eprintid: 10047377
rev_number: 19
eprint_status: archive
userid: 608
dir: disk0/10/04/73/77
datestamp: 2018-06-07 11:29:07
lastmod: 2019-10-17 06:06:52
status_changed: 2018-06-07 11:29:07
type: thesis
metadata_visibility: show
creators_name: Gorton, Rebecca Louise
title: Molecular Diagnosis of Invasive Fungal Disease
ispublished: unpub
divisions: A01
divisions: B02
divisions: C10
divisions: D15
note: Third party copyright material has been removed from ethesis.
abstract: BACKGROUND: Invasive fungal infections (IFI) are opportunistic infections caused by yeast or filamentous fungi, typically presenting in immunocompromised patients (haemato-oncology, intensive care, HIV, solid organ transplant settings). This research aims to comprehensively evaluate molecular diagnostics to address the current shortfall in IFI diagnosis and, where appropriate, embed molecular methods into routine clinical service. METHODS: Molecular methodologies, including PCR, MALDI-TOF MS and PNA-FISH, were evaluated on clinical sample cohorts from the Royal Free Hospital NHS Foundation Trust. Each method was critically appraised for: statistical performance, clinical utility and suitability for service adoption. RESULTS: MALDI-TOF MS improved yeast agar culture identification, demonstrating 97.4% (185/190) concordance with ITS rRNA sequencing, and time to identification was significantly reduced (p<0.01, 24 hrs. v’s 15 mins). Lower identification rates of 66% (33/50) were observed when applying MALDI-TOF MS directly to blood culture for yeast identification. In contrast PNA-FISH identified 98.5% (93/96, CI: 91.2, 98.9) of yeasts direct from blood culture within 30 minutes. Using PCP PCR a 60% (3/5) increase in the detection of PCP from BAL in non-HIV patients was demonstrated compared with GMS staining. Overall sensitivity was 100% (95% CI: 56.6, 100) and specificity was 97.9% (95% CI: 88.9, 99.6) for the diagnosis of PCP. Aspergillus PCR demonstrated a sensitivity of 100% (95% CI: 34.2, 100) and specificity of 93.8% (95% CI: 86.4, 97.3) for the diagnosis of IA but a low PPV of 28.6% (95% CI: 8.2, 64.1). CONCLUSIONS: Molecular diagnostic assays can improve the diagnosis of IFI through improved accuracy of identification and increased detection of fungal pathogens from specimens. Results must be interpreted alongside clinical presentation, as false positivity occurs utilising highly sensitive molecular assays. Dual biomarker strategies may improve the performance of molecular diagnostics but the associated impact on healthcare economics must also be considered.
date: 2018-05-28
date_type: published
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D
language: eng
thesis_view: UCL_Thesis
primo: open
primo_central: open_green
verified: verified_manual
elements_id: 1551158
lyricists_name: Gorton, Rebecca
lyricists_id: RLGOR70
actors_name: Gorton, Rebecca
actors_name: Flynn, Bernadette
actors_id: RLGOR70
actors_id: BFFLY94
actors_role: owner
actors_role: impersonator
full_text_status: public
pages: 316
event_title: UCL (University College London)
institution: UCL (University College London)
department: Infection & Immunity
thesis_type: Doctoral
citation:        Gorton, Rebecca Louise;      (2018)    Molecular Diagnosis of Invasive Fungal Disease.                   Doctoral thesis  (Ph.D), UCL (University College London).     Green open access   
 
document_url: https://discovery-pp.ucl.ac.uk/id/eprint/10047377/8/Gorton_ID_thesis_redacted.pdf