversal agents by inhibiting the drug transporters across the genera. This review also focuses on drug transporters, and mutualistic chemical diversity, exploring drug transporter modulating potential of endophytes.

Background: Due to the limited availability of antibiotics, Gram-negative bacteria (GNB) acquire different levels of drug resistance. It raised an urgent need to identify such agents, which can reverse the phenomenon of drug resistance. Objective: To understand the mechanism of drug resistance reversal of glycosides; niaziridin and niazirin isolated from the pods of Moringa oleifera and ouabain (control) against the clinical isolates of multidrug-resistant Escherichia coli. Methods: The MICs were determined following the CLSI guidelines for broth micro-dilution. In-vitro combination studies were performed by broth checkerboard method followed by Time-Kill studies, the efflux pump inhibition assay, ATPase inhibitory activity, mutation prevention concentration and in-silico studies. Results: The results showed that both glycosides did not possess antibacterial activity of their own, but in combination, they reduced the MIC of tetracycline up to 16 folds. Both were found to inhibit efflux pumps, but niaziridin was the best. In real time expression pattern analysis, niaziridin was also found responsible for the down expression of the two important efflux pump acrB & yojI genes alone as well as in combination. Niaziridin was also able to over express the porin forming genes (ompA & ompX). These glycosides decreased the mutation prevention concentration of tetracycline. Conclusion: This is the first ever report on glycosides, niazirin and niaziridin acting as drug resistance reversal agent through efflux pump inhibition and modulation of expression pattern drug resistant genes. This study may be helpful in preparing an effective antibacterial combination against the drug-resistant GNB from a widely growing Moringa oleifera.

Background: Repeated cross-sectional serosurveys in the same geographic area establish the trend of the evolving pandemic. We present the findings of the third round of a national serosurvey to estimate the seroprevalence of SARS-CoV-2 infection among the general population and health care workers of India. Methods: We conducted the third population-based serosurvey between Dec 18, 2020 and Jan 6, 2021 in the same 700 villages or wards from 70 districts in 21 states across India, which were selected for the first and second serosurveys. We enrolled from each district, at least 400 individuals aged ≥ 10 years from general population and 100 HCWs from sub-district level public health facilities. Serum samples from general population were tested for the presence of IgG antibodies against nucleocapsid (N) and spike protein (S1-RBD) of SARS-CoV-2 using the Abbott and Siemens assays respectively, whereas sera from HCWs were tested for anti-S1-RBD. For general population, sera positive for either of the antibodies were considered positive, while sera positive for anti-S1-RBD were considered as positive for HCW. Weighted seroprevalence estimates were adjusted for sensitivity and specificity of respective assays. Findings: Of the 28,598 sera from general population, 4585 (16%) had IgG antibodies against N, 6647 (23.2%) against S1-RBD and 7436 (26%) against either. The weighted and assay characteristic adjusted seroprevalence against either of the antibodies was 24.1 (95%CI: 23.0% to 25.3%). Seroprevalence was lower in rural areas (21.4%, 95% CI: 20.3% to 22.6%) compared to urban non-slum (29.4%, 95% CI: 26.9% - 32.1%) and slum areas (34.6%, 95% CI: 31.0% to 38.3%). Among 7385 HCWs, the seroprevalence of anti-S1-RBD IgG antibodies was 25.6% (95% CI: 23.5% to 27.8%). Interpretation: Nearly one in four individuals aged 10 years or older from general population as well as HCWs were exposed to SARS-CoV-2 by December 2020 amounting to 271 million infections in India. Funding Statement: Indian Council of Medical Research Declaration of Interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare no competing interests Ethics Approval Statement: The project was approved by Institutional Human Ethics Committee at ICMR-National Institute of Epidemiology.

