Search results for: periodontal pathogens

Authors: V. V. Lakshmi, Y. V. S. Annapurna

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Urinary tract infection (UTI) is one of the most common infectious diseases seen in the community. Susceptible individuals experience multiple episodes, and progress to acute pyelonephritis or uro-sepsis or develop asymptomatic bacteriuria (ABU). Ability to cause extraintestinal infections depends on several virulence factors required for survival at extraintestinal sites. Presence of virulence phenotypes enhances the pathogenicity of these otherwise commensal organisms and thus augments its ability to cause extraintestinal infections, the most frequent in urinary tract infections(UTI). The present study focuses on detection of the virulence characters exhibited by the uropathogenic organism and most common factors exhibited in the local pathogens. A total of 700 isolates of E.coli and Klebsiella spp were included in the study.These were isolated from patients from local hospitals reported to be suffering with UTI over a period of three years. Isolation and identification was done based on Gram character and IMVIC reactions. Antibiotic sensitivity profile was carried out by disc diffusion method and multi drug resistant strains with MAR index of 0.7 were further selected. Virulence features examined included their ability to produce exopolysaccharides, protease- gelatinase production, hemolysin production, haemagglutination and hydrophobicity test. Exopolysaccharide production was most predominant virulence feature among the isolates when checked by congo red method. The biofilms production examined by microtitre plates using ELISA reader confirmed that this is the major factor contributing to virulencity of the pathogens followed by hemolysin production.

Keywords: Escherichia coli, Klebsiella spp, Uropathogens, virulence features

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Authors: Theresa Campbell, Camille Bowen-Forbes, William Aalbersberg

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Differences in the sensory properties of two subtly distinct varieties of Rubus rosifolius lead to the examination of their anthocyanin, essential oil and polyphenol profiles. In both cases, notable differences were identified. Pelargonidin-3-rhutinoside (17.2 mg/100 g FW) and Cyanidin-3-glucoside (66.2 mg/100g FW) proved to be the dominant anthocyanins in the red and wine red varieties respectively. Linalool and terpineol were the major constituents of the essential oil from the red variety; however, those of the wine red variety are unidentified. In regard to phenolic compounds, caffeic acid and quercetin were in a higher concentration in the red variety (1.85 and 0.73 mg/100g FW respectively, compared to 1.22 and 0.34 mg/100g FW respectively in the wine red fruits); while ellagic acid and ferulic acid were of a higher concentration in the wine red variety (0.92 and 0.84mg/100g FW respectively, compared to 0.15 and 0.48 mg/100g FW respectively in the red variety). The methanol extract of both fruit varieties showed great antioxidant activity. Analysis of the antimicrobial activity of the fruit extracts against the growth of drug resistant pathogens revealed that they are active against methicillin resistant S. aureus (MRSA), rifampicin resistant S. aureus (RRSA), wild-type S. aureus (WTSA) and vancomycin-resistant Enterococcus faecium (VREF). Activity was also reported against several food-borne pathogens including two strains of E. coli, L. monocytogenes and Enterobacter aerogenes. The cytotoxicity of the various extracts was assessed and the essential oil extracts exhibited superior activity. The phenolic composition and biological activity of the fruits indicate that their consumption is beneficial to health and also that their incorporation into functional foods and nutraceuticals should be considered.

Keywords: phytochemicals, antimicrobial, cytotoxic, Rubus rosifolius

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Authors: Anderson Chidi Amadioha, Promise Chidi Kenkwo, A. A. Markson

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Cassava (Manihot esculenta Crantz) is an important food and cash crop that provide cheap source of carbohydrate for food, feed and raw material for industries hence a commodity for feature economic development of developing countries. Despite the importance, its production potentials is undermined by disease agents that greatly reduce yield and render it unfit for human consumption and industrial use. Pathogenicity tests on fungal isolates from infected cassava revealed Aspergillus flavus, Rhizopus stolonifer, Aspergillus niger, and Trichodderma viride as rot-causing organisms. Water and ethanol extracts of Piper guineense, Ocimum graticimum, Cassia alata, and Tagetes erecta at 50% concentration significantly inhibited the radial growth of the pathogens in vitro and their development and spread in vivo. Low cassava rot incidence and severity was recorded when the extracts were applied before than after spray inoculating with spore suspension (1x105 spores/ml of distilled water) of the pathogenic organisms. The plant materials are readily available, and their extracts are biodegradable and cost effective. The fungitoxic potentials of extracts of these plant materials could be exploited as potent biopesticides in the management of postharvest fungal deterioration of cassava especially in developing countries where synthetic fungicides are not only scarce but also expensive for resource poor farmers who produce over 95% of the food consumed.

Keywords: cassava, biopesticides, in vitro, in vivo, pathogens, plant extracts

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Authors: Hafiza Javaria Ashraf, Xinghong Wang, Zhanghong Shi, Youming Hou

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Insect’s innate immunity depends on a variety of defense responses for the recognition of invading pathogens. Pathogen recognition involves particular proteins known as pattern recognition receptors (PRRs). These PRRs interact with pathogen-associated molecular patterns (PAMPs) present on the surface of pathogens to distinguish between self and non-self. C-type lectins (CTLs) belong to a superfamily of PPRs which involved in insect immunity and defense mechanism. Rhynchophorus ferrugineus Olivier is a devastating pest of Palm cultivations in China. Although studies on R. ferrugineus immune mechanism and host defense have conducted, however, the role of CTL in immune responses of R. ferrugineus remains elusive. Here, we report RfCTL, which is a secreted protein containing a single-CRD domain. The open reading frame (ORF) of CTL is 226 bp, which encodes a putative protein of 168 amino acids. Transcript expression analysis revealed that RfCTL highly expressed in immune-related tissues, i.e., hemolymph and fat body. The abundance of RfCTL in the gut and fat body dramatically increased upon Staphylococcus aureus and Escherichia coli bacterial challenges, suggesting a role in defense against gram-positive and gram-negative bacterial infection. Taken together, we inferred that RfCTL might be involved in the immune defense of R. ferrugineus and established a solid foundation for future studies on R. ferrugineus CTL domain proteins for better understanding of insect immunity.

Keywords: biological invasion, c-type lectin, insect immunity, Rhynchophorus ferrugineus Oliver

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Authors: Recep Duzsoz, Elif Bilgir, Derya Yildirim, Ozlem Gormez

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Radicular cysts develop in the root apex of tooth that is devitalized. Cysts are pathologic lesions with an epithelial lining encapsulated by connective tissue. Radicular cysts originate from epithelial remnants of the periodontal ligament in the root apex as a result of inflammation. They are most commonly observed in the maxillary anterior region, among men and in the third decade of life. Radiographically, they are seen as ovoid radiolucent lesions surrounded by a thin radioopaque margin. In this case, series was carried out in 15 radicular cysts of the jaws diagnosed in individuals. The cysts were evaluated age, sex, and localization. 12 of the cysts were localized in the maxillae, 3 of them were localised in the mandible. The female/male ratio of the lesions was 1/2. In conclusion, we evaluated age, localization and sex distribution of radicular cysts in this study. The knowledge of the features of the jaw cysts is a basic aspect to achieve diagnosis, complications and proper treatment.

