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New Approaches from Nanomedicine and Pulmonary Drug Delivery for the Treatment of Tuberculosis
Published in Ana Rute Neves, Salette Reis, Nanoparticles in Life Sciences and Biomedicine, 2018
Joana Magalhães, Alexandre C. Vieira, Soraia Pinto, Sara Pinheiro, Andreia Granja, Susana Santos, Marina Pinheiro, Salette Reis
In recent years, novel experimental approaches and detection technologies have provided more sensitive alternatives for TB diagnosis. Recently developed molecular tests can be applied directly to the sputum sample, giving rapid, highly specific, and sensitive diagnosis without the need for culture-based techniques [28]. The most common methods are Xpert® MTB/RIF assay (Cepheid, US), line probe assays (LPAs), and the urine lateral flow lipoarabinomannan (LF-LAM) assay (Alere DetermineTM TB LAM Ag test, Alere Inc., US) [8]. In addition, a diagnostic platform called the GeneXpert Omni® and a next-generation cartridge called Xpert Ultra® are in development. These new diagnostic tools may replace conventional culture as the primary diagnostic method for TB [8]. Despite all the advantages of these molecular tools for TB diagnostics, conventional microscopy and culture-based techniques remain necessary for monitoring patients’ response to treatment.
Transmission of SARS-CoV-2 in the workplace: Key findings from a rapid review of the literature
Published in Aerosol Science and Technology, 2023
Jennie Cox, Brian Christensen, Nancy Burton, Kevin H. Dunn, Mikaela Finnegan, Ana Ruess, Cherie Estill
Investigators added SARS CoV-2 to commercially available human nasal mucus and sputum and assessed persistence of infectivity under three environmental conditions − 4 °C/40% relative humidity (RH), 21 °C/40% RH, and 27 °C/85% RH (Matson et al. 2020). Fifty µL of prepared solution containing 1x105 TCID50/mL was added to either sealed tubes or onto polypropylene disks and sampled at specific time points. SARS-CoV-2 persistence of infectivity was greater in liquid droplets than when dried on surfaces using human nasal mucus and sputum. Lower temperature and lower relative humidity were associated with longer half-lives, but no virus survived more than 48 h. They found viral RNA for up to a week in all samples despite the absence of viable virus (Matson et al. 2020). SARS-CoV-2 stability was tested in nasal mucus, sputum, saliva, tears, feces, urine, breast milk, blood, and semen. Viral stability was assessed by inoculating Vero E6 cells and recovering infectious virus at various time points. Samples were tested in liquid (sealed tubes) and on stainless steel surfaces (except human urine, which was only tested in liquid). The virus was stable for up to 21 days in nasal mucus, sputum, saliva, tear, urine, blood, and semen; it remained infectious significantly longer under winter (5 °C and 75% RH) and spring/fall conditions (13 °C and 66% RH) than under summer conditions (25 °C and 70% RH). The virus was stable up to 24 h in feces and breast milk (Kwon, Gaudreault, and Richt 2021).
Estimating the reduction in SARS-CoV-2 viral load by common face masks with a simple leak model
Published in Aerosol Science and Technology, 2022
Steffen Freitag, Steven G. Howell, Kevin T. C. Jim
The average number size distributions for breath and speech were converted to aerosol volume and multiplied by virus concentrations in respiratory fluids to obtain size distributions of viral load or viral copies as illustrated in Figure 2. The virus concentrations in respiratory fluids were drawn from Munster et al. (2020), who reported the maximum SARS-CoV-2 viral concentration in bronchoalveolar fluid and throat swabs of rhesus macaques infected with COVID-19 at around 108 and 107 copies per mL, respectively (see supplementary material). Similar observations have been made in humans infected with the disease (Pan et al. 2020), if sputum is regarded as proxy for bronchoalveolar fluid (i.e., sputum is coughed up from the trachea and bronchi).
Persistence of SARS-Co-V-2 on N95 filtering facepiece respirators: implications for reuse
Published in Journal of Occupational and Environmental Hygiene, 2021
Edward M. Fisher, Michael R. Kuhlman, Young W. Choi, Traci L. Jordan, Michelle Sunderman
The applicability of culture media and human saliva as surrogates for the droplets released from individuals infected with SARS-CoV-2 is not clear. Saliva is typically 99.5% water with inorganic and organic constituents comprising about 0.5% (w/v) (de Almeida et al. 2008). Sputum is highly variable and is comprised of roughly 90–95% water, 4–9% (w/v) organic constituents, and 1% (w/v) electrolytes (Bansil and Turner 2018). The ratio of water, organic, and inorganic constituents of the cell culture medium used in this study is 94%, 5.8%, and 0.2% (w/v), more like sputum than saliva; however, the specific organic and inorganic constituents vary. Moreover, both saliva and sputum contain antibodies and other proteins that are part of the body’s response to infection. Matson et al. (2020) measured the viability of SARS-CoV-2, suspended in nasal mucus and in sputum, placed onto polypropylene disks. At 21 °C and 40% RH, the mean half-life of SARS-CoV-2 was reported to be 3.1 hr. Under similar conditions, this study reports a half-life of roughly 16 hr on the surfaces of FFRs which are also made of polypropylene. The difference in virus viability reported on similar substrates under similar temperature and humidity conditions suggests that cell culture medium may not be representative of the constituents typical of respiratory secretions and emphasizes the importance of selecting the proper suspension medium to assess persistence.