We report a familial cluster of 24 individuals infected with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The index case had a travel history and spent 24 days in the house before being tested and was asymptomatic. Physical overcrowding in the house provided a favourable environment for intra-cluster infection transmission. Restriction of movement of family members due to countrywide lockdown limited the spread in community. Among the infected, only four individuals developed symptoms. The complete genome sequences of SARS-CoV-2 was retrieved using next-generation sequencing from eight clinical samples which demonstrated a 99.99% similarity with reference to Wuhan strain and the phylogenetic analysis demonstrated a distinct cluster, lying in the B.6.6 pangolin lineage.

Background: India witnessed a severe second wave of COVID-19 during March and June 2021. We did the fourth nationwide serosurvey to estimate prevalence of SARS-CoV-2 antibodies in the general population aged >=6 years and health care workers (HCWs). Methods: We did a cross-sectional study between 14 June and 6 July 2021 in 700 clusters in the same 70 districts across 21 states/Union Territory. From each district, a minimum of 400 individuals aged >=6 years from general population and 100 HCWs from the district public health facilities were included. The serum samples were tested for the presence of IgG antibodies against S1-RBD and nucleocapsid protein of SARS-CoV-2 using chemiluminescence immunoassay. We estimated the weighted and test adjusted seroprevalence of IgG antibodies against S1-RBD and/or nucleocapsid protein along with 95% CI. Findings: Of the 28,975 sera tested, the weighted and test adjusted prevalence of IgG antibodies against S1-RBD and/or nucleocapsid protein among the general population aged >=6 years was 67.6% (95% CI: 66.4 – 68.7). The seroprevalence increased with age and was not different in rural and urban areas. Compared to unvaccinated adults (62.3%, 95% CI: 60.9 – 63.7), seroprevalence was significantly higher among individuals who received one (81.0%, 95% CI: 79.6 - 82.3) and two doses (89.8%, 95% CI: 88.4 - 91.1). The seroprevalence of IgG antibodies among 7,252 health care workers was 85.2% (95% CI: 83.5 - 86.7). Interpretation: Nearly one third of the population is still seronegative. It is necessary to accelerate the coverage of COVID-19 vaccination among adults and continue adherence to non-pharmaceutical interventions. Funding: Indian Council of Medical Research. Declaration of Interest: None to declare. Ethical Approval: The Institutional Human Ethics Committee of the ICMR National Institute of Epidemiology, Chennai approved the study protocol.

Background & objectives: Population-based seroepidemiological studies measure the extent of SARS-CoV-2 infection in a country. We report the findings of the first round of a national serosurvey, conducted to estimate the seroprevalence of SARS-CoV-2 infection among adult population of India. Methods: From May 11 to June 4, 2020, a randomly sampled, community-based survey was conducted in 700 villages/wards, selected from the 70 districts of the 21 States of India, categorized into four strata based on the incidence of reported COVID-19 cases. Four hundred adults per district were enrolled from 10 clusters with one adult per household. Serum samples were tested for IgG antibodies using COVID Kavach ELISA kit. All positive serum samples were re-tested using Euroimmun SARS-CoV-2 ELISA. Adjusting for survey design and serial test performance, weighted seroprevalence, number of infections, infection to case ratio (ICR) and infection fatality ratio (IFR) were calculated. Logistic regression was used to determine the factors associated with IgG positivity. Results: Total of 30,283 households were visited and 28,000 individuals were enrolled. Population-weighted seroprevalence after adjusting for test performance was 0.73 per cent [95% confidence interval (CI): 0.34-1.13]. Males, living in urban slums and occupation with high risk of exposure to potentially infected persons were associated with seropositivity. A cumulative 6,468,388 adult infections (95% CI: 3,829,029-11,199,423) were estimated in India by the early May. The overall ICR was between 81.6 (95% CI: 48.3-141.4) and 130.1 (95% CI: 77.0-225.2) with May 11 and May 3, 2020 as plausible reference points for reported cases. The IFR in the surveyed districts from high stratum, where death reporting was more robust, was 11.72 (95% CI: 7.21-19.19) to 15.04 (9.26-24.62) per 10,000 adults, using May 24 and June 1, 2020 as plausible reference points for reported deaths. Interpretation & conclusions: Seroprevalence of SARS-CoV-2 was low among the adult population in India around the beginning of May 2020. Further national and local serosurveys are recommended to better inform the public health strategy for containment and mitigation of the epidemic in various parts of the country.