Keywords: radicular cyst, jaws, CBCT, treatment

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Authors: Ágota Ábrahám, Md Nurul Islam, Karimane Zeghbib, Gábor Kemenesi, Sazeda Akter

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Collecting palm sap as a food source is an everyday practice in some parts of the world. However, the consumption of palm juice has been associated with regular infections and epidemics in parts of Bangladesh. This is attributed to fruit-eating bats and other vertebrates or invertebrates native to the area, contaminating the food with their body secretions during the collection process. The frequent intake of palm juice, whether as a processed food product or in its unprocessed form, is a common phenomenon in large areas. The range of pathogens suitable for human infection resulting from this practice is not yet fully understood. Additionally, the high sugar content of the liquid makes it an ideal culture medium for certain bacteria, which can easily propagate and potentially harm consumers. Rapid diagnostics, especially in remote locations, could mitigate health risks associated with palm juice consumption. The primary objective of this research is the rapid genomic detection and risk assessment of bacteria that may cause infections in humans through the consumption of palm juice. Utilizing state-of-the-art third-generation Nanopore metagenomic sequencing technology based on 16S rRNA, and identified bacteria primarily involved in fermenting processes. The swift metagenomic analysis, coupled with the widespread availability and portability of Nanopore products (including real-time analysis options), proves advantageous for detecting harmful pathogens in food sources without relying on extensive industry resources and testing.

Keywords: raw date palm sap, NGS, metabarcoding, food safety

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Authors: Wendu Admasu, Assefa Sintayehu, Alemu Gezahgne, Zewdu Terefework

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Eucalyptus is the most widely planted forest tree species in the world. In Ethiopia, pathogenic fungi pose an increasing threat to Eucalyptus species. Due to limited research, there is insufficient information on the associated diseases and pathogens. This study investigated Eucalyptus diseases, the extent of their damage, and the causal fungal pathogens. A Eucalyptus disease survey was conducted in the Eucalyptus forestry areas of Ethiopia during the growth years 2019/20 and 2020/21. Disease assessment and sampling were carried out in eighteen plantations at nine locations. E. camaldulensis was the most dominant species planted in the surveyed areas. The field study shows a high incidence and severity of canker diseases. Diseased stem and branch samples were collected, cultured on malt extract agar media and studied. The results of morphological and ITS sequence analysis confirmed that the fungal species Neofusicoccum parvum, Lasiodiplodia theobromae, and Aplosporella hesperidica caused the observed canker symptoms. This is the first report of Lasiodiplodia theobromae and Aplosporella hesperidica causing diseases in Eucalyptus plants in Ethiopia. Changes in global climate and environmental factors, such as altitude, are believed to have a strong impact on the susceptibility of Eucalyptus plants to diseases. Strict quarantine practices and continuous monitoring of pathogenic and endophytic fungal species associated with Eucalyptus trees are issued to be prioritized to effectively control and manage the disease.

Keywords: Neofusicoccum, Lasiodiplodia, Aplosporella, pathogenicity, phylogeny, severity

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Authors: Zhazira Shemsheyeva, Zhanara Suleimenova, Olga Shemshura, Gulnaz Mombekova, Zhanar Rakhmetova

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Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR). They not only provide nutrients to the plants (direct plant growth promotion) and protect plants against the phytopathogens (indirect plant growth promotion) but also increase the soil fertility. Indirectly PGPRs improve the plant growth by becoming a biocontrol agent for a fungal pathogen. The antifungal activities of the PGPrhizobacteria were assayed against different species of phytopathogenic fungi such as Fusarium tricinctum, Fusarium oxysporum, Sclerotiniasclerotiorum, and Botrytis cinerea. Pseudomonas putidaSM-1, Azotobacter sp., and Bacillus thuringiensis AKS/16 strains have been used in experimental tests on growth inhibition of phytopathogenic fungi infecting Kidney beans. Agar well diffusion method was used in this study. Diameters of the zones of inhibition were measured in millimeters. It was found that Bacillus thuringiensis AKS/16 strain showed the lowest antifungal activity against all fungal pathogens tested. Zones of inhibition were 15-18 mm. In contrast, Pseudomonas putida SM-1 exhibited good antifungal activity against Fusarium oxysporum and Fusarium tricinctum by producing 29-30 mm clear zones of inhibition. The moderate inhibitory effect was shown by Azotobacter sp. against all fungal pathogens tested with zones of inhibition from24 to 26 mm. In summary, Pseudomonas putida SM-1 strain demonstrated the potential of controlling root rot diseases in kidney beans.

Keywords: PGPR, pseudomonas putida, kindey beans, antifungal activity

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Authors: Ling-Ling E, Lin Feng, Hong-Chen Liu, Dong-Sheng Wang, Zhanping Shi, Juncheng Wang, Wei Luo, Yan Lv

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The objective of this study was to compare the effects of the two calcium phosphate composite scaffolds on the attachment, proliferation and osteogenic differentiation of rabbit dental pulp stem cells (DPSCs). One nano-hydroxyapatite/collagen/poly (L-lactide) (nHAC/PLA), imitating the composition and the micro-structure characteristics of the natural bone, was made by Beijing Allgens Medical Science & Technology Co., Ltd. (China). The other beta-tricalcium phosphate (β-TCP), being fully interoperability globular pore structure, was provided by Shanghai Bio-lu Biomaterials Co, Ltd. (China). We compared the absorption water rate and the protein adsorption rate of two scaffolds and the characterization of DPSCs cultured on the culture plate and both scaffolds under osteogenic differentiation media (ODM) treatment. The constructs were then implanted subcutaneously into the back of severe combined immunodeficient (SCID) mice for 8 and 12 weeks to compare their bone formation capacity. The results showed that the ODM-treated DPSCs expressed osteocalcin (OCN), bone sialoprotein (BSP), type I collagen (COLI) and osteopontin (OPN) by immunofluorescence staining. Positive alkaline phosphatase (ALP) staining, calcium deposition and calcium nodules were also observed on the ODM-treated DPSCs. The nHAC/PLA had significantly higher absorption water rate and protein adsorption rate than ß-TCP. The initial attachment of DPSCs seeded onto nHAC/PLA was significantly higher than that onto ß-TCP; and the proliferation rate of the cells was significantly higher than that of ß-TCP on 1, 3 and 7 days of cell culture. DPSCs+ß-TCP had significantly higher ALP activity, calcium/phosphorus content and mineral formation than DPSCs+nHAC/PLA. When implanted into the back of SCID mice, nHAC/PLA alone had no new bone formation, newly formed mature bone and osteoid were only observed in β-TCP alone, DPSCs+nHAC/PLA and DPSCs+β-TCP, and this three groups displayed increased bone formation over the 12-week period. The percentage of total bone formation area had no difference between DPSCs+β-TCP and DPSCs+nHAC/PLA at each time point，but the percentage of mature bone formation area of DPSCs+β-TCP was significantly higher than that of DPSCs+nHAC/PLA. Our results demonstrated that the DPSCs on nHAC/PLA had a better proliferation and that the DPSCs on β-TCP had a more mineralization in vitro, much more newly formed mature bones in vivo were presented in DPSCs+β-TCP group. These findings have provided a further knowledge that scaffold architecture has a different influence on the attachment, proliferation and differentiation of cells. This study may provide insight into the clinical periodontal bone tissue repair with DPSCs+β-TCP construct.

