Multidrug-resistant Human Pathogens Research Articles

Culturable rare Actinomycetes: diversity, isolation and marine natural product discovery

Rare Actinomycetes from underexplored marine environments are targeted in drug discovery studies due to the Actinomycetes' potentially huge resource of structurally diverse natural products with unusual biological activity. Of all marine bacteria, 10 % are Actinomycetes, which have proven an outstanding and fascinating resource for new and potent bioactive molecules. Past and present efforts in the isolation of rare Actinomycetes from underexplored diverse natural habitats have resulted in the isolation of about 220 rare Actinomycete genera of which more than 50 taxa have been reported to be the producers of 2,500 bioactive compounds. That amount represents greater than 25 % of the total Actinomycetes metabolites, demonstrating that selective isolation methods are being developed and extensively applied. Due to the high rediscovery rate of known compounds from Actinomycetes, a renewed interest in the development of new antimicrobial agents from rare and novel Actinomycetes is urgently required to combat the increasing number of multidrug-resistant human pathogens. To facilitate that discovery, this review updates all selective isolation media including pretreatment and enrichment methods for the isolation of marine rare Actinomycetes. In addition, this review demonstrates that discovering new compounds with novel scaffolds can be increased by intensive efforts in isolating and screening rare marine genera of Actinomycetes. Between 2007 and mid-2013, 80 new rare Actinomycete species were reported from marine habitats. They belong to 23 rare families, of which three are novel, and 20 novel genera. Of them, the family Micromonosporaceae is dominant as a producer of promising chemical diversity.

Green synthesis of silver nanoparticles using hypericin-rich shoot cultures of Hypericum hookerianum and evaluation of anti-bacterial activities

The paper reports a green chemistry approach for the synthesis of silver nanoparticles (AgNPs) using hypericin-rich shoot cultures of Hypericum hookerianum as reducing agent. Normal green shoot cultures deficient in hypericin and red-pigmented shoot cultures rich in hypericin (3.01% DW) were raised in Murashige and Skoog nutrient medium containing 1.0 mg/L kinetin (KIN) and 0.2 mg/L naphthaleneacetic acid (NAA), respectively. Dried powder extracts of whole shoots were used for AgNPs formation. The effect of temperature on the formation of AgNPs is investigated. The nanoparticles obtained were characterised using UV–Vis spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses. The UV–Vis spectra of AgNPs gave surface plasmon resonance (SPR) at 440 nm. The synthesised AgNPs were effective against different multidrug-resistant human pathogens such as Bacillus subtillis (Gram positive) and Pseudomonas aeruginosa (Gram negative) species. Further, the effect of hypericin concentration on anti-bacterial activity was investigated and was found to increase with increase in concentration.

Green Synthesis of Silver Nanoparticles and Their Antibacterial Activity Against Multi-Drug Resistant Human Pathogens

Green Synthesis of Silver Nanoparticles and Their Antibacterial Activity Against Multi-Drug Resistant Human Pathogens

Cytotoxic and antibacterial substances against multi-drug resistant pathogens from marine sponge symbiont: Citrinin, a secondary metabolite of Penicillium sp.

ObjectiveTo Isolate, purify, characterize, and evaluate the bioactive compounds from the sponge-derived fungus Penicillium sp. FF001 and to elucidate its structure. MethodsThe fungal strain FF001 with an interesting bioactivity profile was isolated from a marine Fijian sponge Melophlus sp. Based on conidiophores aggregation, conidia development and mycelia morphological characteristics, the isolate FF001 was classically identified as a Penicillium sp. The bioactive compound was identified using various spectral analysis of UV, high resolution electrospray ionization mass spectra, 1H and 13C NMR spectral data. Further minimum inhibitory concentrations (MICs) assay and brine shrimp cytotoxicity assay were also carried out to evaluate the biological properties of the purified compound. ResultsBioassay guided fractionation of the EtOAc extract of a static culture of this Penicillium sp. by different chromatographic methods led the isolation of an antibacterial, anticryptococcal and cytotoxic active compound, which was identified as citrinin (1). Further, citrinin (1) is reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus (S. aureus), rifampicin-resistant S. aureus, wild type S. aureus and vancomycin-resistant Enterococcus faecium showed MICs of 3.90, 0.97, 1.95 and 7.81 μg/mL, respectively. Further citrinin (1) displayed significant activity against the pathogenic yeast Cryptococcus neoformans (MIC 3.90 μg/mL), and exhibited cytotoxicity against brine shrimp larvae LD50 of 96 μg/mL. ConclusionsCitrinin (1) is reported from sponge associated Penicillium sp. from this study and for its strong antibacterial activity against multi-drug resistant human pathogens including cytotoxicity against brine shrimp larvae, which indicated that sponge associated Penicillium spp. are promising sources of natural bioactive metabolites.

