Personne :
Duchaine, Caroline

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Université Laval. Faculté de médecine
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Voici les éléments 1 - 10 sur 74
  • Publication
    Saccharopolyspora rectivirgula from Quebec dairybarns: application of simplified criteria for the identification of an agent responsible for farmer’s lung disease
    (Longman, 1999-02-01) Duchaine, Caroline; Mériaux, Anne; Brochu, Gilles; Bernard, Kathryn; Cormier, Yvon
    Saccharopolyspora rectivirgula (Micropolyspora faeni) is one of the major agents responsible for farmer's lung disease, a form of hypersensitivity pneumonitis. It is frequently isolated from the air of contaminated barns. The identification of this actinomycete is difficult because most of its phenotypic characteristics are variable and classical tests are not easy to perform on actinomycetes. Fatty acid analysis is very useful for the identification of these strains, but is not available except in some research or reference laboratories. Morphological (microscopic and macroscopic observations), physiological and biochemical tests (growth properties; macromolecules degraded; citrate utilisation and acid production from carbohydrates; resistance to antibiotics, lysozyme and heat), cell wall and fatty acid analyses and IgG analyses with serum from patients with farmer's lung were performed on 12 environmental isolates presumed to be S. rectivirgula and two control strains of S. rectivirgula. From this, a simple and rapid scheme for the identification of this actinomycete is proposed: optimal growth temperature (55°C); colony appearance based on morphology (filamentous) and colour (beige to orange-brown); microscopic morphology (chains of spores on both aerial and substrate mycelium); growth on NaCl 10%; cell-wall analysis (type IV); and the verification of antibody response with serum from a patient with farmer's lung. This last criterion is important to confirm the immunogenicity of the strains identified as S. rectivirgula. This scheme provides an accurate and efficient way of identifying S. rectivirgula strains and evaluating exposure to this bacterium. The study shows the limited value and the lack of reproducibility of some classical biochemical tests.
  • Publication
    A simple and rapid fluorescent neuraminidase enzymatic assay on a microfluidic chip
    (Elsevier Science, 2012-09-15) Zhang, Fang; Duchaine, Caroline; Toulouse, Marie-Josée; Turgeon, Nathalie; Li, Dongqing
    Neuraminidase enzymatic assay is an inexpensive, reliable, and quick method of detecting viruses. However, the assay in conventional laboratories requires a large amount of samples and reagents and multiple steps, which makes the conventional assay labor intensive and time consuming. This article reports a novel and simple method for conducting the neuraminidase enzymatic assay on a microfluidic chip. By using 4-methylumbelliferyl-N-acetyl-a-d-neuraminic acid as the fluorescent substrate and applying an electric field, the newly developed assay is simple, fast, and automatic. Fluorescence of the enzymatic reaction product was recorded as the assay result, and the fluorescence intensity quantitatively indicates the concentration of the sample, which proves that the novel assay on a microfluidic chip has a potential to be developed into a portable device for on-site detection of environmental samples.
  • Publication
    Assessment of bacterial endospore viability with fluorescent dyes
    (Blackwell Science, 2004-02-23) Duchaine, Caroline; Lavigne, S.; Ho, Jim; Laflamme, Christian.
    Aim: To validate three fluorescence viability assays designed primarily for vegetative cells on pure Bacillus endospores. Methods and Results: Purified fresh and gamma-irradiated Bacillus endospores (Bacillus cereus, B. coagulans and two strains of B. subtilis) were used. The viability assays were: 5-cyano-2,3-diotolyl tetrazolium chloride (CTC) to test respiratory activity and early germination, DiBAC4(3) and Live/Dead BacLight to measure membrane energization and permeabilization, respectively. Gamma irradiation treatment completely eliminated spore culturability and was used as negative control. The untreated spores showed respiratory activity after 1 h of incubation and this was characteristic of almost 100% of spores after 24 h. The membrane potential assessment gave no answer about spore viability. A lower proportion of untreated spores had permeabilized membrane compared with gamma-irradiated spores using Live/Dead BacLight (P < 0·02). Conclusion: It is possible to use CTC and Live/Dead BacLight to rapidly test endospore viability and evaluate the proportion of spores in a preparation that could not be recovered with plate count. Significance and Impact of the Study: This study shows that fluorescence tests could be applied to assess viability in potentially pathogenic Bacillus spore preparations within 1 h.