Keywords: dental pulp stem cells, nano-hydroxyapatite/collagen/poly(L-lactide), beta-tricalcium phosphate, periodontal tissue engineering, bone regeneration

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Authors: Pukhrambam Helena Chanu, Janardan Yadav

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This study investigates the potential of various fungal isolates to solubilize zinc and counteract rice pathogens, with the aim of mitigating zinc deficiency and disease prevalence in rice farming. Soil samples from the rhizosphere were collected, and zinc-solubilizing fungi were isolated and purified. Molecular analysis identified Talaromyces sp, Talaromyces versatilis, Talaromyces pinophilus, and Aspergillus terreus as effective zinc solubilizers. Through qualitative and quantitative assessments, it was observed that solubilization efficiencies varied among the isolates over time, with Talaromyces versatilis displaying the highest capacity for solubilization. This variability in solubilization rates may be attributed to differences in fungal metabolic activity and their ability to produce organic acids that facilitate zinc release from insoluble sources in the soil. In inhibition assays against rice pathogens, the fungal isolates exhibited antagonistic properties, with Talaromyces versatilis demonstrating the most significant inhibition rates. This antagonistic activity may be linked to the production of secondary metabolites, such as antibiotics or lytic enzymes by fungi, which inhibit the growth of rice pathogens. The ability of Talaromyces versatilis to outperform other isolates in both zinc solubilization and pathogen inhibition highlights its potential as a multifunctional biocontrol agent in rice cultivation systems. These findings emphasize the potential of fungi as natural solutions for enhancing zinc uptake and managing diseases in rice cultivation. Utilizing indigenous zinc-solubilizing fungi offers a sustainable and environmentally friendly approach to addressing zinc deficiency in soils, reducing the need for chemical fertilizers. Moreover, harnessing the antagonistic activity of these fungi can contribute to integrated disease management strategies, minimizing reliance on synthetic pesticides and promoting ecological balance in agroecosystems. Additionally, the study included the evaluation of dipping time under different concentrations, viz.,10 ppm, 20 ppm, and 30 ppm of biosynthesized nano ZnO on rice seedlings. This investigation aimed to optimize the application of nano ZnO for efficient zinc uptake by rice plants while minimizing potential risks associated with excessive nanoparticle exposure. Evaluating the effects of varying concentrations and dipping durations provides valuable insights into the safe and effective utilization of nano ZnO as a micronutrient supplement in rice farming practices.

Keywords: biosynthesized nano ZnO, rice, root dipping, zinc solubilizing fungi.

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Authors: Sandy Van Vuuren, Lerato Kose, Annah Moteetee

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Lesotho, a country surrounded by South Africa has one of the highest rates of sexually transmitted infections (STI’s) in the world. In fact, the country ranks third highest with respect to infections related to the human immunodeficiency virus (HIV). Despite the high prevalence of STI’s, treatment has been a challenge due to limited accessibility to health facilities. An estimated 77% of the population lives in rural areas and more than 60% of the country is mountainous. Therefore, many villages remain accessible only by foot or horse-back. Thus, the Basotho (indigenous people from Lesotho) have a rich cultural heritage of plant use. The aim of this study was to determine what plant species are used for the treatment of STI’s and which of these have in vitro efficacy against pathogens such as Candida albicans, Gardnerella vaginalis, Oligella ureolytica, and Neisseria gonorrhoeae. A total of 34 medicinal plants were reported by traditional practitioners for the treatment of STI’s. Sixty extracts, both aqueous and organic (mixture of methanol and dichloromethane), from 24 of the recorded plant species were assessed for antimicrobial activity using the minimum inhibition concentration (MIC) micro-titre plate dilution assay. Neisseria gonorrhoeae (ATCC 19424) was found to be the most susceptible among the test pathogens, with the majority of the extracts (21) displaying noteworthy activity (MIC values ≤ 1 mg/ml). Helichrysum caespititium was found to be the most antimicrobially active species (MIC value of 0.01 mg/ml). The results of this study support, to some extent, the traditional medicinal uses of the evaluated plants for the treatment of STI’s, particularly infections related to gonorrhoea.

Keywords: Africa, Candida albicans, Gardnerella vaginalis, Neisseria gonorrhoeae, Oligella urealytica

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Authors: Gajanan V. Mane, Rashmi More, Mahesh S. Sonawane, Tushar Lodha, Rohit Sharma

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The diversity of fungi isolated from two different termite species viz., Odontoterms assmuthi and O. abesus was investigated by dilution- plate method, combined with morphological characteristics and sequencing of internal transcribed spacer region. In total, ninety-six fungi were isolated and purified, out of which 69 isolates were obtained from O. assmuthi belonging to 18 genera and 31 species, whereas 27 isolates were obtained from O. abesus belonging to 15 genera and 17 species. The fungal strains were screened for laccase, amylase, cellulase and pectinase enzymes production. Twenty-seven strains were positive for laccase, 59 strains were positive for amylase, 71 strains were positive for cellulase and 72 strains were positive for pectinase enzymes. The antimicrobial activities of the isolated fungi were tested by the dual plate culture method against standard pathogens. Bioactive secondary metabolites were identified by HPLC and LCMS. Four isolates viz., Penicillium goetzii MG 57, Epicoccum sp. MG 39, Penicillium tanzanicum MG 30, Aspergillus polyporicola MG 54, showed positive antimicrobial activity against standard pathogens, Streptococcus pneumonia MCC 2425, Staphylococcus aureus MCC 2408, Pseudomonas aeruginosa MCC 2080, Escherichia coli MCC 2412, Enterococcus faecalis MCC 2409, Klebsiella pneumonia MCC 2451, Micrococcus luteus MCC 2155 and Candida albicans MCC 1151. In conclusion, the study showed that the insect gut harbor fungal diversity, which is futuristic with biotechnological potential and could be a good source of enzymes and antibiotics.

