New Approach for Serological Testing for Leptospirosis by Using Detection of
            <i>Leptospira</i>
            Agglutination by Flow Cytometry Light Scatter Analysis

Yitzhaki, Shmuel; Barnea, Ada; Keysary, Avi; Zahavy, Eran

doi:10.1128/jcm.42.4.1680-1685.2004

Cited by 23 publications

(17 citation statements)

References 28 publications

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“…Immunofl uorescence detection of bacteria by FCM have been described in the past (Zahavy et al 2003 ;Yitzhaki et al 2004 ;Nebe-von-Caron et al 2000 ;Shapiro 2000 ;Stopa 2000 ;Falcioni et al 2006 ;McHugh and Tucker 2007 ) . Recently other works (Bartek et al 2008 ;Venkatapathi et al 2008 ) have shown the identifi cation of bacteria by light scatter parameters solely.…”

Section: Introductionmentioning

confidence: 99%

Application of Nanoparticles for the Detection and Sorting of Pathogenic Bacteria by Flow-Cytometry

Zahavy

Ber

Gur

et al. 2011

Nano-Biotechnology for Biomedical and Diagnostic Research

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In this paper we will describe a new developed contribution of fluorescence nano-crystal (q-dots) as a fluorescence label for detecting pathogenic bacteria by flow cytometry (FCM) and the use of nano-magnetic particles to improve bacterial sorting by Flow cytometry cell sorting (FACS).FCM or FACS systems are based upon single cell detection by light scatter and Immunofluorescence labeling signals. The common FACS systems are based upon single or dual excitation as excitation source both for light scatter parameters and for several fluorescence detectors. Hence, for multi-labeling detection, there is a need for fluorophores with broad excitation wave length and sharp emission bands. Moreover, such fluorophores should be with high fluorescence efficiency, stable, and available for bio-molecules conjugation. Q-dots benefit from practical features which meet those -criteria. We will describe the use of q-dots as fluorescence labels for specific conjugates against Bacillus anthracis spores and Yersinia pestis bacteria, which enable the specific detection of the different species. A specific and sensitive multiplex analysis procedure for both pathogens was achieved, with high sensitivity down to 10(3) bacteria per ml in the sample.Sorting bacteria by FACS has a tremendous advantage for sensitive and selective analysis and sorting of sub-populations. However it has always been a difficult task due to the fact that bacteria are small particles (usually 1-3 μm). For such small particles, light scatter signal is on the threshold level, and many positive events may be lost. Here we will present the development of a procedure for sorting of the gram negative bacteria Y. pestis from environment samples. We will show that the application of nano-magnetic particles, as a tool for the immunomagnetic labeling and separation of the bacteria, enables fast sorting in high and low bacterial concentration down to 10 (5) cfu/ml. The nano-metric physical size of the immunospecific labeling particles disguises them from the FACS detectors; hence the bacterial population becomes the major population as opposed to being "rare events population" when using standard micro-magnetic beads for pre-enrichment.The procedure of separation and collection of bacteria enables sensitive detection and characterization methods of bacteria from complex samples.

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Section: Introductionmentioning

confidence: 99%

Application of Nanoparticles for the Detection and Sorting of Pathogenic Bacteria by Flow-Cytometry

Zahavy

Ber

Gur

et al. 2011

Nano-Biotechnology for Biomedical and Diagnostic Research

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“…Agglutination was quantified by calculating the proportion of the bacterial population with altered FSC and SSC and values were expressed as % of agglutination, as previously described 35 . All samples were analysed in duplicate and 30,000 events were acquired using FacsDiva Software 6.1 (BD Biosciences, San Jose, CA, USA).…”

Section: Agglutination Assay By Flow Cytometrymentioning

confidence: 99%

Experimental Human Challenge Reveals Distinct Mechanisms of Acquisition or Protection Against Pneumococcal Colonization

