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Invasive aspergillosis : Update on conventional diagnosis

Invasive aspergillosis : Update on conventional diagnosis. Jacques Bille, MD Institut of Microbiology University Hospital Lausanne, Switzerland. Invasive aspergillosis : update on conventional diagnosis. The problems The disease is evolving Clinical signs/ symptoms are non specific

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Invasive aspergillosis : Update on conventional diagnosis

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  1. Invasive aspergillosis : Update on conventional diagnosis Jacques Bille, MD Institut of Microbiology University Hospital Lausanne, Switzerland

  2. Invasive aspergillosis : update on conventional diagnosis The problems The disease is evolving Clinical signs/ symptoms are non specific Conventional diagnosis is insensitive or too late Non conventional diagnosis is "promising"

  3. Invasive aspergillosis : update on conventional diagnosis The disease is evolving A continuum of clinical presentations New (?) hosts Underdiagnosed ante-mortem

  4. Invasive aspergillosis : update on conventional diagnosis Hope, WW, Walsh TJ, Denning DW. The invasive and saprophytic syndromes due to Aspergillus species. Medical Mycology 2005, 43: S 207-238

  5. Invasive aspergillosis : update on conventional diagnosis Clinical signs/symptoms are non specific fever dyspnea non productive cough hemoptysis chest pain pleural rib In a proper host rapidly progressive

  6. Invasive aspergillosis : update on conventional diagnosis Conventional diagnosis • direct examination of tissue of indirect clinical specimens (sputum, BAL) sputum/BALtissue unstained wet prep ± KOH routine stains Gram HE fungal stains GMS, PAS GMS, PAS fluorescent Calcofluor white dyes Uvitex 2B Blankophor

  7. Invasive aspergillosis : update on conventional diagnosis In: Hope et al., Lancet Infectious Diseases5: 609, 2005

  8. Invasive aspergillosis : update on conventional diagnosis Histopathologic diagnosis of Aspergillosis Improvement by immunohistochemical detection Monoclonal antibodies • WF-AF-1 (Dako) 1) • EB-A1 2) Sensitivity in culture-proven cases : 89-94% Genus or species specific results 1) Choi JK et al., Am J Clin Pathol121: 18, 2004 2) Pierard GE et al., Am J Clin Pathol96: 373, 1991 Verweij PE et al., Am J Clin Pathol49: 798, 1996

  9. Invasive aspergillosis : update on conventional diagnosis In: Choi JK, Am J Clin Pathol121: 18, 2004

  10. Invasive aspergillosis : update on conventional diagnosis Culture Isolation: Sabouraud (+ antibiotics) Media blood agar, chocolate agar Identification : malt-extract, corn-meal agar Czapek agar Incubation temperature 25-30°C  improvement ? athmosphere aerobic duration 2-6 weeks

  11. Invasive aspergillosis : update on conventional diagnosis In: Andreoni et al., Medical Mycology Atlas

  12. Invasive aspergillosis : update on conventional diagnosis Culture • Can we improve the sensitivity ? (in tissue) • What is the best indirect specimen ? Sputum or BAL • What are the PPV of a positive culture for IA, and the sensitivity of culture to diagnose IA ?

  13. Invasive aspergillosis : update on conventional diagnosis • Performance of a diagnostic test • Caveat • timing of sampling - evolution of the disease • per test vs per episode analysis • patient population • Prior antifungal prophylaxis or therapy

  14. Invasive aspergillosis : update on conventional diagnosis Yield of culture for molds in histopathologic positive samples n= culture positive Autopsy samples 23 12 52% Surgical or biopsy tissue 30 9 30% Tarrand JJ et al., Am J Clin Pathol 2003; 119: 854

  15. Invasive aspergillosis : update on conventional diagnosis Culture Can we do better ? Mimic physiologic termperature and decreased oxygen environment : 35°C, 6% O2 -10% CO2  significant increase of Aspergillus spp from autopsy tissue and various clinical samples (+ 31%) Tarrand JJ et al., J Clin Microbiol 2005; 43: 382

  16. Invasive aspergillosis : update on conventional diagnosis Culture : BAL is better than sputum (?) Overall sensitivity 50% Adapted from Reichenberger et al., Bone Marrow Transplantation 1999; 24: 1195 Diagnostic yield of bronchoscopy specimen in histologically proven IPA No. of cases Bronchoscopy diagnostic Albeda 1984 15 14 5 36 % Treger 1985 16 12 8 67 % Kahn 1986 17 27 13 48 % Saito 1988 18 9 0 0 % Levy 1992 11 16 9 56 % Mc Whinney 1993 19 12 6 50 % Saugier-Weber 1993 2 10 3 30 % Von Eiff 1995 12 12 6 50 % Horvath 1996 8 29 11 38 % Caillot 1997 20 18 8 45 % Baron 1998 4 13 8 61 % Reichenberger 1999 9 23 7 30 % Overall 195 84 43 %

  17. Invasive aspergillosis : update on conventional diagnosis The paradox of a positive sputum culture for Aspergillus low sensitivity for IA low specificity for IA Can we improve ?

  18. Invasive aspergillosis : update on conventional diagnosis How to increase the PPV for IA of a positive sputum culture • at (high) risk patient • multiple positive samples 1) • quantitative culture 1) 2) • use of a score 2) 3) 1) Nalesnik et al., J Clin Microbiol 1980; 11: 370 2) Greub and Bille, Clin Microbiol Infect 1998; 4: 710 3) Bouza and Muñoz, J Clin Microbiol 2005; 43: 2075

  19. Invasive aspergillosis : update on conventional diagnosis Positive predictive value of a positive sputum culture for IA Highly variable (15-77%) Depends on host factors allo BMT 60% leukemia + neutropenia 70-80% SOT 20-60% HIV/AIDS 14-20% Corticosteroids 20% Perfect et al. (MSG), Clin Infect Dis 2001; 33: 1824 Yu et al., Am J Med 1986; 81: 249 Horvath and Dummer, Am J Med 1996; 100: 171

  20. Invasive aspergillosis : update on conventional diagnosis Prospective assessment of the clinical signi- ficance of isolating A.fumigatus by culture 404 A.fumigatus positive cultures (260 patients) 90 (22.3%) from 31 (12%) patients with IA 6% if 1+ cult. 18% 2+ 38% 3+ 10% if 1-2 score 40% 3-4 70%  5 Bouza et al., J Clin Microbiol 2005; 43: 2075 Score Criteriapoints Invasive procedure 1  2 + cultures 1 Leukemia 2 Corticosteroids 2 Neutropenia 5

  21. Invasive aspergillosis : update on conventional diagnosis Radiology 2 interesting recent findings : Systematic CT• is more sensitive than galactomannan for early detection of IA1) • reduces the amount of antifungal therapy when combined to GM screening2) Angio CThas a higher specificity than CT for IA3) 1) Weisser et al., Clinical Infectious Diseases 2005; 41: 1143 2) Maertens et al., Clinical Infectious Diseases 2005; 41: 1242 3) Sonnet et al., Am J Roentgenol 2005;184:746

  22. Invasive aspergillosis : update on conventional diagnosis • Conclusions • Conventional diagnosis of IA is : • suboptimal • indispensable  genus, species  AFST • perfectible

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