Keywords: termites, fungi, its, enzyme, antimicrobial activity

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Authors: I. Schäfer, B. Kohn, M. Volkmann, E. Müller

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Introduction: Blood-feeding arthropods transmit parasitic, bacterial, or viral pathogens to domestic animals and wildlife. Vector-borne infections are gaining significance due to the increase of travel, import of domestic animals from abroad, and the changing climate in Europe. Aims of the study: The main objective of this retrospective study was to assess the prevalence of vector-borne infections in cats in which a ‘Feline Travel Profile’ had been conducted. Material and Methods: This retrospective study included test results from cats for which a ‘Feline Travel Profile’ established by LABOKLIN had been requested by veterinarians between April 2012 and December 2019. This profile contains direct detection methods via polymerase chain reaction (PCR) for Hepatozoon spp. and Dirofilaria spp. as well as indirect detection methods via immunofluorescence antibody test (IFAT) for Ehrlichia spp. and Leishmania spp. This profile was expanded to include an IFAT for Rickettsia spp. from July 2015 onwards. The prevalence of the different vector-borne infectious agents was calculated. Results: A total of 602 cats were tested using the ‘Feline Travel Profile’. Positive test results were as follows: Rickettsia spp. IFAT 54/442 (12.2%), Ehrlichia spp. IFAT 68/602 (11.3%), Leishmania spp. IFAT 21/602 (3.5%), Hepatozoon spp. PCR 51/595 (8.6%), and Dirofilaria spp. PCR 1/595 cats (0.2%). Co-infections with more than one pathogen could be detected in 22/602 cats. Conclusions: 170/602 cats (28.2%) were tested positive for at least one vector-borne pathogen. Infections with multiple pathogens could be detected in 3.7% of the cats. The data emphasizes the importance of considering vector-borne infections as potential differential diagnoses in cats.

Keywords: arthopod-transmitted infections, feline vector-borne infections, Germany, laboratory diagnostics

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Authors: Mudawi M. Nour

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Background: Now a days, the multidisciplinary scientific research conception in the field of nanotechnology has witnessed development with regard to the numerous applications and synthesis of nanomaterials. Objective: The current investigation has been conducted with the main focus on the green synthesis of silver nanoparticles from the leaves of Salvadora persica and its antibacterial activity against MDR pathogens E. coli and S. aureus. Methodology: Silver nanoparticles (AgNPs) were prepared after addition of aqueous extract of Salvadora persica leaves. The UV-Vis spectrophotometer, Transmission Electron Microscopy (TEM), zeta potential and Scanning Electron Microscopy (SEM) were employed to detect the particle size and morphology, besides Fourier transform infra-red spectrometer (FTIR) analysis was performed to determine the capping and stabilizing agents in the extract. Antibacterial assay for the biogenic AgNPs was conducted against E. coli and S. aureus. Results: Color change of the mixture from yellow to dark brown is the first indication to AgNPs formation. Furthermore, 420 nm was the peak value for UV-Vis spectroscopy absorption of the mixture. Besides, TEM and SEM micrographs showed wide variability in the diameter of smaller NPs aggregated together with spherical shapes, and zeta sizer showed about 153.3 nm as an average size of nanoparticles. Microbial suppression was noticed for the tested microorganisms. Furthermore, with the help of FTIR analysis, the biomolecules that act as capping and stabilizing agents of AgNPs are proteins and phenols present in the plant extract. Conclusion: Salvadora persica leaves extract act as a reducing and stabilizing agent for the synthesis of AgNPs, keeping its ability to suppress the MDR pathogen.

Keywords: green synthesis, FTIR, MDR pathogen, salvadora persica

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Authors: Malalage Mudara Peiris

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Objectives of the study are: the biosynthesis of silver nanoparticles (AgNPs) using Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus, characterization of silver nanoparticles and determination of antimicrobial activity against E. coli, P. aeruginosa, S. aureus, MRSA, and C. Albicans. Methods: E. coli (ATCC 25922), A. baumanii (clinical strain), S. aureus (clinical strain) cultured in nutrient broth medium were used for biosynthesis of AgNPs. Culture conditions (AgNO3 concentration, pH, incubation time and temperature) were optimized. Characterization of synthesized NPs was done by UV-Visible spectroscopy. The antimicrobial activity of the synthesized NPs was studied using the good diffusion assay against E. coli, S. aureus, MRSA (Methicillin-resistant Staphylococcus aureus), P. aeruginosa and C. Albicans. Results: All the selected bacteria produced silver nanoparticles at alkaline pH above 0.3 g/L AgNO3 concentration. The optimum reaction temperature was 60oC. According to the UV-Visible spectroscopy, the maximum absorbance was found to be around 420 - 430 nm indicating the presence of AgNPs. According to the good diffusion results, AgNPs produced by S. aureus resulted in the larger zone of inhibition (ZOI) against the selected pathogens, while AgNPs produced by E. coli showed comparatively smaller ZOI. In general, biosynthesized AgNPs were highly effective against gram-negative bacteria compared to gram-positive bacterial and fungal species. Conclusions: Green AgNPs produced by each bacterium show antimicrobial activity against the selected pathogens. AgNPs produced by S. aureus are the most effective NPs among tested AgNPs, while AgNPs produced by E. coli are the least effective. Further characterization of NPs is required to study the physical properties of silver NPs.

Keywords: green nanotechnology, silver nanoparticles, bacteria, antimicrobial activity

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Authors: Boukhatem Mohamed Nadjib, Ferhat Mohamed Amine

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Essential Oils (EO) produced by medicinal plants have been traditionally used for respiratory tract infections and are used nowadays as ethical medicines for colds. The aim of this study was to test the efficacy of the Algerian EGEO against some respiratory tract pathogens by disc diffusion and vapour diffusion methods at different concentrations. The chemical composition of the EGEO was analysed by Gas Chromatography-Mass Spectrometry. Fresh leaves of E. globulus on steam distillation yielded 0.96% (v/w) of essential oil whereas the analysis resulted in the identification of a total of 11 constituents, 1.8 cineole (85.8%), α-pinene (7.2%) and β-myrcene (1.5%) being the main components. By disc diffusion method, EGEO showed potent antimicrobial activity against Gram-positive more than Gram-negative bacteria. The Diameter of Inhibition Zone (DIZ) varied from 69 mm to 75 mm for Staphylococcus aureus and Bacillus subtilis (Gram +) and from 13 to 42 mm for Enterobacter sp and Escherichia coli (Gram-), respectively. However, the results obtained by both agar diffusion and vapour diffusion methods were different. Significantly higher antibacterial activity was observed in the vapour phase at lower concentrations. A. baumanii and Klebsiella pneumoniae were the most susceptible strains to the oil vapour with DIZ varied from 38 to 42 mm. Therefore, smaller doses of EO in the vapour phase can be inhibitory to pathogenic bacteria. Else, the DIZ increased with increase in the concentration of the oil. There is growing evidence that EGEO in the vapour phase are effective antibacterial systems and appears worthy to be considered for practical uses in the treatment or prevention of patients with respiratory tract infections or as air decontaminants in the hospital. The present study indicates that EGEO has considerable antimicrobial activity, deserving further investigation for clinical applications.

