Early Diagnosis and Pre-emptive Therapy of Fungal Pneumonia in High Risk Patients: Current Thinking Kieren Marr MD Fred Hutchinson Cancer Research Center.

Early Diagnosis and Pre-emptive Therapy of Fungal

Pneumonia in High Risk Patients: Current Thinking

Kieren Marr MD

Fred Hutchinson Cancer Research Center

University of Washington

Seattle, WA

A case

58 year old F with Hodgkin’s lymphoma received autologous BMT after conditioning with “BuMELT”.

2 days after BMT noted to have what appeared to be a cellulitis in R foot, CNS bacteremia. Treated with imipenem and vancomycin.

3 days afterwards, developed hypotension requiring 3 pressors, acute renal failure, severe metabolic acidosis, DIC. Small myocardial infarct likely by enzymes; TTE showed good EF.

Exam revealed early gangrenous lesion on R 2nd toe. CXR- ‘bibasilar atelectasis’. Received imipenem, ciprofloxacin, vancomycin, caspofungin. Hemodialysis as tolerated.

3 days later, better. Off pressors. Exam: foot worse (all toes). Pelvic ‘ischemia’ (no signs of soft tissue infection). Blood cultures all without growth.

CT abd and pelvis: fluid. Lungs: BL consolidations

What do you want to do:

1. BAL. Continue current antifungal therapy

2. BAL. Change to caspofungin to voriconazole

3. BAL. Change to lipid based amphotericin B formulation

4. Change to voriconazole empirically. Obtain serum GM EIA

5. None of the above

Early Diagnosis

and Pre-emptive Therapy

Antifungal therapy administered late is rarely successful– Dependent on immune system of the

host and extent of disease

– What is late?? With culture documentation of disease

High disease burden when radiographic abnormalities become apparent

Sensitivity of culture is very poor Organisms are difficult to cultivate in the

lab

Establishing culture-defined diagnoses are difficult– Review of 391 cases of IFI in patients with

hematological malignancies, 20011

Diagnosis made pre-mortem 79% BAL culture sensitivity 66%

1Pagano et al. Pagano et al. Haematologica 86 Haematologica 86

(2001)(2001)

How to Diagnose Early

CXR screening lacks sensitivity

Patients at risk require screening based on more sensitive parameters

– Early CT scans with signs / symptoms of disease

– Serial CT scans in patients at risk

Day 0: halo Day 4: size, halo Day 7: air crescent

Caillot et al, J Clin Oncol 2001: 19(1)

Halo Signs

Lee et al. Brit J Radiol Lee et al. Brit J Radiol 78 (2005)78 (2005)

Radiographic Abnormalities Vary

Post-engraftment IA

Kojima et al. BBMT 11(7): 506-11 (2005)Kojima et al. BBMT 11(7): 506-11 (2005)

Radiography

Sequential CT characterized in 45 patients with IPA1

– No radiographic finding predicted outcome

PET scans may be useful for early diagnosis 2,3

1Horger et al. Eur J Radiol Horger et al. Eur J Radiol 55 (2005)55 (2005)

22Hot et al. ICAAC 2006 Hot et al. ICAAC 2006 M1307M1307

33Li et al. ICAAC 2006 M1684Li et al. ICAAC 2006 M1684

BAL for diagnosis

Nonspecific findings warrant evaluation for microbial etiology– Different therapies; frequent co-

pathogens

Problem:– BAL culture is not sensitive

Sensitivity 50-65% of cases of documented IA

Ways to make facilitate diagnosis? – Culture under different conditions

Adjunctive tests– Serum based assays

Galactomannan EIA, qPCR, glucan

– Adjunctive assays on BAL fluid Galactomannan EIA, qPCR

Diagnostic Tests for

Aspergillosis

Natural history of infection not well understood

– When do people become infected?

How do you analyze sensitivity and specificity with multiple test results in one patient?

– Per-patient analysis

– Per-test analysis

Imperfect gold standard tests

– False or true positive?

Marr and Leisenring. Marr and Leisenring. Clin Infect Dis 2005:41: Clin Infect Dis 2005:41:

S381S381

GMEvolution of

Testing Methods

dsELISA: Bio Rad Platelia EIA–Measures GM using rat EBA-2

monoclonal antibody as acceptor and detector

–0.5-1 ng/mL galactomannan Results: OD index

Mennenk-Kersten et al Lancet Infect Dis 2004 4 349

Frequent false-positives in children

Aspergillosis

Galactomannan EIA

Marr and Leisenring Clin Infect Dis 2005; 41:S381

Issues Antifungal administration decreases sensitivity of the assay1

– Variability in the literature

– Challenges current preventative paradigms

False positive tests occur– lactam antibiotics containing GM

(or cross-reactive antigen)

– GI tract translocation of GM (or cross-reactive antigen)

– Other infections: Histoplasmosis3

1Marr et al. Clin Infect Dis 2005; 40: 1762-9

2Machetti and Viscoli. Antimicrob Agents

Chemother 2005 49(9)3Wheat et al. ICAAC 06

Diagnostic tests relying on identification of (1-3)--D-Glucan

Activates Limulus amebocyte lysate

Factor G initiates cascade. Output measured by – Turbidity after gel clot: WB003 (Wako Pure Chem. Indust.)1

