scholarly journals Assessing the airborne survival of bacteria in populations of aerosol droplets with a novel technology

2019 ◽  
Vol 16 (150) ◽  
pp. 20180779 ◽  
Author(s):  
Mara Otero Fernandez ◽  
Richard J. Thomas ◽  
Natalie J. Garton ◽  
Andrew Hudson ◽  
Allen Haddrell ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Control Strategies ◽  
Disease Outbreaks ◽  
New Approach ◽  
Novel Technology ◽  
Time Period ◽  
Colony Forming Units ◽  
Droplet On Demand ◽  
The Impact

The airborne transmission of infection relies on the ability of pathogens to survive aerosol transport as they transit between hosts. Understanding the parameters that determine the survival of airborne microorganisms is critical to mitigating the impact of disease outbreaks. Conventional techniques for investigating bioaerosol longevity in vitro have systemic limitations that prevent the accurate representation of conditions that these particles would experience in the natural environment. Here, we report a new approach that enables the robust study of bioaerosol survival as a function of relevant environmental conditions. The methodology uses droplet-on-demand technology for the generation of bioaerosol droplets (1 to greater than 100 per trial) with tailored chemical and biological composition. These arrays of droplets are captured in an electrodynamic trap and levitated within a controlled environmental chamber. Droplets are then deposited on a substrate after a desired levitation period (less than 5 s to greater than 24 h). The response of bacteria to aerosolization can subsequently be determined by counting colony forming units, 24 h after deposition. In a first study, droplets formed from a suspension of Escherichia coli MRE162 cells (10 8 ml −1 ) with initial radii of 27.8 ± 0.08 µm were created and levitated for extended periods of time at 30% relative humidity. The time-dependence of the survival rate was measured over a time period extending to 1 h. We demonstrate that this approach can enable direct studies at the interface between aerobiology, atmospheric chemistry and aerosol physics to identify the factors that may affect the survival of airborne pathogens with the aim of developing infection control strategies for public health and biodefence applications.

scholarly journals Robustness of local control strategies under modelling uncertainties: the 2004 avian influenza H5N1 outbreak in Thailand

2018 ◽  
Author(s):  
Renata Retkute ◽  
Chris P. Jewell ◽  
Thomas P. Van Boeckel ◽  
Geli Zhang ◽  
Xiangming Xiao ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Control Strategies ◽  
Model Fitting ◽  
Significant Risk ◽  
Disease Outbreaks ◽  
Control Policy ◽  
Poultry Industry ◽  
Epidemic Size ◽  
Hpai H5n1 ◽  
The Impact

AbstractThe Highly Pathogenic Avian Influenza (HPAI) subtype H5N1 virus persists in many countries and has been circulating in poultry, wild birds. In addition, the virus has emerged in other species and frequent zoonotic spillover events indicate that there remains a significant risk to human health. It is crucial to understand the dynamics of the disease in the poultry industry to develop a more comprehensive knowledge of the risks of transmission and to establish a better distribution of resources when implementing control. In this paper, we develop a set of mathematical models that simulate the spread of HPAI H5N1 in the poultry industry in Thailand, utilising data from the 2004 epidemic. The model that incorporates the intensity of duck farming when assessing transmision risk provides the best fit to the spatiotemporal characteristics of the observed outbreak, implying that intensive duck farming drives transmission of HPAI in Thailand. We also extend our models using a sequential model fitting approach to explore the ability of the models to be used in “real time” during novel disease outbreaks. We conclude that, whilst predictions of epidemic size are estimated poorly in the early stages of disease outbreaks, the model accurately predicts the preferred control policy that should be deployed to minimise the impact of the disease.

The effects of glyphosate on the in vitro linear growth of selected microfungi from a boreal forest soil

2010 ◽  
Vol 56 (2) ◽  
pp. 138-144 ◽  
Author(s):  
Joey B. Tanney ◽  
Leonard J. Hutchison
Keyword(s):  
Boreal Forest ◽  
Forest Soil ◽  
Linear Growth ◽  
Plant Competition ◽  
Fungal Growth ◽  
Fungal Species ◽  
Differential Sensitivity ◽  
Colony Forming Units ◽  
The Impact

