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Title: Bridging the gap between detection and confirmation of B. anthracis in blood cultures
Author: Hawkey, Suzanna
ISNI:       0000 0004 5366 4468
Awarding Body: University of Portsmouth
Current Institution: University of Portsmouth
Date of Award: 2015
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The spore forming bacterium, Bacillus anthracis is the aetiological agent of anthrax. The 2001 US anthrax letter attacks and the 2009‐2010 outbreak of injectional anthrax in the UK highlighted the importance of early detection and confirmation of this agent, both for patient outcome and forensic investigations. A reliable and consistent method was used in this study to safely simulate blood cultures with B. anthracis and used to determine the time to positive detection. This was performed with different strains and with varying concentrations of inoculum. An inverse linear relationship was observed with all strains and used to estimate the bacterial blood concentration of anthraxpatients based on data gathered from the literature and front‐line laboratories in the UK. The study explored a method to potentially reduce the turnaround times for the confirmation of B. anthracis at the national reference laboratory. Serum separator tubes were used to concentrate the bacteria from simulated blood cultures. A simple wash step was performed prior to performing confirmatory phenotypic tests and inactivation for rapid molecular detection. A comparison of test results with and without serum separator tube processing was made for B. anthracis and bacterial isolates referred during the outbreak of injectional anthrax. Simulated mixed blood cultures of B. anthracis and possible common contaminants were also tested. Compared to routine methods, confirmatory phenotypic test results were achieved 24 hours sooner using the method. The simple wash step and inactivation was sufficient to provide nucleic acid for molecular confirmatory assays and genotyping. A new ‘sample to answer’ platform, the Biofire Filmarray® was also trialled and correctly identified B. anthracis directly from simulated blood culture and provided results within one hour. Aspects relating to potential biosafety concerns for processing B. anthracis blood cultures were explored. The data generated suggests the aerosol risk is low for B. anthracis. Viability of material on microscopy slides was examined and the data supports the recommended use of alcohol fixation for slide preparation. There has been no previous evidence reported for sporulation occurring in blood culture bottles and the study findings suggest this is possible five days post positive detection. Interactive e‐learning modules have been produced to disseminate the study outcome. The e‐learning is intended for front‐line laboratories to raise awareness for the safe handling and laboratory identification of B. anthracis.
Supervisor: Mills, Graham ; Fouch, Sarah Elizabeth Sponsor: Not available
Qualification Name: Thesis (D.Biom.Sc.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Biomedical Sciences ; Pharmacy