Keywords: eucalyptus globulus, essential oils, respiratory tract pathogens, antimicrobial activity, vapour phase

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Authors: Pratibha Goyal, Nupur Mathur, Anuradha Singh

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Antibiotic resistance is the worldwide threat to human health in this century. Excessive use of antibiotic after their discovery in 1940 makes certain bacteria to become resistant against antibiotics. Most common antibiotic-resistant bacteria include Staphylococcus aureus, Salmonella typhi, E.coli, Klebsiella pneumonia, and Streptococcus pneumonia. Among all Staphylococcus resistant strain called Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for several lives threatening infection in human commonly found in the hospital environment. Our study aimed to isolate bacteriophage against MRSA from the hospital sewage treatment plant and to analyze its efficiency In Vivo in Swiss albino mice model. Sewage sample for the isolation of bacteriophages was collected from SDMH hospital sewage treatment plant in Jaipur. Bacteriophages isolated by the use of enrichment technique and after characterization, isolated phages used to determine phage treatment efficiency in mice. Mice model used to check the safety and suitability of phage application in human need which in turn directly support the use of natural bacteriophage rather than synthetic chemical to kill pathogens. Results show the plaque formation in-vitro and recovery of MRSA infected mice during the experiment. Favorable lytic efficiency determination of MRSA and Salmonella presents a natural way to treat lethal infections caused by Multidrug-resistant bacteria by using their natural host-pathogen relationship.

Keywords: antibiotic resistance, bacteriophages, methicillin resistance Staphylococcus aureus, pathogens, phage therapy, Salmonella typhi

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Authors: Saimir Heta, Ilma Robo, Vera Ostreni, Glorja Demika, Sonila Kapaj

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Suturing, as a procedure of joining the lips of the lembo or wound, is important at the beginning of the healing process. This procedure helps to pass the healing process from the procedure per secundam to the stages of healing per primam, thus logically reducing the healing time of the wound. The element that remains in the individual selection of the dentist applying the suture is the selection of the suture material. At a moment when some types of sutures are offered for use, some elements should be considered in the selection of the suture depending on the constituent material, the cross-section of the suture elements, and whether it collects bacteria in the "pits" created by the material. The presence of bacteria is a source of infection and possible delay in the healing of the sutured wound. Conclusion: The marketing of suture types offers a variety of materials, from which the selection of the most suitable suture type for specific application cases is a personal indication of the dental surgeon, based on professional experiences and knowledge in the field.

Keywords: suture, suture material, types of sutures, clinical application

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Authors: Syeda Fahria Hoque Mimmi

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Many new and promising treatments for reducing or diminishing the adverse effects of microorganisms are being discovered day by day. On the other hand, the dairy industry is accelerating the economic wheel of Bangladesh. Considering all these facts, new thoughts were developed to isolate milk proteins by the present experiment for opening up a new era of developing natural antibiotics from milk. Lactoferrin, an iron-binding glycoprotein with multifunctional properties, is crucial to strengthening the immune system and also useful for commercial applications. The protein’s iron-binding capacity makes it undoubtedly advantageous to immune system modulation and different bacterial strains. For fulfilling the purpose, 4 of raw and 17 of commercially available milk samples were collected from different farms and stores in Bangladesh (Dhaka, Chittagong, and Cox’s Bazar). Protein quantification by nanodrop technology has confirmed that raw milk samples have better quantities of protein than the commercial ones. All the samples were tested for their antimicrobial activity against 18 pathogens, where raw milk samples showed a higher percentage of antibacterial activity. In addition to this, SDS-PAGE (Sodium Dodecyl Sulfate–Polyacrylamide Gel Electrophoresis) was performed to identify lactoferrin in the milk samples. Lactoferrin was detected in 9 samples from which 4 were raw milk samples. Interestingly, Streptococcus pyogenes, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, Vibrio cholera, Staphylococcus aureus, and enterotoxigenic E. coli significantly displayed sensitivity against lactoferrin collected from raw milk. Only Bacillus cereus, Pseudomonas aeruginosa, Streptococcus pneumonia, Enterococcus faecalis, and ETEC (Enterotoxigenic Escherichia coli) were susceptible to lactoferrin obtained from a commercial one. This study suggested that lactoferrin might be used as the potential alternative of antibiotics for many diseases and also can be used to reduce microbial deterioration in the food and feed industry.

Keywords: alternative of antibiotics, commercially available milk, lactoferrin, nanodrop technology, pathogens, raw milk

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Authors: Kin On Kwok, Vivian Wei, Benjamin Cowling, Steven Riley, Jonathan Read

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Background: The role of social contact behavior measured in different contact constructs in the transmission of respiratory pathogens with acute respiratory illness (ARI) remains unclear. We, therefore, aim to depict the individual pattern of ARI in the community and investigate the association between different contact dimensions and ARI in Hong Kong. Methods: Between June 2013 and September 2013, 620 subjects participated in the last two waves of recruitment of the population based longitudinal phone social contact survey. Some of the subjects in this study are from the same household. They are also provided with the symptom diaries to self-report any acute respiratory illness related symptoms between the two days of phone recruitment. Data from 491 individuals who were not infected on the day of phone recruitment and returned the symptom diaries after the last phone recruitment were used for analysis. Results: After adjusting different follow-up periods among individuals, the overall incidence rate of ARI was 1.77 per 100 person-weeks. Over 75% ARI episodes involve running nose, cough, sore throat, which are followed by headache (55%), malagia (35%) and fever (18%). Using a generalized estimating equation framework accounting for the cluster effect of subjects living in the same household, we showed that both daily number of locations visited with contacts and the number of contacts, explained the ARI incidence rate better than only one single contact construct. Conclusion: Our result suggests that it is the intertwining property of contact quantity (number of contacts) and contact intensity (ratio of subject-to-contact) that governs the infection risk by a collective set of respiratory pathogens. Our results provide empirical evidence that multiple contact constructs should be incorporated in the mathematical transmission models to feature a more realistic dynamics of respiratory disease.