A Facile Green Synthesis of Silver Nanoparticles Using the Medicinal Plant Leucas Aspera and Their Antibacterial Activity

Normal 0 7.8 磅 0 2 false false false EN-US ZH-CN X-NONE MicrosoftInternetExplorer4 The junction of nanotechnology and biomedical sciences unfasten the possibility for a wide range of biological research topics and medical uses at the molecular and cellular level. In the present study silver nanoparticles were synthesized by using Leucas aspera leaf extract support of biological process. The extract incubated with 1mM AgNO 3 solution showed gradual change in the colour of the extract from greenish to reddish brown. Reduction of silver ions by the leaf extract was examined by UV-visible spectroscopic technique. Further, it was confirmed by Fourier Transformations Infrared spectroscopic (FTIR) analysis. The purity of the synthesized silver nanoparticles was examined through X-Ray Diffraction (XRD) analysis. The nanoparticles were examined for the antibacterial activities of antibiotic (Tetracycline), silver nanoparticles and the combined effect of both antibiotic and nanoparticles against the multi drug resistant human pathogens .

In vitro antibacterial potential of Eugenia jambolana seed extracts against multidrug-resistant human bacterial pathogens

The present study was carried out to evaluate the possible in vitro antibacterial potential of extracts of Eugenia jambolana seeds against multidrug-resistant human bacterial pathogens. Agar well diffusion and microbroth dilution assay methods were used for antibacterial susceptibility testing. Kill-kinetics study was done to know the rate and extent of bacterial killing. Phytochemical analysis and TLC-bioautography were performed by colour tests to characterize the putative compounds responsible for this antibacterial activity. Cytotoxic potential was evaluated on human erythrocytes by haemolytic assay method and acute oral toxicity study was done in mice. The plant extracts demonstrated varying degrees of strain specific antibacterial activity against all the test isolates. Further, ethyl acetate fraction obtained from fractionation of most active ethanol extract showed maximum antibacterial effect against all the test isolates. Phytochemical analysis and TLC-bioautography of ethyl acetate fraction revealed that phenolics were the major active phytoconstituents. Ethyl acetate fraction also demonstrated no haemolytic activity on human erythrocytes and no gross behavioural changes as well as toxic symptoms were observed in mice at recommended dosage level. The results provide justification for the use of E. jambolana in folk medicine to treat various infectious diseases and may contribute to the development of novel antimicrobial agents for the treatment of infections caused by these drug-resistant bacterial pathogens.

Hospital bath basins are frequently contaminated with multidrug-resistant human pathogens

The hospital environment is increasingly recognized as a reservoir for hospital-acquired pathogens. During a 44-month study period, a total of 1,103 basins from 88 hospitals in the United States and Canada were sampled. Overall, 62.2% of the basins (at least 1 basin at each hospital) were contaminated with commonly encountered hospital-acquired pathogens.

Antibacterial activity of chloroform and ethanol extracts of black cumin seeds (Nigella sativa) against multi-drug resistant human pathogens under laboratory conditions.

Chloroform and ethanol extracts of black cumin seeds (Nigella sativa) were analyzed for antibacterial activity against five food and water borne pathogens, namely, Staphylococcus aureus, Bacillus cereus, Vibrio cholerae, Klebsiella pneumoniae, Escherichia coli, and one food spoilage bacteria Bacillus subtilis, all of which were previously found to be resistant to different antibiotics. The antibacterial activities of the extracts were determined by disc diffusion and tube dilution methods. All the bacterial strains except E. coli and K. pneumoniae, showed sensitivity to the chloroform extract as well as the bacterial strains except the K. pneumoniae showed sensitivities to ethanol extract. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of both extracts were also evaluated. Ethanol extract of black cumin was as found to be highly effective for B. subtilis (MIC value 375 µg/ml), followed by S. aureus (MIC value 1125 µg/ml). The highest concentration of extract was required for E. coli for complete inhibition of their growth. MIC value for E. coli was 3000 µg/ml. These results suggest that black cumin seeds may have potential antibacterial activity against multiple antibiotic-resistant bacteria. Key words: Black cumin, multi-drug resistant bacteria, ethanol extract, chloroform extract.