Glyphosate-based herbicides are used extensively in forestry and agriculture to control broadleaf plant competition. A review of the literature offers conflicting results regarding the impact of glyphosate on fungal growth. This study investigated the effects of 7 glyphosate concentrations (1, 2, 5, 10, 50, 100, and 1000 µg·mL–1) of Roundup (35.6% glyphosate) on the number of colony-forming units (CFUs) of soilborne microfungi from a boreal forest soil sample and on the in vitro linear growth of 20 selected species of microfungi representative of this boreal forest soil. Concentrations of glyphosate at 50 µg·mL–1and higher significantly decreased the number of CFUs observed. At glyphosate concentrations equal to 5 µg·mL–1, 13 fungal species exhibited colony diameters less than 50% than that of their respective controls. Several species showed an inhibition of pigmentation and sporulation when subjected to glyphosate concentrations of 1 µg·mL–1. Differential sensitivity was observed among species at the various concentrations, suggesting the possibility of a shift towards tolerant species of fungi when they are exposed to glyphosate.

scholarly journals Effect of Hydrogen Peroxide on the Antibacterial Substantivity of Chlorhexidine

2010 ◽  
Vol 2010 ◽  
pp. 1-4 ◽  
Author(s):  
Shahriar Shahriari ◽  
Zahed Mohammadi ◽  
Mohammadi Mehdi Mokhtari ◽  
Rasoul Yousefi
Keyword(s):  
Hydrogen Peroxide ◽  
Antibacterial Activity ◽  
Enterococcus Faecalis ◽  
Time Lapse ◽  
Positive Control ◽  
Negative Control ◽  
The Other ◽  
Time Period ◽  
Colony Forming Units

The purpose of thisin vitrostudy was to assess the effect of hydrogen peroxide on the antibacterial substantivity of chlorhexidine (CHX). Seventy-five dentine tubes prepared from human maxillary central and lateral incisor teeth were used. After contamination withEnterococcus faecalisfor 14 days, the specimens were divided into five groups as follows: CHX, H2O2, CHX + H2O2, infected dentine tubes (positive control), and sterile dentine tubes (negative control). Dentine chips were collected with round burs into tryptic soy broth, and after culturing, the number of colony-forming units (CFU) was counted. The number of CFU was minimum in the first cultures in all experimental groups, and the results obtained were significantly different from each other at any time period (). At the first culture, the number of CFU in the CHX + H2O2group was lower than other two groups. At the other experimental periods, the CHX group showed the most effective antibacterial action (). Hydrogen peroxide group showed the worst result at all periods. In each group, the number of CFU increased significantly by time lapse (). In conclusion, H2O2had no additive effect on the residual antibacterial activity of CHX.

Leukemic transformation of hematopoietic progenitors by MLL-GAS7 in the absence of Hoxa7 or Hoxa9

Blood ◽  
2004 ◽  
Vol 103 (8) ◽  
pp. 3192-3199 ◽  
Author(s):  
Chi Wai So ◽  
Holger Karsunky ◽  
Piu Wong ◽  
Irving L. Weissman ◽  
Michael L. Cleary
Keyword(s):  
Hox Genes ◽  
Hematopoietic Progenitor ◽  
Erythroid Progenitor ◽  
Hematopoietic Stem ◽  
Retroviral Transduction ◽  
Colony Forming Units ◽  
Reduced Penetrance ◽  
The Impact ◽  
Dependent Mechanism

Abstract Differential expression of Hox genes is associated with normal hematopoiesis, whereas inappropriate maintenance of Hox gene expression, particularly Hoxa7 and Hoxa9, is a feature of leukemias harboring mixed-lineage leukemia (MLL) mutations. To understand the pathogenic roles of Hox genes in MLL leukemias, we assessed the impact of Hoxa7 or Hoxa9 nullizygosity on hematopoietic progenitor compartments and their susceptibility to MLL-induced leukemias. Selective reductions in the absolute numbers of committed progenitors, but not of hematopoietic stem cells, distinguished Hoxa7- and Hoxa9-deficient mice. Megakaryocytic/erythroid progenitor (MEP) reductions in Hoxa7-/-mice correlated with reticulocytosis and thrombocytopenia without anemia. Conversely, Hoxa9-/- mice displayed marked lymphopenia and substantial reductions of common lymphoid progenitors (CLPs) and lymphoid precursors, in addition to significant reductions of common myeloid progenitors (CMPs) and granulocyte/monocyte progenitors (GMPs). In retroviral transduction/transplantation assays, Hoxa7- and Hoxa9-deficient progenitors remained susceptible to transformation by MLL-GAS7, which activates MLL through a dimerization-dependent mechanism. However, Hoxa7-/- or Hoxa9-/-progenitors were less efficient in generating transformed blast colony-forming units (CFUs) in vitro and induced leukemias with longer disease latencies, reduced penetrance, and less mature phenotypes. Thus, Hoxa7 and Hoxa9 contribute to hematopoietic progenitor homeostasis but are not necessary for MLL-GAS7–mediated leukemogenesis, yet they appear to affect disease latency, penetrance, and phenotypes consistent with their critical roles as downstream targets of MLL fusion proteins. (Blood. 2004;103:3192-3199)