Keywords: acute respiratory illness, longitudinal study, social contact, symptom diaries

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Authors: Esraa Elaraby, Dania Abu Zahra, Ghidaa Maswadah, Osama Amira, Mohamed Alshoura, Nihar Dash

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Background: Human being uses salon for a variety of purposes, from trimming of hair and shaving to a range of beauty treatments such as manicure and pedicure. Salon activities involve use of several instruments including scissors, scalpels and razors, materials such as soaps, solutions, creams and gels on human skin and body. Besides, salon customers also use chair, bed and many other common shared utensils and appliances. These salons related activities create a suitable environment for the transmission of several diseases and pathogens including hepatitis B and C, scabies, tuberculosis, staphylococcus and MRSA etc. The transmission of these pathogens can be prevented by maintenance of adequate hygiene and standard preventive measures. Aim: To assess the customer’s level of knowledge about salon-acquired infections and practices taken to prevent their transmission. Methods: A cross-sectional study was conducted among 500 participants across the Emirates. Moreover, self-administered questionnaires (in English and Arabic) were distributed through convenience sampling methods between February and April 2017. Results: The study included 500 participants of which 250 were females. The mean age of the study population was 33 years (SD=4.77). The participants were from several nationalities including 325 Arabs (Non-GCC) (66.2%), 108 Non-Arabs (22%), and 59 Arabs (GCC) (11.8%). The majority of the participants 421 (84.4%) had required knowledge about salon-associated infections with a mean knowledge score of 6/10 (60%). However, when it comes down to preventive practices, only 73 of the 500 participants (14.6%) did carry their own equipment. Thus, there was insufficient correlation between the level of knowledge and preventive practices (p=0.139) of salon-associated infections. Conclusion: People’s knowledge about the salon-associated infections among UAE residents was good, but only a small number practically took the required preventative measures towards this issue. Therefore, a public awareness program is recommended to enhance the deficiencies in knowledge and practices to prevent salon-acquired infections among the users. Up to our knowledge, this is the first study of this kind in the UAE targeting the salon customers about this important issue.

Keywords: awareness, knowledge, practices, salon-associated infections

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Authors: J. Lamilla-Monje, C. Solano-Puerto, L. Franco-Lara

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Trees play an essential role in cities due to their ability to provide multiple ecosystem goods and services. Bogota trees are threatened by factors such as pests, pathogens, contamination, among others. Among the pathogens, phytoplasmas are a potential risk for urban trees, generating symptoms that affect the ecosystem services that these trees provide in Bogota, an example of this is the affectation of Q. humboldtii by phytoplasmas, these bacteria are transmitted for insects of the order Hemiptera, this is why the objective of this work was to know if the climatic variables (humidity, precipitation, and temperature) and environmental variables (PM10 and PM2.5) could be related to the distribution of the Oak Quercus entomofauna and specifically with the phytoplasma vector insects in Bogota. For this study, the sampling points were distributed in areas of the city with contrasting variables in two types of locations: parks and streets. A total of 68 trees were sampled in which the associated insects were collected using two methodologies: jameo and agitation traps. The results show that insects of the order Hemiptera were the most abundant, including a total of 1682 individuals represented by 29 morphotypes, within this order individuals from eight families were collected (Aphidae, Aradidae, Berytidae, Cicadellidae, Issidae, Membracidae, Miridae, and Psyllidae), finding as possible vectors the families Cicadellidae, Membracidae, and Psyllidae with 959, 8 and 14 individuals respectively. Within the Cicadellidae family, 21 morphotypes were found, being reported as vectors in the literature: Amplicephalus, Exitianus atratus, Haldorus sp., Xestocephalus desertorum, Idiocerinae sp., Scaphytopius sp., the Membracidae family was represented by two morphotypes and the Psyllidae by one. Results that suggest that there is no correlation between climatic and environmental variables with the diversity of insects associated with oak. Knowing the vector insects of phytoplasmas in oak trees will complete the pathosystem and generate effective vector control.

Keywords: vector insects, diversity, phytoplasmas, Cicadellidae

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Authors: F. Lops, G. Disciglio, A. Carlucci, G. Gatta, L. Frabboni, A. Tarantino, E. Tarantino

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Phelipanche ramosa L. Pomel is a root holoparasitic weed plant of many cultivations, particularly of tomato (Lycopersicum esculentum L.) crop. In Italy, Phelipanche problem is increasing, both in density and in acreage. The biological control of this parasitic weed involves the use of living organisms as numerous fungi and bacteria that can infect the parasitic weed, while it may improve the crop growth. This paper deals with the biocontrol with microorganism, including Arbuscular mycorrhizal (AM) fungi and fungal pathogens as Fusarium oxisporum spp. Colonization of crop roots by AM fungi can provide protection of crops against parasitic weeds because of a reduction in their seed germination and attachment, while F. oxisporum, isolated from diseased broomrape tubercles, proved to be highly virulent on P. ramosa. The experimental trial was carried out in open field at Foggia province (Apulia Region, Southern Italy), during the spring-summer season 2016, in order to evaluate the effect of four biological treatments: AM fungi and Fusarium oxisporum applied in the soil alone or combined together, and Rizosum Max^® product, compared with the untreated control, to reduce the P. ramosa infestation in processing tomato crop. The principal results to be drawn from this study under field condition, in contrast of those reported previously under laboratory and greenhouse conditions, show that both AM fungi and F. oxisporum do not provide the reduction of the number of emerged shoots of P. ramosa. This can arise probably from the low efficacy seedling of the agent pathogens for the control of this parasite in the field. On the contrary, the Rizosum Max^® product, containing AM fungi and some rizophere bacteria combined with several minerals and organic substances, appears to be most effective for the reduction of P. ramosa infestation.

Keywords: Arbuscular mycorrhized fungi, biocontrol methods, Phelipanche ramosa, tomato crop

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Authors: Michelle Maurer, Antonia Last, Mark S. Gresnigt, Bernhard Hube, Alexander S. Mosig