– Chromogenic substrate: Fungitec G test (Seikagaku) and Fungitell, (Assoc. Cape Cod)2

Endotoxin (1-3)--D-glucan

Factor C Activated Fact. C Activated Fact G Factor G

Factor B Activated Fact. B

Proclotting Enzyme Clotting Enzyme

Coagulogen Coagulin (gel) 1

Chromogenic method 2

D glucan Performance not calculated from

large numbers of patients with fungal pneumonia

Smaller studies: sensitivity in setting of IA – 80%

Recent observations– 555 assays, 320 patients

– 74 positive tests

– 49 patients proven / probable IFISensitivity 71%

– Positive in several IFIsPCP

Ostrosky-Zeichner et al. Clin Ostrosky-Zeichner et al. Clin Infect Dis 2005; 41:654Infect Dis 2005; 41:654

Koo et al. ICAAC 2006 (M-1600)Koo et al. ICAAC 2006 (M-1600)Marty et al. ICAAC 2006 (M-Marty et al. ICAAC 2006 (M-

1606)1606)

Utility of Galactomannan Detection in BAL Samples

# pt

160

Sens

(%)

Spec

(%)

PPV

(%)

NPV

(%)

Serum 47 93 73 82

BAL 85 100 100 88

Becker et al. Br J Haematol 2003; 121: 448

Musher et al. J Clin Microbiol 2004: 42(12): 5517-22

Early Diagnostic

s

Current standard of relying on culture based detection of filamentous fungi is not adequate

Need to incorporate adjunctive diagnostic tests in patients who have signs of disease (radiographic abnormalities)

Can these tests be used “pre-emptively”?

Pre-emptive Therapy ?

-7-7 00 77 1414 2121 2828 3535 4242 4949 5656-14-14

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DayDay

ProphylaxisProphylaxis

EmpiricalEmpirical

Pre-emptive approachPre-emptive approach

Risk based approachBiomarker approach

6363

Screening for Early

Diagnosis PCR assays and immunoassays (GM EIA) have been studied– Particularly strong negative

predictive values

Can diagnostic assays be used to spare empiric therapy in patients who are receiving prophylaxis? – Nested PCR to guide antifungal

therapy1

42 patients with cancer, neutropenia

AmB required in only 2 patients

11Lin et al. Lin et al. Clin Infect DisClin Infect Dis. . 2001;33:1621-1627.2001;33:1621-1627.

Galactomannan EIA

Followed 136 episodes to neutropenia to see if GM EIA can be used to avoid empirical therapy– Patients receiving

fluconazole prophylactically

– 3 breakthrough infections 2 candidemias1 Zygomycetes

Maertens et al. Clin Infect Dis 2005; 41: 1242

Risk-based approach: Posaconazole in SCT Recipients

with GVHD Randomized, double-blind

– Posa: 200 mg po tid (301 Pts)

– Flu: 400 mg po qd (299 Pts)

Drug: GVHD-- to 112 days (16 wks)

Outcomes measured after 16 weeks

Decreased probability of IFI; IA

Many patients who developed IA had a positive GM EIA at randomization

– Can this be used to guide therapy?

Ullmann AJ, et al. Presented at the 45th Interscience Conference on Antimicrobial Agents and Chemotherapy. Dec. 16-19, 2005. Washington, DC.

Targeted therapy

Consider observation that everyone exposed to this organism, yet only 10% develop disease– Are there “biologic risks” that can be

measured and more predictive than clinical variables?

Epidemiologic studies: role of cellular immunity in conferring risks for late IA1

– CD4+ T cells with Th1-type cytokine: protective

Immune-reconstitution studies confirmed importance of cellular immunity2

Developed functional assays to measure Aspergillus-specific PBMC responses – Upcoming study to measure Aspergillus-

specific immune reconstitution in allogeneic HSCT patients

1Marr et al. Blood; 100(13):4358-66

(2002) 2Storek et al. Blood; 97(11) 3380-89

(2001)

Our patient

Serum GM EIA- negative

BAL performed– No growth on culture

– Galactomannan index 0.8 / 1.4

– qPCR (light cycler assay) detected fungal DNA, but not Aspergillus

What would you do? 1. Continue caspofungin

2. Change caspofungin to voriconazole

3. Change caspofungin to Ambisome

4. Add voriconazole

5. Add Ambisome

Outcome Progressive pulmonary infection;

therapy withdrawn

Autopsy– Large fungal infarcts in both upper

and lower lung lobes bilaterally

– Erythema and necrosis of vagina, urethra, lower ¾ of bladder mucosa and uterine cervix: invasive mould

– Gangrenous foot with vascular involvement of mould

– Splenic infarcts

– Culture of lungs, pelvic swab

Rhizopus microsporus var. rhizopodiformis

Conclusions

Early therapy is an important goal

Microbe-specific given toxicities, differential activities of drugs, and changing epidemiology

Current culture-based standards are not adequate

Multiple adjunctive tests being developed– Need to learn how to apply them

– Clinical study is tricky given inadequate ‘gold standard’ (culture)