Being crucial part of plant-based novel discovery of drug from natural resources, a study was done to explore the antibacterial potential of curcumin mimics in combination with antibiotics against multidrug resistant isolates of Pseudomonas aeruginosa. The best candidate Van D, a curcumin mimics reduced the MIC of tetracycline (TET) up to 16 folds against multidrug resistant clinical isolates. VanD further inhibited the efflux pumps as evident by ethidium bromide efflux and by in-silico docking studies. In another experiment, it was also found that Van D inhibits biofilm synthesis. This derivative kills the KG-P2, an isolate of P. aeruginosa in a time dependent manner, the post-antibiotic effect (PAE) of tetracycline was extended as well as mutant prevention concentration (MPC) of TET was also decreased. In Swiss albino mice, Van D reduced the proinflammatory cytokines concentration. In acute oral toxicity study, this derivative was well tolerated and found to be safe up to 1000 mg/kg dose. To the best of our knowledge, this is the first report on curcumin mimics as synergistic agent via inhibition of efflux pump.

Background: The first round of national serosurvey in India was conducted in May-June 2020 among adults from 21 States. The second serosurvey was conducted in August-September 2020 to estimate the nationwide seroprevalence for SARS-CoV-2 infection in the general population aged ten years and above. Methods: The household serosurvey was conducted among individuals aged ten years and above in the same 700 villages and wards from 70 districts selected during the first serosurvey. Blood samples were tested using the Abbott SARS-CoV-2 IgG assay. Seroprevalence was estimated after applying the sampling weights and adjusting for clustering and assay characteristics. In order to compare the adult seroprevalence between the two surveys, we randomly selected one adult serum sample from each household. Findings: The weighted and adjusted prevalence of infection among 29,082 individuals aged ten years and above was 6·6% (95% CI: 5·8% - 7·4%). The seroprevalence among adults was 7·1% (95% CI: 6·2% – 8·2%). Seroprevalence was similar across age groups, sex, and occupation. Seroprevalence was highest in urban slum areas followed by urban non-slum and rural areas. We estimated a cumulative 74·3 million infections in the country, with 26 – 32 infections for every reported COVID-19 case by August 2020. Interpretation: Nearly one in 15 individuals aged ten years and above had SARS-CoV-2 infection by August 2020. The adult seroprevalence increased ten times between May and August 2020. Lower infection to case ratio in August compared to May reflects a substantial increase in testing across the country. Funding: The study was funded by the Indian Council of Medical Research, New Delhi, India. The study sponsor was involved in reviewing the study design, writing of the manuscript and the decision to submit the paper for publication. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The authors obtained written informed consent from individuals aged 18 years and older. We obtained assent from children aged between 10–17 years, and written informed consent from their parents or guardians prior to the survey. The Central Ethics Committee of Health Research of Indian Council of Medical Research and the Institutional Human Ethics Committee of ICMR-National Institute of Epidemiology, Chennai approved the study protocol.

Download : Download full-size image Microbes produce antibiotics to show the dominancy to others and these secondary metabolites of the microorganisms become the source of novel antibiotics. Cephalosporin was the first stable β-lactam antibiotic and was introduced in the late 1940s. However, although cephalosporins are produced by many microorganisms, they are industrially produced by Acremonium chrysogenum. Cephalosporin is supposed to be the end product of complex reactions mediated by different enzymes. The genetics of the cephalosporin synthesis reveals that there are six genes which control the cephalosporin biosynthesis. This chapter focuses on the genetics of cephalosporin biosynthesis and its expression pattern as well as the molecular biology of A. chrysogenum.