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The intestinal epithelium forms an essential barrier to prevent translocation of microorganisms, toxins or other potentially harmful molecules into the bloodstream. In particular, dendritic cells of the intestinal epithelium orchestrate an adapted response of immune tolerance to commensals and immune defense against invading pathogens. Systemic inflammation is typically associated with a dysregulation of this adapted immune response and is accompanied by a disruption of the epithelial and endothelial gut barrier which enables dissemination of pathogens within the human body. To understand the pathophysiological mechanisms underlying the inflammation-associated gut barrier breakdown, it is crucial to elucidate the complex interplay of the host and the intestinal microbiome. A microfluidically perfused three-dimensional intestine-on-chip model was established to emulate these processes in the presence of immune cells, commensal bacteria, and facultative pathogens. Multi-organ tissue flow (MOTiF) biochips made from polystyrene were used for microfluidic perfusion of the intestinal tissue model. The biochips are composed of two chambers separated by a microporous membrane. Each chamber is connected to inlet and outlet channels allowing independent perfusion of the individual channels and application of microfluidic shear stress. Human umbilical vein endothelial cells (HUVECs), monocyte-derived macrophages and intestinal epithelial cells (Caco-2) were assembled on the biochip membrane. Following 7 – 14 days of growth in the presence of physiological flow conditions, the epithelium was colonized with the commensal bacterium Lactobacillus rhamnosus, while the endothelium was perfused with peripheral blood mononuclear cells (PBMCs). Additionally, L. rhamnosus was co-cultivated with the opportunistic fungal pathogen Candida albicans. Within one week of perfusion, the epithelial cells formed self-organized and well-polarized villus- and crypt-like structures that resemble essential morphological characteristics of the human intestine. Dendritic cells were differentiated in the epithelial tissue that specifically responds to bacterial lipopolysaccharide (LPS) challenge. LPS is well-tolerated at the luminal epithelial side of the intestinal model without signs of tissue damage or induction of an inflammatory response, even in the presence of circulating PBMC at the endothelial lining. In contrast, LPS stimulation at the endothelial side of the intestinal model triggered the release of pro-inflammatory cytokines such as TNF, IL-1β, IL-6, and IL-8 via activation of macrophages residing in the endothelium. Perfusion of the endothelium with PBMCs led to an enhanced cytokine release. L. rhamnosus colonization of the model was tolerated in the immune competent tissue model and was demonstrated to reduce damage induced by C. albicans infection. A microfluidic intestine-on-chip model was developed to mimic a systemic infection with a dysregulated immune response under physiological conditions. The model facilitates the colonization of commensal bacteria and co-cultivation with facultative pathogenic microorganisms. Both, commensal bacteria alone and facultative pathogens controlled by commensals, are tolerated by the host and contribute to cell signaling. The human intestine-on-chip model represents a promising tool to mimic microphysiological conditions of the human intestine and paves the way for more detailed in vitro studies of host-microbiota interactions under physiologically relevant conditions.

Keywords: host-microbiota interaction, immune tolerance, microfluidics, organ-on-chip

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Authors: Ann Ying-An Chen, Yi-Lun Tsai, Hso-Chi Chaung

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An understanding of pathogens and the immune system has played an utmost important role in agricultural research for the development of vaccinations. The immunological synapse, cell to cell interaction play a crucial role in triggering the body's immune system, such as activation between antigen-presenting cells (APCs) and different subsets of T-cell. If these interactions are regulated appropriately, the host has the ability to defend itself against a wide spectrum of infectious pathogens. The aim of this study is to establish and to characterize a porcine immune synapse system by co-culturing T cell/APC. In this study, blood samples were collected from specific-pathogen-free piglets, and peripheral blood mononuclear cells (PBMC) were separated by using Ficoll-Pague. The PBMC were then stained with CD4 (FITC) and CD25 (PE) antibodies. Different subsets of T cells sorted by fluorescence-activated cell sorting flow cytometer were co-cultured for 24 hrs with alveolar macrophages, and the profiles of cytokine secretion and mRNA transcription levels of Toll-like receptors were examined after. Results showed that the three stages of immune synapse were clearly visible and identified under both transmission and scanning electron microscope (TEM and SEM). The significant interaction differences in toll-like receptor expressions within the co-cultured cell system were observed. The TLR7 mRNA expressions in CD4+CD25- cells were lower than those in CD4+CD25+ and CD4 -CD25+. Interestingly, the IL-10 production levels in CD4+CD25- cells (7.732 pg/mL) were significantly higher than those of CD4+CD25+ (2.636 pg/mL) and CD4 -CD25+ (2.48 pg/mL). These findings demonstrated that a clear understanding of the porcine immune synapse system can contribute greatly for further investigations on the mechanism of T-cell activation, which can benefit in the discovery of potential adjuvant candidate or effective antigen epitopes in the development of vaccinations with high efficacy.

Keywords: antigen-presenting cells, immune synapse, pig, T subsets, toll-like receptor

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Authors: Saima Sharif Nilla, Mahmudur Rahman Khan, Anisur Rahman Khan, Ghulam Mustafa1

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The microbial quality of Indian white shrimp (Peneaus indicus) from Bagerhat, Khulna and Satkhira of southwest Bangladesh was assessed where the parameters varied with different sources and the quality was found to be poor for Satkhira shrimp samples. Shrimp samples in fresh condition were collected to perform the microbial assessment and 10 pathogenic isolates for antibiotic sensitivity test to 12 antibiotics. The results show that total bacterial count of all the samples were beyond the acceptable limit 105 cfu/g. In case of total coliform and E. coli density, no substantial difference (p<0.5) was found between the different shrimp samples from different districts and also high quantity of TC exceeding the limit (>102 cfu/g) proves the poor quality of shrimp. The FC abundance found in shrimps of Bagerhat and Satkhira was similar and significantly higher (p<0.5) than that of Khulna samples. No significant difference (p<0.5) was found among the high density of Salmonella-Shigella, Vibrio spp., and Staphylococcus spp. of the shrimp samples from the source places. In case of antibiotic sensitivity patterns, all of them were resistant to ampicillin, Penicillin and sensitive to kanamycin. Most of the isolates were frequently sensitive to ciprofloxacin and streptomycin in the sensitivity test. In case of nutritional composition, no significant difference (t-test, p<0.05) was found among protein, lipid, moisture and ash contents of shrimp samples. The findings prove that shrimp under this study was more or less contaminated and samples from Satkhira were highly privileged with food borne pathogens which confirmed the unhygienic condition of the shrimp farms as well as the presence of antibiotic resistance bacteria in shrimp fish supposed to threat food safety and deteriorate the export quality.

Keywords: food borne pathogens, satkhira, penaeus indicus, antibiotic sensitivity, southwest Bangladesh, food safety

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Authors: Kiran Nawaz, Waheed Anwar, Sehrish Iftikhar, Muhammad Nasir Subhani, Ahmad Ali Shahid

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Plant growth promoting rhizobacteria (PGPR) have been extensively studied and applied for the biocontrol of many soilborne diseases. These rhizobacteria are very efficient against root rot and many other foliar diseases associated with solanaceous plants. These bacteria may inhibit the growth of various pathogens through direct inhibition of target pathogens or indirectly by the initiation of systemic resistance (ISR) which is active all over the complete plant. In the present study, 20 different rhizobacterial isolates were recovered from the root zone of healthy chili plants. All soil samples were collected from various chili-growing areas in Punjab. All isolated rhizobacteria species were evaluated in vitro and in vivo against Phytophthora capsici. Different species of Bacillus and Pseudomonas were tested for the antifungal activity against P. capsici the causal organism of Root rot disease in different crops together with chili. Dual culture and distance culture bioassay were carried out to study the antifungal potential of volatile and diffusible metabolites secreted from rhizobacteria. After seven days of incubation at 22°C, growth inhibition rate was recorded. Growth inhibition rate depended greatly on the tested bacteria and screening methods used. For diffusible metabolites, inhibition rate was 35-62% and 20-45% for volatile metabolites. The screening assay for plant growth promoting and disease inhibition potential of chili associated PGPR indicated 42-100% reduction in disease severity and considerable enhancement in roots fresh weight by 55-87%, aerial parts fresh weight by 35-65% and plant height by 65-76% as compared to untreated control and pathogen-inoculated plants. Pseudomonas flourescene, B. thuringiensis, and B. subtilis were found to be the most efficient isolates in inhibiting P. capsici radial growth, increase plant growth and suppress disease severity.