  • Publication
    Accès libre
    Methods for Sampling of Airborne Viruses
    (American Society for Microbiology, 2008-09-01) Verreault, Daniel; Duchaine, Caroline; Moineau, Sylvain
    Summary: To better understand the underlying mechanisms of aerovirology, accurate sampling of airborne viruses is fundamental. The sampling instruments commonly used in aerobiology have also been used to recover viruses suspended in the air. We reviewed over 100 papers to evaluate the methods currently used for viral aerosol sampling. Differentiating infections caused by direct contact from those caused by airborne dissemination can be a very demanding task given the wide variety of sources of viral aerosols. While epidemiological data can help to determine the source of the contamination, direct data obtained from air samples can provide very useful information for risk assessment purposes. Many types of samplers have been used over the years, including liquid impingers, solid impactors, filters, electrostatic precipitators, and many others. The efficiencies of these samplers depend on a variety of environmental and methodological factors that can affect the integrity of the virus structure. The aerodynamic size distribution of the aerosol also has a direct effect on sampler efficiency. Viral aerosols can be studied under controlled laboratory conditions, using biological or nonbiological tracers and surrogate viruses, which are also discussed in this review. Lastly, general recommendations are made regarding future studies on the sampling of airborne viruses
  • Publication
    Design of an environmentally controlled rotating chamber for bioaerosol aging studies
    (Hemisphere Pub. Corp., 2014-07-15) Duchaine, Caroline; Marcoux-Voiselle, Mélissa; Verreault, Daniel; Marcoux-Voiselle, Marcoux-Voiselle; Turgeon, Nathalie; J. Roy, Chad
    A chamber was designed and built to study the long-term effects of environmental conditions on air-borne microorganisms. The system consists of a 55.5-L cylindrical chamber, which can rotate at variable speeds on its axis. The chamber is placed within an insulated temperature controlled enclosure which can be either cooled or heated with piezoelectric units. A germicidal light located at the chamber center irradiates at a 360° angle. Access ports are located on the stationary sections on both ends of the chamber. Relative humidity (RH) is controlled by passing the aerosol through meshed tubes surrounded by desiccant. Validation assay indicates that the interior temperature is stable with less than 0.5 °C in variation when set between 18 and 30 °C with the UV light having no effect of temperature during operation. RH levels set at 20%, 50% and 80% varied by 2.2%, 3.3% and 3.3%, respectively, over a 14-h period. The remaining fraction of particles after 18 h of suspension was 8.8% at 1 rotation per minute (rpm) and 2.6% at 0 rpm with the mass median aerodynamic diameter (MMAD) changing from 1.21 ± 0.04 µm to 1.30 ± 0.02 µm at 1 rpm and from 1.21 ± 0.04 µm to 0.91 ± 0.01 µm at 0 rpm within the same time period. This chamber can be used to increase the time of particle suspension in an aerosol cloud and control the temperature, RH and UV exposure; the design facilitates stationary sampling to be performed while the chamber is rotating.
  • Publication
    Comparison of polycarbonate and polytetrafluoroethylene filters for sampling of airborne bacteriophages
    (Elsevier, 2010-01-22) Duchaine, Caroline; Moineau, Sylvain; Massé, Daniel; Verreault, Daniel; Rousseau, Geneviève M.; Gendron, Louis
    Aerosolized coliphage phiX174 and lactococcal phage P008 were sampled with two types of filter, polycarbonate (PC) and polytetrafluoroethylene (PTFE). The recovery was determined by plaque assays and quantitative polymerase chain reaction (qPCR). Recovery by qPCR was greater than by culture and PC filters outperformed PTFE filters both by culture and by qPCR relative recovery. The results of the plaque assays showed that the infectivity of the recovered phages was affected by the aerosolization/air sampling. The presence of viruses in air samples should be determined by culture-independent assays.
  • Publication
    Airborne porcine circovirus in Canadian swine confinement buildings
    (Oxford, 2009-09-11) Duchaine, Caroline; Massé, Daniel; Verreault, Daniel; Létourneau, Valérie.; Gagnon, Carl A.; Gendron, Louis
    Porcine circovirus type 2 has been linked to many diseases, such as postweaning multisystemic wasting syndrome and can be found in most commercial swine confinement buildings around the world. Although the exact role of the virus in the appearance of disease in animals is not fully understood, the mechanisms responsible for the transmission of the virus are currently believed to happen mostly by contact. Nevertheless, the possibility of airborne transmission cannot be rejected. This study investigated the presence of the virus, total bacteria and total dusts in aerosols. Air samples were taken with gelatin filters in swine confinement buildings and were analyzed by quantitative polymerase chain reaction. Interestingly, concentrations of airborne PCV2 of up to 10(7) genomes per cubic meter of air were detected. Airborne dust concentrations were correlated to airborne concentrations of PCV2 and total bacteria. Although the infectivity potential of the airborne viral loads were not evaluated, it is clear that the virus can become airborne in detectable concentrations in commercial swine confinement building environments. The significance of this finding in an epidemiological point of view will need further investigation.