Many microbes display antibiosis as a mechanism of their survival and dominancy. This mechanism of the microbes has eventually become the source of the evolution of novel drugs/antibiotics. Microorganisms secrete diverse compounds known as secondary metabolites. However, these unique chemical fingerprints are produced in very low amounts under typical laboratory conditions, which happen to be the major bottlenecks for the production of particular compounds of interest, especially in combination with metabolic modeling. The systematic study of the set of metabolites (unique chemical fingerprints) present within an organism, cell, or tissue is known as metabolomics. Being the part of synthetic biology of secondary metabolism it aims to redesign the biological systems for novel purposes and applications. Metabolomics has now become an important tool in synthetic biology which apart from its crucial role in the discovery of novel compounds from microbes also enables entire sets of metabolites, where the compounds of interest or their precursors can be produced with desired titers. This book chapter is focused on metabolomics in the search for secondary metabolites with chemical novelty and the engineered production and optimization of bioactive molecules.

Being crucial part of plant-based novel discovery of drug from natural resources, a study was done to explore the antibacterial potential of curcumin mimics in combination with antibiotics against multidrug resistant isolates of Pseudomonas aeruginosa. The best candidate Van D, a curcumin mimics reduced the MIC of tetracycline (TET) up to 16 folds against multidrug resistant clinical isolates. VanD further inhibited the efflux pumps as evident by ethidium bromide efflux and by in-silico docking studies. In another experiment, it was also found that Van D inhibits biofilm synthesis. This derivative kills the KG-P2, an isolate of P. aeruginosa in a time dependent manner, the post-antibiotic effect (PAE) of tetracycline was extended as well as mutant prevention concentration (MPC) of TET was also decreased. In Swiss albino mice, Van D reduced the proinflammatory cytokines concentration. In acute oral toxicity study, this derivative was well tolerated and found to be safe up to 1000 mg/kg dose. To the best of our knowledge, this is the first report on curcumin mimics as synergistic agent via inhibition of efflux pump.

The purpose of the present study was to study the synergy potential of gallic acid-based derivatives in combination with conventional antibiotics using multidrug resistant cultures of Escherichia coli. Gallic acid-based derivatives significantly reduced the MIC of tetracycline against multidrug resistant clinical isolate of E. coli. The best representative, 3-(3',4,'5'-trimethoxyphenyl)-4,5,6-trimethoxyindanone-1, an indanone derivative of gallic acid, was observed to inhibit ethidium bromide efflux and ATPase which was also supported by in silico docking. This derivative extended the post-antibiotic effect and decreased the mutation prevention concentration of tetracycline. This derivative in combination with TET was able to reduce the concentration of TNFα up to 18-fold in Swiss albino mice. This derivative was nontoxic and well tolerated up to 300 mg/kg dose in subacute oral toxicity study in mice. This is the first report of gallic acid-based indanone derivative as drug resistance reversal agent acting through ATP-dependent efflux pump inhibition.

Multidrug resistance (MDR) put an alarming situation like preantibiotic era which compels us to invigorate the basic science of anti-infective chemotherapy. Hence, the drug resistant genes/proteins were explored as promising drug targets. Keeping this thing in mind, proteome of Pseudomonas aeruginosa PA01 was explored, which resulted in the identification of tripartite protein complexes (MexA, MexB, and OprM) as promising drug target for the screening of natural and synthetic inhibitors. The purpose of present investigation was to explore the drug resistance reversal potential mechanism of catharanthine isolated from the leaves of Catharanthus roseous. Hence, the test compound catharanthine was in silico screened using docking studies against the above receptors, which showed significant binding affinity with these receptors. In order to validate the in silico findings, in vitro evaluation of the test compound was also carried out. In combination, catharanthine reduced the minimum inhibitory concentration MIC of tetracycline (TET) and streptomycin up to 16 and 8 folds, respectively. Further, in time kill assay, catharanthine in combination with TET reduced the cell viability in concentration dependent manner and was also able to reduce the mutation prevention concentration of TET. It was also deduced that drug resistance reversal potential of catharanthine was due to inhibition of the efflux pumps.