Keywords: rhizobacteria, chili, phytophthora, root rot

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Authors: Kayla Murray, Andrew Green, Gopi Paliyath, Keith Warriner

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Introduction: It is now acknowledged that control of human pathogens associated with fresh produce requires an integrated approach of several interventions as opposed to relying on post-harvest washes to remove field acquired contamination. To this end, current research is directed towards identifying such interventions that can be applied at different points in leafy green processing. Purpose: In the following the efficacy of different gas phase treatments to decontaminate whole lettuce heads during pre-processing storage were evaluated. Methods: Whole Cos lettuce heads were spot inoculated with L. monocytogenes, E. coli O157:H7 or Salmonella spp. The inoculated lettuce heads were then placed in a treatment chamber and exposed to ozone, chlorine dioxide or hydroxyl radicals at different time periods under a range of relative humidity. Survivors of the treatments were enumerated along with sensory analysis performed on the treated lettuce. Results: Ozone gas reduced L. monocytogenes by 2-log10 after ten-minutes of exposure with Salmonella and E. coli O157:H7 being decreased by 0.66 and 0.56-log cfu respectively. Chlorine dioxide gas treatment reduced L. monocytogenes and Salmonella on lettuce heads by 4 log cfu but only supported a 0.8 log cfu reduction in E. coli O157:H7 numbers. In comparison, hydroxyl radicals supported a 2.9 – 4.8 log cfu reduction of model human pathogens inoculated onto lettuce heads but required extended exposure times and relative humidity < 0.8. Significance: From the gas phase sanitizers tested, chlorine dioxide and hydroxyl radicals are the most effective. The latter process holds most promise based on the ease of delivery, worker safety and preservation of lettuce sensory characteristics. Although expose times for hydroxyl radicles was relatively long (24h) this should not be considered a limitation given the intervention is applied in store rooms or in transport containers during transit.

Keywords: gas phase sanitizers, iceberg lettuce heads, leafy green processing

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Authors: Julie Connelly, Tanvi Toprani, Xin Xie, Dhinoth Kumar Bangarusamy, Kris C. Gunsalus

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The overuse of antibiotics worldwide has contributed to the development of multi-drug resistant (MDR) pathogenic bacterial strains. There is an increasing urgency to discover antibiotics to combat MDR pathogens. The microbiome of the Arabian Gulf is a largely unexplored and potentially rich source of novel bioactive compounds. Microbes that inhabit the Abu Dhabi coastal regions adapt to extreme environments with high salinity, hot temperatures, large temperature fluctuations, and acute exposure to solar energy. The microbes native to this region may produce unique metabolites with therapeutic potential as antibiotics and antifungals. We have isolated 200 pure bacterial strains from mangrove sediments, cyanobacterial mats, and coral reefs of the Abu Dhabi region. In this project, we aim to screen the marine bacterial strains to identify antibiotics, in particular undocumented compounds that show activity against existing antibiotic-resistant strains. We have acquired the ESKAPE pathogen panel, which consists of six antibiotic-resistant gram-positive and gram-negative bacterial pathogens that collectively cause most clinical infections. Our initial efforts of the primary screen using colony-picking co-culture assay have identified several candidate marine strains producing potential antibiotic compounds. We will next apply different assays, including disk-diffusion and broth turbidity growth assay, to confirm the results. This will be followed by bioactivity-guided purification and characterization of target compounds from the scaled-up volume of candidate strains, including SPE fraction, HPLC fraction, LC-MS, and NMR. For antimicrobial compounds with unknown structures, our final goal is to investigate their mode of action by identifying the molecular target.

Keywords: marine bacteria, natural products, drug discovery, ESKAPE panel

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Authors: Jong H. Kim, Kathleen L. Chan, Luisa W. Cheng

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Control of fungal pathogens, such as foodborne mycotoxin producers, is problematic as effective antimycotic agents are often very limited. Mycotoxin contamination significantly interferes with the safe production of foods or crops worldwide. Moreover, expansion of fungal resistance to commercial drugs or fungicides is a global human health concern. Therefore, there is a persistent need to enhance the efficacy of commercial antimycotic agents or to develop new intervention strategies. Disruption of the cellular antioxidant system should be an effective method for pathogen control. Such disruption can be achieved with safe, redox-active compounds. Natural phenolic derivatives are potent redox cyclers that inhibit fungal growth through destabilization of the cellular antioxidant system. The goal of this study is to identify novel, redox-active compounds that disrupt the fungal antioxidant system. The identified compounds could also function as sensitizing agents to conventional antimycotics (i.e., chemosensitization) to improve antifungal efficacy. Various benzo derivatives were tested against fungal pathogens. Gene deletion mutants of the yeast Saccharomyces cerevisiae were used as model systems for identifying molecular targets of benzo analogs. The efficacy of identified compounds as potent antifungal agents or as chemosensitizing agents to commercial drugs or fungicides was examined with methods outlined by the Clinical Laboratory Standards Institute or the European Committee on Antimicrobial Susceptibility Testing. Selected benzo derivatives possessed potent antifungal or antimycotoxigenic activity. Molecular analyses by using S. cerevisiae mutants indicated antifungal activity of benzo derivatives was through disruption of cellular antioxidant or cell wall integrity system. Certain benzo analogs screened overcame tolerance of Aspergillus signaling mutants, namely mitogen-activated protein kinase mutants, to fludioxonil fungicide. Synergistic antifungal chemosensitization greatly lowered minimum inhibitory or fungicidal concentrations of test compounds, including inhibitors of mitochondrial respiration. Of note, salicylaldehyde is a potent antimycotic volatile that has some practical application as a fumigant. Altogether, benzo derivatives targeting cellular antioxidant system of fungi (along with cell wall integrity system) effectively suppress fungal growth. Candidate compounds possess the antifungal, antimycotoxigenic or chemosensitizing capacity to augment the efficacy of commercial antifungals. Therefore, chemogenetic approaches can lead to the development of novel antifungal intervention strategies, which enhance the efficacy of established microbe intervention practices and overcome drug/fungicide resistance. Chemosensitization further reduces costs and alleviates negative side effects associated with current antifungal treatments.

Keywords: antifungals, antioxidant system, benzo derivatives, chemosensitization

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