Nikolaou

Jochems

Mitsi

et al. 2018

Preprint

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Colonization of the upper respiratory tract with Streptococcus pneumoniae is the precursor of pneumococcal pneumonia and invasive disease. Following exposure, however, it is unclear which human immune mechanisms determine whether a pathogen will colonize. We used a human challenge model to investigate host-pathogen interactions in the first hours and days following intranasal exposure to Streptococcus pneumoniae. Using a novel home sampling method, we measured early immune responses and bacterial density dynamics in the nose and saliva after pneumococcal exposure. We found that nasal colonization can take up to 24 hours to become established. Also, two distinct bacterial clearance profiles were associated with protection: nasal clearers with immediate clearance of bacteria in the nose by the activity of pre-existent mucosal neutrophils and saliva clearers with detectable pneumococcus in saliva at one-hour post challenge and delayed clearance mediated by an inflammatory response and increased neutrophil activity 24 hours post bacterial encounter.The human respiratory tract is a major site of contact with aerosolised bacteria. Acute respiratory tract infections are common, and pneumonia causes more than 1.3 million child deaths annually 1,2 ; as well as frequent hospitalisations in at-risk groups such as the elderly, people with chronic lung disease and asthmatics 3 .The first stage of such infections is the successful colonization of the upper respiratory tract by the pathogen 4 . Streptococcus pneumoniae (Spn), the major bacterial cause of pneumonia, inhabits the nasopharynx of 40-95% of infants and 10-25% of adults without causing disease 5 .Colonization is usually asymptomatic in adults but can be associated with mild rhinitis symptoms in children 6 . Different serotypes of pneumococcus may inhabit the nasopharynx at varying densities 7,8 , which is especially common in children 9 . Colonization may continue for a period of weeks or months and be eliminated and reacquired many times during lifetime 10 .As pneumococcal colonization is the primary reservoir for transmission 11 and a prerequisite of invasive disease 12 , its control is key to preventing disease. Importantly, the determinants of whether exposure to a bacterium leads to colonization have not been identified.Epidemiological studies and pre-clinical studies with animal models point to factors such as host age, immune status, virus co-infection, exposure to antibiotics, smoking and overcrowded living conditions 13,14,15 . However, evidence from in vivo human studies is lacking.Our well-established Experimental Human Pneumococcal Challenge (EHPC) model allows for the rapid, safe and accurate study of bacterial encounter at the nasopharynx in humans 16 .The precise dose and timing of infection are known. Individuals are inoculated with live type 6B pneumococcus and pneumococcal colonization (detection and density), is assessed by nasal washes collected from 48 hours onwards post-exposure. After this point, approximately

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“…Of these subjects, 5ml blood sample was taken to carry out the MAT serologic test. According to the standard guidelines, the titre ≥1: 200 was considered positive (Yitzhaki et al, 2004). In this study, MAT panel of 23 serovars was used.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Clinical Symptoms Related to Common Serogroups of Leptospirosis in North of Iran

Javanian¹,

Zavareh²,

Vahedi³

et al. 2017

JMBR

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Leptospirosis is a common disease between humans and animals. Identifying common serogroups and comparing different clinical symptoms among them can help in finding the clinical pattern associated with pathogen serogroupes of leptospirosis. Therefore, the purpose of this study has been to investigate the common serotypes of the infection and their clinical symptoms in northern Iran. This cross-sectional study was carried out in educational hospitals of Babol University of Medical Sciences during the years 2011-2014. Subjects with clinical findings consistent with leptospirosis were included in the study. According to the standard MAT guidelines, the titre ≥1: 200 was considered positive. Then, the patients identified by serogroup separation, were examined and compared clinical symptoms. Among 6o patients with primary diagnosis of leptospirosis in this study, 35 of them proved to be infected to the disease. The most common serogroups were serjoe (40%) and icterohemorrhagia (31.4%). Autumnalis (22.8%), grippotyphosa (11.4%), canicola (8.6%), and pomona (2.8%) were included the subsequent serogroups. The highest frequency of fever (28%) and gastrointestinal manifestations (36%) were observed in icterohemorrhagia and the highest icterus (30%) was found in serjoe serogroup. In this study, serjoe serogroup with fever and icterus, and then icterohemorrhagia with fever and gastrointestinal symptoms were introduced as the most common serogroups of Leptospirosis. Also the rarest serogroups were canicola and pomona.

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New Approach for Serological Testing for Leptospirosis by Using Detection of Leptospira Agglutination by Flow Cytometry Light Scatter Analysis

Cited by 23 publications

References 28 publications

Application of Nanoparticles for the Detection and Sorting of Pathogenic Bacteria by Flow-Cytometry

Application of Nanoparticles for the Detection and Sorting of Pathogenic Bacteria by Flow-Cytometry

Experimental Human Challenge Reveals Distinct Mechanisms of Acquisition or Protection Against Pneumococcal Colonization

Evaluation of Clinical Symptoms Related to Common Serogroups of Leptospirosis in North of Iran

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