As a part of our drug discovery program, ursolic acidwas chemically transformed into six semi-syntheticderivatives, which were evaluated for their antibacterialand drug resistance reversal potential in combinationwith conventional antibiotic nalidixic acid against thenalidixic acid-sensitive and nalidixic acid-resistantstrains of Escherichia coli. Although ursolic acidand its all semi-synthetic derivatives did not showantibacterial activity of their own, but in combination,they significantly reduced the minimum inhibitoryconcentration of nalidixic acid up to eightfold. The3-O-acetyl-urs-12-en-28-isopropyl ester (UA-4) and3-O-acetyl-urs-12-en-28-n-butyl ester (UA-5) deriva-tives of ursolic acid reduced the minimum inhibitoryconcentration of nalidixic acid by eightfold againstnalidixic acid-resistant and four and eightfold againstnalidixic acid-sensitive, respectively. The UA-4 andUA-5 were further evaluated for their synergy potentialwith another antibiotic tetracycline against the multi-drug-resistant clinical isolate of Escherichia coli-KG4.The results showed that both these derivatives in com-bination with tetracycline reduced the cell viability inconcentration-dependent manner by significantly inhib-iting efflux pump. This was further supported by the insilico binding affinity of UA-4 and UA-5 with effluxpump proteins. These ursolic acid derivatives may findtheir potential use as synergistic agents in the treat-ment of multidrug-resistant Gram-negative infections.Key words: ester analog, multidrug-resistant, nalidixic acid,non-antibiotics, tetracycline, triterpenoidsReceived 27 May 2014, revised 1 December 2014 andaccepted for publication 1 December 2014

The purpose of present investigation was to understand the drug resistance reversal mechanism of 4-hydroxy-α-tetralone (1) isolated from Ammannia spp. along with its semi-synthetic derivatives (1a-1e) using multidrug resistant Escherichia coli (MDREC). The test compounds did not show significant antibacterial activity of their own, but in combination, they reduced the minimum inhibitory concentration (MIC) of tetracycline (TET). In time kill assay, compound 1 and its derivative 1e in combination with TET reduced the cell viability in concentration dependent manner. Compounds 1 and 1e were also able to reduce the mutation prevention concentration of TET. Both compounds showed inhibition of ATP dependent efflux pumps. In real time polymerase chain reaction (RT-PCR) study, compounds 1 and 1e alone and in combination with TET showed significant down expression of efflux pump gene (yojI) encoding multidrug ATP binding cassettes (ABC) transporter protein. Molecular mechanism was also supported by the in silico docking studies, which revealed significant binding affinity of compounds 1 and 1e with YojI. This study confirms that compound 1 and its derivative 1e are ABC efflux pump inhibitors which may be the basis for development of antibacterial combinations for the management of MDR infections from inexpensive natural product.

Fast centrifugal partition chromatography (FCPC) was successfully applied in the separation of close R f complex bioactive iridoid, loganetin directly from the ethyl acetate extract of Alstonia scholaris . The experiment was performed with a two-phase solvent system composed of methyl tert- butyl ether (MtBE)/ACN/Water (3:1.5:3 v/v/v) where the lower phase of the biphasic system, the aqueous layer containing 8 mM HCl, was the stationary phase, while the upper organic layer supplemented with 15 mM triethylamine TEA was designated as the mobile phase. From 1.5 g of EtOAc extract, 48 mg of loganetin (1) was obtained in 94.4% purity as determined by HPLC. The isolated compound (1) was characterized on the basis of its 1 H, 13 C–NMR, and ESI-MS spectroscopic data. Although loganetin does not possess antibacterial activity of its own, but in combination, it appreciably reduces the minimum inhibitory concentration (MIC) of nalidixic acid (NA) against nalidixic acid resistant (NAREC) and nalidixic acid sensitive ...