Methods for Removing Bacterial Biofilms: In Vitro Study using Clinical Chronic Rhinosinusitis Specimens

2007 ◽  
Vol 21 (5) ◽  
pp. 527-532 ◽  
Author(s):  
Martin Desrosiers ◽  
Matthew Myntti ◽  
Garth James
Keyword(s):  
Chronic Rhinosinusitis ◽  
In Vitro Study ◽  
Confocal Scanning Laser Microscopy ◽  
Bacterial Biofilms ◽  
New Approach ◽  
Colony Forming Units ◽  
Confocal Scanning ◽  
Confocal Scanning Laser ◽  
Hydrodynamic Delivery

Background Bacterial biofilms may be involved in refractory chronic rhinosinusitis (CRS). In vitro, we studied methods for removing biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa. Methods Bacterial isolates were obtained from patients with refractory CRS and were plated and treated with either static administration of citric acid/zwitterionic surfactant (CAZS), saline delivered with hydrodynamic force, or CAZS delivered hydrodynamically. Results were assessed by counting colony-forming units (CFUs) and by confocal scanning laser microscopy (CSLM). Results All treatments produced significant reductions in CFU counts (p ≥ 0.002). Hydrodynamic CAZS provided the greatest reduction, decreasing CFU counts from control values by 3.9 ± 0.3 logs and 5.2 ± 0.5 logs for S. aureus and P. aeruginosa, respectively (99.9% reduction; p = 0.001). CSLM showed decreases in biofilm coverage. Conclusion Hydrodynamic delivery of a soap-like surfactant and a calcium-ion sequestering agent may disrupt biofilms associated with CRS. Our results may be relevant to a new approach to refractory CRS.

scholarly journals Susceptibility ofStreptococcus pneumoniaeto Fluoroquinolones in Canada

2011 ◽  
Vol 55 (8) ◽  
pp. 3703-3708 ◽  
Author(s):  
Samir N. Patel ◽  
Allison McGeer ◽  
Roberto Melano ◽  
Gregory J. Tyrrell ◽  
Karen Green ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Fluoroquinolone Resistance ◽  
Pneumococcal Infections ◽  
Surveillance Period ◽  
Time Period ◽  
Multivariable Analyses ◽  
Tract Infections ◽  
The Impact ◽  
Emergence Of Resistance

ABSTRACTCiprofloxacin, the first fluoroquinolone to be used to treat lower respiratory tract infections (LRTI), demonstrates poor potency againstStreptococcus pneumoniae, and its use has been associated with the emergence of resistance. During the last decade, fluoroquinolones with enhancedin vitroactivity againstS. pneumoniaehave replaced ciprofloxacin for the treatment of LRTI. Here, we analyzed the impact of more active fluoroquinolone usage on pneumococci by examining the fluoroquinolone usage, prevalence of fluoroquinolone resistance, and mutations in the genes that encode the major target sites for the fluoroquinolones (gyrAandparC) in pneumococcal isolates collected in Canada-wide surveillance. A total of 26,081 isolates were collected between 1998 and 2009. During this time period, total per capita outpatient use of fluoroquinolones increased from 64 to 96 prescriptions per 1,000 persons per year. The proportion of prescriptions for respiratory tract infection that were for fluoroquinolones increased from 5.9% to 10.7%, but the distribution changed: the proportion of prescriptions for ciprofloxacin decreased from 5.3% to 0.5%, and those for levofloxacin or moxifloxacin increased from 1.5% in 1999 to 5.9% in 2009. The prevalence of ciprofloxacin resistance (MIC ≥ 4 μg/ml), levofloxacin resistance, and moxifloxacin resistance remained unchanged at <2%. Multivariable analyses showed that prevalence of mutations known to be associated with reduced susceptibility to fluoroquinolones did not change during the surveillance period. If fluoroquinolone therapy is required, the preferential use of fluoroquinolones with enhanced pneumococcal activity to treat pneumococcal infections may slow the emergence of resistance inS. pneumoniae.