  • Publication
    Accès libre
    Detection of airborne lactococcal bacteriophages in cheese manufacturing plants
    (American Society for Microbiology, 2011-01-01) Duchaine, Caroline; Veillette, Marc; Moineau, Sylvain; Massé, Daniel; Verreault, Daniel; Lindsley, William G.; Rousseau, Geneviève M.; Gendron, Louis
    The dairy industry adds starter bacterial cultures to heat-treated milk to control the fermentation process during the manufacture of many cheeses. These highly concentrated bacterial populations are susceptible to virulent phages that are ubiquitous in cheese factories. In this study, the dissemination of these phages by the airborne route and their presence on working surfaces were investigated in a cheese factory. Several surfaces were swabbed, and five air samplers (polytetrafluoroethylene filter, polycarbonate filter, BioSampler, Coriolis cyclone sampler, and NIOSH two-stage cyclone bioaerosol personal sampler) were tested. Samples were then analyzed for the presence of two Lactococcus lactis phage groups (936 and c2), and quantification was done by quantitative PCR (qPCR). Both lactococcal phage groups were found on most swabbed surfaces, while airborne phages were detected at concentrations of at least 103 genomes/m3 of air. The NIOSH sampler had the highest rate of air samples with detectable levels of lactococcal phages. This study demonstrates that virulent phages can circulate through the air and that they are ubiquitous in cheese manufacturing facilities.
  • Publication
    Real-time PCR quantification of mycobacterium immunogenum in used metalworking fluids
    (Taylor and Francis, 2008-10-29) Duchaine, Caroline; Veillette, Marc; Thorne, Peter S.; Pagé, Gabrielle
    Rapid detection and quantification of Mycobacterium immunogenum in field samples of metalworking fluids (MWFs) is important for factory fluid surveillance programs. The applicability of the developed DNA extraction and quantitative real-time PCR (qPCR) methods to detect and quantify M. immunogenum in used MWFs was evaluated. Total DNA from these samples was extracted, and M. immunogenum measured by qPCR by comparison with a standard curve derived from plasmid vectors. PCR counts were compared with bacterial culture counts. PCR counts of M. immunogenum varied from 1.42 × 103 to 3.68 × 106 cells/mL of MWFs. Recovery of M. immunogenum by bacterial culture varied from 2.5% to 70% of qPCR count in corresponding samples. Quantitative PCR could be used to measure M. immunogenum load in MWF samples with greater sensitivity and shorter processing time than the classic bacterial culture-based approach. The proposed qPCR approach could be routinely used in real-time PCR-equipped laboratories to provide early detection of M. immunogenum and to control proliferation that probably leads to hypersensitivity pneumonitis in exposed workers.
  • Publication
    Accès libre
    Microbial contents of vacuum cleaner bag dust and emitted bioaerosols and their implications for human exposure indoors
    (American Society for Microbiology, 2013-08-09) Duchaine, Caroline; Knibbs, Luke D.; Pelletier, Ariane; Veillette, Marc; Blais Lecours, Pascale; Charlebois, Rémi; He, Congrong; Morawska, Lidia
    Vacuum cleaners can release large concentrations of particles, both in their exhaust air and from resuspension of settled dust. However, the size, variability, and microbial diversity of these emissions are unknown, despite evidence to suggest they may contribute to allergic responses and infection transmission indoors. This study aimed to evaluate bioaerosol emission from various vacuum cleaners. We sampled the air in an experimental flow tunnel where vacuum cleaners were run, and their airborne emissions were sampled with closed-face cassettes. Dust samples were also collected from the dust bag. Total bacteria, total archaea, Penicillium/Aspergillus, and total Clostridium cluster 1 were quantified with specific quantitative PCR protocols, and emission rates were calculated. Clostridium botulinum and antibiotic resistance genes were detected in each sample using endpoint PCR. Bacterial diversity was also analyzed using denaturing gradient gel electrophoresis (DGGE), image analysis, and band sequencing. We demonstrated that emission of bacteria and molds (Penicillium/Aspergillus) can reach values as high as 1E5 cell equivalents/min and that those emissions are not related to each other. The bag dust bacterial and mold content was also consistent across the vacuums we assessed, reaching up to 1E7 bacterial or mold cell equivalents/g. Antibiotic resistance genes were detected in several samples. No archaea or C. botulinum was detected in any air samples. Diversity analyses showed that most bacteria are from human sources, in keeping with other recent results. These results highlight the potential capability of vacuum cleaners to disseminate appreciable quantities of molds and human-associated bacteria indoors and their role as a source of exposure to bioaerosols.