Antibacterial activity of lysergol (1) and its semi-synthetic derivatives (2-14) and their synergy with the conventional antibiotic nalidixic acid (NA) against nalidixic acid-sensitive (NASEC) and nalidixic acid-resistant (NAREC) strains of Escherichia coli were evaluated. Lysergol (1) and derivatives (2-14) did not possess antibacterial activity of their own, but in combination, they significantly reduced the minimum inhibitory concentration (MIC) of NA. All the derivatives showed two- to eightfold reduction in the MIC of NA against NAREC and NASEC. Further, lysergol (1) and its derivatives 10 and 11 brought down eightfold reductions in the MIC of tetracycline (TET) against multidrug-resistant clinical isolate of E. coli (MDREC). Treatment of these strains with the combinations of antibiotics and lysergol and its derivatives 10 and 11 (at reduced concentrations) significantly decreased the viability of cells. In an another observation, lysergol and its derivatives 10 and 11 inhibited ATP-dependent efflux pumps, which was evident by ATPase inhibition and down-regulation of multidrug ABC transporter ATP-binding protein (yojI) gene. These results may be of great help in antibacterial drug development from a very common, inexpensive, and non-toxic natural product.

DbMDR is non-redundant reference database of multidrug resistance (MDR) genes and their orthologs acting as potential drug targets. Drug resistance is a common phenomenon of pathogens, creating a serious problem of inactivation of drugs and antibiotics resulting in occurrence of diseases. Apart from other factors, the MDR genes present in pathogens are shown to be responsible for multidrug resistance. Much of the unorganized information on MDR genes is scattered across the literature and other web resources. Thus, consolidation of such knowledge about MDR genes into one database will make the drug discovery research more efficient. Mining of text for MDR genes has resulted into a large number of publications but in scattered and unorganized form. This information was compiled into a database, which enables a user not only to look at a particular MDR gene but also to find out putative homologs based on sequence similarity, conserved domains, and motifs in proteins encoded by MDR genes more efficiently. At present, DbMDR database contains 2843 MDR genes characterized experimentally as well as functionally annotated with cross-referencing search support. The DbMDR database (http://203.190.147.116/dbmdr/) is a comprehensive resource for comparative study focused on MDR genes and metabolic pathway efflux pumps and intended to provide a platform for researchers for further research in drug resistance.

The essential oil of Vetiveria zizanioides showed significant antimycobacterial activity against the drug-resistant strains of Mycobacterium smegmatis, which on activity guided fractionation afforded four bioactive fractions Vz-2, Vz-7, Vz-8, and Vz-9. Further purification of these bioactive fractions over preparative thin layer chromatographic resulted in the characterization of six compounds: 5, 10-pentadecadiyn-1-ol (1), α-curcumene (3), hydroxy junipene (4), (+) cycloisosativene (5), valencine (6), and selino 3,7 (11)-diene (7). All these compounds showed significant antimycobacterial activity against the drug-resistant strains (MDR-R and MDR-40) of M. smegmatis and their MIC was in the range of 31.25–62.5 μg/ml. These results may be of great help in antimycobacterial drug development from a very common, inexpensive, and non toxic natural product.

Several diverse analogues of Oenostacin, a naturally occurring potent antibacterial phenolic acid derivative, have been synthesized. A small library with more than forty analogues having different aromatic rings and varied side chains has been achieved through solution phase synthesis. Some of these analogues, that is, 22 , 23 and 42 , possessed potent antibacterial activities against Staphylococcus epidermidis and Staphylococcus aureus having EC 50 ranging from 0.49 to 0.67 μM as compared to Oenostacin (EC 50 = 0.12 μM).