scholarly journals Preparing for the KIL: Receptor Analysis of Pseudomonas syringae pv. porri Phages and Their Impact on Bacterial Virulence

2020 ◽  
Vol 21 (8) ◽  
pp. 2930 ◽  
Author(s):  
Dominique Holtappels ◽  
Alison Kerremans ◽  
Yoni Busschots ◽  
Johan Van Vaerenbergh ◽  
Martine Maes ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Control Strategies ◽  
Resistance Mutations ◽  
Bacterial Concentration ◽  
Phage Cocktail ◽  
Additional Protein ◽  
The Impact ◽  
Agricultural Setting ◽  
The Ideal

The prevalence of Pseudomonas syringae pv. porri (Pspo) in Belgium continues to increase and sustainable treatments for this pathogen remain unavailable. A potentially attractive biocontrol strategy would be the application of bacteriophages. The ideal application strategy of phages in an agricultural setting remains unclear, especially in a field-based production such as for leek plants in Flanders. Therefore, more insight in bacteria–phage interaction is required, along with the evaluation of different application strategies. In this study, we further characterized the infection strategy of two Pspo phages, KIL3b and KIL5. We found that both phages recognize lipopolysaccharide (LPS) moieties on the surface of the bacterium. LPS is an important pathogenicity factor of Pspo. Our data also suggest that KIL5 requires an additional protein in the bacterial cytoplasmatic membrane to efficiently infect its host. Virulence tests showed that this protein also contributes to Pspo virulence. Furthermore, a cocktail of both phages was applied in a seed bioassay. A combination of KIL3b and KIL5 reduced the bacterial concentration 100-fold. However, in vitro Pspo resistance against phage infection developed quite rapidly. However, the impact of this phage resistance might be mitigated as is suggested by the fact that those resistance mutations preferably occur in genes involved in LPS metabolism, and that the virulence of those mutants is possibly reduced. Our data suggest that the phage cocktail has promising potential to lower the prevalence of Pspo and to be integrated in a pest management strategy. Targeted research is needed to further explore the applicability of the phages in combination with other disease control strategies.

Asexual blood stages of malaria modulate gametocyte infectivity to the mosquito vector – possible implications for control strategies

Parasitology ◽  
1991 ◽  
Vol 103 (2) ◽  
pp. 191-196 ◽  
Author(s):  
R. E. Sinden
Keyword(s):  
Malaria Transmission ◽  
Plasmodium Berghei ◽  
Host Response ◽  
Control Strategies ◽  
Malarial Parasite ◽  
Mosquito Vector ◽  
Published Evidence ◽  
The Impact

In the rodent malarial parasitePlasmodium bergheisexual parasites are produced in a single major wave with maximal numbers between day 7 and day 16. Irrespective of their time of appearance during infection these sexual parasites are equally fertilein vitro. In contrast,in vivoinfectivity to the mosquito is maximal at day 3–5 when gametocyte numbers are only 9% of the peak levels seen between days 7 and 16. Up to 96% of natural potential infectivity of gametocytes for the mosquito is therefore suppressed. The suppression is humoral, reversible and correlates with the appearance of an effective host response to the initial rapid increase in asexual parasitaemia. These data are consistent with published evidence which indicates that a reduction in parasitaemia may cause an increase in infectivity of gametocytes to the mosquito vector. Therefore the impact of strategies aiming to control asexual parasites is re-examined. Inefficient strategies might be predicted to increase and not suppress malaria transmission.

scholarly journals Influence of synoptic patterns on surface ozone variability over the eastern United States from 1980 to 2012

2015 ◽  
Vol 15 (19) ◽  
pp. 10925-10938 ◽  
Author(s):  
L. Shen ◽  
L. J. Mickley ◽  
A. P. K. Tai
Keyword(s):  
United States ◽  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Empirical Orthogonal Functions ◽  
Eastern United States ◽  
Orthogonal Functions ◽  
Synoptic Patterns ◽  
Time Period ◽  
Relative Standard ◽  
The Impact

