Methods: A review of the literature was undertaken, utilizing electronic databases on infection with Bacillus Anthracis, as well as consultation with experts in this field. Emphasis was placed on the diagnosis and treatment of complications of infection that might require surgical intervention. Results: Cutaneous anthrax infection results in eschar formation and massive soft tissue edema Researchers have sought a B. anthracis-specific medium that deters background cultures and other Bacillus species and yet allows B. anthracis propagation and identification. Based upon the amount of specificity testing, modified PLET medium was identified as the most promising selective culture medium for B. anthracis documented in the reviewed blogger.com by: 10 Information about B. anthracis for this literature review was considered from reports, peer-reviewed journal articles, books, and government publications focusing on publications in the last ten years, but including relevant information dating back to the s from open literature
Bacillus anthracis
Annals of Microbiology volume 65pages — Cite this article. Metrics details. Identifying virulent Bacillus anthracis within soil is a difficult task due to the number and diversity of other organisms and impeding chemical constituents within soil. Regardless of the detection assay, the initial sample must be processed efficiently to ensure that debris, chemical components, and biological impurities do not obstruct downstream analysis.
Soil sample processing protocols can be divided into two general types: indirect and direct, bacillus anthracis literature review.
Bacillus anthracis literature review are two requirements for successful indirect isolation of B. anthracis from soil samples: dissociate the spores from the soil particles and physically separate the free spores from the soil particles. Adding an aqueous carrier medium to a soil sample creates a sample slurry for easier manipulation.
Centrifugation, high specific gravity separation, immunomagnetic separation, filtration, and settling have been used to physically separate spores from soil. Direct processing utilizes a soil sample without first separating the spores from the bulk sample and falls under two principal types: culturing on B. anthracis selective agar and bulk DNA extraction.
Direct and indirect processing steps each have associated advantages and disadvantages. The objective of this review was to consolidate information acquired from previous research, focusing primarily on data gleaned in the last decade, on the processing of soils contaminated with B. As shown in this review, an optimized soil-processing protocol with a known recovery rate and associated confidence intervals is needed.
A reliable processing protocol would allow for multiple investigators and laboratories to produce high-quality, uniform results in the event of a Bacillus anthracis literature review. anthracis release.
Bacillus anthracisthe etiological agent of anthrax, is a naturally occurring Gram-positive spore-forming bacteria found in many soil environments Van Ert et al. Exposure of humans to Bacillus anthracis literature review anthracis spores has been historically associated with agricultural contact with infected animals or animal products. Outbreaks of anthrax in livestock in the United States have been reported since the early s Mikesell et al.
In many instances, recent anthrax cases were associated with old graves of anthrax-stricken animals and adequate soil conditions Pepper and Gentry ; Griffin et al. There are a number of alternative theories regarding the lifecycle of B.
anthracis in soil Minett ; Lindeque and Turnbull ; Dragon and Rennie ; Atlas ; Coker ; Dragon et al. Regardless of how B.
anthracis spores came to a soil, it is generally accepted that some soils are bacillus anthracis literature review at harboring spores than others, and weather conditions influence the occurrence of environmental anthrax cases. anthracis is most often found in dry conditions with soils that are high in organic matter and calcium and are relatively alkaline above pH 6 Van Ness ; Johnson ; Hugh-Jones and Blackburn Spores are metabolically dormant and extremely resistant to environmental stresses Ghosh and Setlow Spores can persist in soil for years Graham-Smith ; Wilson and Russell ; Lewis ; Manchee et al.
Soil is a complex matrix with multiple components and a plethora of microbial activities, and the properties of soil change with the seasons and over extended periods of time Bacillus anthracis literature review One gram of soil reportedly contains up to 10 billion microorganisms, and thousands of different species Delmont et al.
bacillus anthracis literature review can be collocated in the soil environments Kuske et al. Chemical constituents of soil such as organics, humic acids, etc. Due to the number and diversity of organisms and impeding chemical constituents within soil, identifying B. anthracis within a soil sample is a difficult task. Bacillus anthracis literature review there are many B. anthracis detection assays, only a few of them can be utilized directly with environmental soil samples, bacillus anthracis literature review.
The initial sample must be efficiently processed to ensure that debris, chemical components, and biological impurities do not obstruct microbiological detection. Without appropriate sample processing, the most sensitive detection assay will be ineffective. There is a need for a universal sample processing bacillus anthracis literature review to separate, concentrate, and purify target agents from any sample type Lim et al.
There have been multiple reviews detailing the various detection assays for B. anthracis Edwards et al. Multiple processing protocols have been developed either to separate spores from soil samples before microbiological assessment or to directly extract bulk DNA to identify the initial bacillus anthracis literature review s present within the soil.
However, these studies have never been integrated to determine the overall breadth of knowledge regarding the processing efficiency. Therefore, the objective of this project was to consolidate information acquired from previous research and provide a summary regarding the direct and indirect processing of soils contaminated with B. anthracis that have been utilized in the recent literature.
The search focused primarily on data gleaned in the last decade. A brief summary of the literature review findings are summarized here.
Literature for processing protocols of similar pathogens or similar matrices were also included in the summary if found during the search and deemed to be applicable. Two types of processing protocols, indirect and direct, were identified in the literature by Delmont et al. For indirect processing, spores are extracted from soil particles and concentrated prior to downstream detection with an analysis assay such as culture or polymerase chain reaction PCR. Conversely, bacillus anthracis literature review, direct processes refers to utilization of a soil matrix with a detection assay without first extracting and concentrating the spores from the bulk sample.