Burkholderia cepaciaComplex: Emerging Multihost Pathogens Equipped with a Wide Range of Virulence Factors and Determinants

The Burkholderia cepacia complex (Bcc) comprises at least 17 closely-related species of the β-proteobacteria subdivision, widely distributed in natural and man-made inhabitats. Bcc bacteria are endowed with an extraordinary metabolic diversity and emerged in the 1980s as life-threatening and difficult-to-treat pathogens among patients suffering from cystic fibrosis. More recently, these bacteria became recognized as a threat to hospitalized patients suffering from other diseases, in particular oncological patients. In the present paper, we review these and other traits of Bcc bacteria, as well as some of the strategies used to identify and validate the virulence factors and determinants used by these bacteria. The identification and characterization of these virulence factors is expected to lead to the design of novel therapeutic strategies to fight the infections caused by these emergent multidrug resistant human pathogens.

Biosynthesis of silver nanoparticles using mangosteen leaf extract and evaluation of their antimicrobial activities

There is an increasing commercial demand for nanoparticles due to their wide applicability in various areas such as electronics, catalysis, chemistry, energy and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. In this research article we present a simple and eco-friendly biosynthesis of silver nanoparticles using Garcinia mangostana leaf extract as reducing agent. The aqueous silver ions when exposed to leaf extract were reduced and resulted in silver nanoparticles whose average size was 35nm. The silver nanoparticles were characterized by UV–Visible, Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM) techniques. Furthermore these biologically synthesized nanoparticles were found to be highly effective against different multi-drug resistant human pathogens.

Clinical Microbiology in Pharmacy Education: A Practice-based Approach

The increasing incidence of multi-drug resistant pathogenic bacteria, alongside viral and fungal human pathogens, supports the argument that skills in microbiology and infectious disease diagnosis, treatment and prevention are of growing global importance to be held among primary care clinicians. In Canada, inevitable future astronomical health care costs largely due to an aging population, have forced eyes upon pharmacists as one of (if not) the primary clinical professions to accommodate the growing need to accommodate patient access to health care while maintaining lower health care costs. As such, the role of pharmacists in health care is expanding, punctuating the need to enhance and improve Pharmacy education. Accurate assessment of the current gaps in Pharmacy education in Canada provides a unique opportunity for a new Pharmacy School at the University of Waterloo to establish a non-traditional, outcomes-based model to curricular design. We are applying this iterative curriculum assessment and design process to the establishment of a Medical Microbiology program, deemed as a prominent gap in former Pharmacy educational training programs. A PILOT STUDY WAS CARRIED OUT DISTRIBUTING A COMPREHENSIVE SURVEY TO A LOCAL GROUP OF PHARMACISTS PRACTICING IN A VARIETY OF SETTINGS INCLUDING: hospital, clinic, community, independent, industry and government, to assess perceived gaps in Pharmacy microbiology and infectious disease education. Preliminary findings of the surveys indicate that practitioners feel under-qualified in some areas of microbiology. The results are discussed with respect to a curricular redesign model and next steps in the process of curricular design are proposed.

Virulence and antimicrobial resistance determinants of human pathogenic and commensal strains ofPseudomonas aeruginosa

Pseudomonas aeruginosa (Pa) is an opportunistic pathogen, frequently causing local infections in tissues with decreased innate immunity in animals and man, which are difficult to treat due to antimicrobial resistance. In order to survive in host tissues, the Pa strains are known to utilize a wide range of virulence-, and fitness factors. Many of these virulence-, and drug resistance factors have their genetic determinants on the chromosome, but some others reside on mobile genetic elements [1]. One of the most remarkable and concerning characteristics of Pa is the low antibiotic susceptibility, which under certain conditions can be enhanced by the uptake of mobile elements that may help commensal strains of Pa to develop into multidrug resistant human pathogens [2]. Phenotypic resistance can be further increased by appropriate changes in colony formation such as biofilms, or small colony variation [3].