Abstract. We investigate the effect of synoptic-scale weather patterns on observed maximum daily 8-hour average (MDA8) surface ozone over the eastern United States during 1980–2012 in summer (June–August, JJA). Zonally averaged, the relative standard deviation (SD) of daily MDA8 JJA ozone shows a bimodal structure, with peaks at 28–32 and 40–45° N, and we show that those regions are most influenced by the variability in daily weather. We apply empirical orthogonal functions (EOFs) to understand the causes of this structure. The first three leading EOF patterns explain 53 % of the total variance in detrended surface ozone, displaying (1) a widespread response of ozone in the eastern United States associated with north–south movement of jet wind latitude, (2) a north–south pattern linked to the Bermuda High system when its west boundary is located along the east coast, and (3) an east–west pattern characteristic of a westward extension of the Bermuda High and an enhanced Great Plains low level jet (GPLLJ). The northern peak of ozone relative SD can be explained by polar jet activity, while the southern peak appears related to variability in the Bermuda High and GPLLJ. We define a new metric polar jet frequency as the total number of days the jet traverses the Midwest and northeast each summer. In the Midwest and northeast, we find that the correlation coefficient r between detrended mean JJA MDA8 ozone and the polar jet frequency ranges between −0.76 and −0.93 over 1980–2012 depending on the time period selected, suggesting that polar jet frequency could provide a simple metric to predict ozone variability in future climate regimes. In the southeast, the influence of the Bermuda High on mean JJA MDA8 ozone depends on the location of its west edge. For those summers when the average position of the west edge is located west of ~ 85.4° W, a westward shift in the Bermuda High west edge increases ozone in the southeast by ~ 1 ppbv deg−1 in longitude. For all summers, a northward shift in the Bermuda High west edge increases ozone over the entire eastern United States by 1–2 ppbv deg−1 in latitude. None of the synoptic patterns identified in this study show a significant trend from 1980 to 2012, confirming that the observed ozone decrease over the eastern United States during this time period is mainly caused by emission controls. Our work underscores the impact of synoptic patterns on ozone variability and suggests that a combination of changing local and synoptic meteorology together with trends in background ozone will determine the influence of climate change on US ozone air quality in future decades. The observed relationships of US surface ozone and synoptic circulations in this study can also be used to validate models of atmospheric chemistry.

scholarly journals Maintenance of Fish Health in Aquaculture: Review of Epidemiological Approaches for Prevention and Control of Infectious Disease of Fish

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ayalew Assefa ◽  
Fufa Abunna
Keyword(s):  
Infectious Disease ◽  
Traffic Control ◽  
Prevention And Control ◽  
Control Strategies ◽  
Disease Outbreaks ◽  
Effective Prevention ◽  
Disease Case ◽  
And Control ◽  
Water Treatments ◽  
The Impact

Aquaculture is rapidly growing part of agriculture worldwide. It makes up around 44 percent of total fish production globally. This increased growth of production is achieved despite facing many challenges in the aquaculture environment. Among production limiting challenges, the infectious disease takes the lion share by causing multibillion-dollar loss annually. To reduce the impact of the fish disease, it is necessary to address health constraints based on scientifically proven and recommended ways. This review aims at pointing out some of the best approaches to prevention and control of infectious disease in aquaculture. Among the effective prevention and control strategies, vaccination is one of the key practices. Types of vaccines for use in fish include killed vaccines, attenuated vaccines, DNA vaccines, recombinant technology vaccines, and synthetic peptide vaccines. Administration techniques of vaccines in fish include oral, injection, or immersion methods. Antibiotics are also in use in aquaculture despite their side effects in the development of drug resistance by microorganisms. Biological and chemical disease control strategies such as using probiotics, prebiotics, and medicinal plants are widely in use. Biosecurity measures in aquaculture can keep the safety of a facility from certain disease-causing agents that are absent in particular system. Farm-level biosecurity measures include strict quarantine measures, egg disinfection, traffic control, water treatments, clean feed, and disposal of mortalities. In conclusion, rather than trying to treat every disease case, it advisable to follow a preventive approach before the event of any disease outbreaks.

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