Direct and indirect processing are discussed in more detail in the subsequent sections. Because spores have the potential to adhere to large soil aggregates Nicholson and Lawthere are two requirements for successful isolation of B. anthracis from soil samples: dissociate the spores from the soil particles and separate the free spores physically from the soil particles. Protocols for spore purification from soil particles prior to use of detection assays for example culture or PCR involve steps to accomplish both of these objectives.
In some cases, additional steps are taken to concentrate and further purify the final spore sample. The hydrophobic exosporidium of B. anthracis interacts with solid soil particles and requires treatment prior to efficient spore recovery Saikaly et al. Adding an aqueous carrier medium to a soil sample creates a sample slurry that can be manipulated. While deionized water has been utilized Dragon and Renniechemical additives buffers, chelating agents, surfactants, salts, emulsifiers are often included to aid spore—soil dissociation.
Chelating agents [e. The carrier medium or spore extraction solution has been said to be the most important factor influencing the efficiency of extracting spores from wipes Da Silva et al.
Within the reviewed studies, there were many different aqueous media used to separate spores from soil samples. The most common type of carrier medium was a buffered solution or a buffer solution with a surfactant. Recovery efficiency data are lacking in many studies. Three B. anthracis studies contained spore recovery data for various soil types. Spore recovery efficiency varied depending on the soil type and aqueous carrier medium.
A number of other parameters such as sample age, sample amount, and dissociation protocol may also have influenced the overall extraction efficiency. Carrier media that were typically used for comparisons of recovery of pathogens other than B. anthracis in soil in the literature included sterile deionized water Dabiré et al. Studies in which recovery efficiency data were lacking Rastogi et al.
While no study provided statistical evidence for an optimized aqueous carrier medium, the individual studies each concluded that the addition of a surfactant aided spore recovery when compared to PBS or sucrose solutions alone Dragon and Rennie ; Da Silva et al. Determination of an optimum aqueous carrier medium from the available information is therefore difficult, bacillus anthracis literature review. Microbial cells are tightly bound to soil colloids with clay and organic matter posing particular challenges in spore—soil separation Zhou et al.
Bacillus anthracis literature review additives added to the aqueous carrier medium are used to help dissociate spores from soil; however, physical means are also utilized. More energetic dispersion protocols may yield greater spore recovery efficiencies Dabiré et al.
Dissociation of large soil aggregates was suggested as the primary cause for the increased spore recoveries. Other studies have confirmed that more energetic dispersion protocols aid in overall recovery rates. Vortexing was found to be statistically superior to sonication for separating B.
anthracis spores from wipe samples Da Silva et al. Ultrasonication treatment and shaking have been found to be inferior bacillus anthracis literature review protocols when compared to using a Waring ® blender Lindahl and Bakken Even with significant physical disruption, spore-soil interactions are powerful and may be only slightly interrupted by physical agitation Nicholson and Law After spore—soil dissociation, bacillus anthracis literature review, spores can be separated physically from soil particles using methods such as density separation [e.
While some protocols do not require debris-free sample material for downstream detection assays culture, direct DNA extraction followed by molecular detectionmany assays have higher sensitivities with purified samples. Indirect soil processing steps. a Initial soil sample with soil-bound spores. b Soil sample with added aqueous carrier medium. c Soil slurry with soil-bound spores and dissociated spores. d — i Separation and concentration methods; density separation via: d low-speed centrifugation; e high-speed centrifugation; f high specific gravity separation; g settling.
h affinity capture imperfectly specific using antibody-labeled magnetic beads ; i filtration with and 0. Density separation methods include low-speed centrifugation, high-speed centrifugation, bacillus anthracis literature review, and HSGS.
Low-speed centrifugation precipitates only dense soil particles leaving the more buoyant free dissociated spores within the supernatant. Spores remaining bound to soil particles after dissociation steps are removed with the soil particles. Spores within the supernatant can be detected directly or concentrated through additional steps.
Two studies used low-speed centrifugation speeds of g Fitzpatrick et al. However, neither study specifically targeted B. anthracis within the soil samples. The study using the 2, g centrifugation speed concluded that separation of cells prior to DNA extraction indirect DNA extraction yielded a lower quantity of higher quality DNA extracts when compared to directly extracted soil samples Roh et al.
Low-speed centrifugation g and 2, rpm, respectively was also used as part of the isolation steps of the GABRI ground anthrax Bacillus refined identification protocol and was successful in recovering B, bacillus anthracis literature review.
R\u0026D100 Winner 2014: Bacillus Anthracis Detection in Ultra-Low Resource Environments
, time: 5:41Gastrointestinal anthrax: review of the literature
This review provides background information on the gastrointestinal form of the disease. We describe the clinical course of gastrointestinal anthrax, outline current therapy, review the microbiology of B anthracis, examine the epidemiology of natural outbreaks, discuss considerations regarding deliberate contamination, and summarize existing literature on the Cited by: A review of the literature suggests that the major neurologic symptom complex of infection by Bacillus anthracis is a fulminant and rapidly fatal hemorrhagic meningoencephalitis and that the reported initial mode of entry can be via the cutaneous or inhalation blogger.com by: 25 Bacillus anthracis, the etiological agent of anthrax, is a natu-rallyoccurringGram-positivespore-formingbacteriafoundin many soil environments (Van Ert et al. ). Exposure of humans to Bacillus anthracis spores has been historically associated with agricultural contact with infected animals or animal products. Outbreaks of anthrax in livestock in the
No comments:
Post a Comment