Activity of Some Plant Extracts Against Multi-Drug Resistant Human Pathogens

Plants used for traditional medicine contain a wide range of substances which can be used to treat various infectious diseases. Hence, antibacterial activities of ethanolic extracts of 19 plant species were studied against multi-drug resistant clinical isolates using agar well diffusion method. Extracts of Liquidambar orientalis, Vitis vinifera,?? ?????????????????????? ????????????????????, Punica granatum, Cornus sanguinea, Euphorbia peplus, Ecballium elaterium, Inula viscosa and Liquidambar orientalis showed broad-spectrum antibacterial activity with inhibition zones ranging from 8 to 26 mm. The most resistant organisms were Escherichia coli (E. coli) (Ampicillin-, amoxycillin- and sulfamethoxazole-resistant), Stenotrophomonas maltophilia (S. maltophilia) (Amoxycillin- and nalidixic acid-resistant) and Klebsiella pneumoniae (K. pneumoniae) (Ampicillin-, amoxycillin- and aztreonam-resistant), and the most susceptible species were Staphylococcus aureus (S. aureus) (Penicillin G- and oxacillin-resistant), Streptococcus pyogenes (S. pyogenes) (Penicillin G-, erythromycin- and clindamycin-resistant) and Pseudomonas aeruginosa (P. aeruginosa) (Sulfamethoxazole- and novobiocin-resistant), respectively. Minimum Inhibitory Concentrations (MIC) of crude extracts were determined for the seven highly active plants showing activity against methicillin resistant S. aureus (MRSA), E. coli, P. aeruginosa, S. pneumoniae and the reference bacteria (E. coli ATCC 11229 and Kocuria rhizophila ATCC 9341 NA). MICs of active extracts ranged from 8 to 14.2 mg/mL against one or other test bacteria.

In Vitro Screening of the Antibacterial Activity and Identification of Bioactive Compounds From Plants against Selected Vibrio spp. Pathogens

In vitro investigation of the vibriocidal activity of acetone extracts of Saraca indica Linn (Caesalpinaceae) and Datura stramonium Linn (Solanaceae), and aqueous extracts of Allium sativum Linn (Liliaceae) showed that they have antibacterial activity against multidrug-resistant human pathogens. Disc diffusion assay showed that there was significant concentration-dependent antibacterial activity against standard strains of Vibrio cholerae, Vibrio parahaemolyticus, and 12 multidrug-resistant isolates of Vibrio cholerae non-O1. The crude plant extracts had zones of inhibition in the range of 7-27 mm against 1 or more test bacteria, with MIC ranging from 2.5 to 15 mg/ml. Acetone extracts of S. indica and D. stramonium, in most cases, had more potency (low MIC value) than ethanol and aqueous extracts; however, the aqueous extract of A. sativum was the most effective. Thin layer chromatography (TLC), bioautography, and high performance liquid chromatography (HPLC) analysis of the crude extracts revealed that saponin, tannin, scopolamine, atropine, and allicin were the active constituents.

Antibacterial Activity Of Marine Microalgae Against Multidrug Resistant Human Pathogens

Marine microalgal extracts were studied for their antibacterial activity against the multidrug resistant human pathogens. Twenty marine microalgae were cultured and extracts were screened against 10 human pathogens. Among them, Isochrysis galbana extract showed highest percentage of antibacterial activity. Among the 5 solvents used for the extraction of antimicrobials, n-butanol showed maximum extraction (41.3%) of antimicrobials. The percentage inhibition of bacterial pathogens by these microalgae showed the maximum inhibition of Escherichia coli.

Antimicrobial Potential of Callistemon rigidus.

In vitro. investigation of the antimicrobial activity of a crude methanol extract of leaves of Callistemon rigidus. R.Br. (Myrtaceae) revealed potential antibacterial activity against a broad spectrum of multidrug-resistant human pathogens. Agar well diffusion assays of the test extract established significant concentration-dependent antibacterial activity against methicillin-resistant Staphylococcus aureus., vancomycin-intermediate Staphylococcus aureus., vancomycin-resistant Escherichia coli., extended spectrum β.-lactamase-producing E. coli., and multidrug-resistant Pseudomonas. spp.

Antimicrobial and phytochemical studies on 45 Indian medicinal plants against multi-drug resistant human pathogens

Ethanolic extracts of 45 Indian medicinal plants traditionally used in medicine were studied for their antimicrobial activity against certain drug-resistant bacteria and a yeast Candida albicans of clinical origin. Of these, 40 plant extracts showed varied levels of antimicrobial activity against one or more test bacteria. Anticandidal activity was detected in 24 plant extracts. Overall, broad-spectrum antimicrobial activity was observed in 12 plants ( L. inermis, Eucalyptus sp. , H. antidysentrica, H. indicus, C. equistifolia. T. belerica, T. chebula, E. officinalis, C. sinensis, S. aromaticum and P. granatum) . No correlation was observed between susceptibility of test strains with plant extracts and antibiotic resistance behaviour of the microbial strains ( Staphylococcus aureus, Salmonella paratyphi, Shigella dysenteriae, Escherichia coli, Bacillus subtilis, Candida albicans). Qualitative phytochemical tests, thin layer chromatography and TLC-bioautography of certain active extracts demonstrated the presence of common phytocompounds in the plant extracts including phenols, tannins and flavonoids as major active constituents.