Infectious diseases are one of the major causes of morbidity and mortality in children in developing and underdeveloped countries. Limited knowledge of targets (cell wall synthesis, replication, transcription, protein synthesis) for antibiotics and lack of novel antibiotics have lead to an emergence of different level of resistance in bacterial pathogens. Multidrug resistance is the phenomenon by which the bacteria exerts resistance against the two or more structurally unrelated drugs/antibiotics. A common goal in the post-genomic era is to identify novel targets/drugs for various life threatening bacterial pathogens. Nanoparticles are broadly defined as submicron colloidal particles of size less than 1μm. Nanoparticles of size less than 100nm are the most promising warheads to overcome microbial drug resistance because they can act as antibacterial/antibiotic modulating agents at the site of infection and may have more than one mode of action. These nanoparticles will be of immense help in transporting drugs directly at the infected sites. Thus prevent drug resistance development to a great extent. In this review, the key mechanisms of resistance in bacterial superbugs have been discussed as well as how nanoparticles can overcome them. It is hypothesized that the nanoparticles can overcome the drug resistance via a novel mechanism of action. Additionaly, nanopaticles may also work synergistically with antibiotics via increased uptake, decreased efflux and inhibition of biofilm formation. The degradation by metallo beta lactamases and synthesis of porins may also be facilitated through these nanoparticles.

Antibacterial and synergy potential of naturally occurring indole alkaloids (IA): 10-methoxy tetrahydroalstonine (1), isoreserpiline (2), 10 and 11 demethoxyreserpiline (3), reserpiline (4), serpentine (5), ajmaline (6), ajmalicine (7), yohimbine (8), and α-yohimbine (9) was evaluated using microbroth dilution assay. Further, α-yohimbine (9) was chemically transformed into six semisynthetic derivatives (9A-9F), and their antibacterial and synergy potential in combination with nalidixic acid (NAL) against E. coli strains CA8000 and DH5α were also evaluated. The IA 1, 2, 4, 5, 9 and the derivative 9F showed eightfold reduction in the MIC of NAL against the DH5α and four- to eightfold reduction against CA8000. These alkaloids also reduced MIC of another antibiotic, tetracycline up to 8folds, against the MDREC-KG4, a multidrug-resistant clinical isolate of E. coli. Mode of action study of these alkaloids showed efflux pumps inhibitory potential, which was supported by their in silico binding affinity and downregulation of efflux pump genes. These results may be of great help in the development of cost-effective antibacterial combinations for treating patients infected with multidrug-resistant Gram-negative infections.

The methanolic extract of Ammannia multiflora (Lythraceae) showed significant bioenhancing activity with the antibiotic nalidixic acid. Bioassay-guided fractionation of MeOH extract resulted in the isolation of a novel compound, 2,5-bis-(3,3'-hydroxyaryl)tetrahydrofuran, named as ammaniol (5), along with 9 other known compounds (1-4, 6-10). Furthermore, compound 4-hydroxy- α-tetralone (1) was converted into five semisynthetic acyl derivatives, 1A-1E, which were evaluated along with compounds 1, 5, 6, 9, and 10 for their bioenhancing activity in combination with nalidixic acid against the two strains, CA8000 and DH5 α, of Escherichia coli. The results showed that the methanolic extract of A. multiflora and compounds 1 and 9 possessed significant bioenhancing activity and reduced the dose of nalidixic acid fourfold while compounds 5, 6, 10 and semisynthetic derivatives 1A- 1E reduced the dose of nalidixic acid twofold. Compound 5 was also tested for antimycobacterial activity against Mycobacterium H37Rv and was found to show moderate activity (MIC 25 µg/mL) against this pathogen.

Phytol was chemically transformed into fifteen semi-synthetic derivatives, which were evaluated for their antibacterial and drug resistance reversal potential in combination with nalidixic acid against E. coli strains CA8000 and DH5α. The pivaloyl (4), 3,4,5-trimethoxybenzoyl (9), 2,3-dichlorobenzoyl (10), cinnamoyl (11), and aldehyde (14) derivatives of phytol ((2E,7R,11R)-3,7,11,15-tetramethyl-2-hexadecen-1-ol) were evaluated by using another antibiotic, tetracycline, against the MDREC-KG4 clinical isolate of E. coli. Derivative 4 decreased the maximal inhibitory concentration (MIC) of the antibiotics by 16-fold, while derivatives 9, 10, 11, and 14 reduced MIC values of the antibiotics up to eightfold against the E. coli strains. Derivatives 4, 9, 10, 11, and 14 inhibited the ATP-dependent efflux pump; this was also supported by their in silico binding affinity and down-regulation of the efflux pump gene yojI, which encodes the multidrug ATP-binding cassette transporter protein. This study supports the possible use of phytol derivatives in the development of cost-effective antibacterial combinations.

Two bioactive constituents, khusenic acid (1) and khusimol (2), were isolated and characterized from hexane fraction of Vetiveria zizanoides roots. Compounds, 1 and 2, were tested against the various drug-resistant mutants of Mycobacterium smegmatis. The results showed that compound 1 was 4 times more active than the standard drugs ciprofloxacin (CF) and nalidixic acid (NA) against the ciprofloxacin (CSC 101) and lomefloxacin(LOMR5)-resistant mutants, whereas the compound 2 was 2 times more active against the CSC 101 than the NA and CF. Further, these compounds were tested against the virulent strain H37Rv of Mycobacterium tuberculosis, which showed that 1 was two times more active than NA, while 2 was equally active to NA. In in silico docking study, 1 showed better binding affinity than 2 with both subunits of the bacterial DNA gyrase, which was further confirmed from the in vitro bacterial DNA gyrase inhibition study. The in silico ADME analysis of 1 and 2 showed better intestinal absorption, aqueous solubility and ability to penetrate blood-brain barrier. Finally, compound 2 was found safe at the highest dose of 2000 mg/kg body weight. Being edible, fragrant natural products, 1 and 2 will have advantage over the existing synthetic drugs.

DbMDR is non-redundant reference database of multidrug resistance (MDR) genes and their orthologs acting as potential drug targets. Drug resistance is a common phenomenon of pathogens, creating a serious problem of inactivation of drugs and antibiotics resulting in occurrence of diseases. Apart from other factors, the MDR genes present in pathogens are shown to be responsible for multidrug resistance. Much of the unorganized information on MDR genes is scattered across the literature and other web resources. Thus, consolidation of such knowledge about MDR genes into one database will make the drug discovery research more efficient. Mining of text for MDR genes has resulted into a large number of publications but in scattered and unorganized form. This information was compiled into a database, which enables a user not only to look at a particular MDR gene but also to find out putative homologs based on sequence similarity, conserved domains, and motifs in proteins encoded by MDR genes more efficiently. At present, DbMDR database contains 2843 MDR genes characterized experimentally as well as functionally annotated with cross-referencing search support. The DbMDR database (http://203.190.147.116/dbmdr/) is a comprehensive resource for comparative study focused on MDR genes and metabolic pathway efflux pumps and intended to provide a platform for researchers for further research in drug resistance.

Biological and chemical investigations were carried out to evaluate the antimicrobial potential of Melaleuca genistifolia leaf oil for herbal medicines. The disk diffusion and micro broth dilution methods were used for the evaluation of the antimicrobial activity of the essential oil and its major constituent, methyl eugenol against the five selected bacterial and five fungal strains. The oil was active against all the tested bacterial and fungal strains. The oil was highly active against Staphylococcus epidermidis and significantly active against S. aureus, Sporothrix schenckii and Trichophyton rubrum, while methyl eugenol was significantly active against Enterococcus faecalis, Streptococcus mutans and Escherichia coli. GC and GC-MS analysis of the oil resulted in the identification of twenty two constituents representing 99.4% of the oil. The chemo type identified had a high methyl eugenol (88.1%) content. The essential oil could be of use for the future development of antimicrobial herbal products.