Old tests, quick results J Peter Donnelly BSc FIMLS MIBiol PhD Department of Haematology University Medical Centre St Radboud Nijmegen, The Netherlands

1
The importance of epidemiology in the diagnosis
of invasive fungal infections J Peter Donnelly
BSc PhDDepartment of HaematologyUniversity
Medical Centre St RadboudNijmegen, The
Netherlands
2
Some issues

• Microscopy and culture are essentially
  unavailable to microbiologists with respect to
  invasive fungal infections (IFI)
• Because
• IFI commonly affects the lungs initially but
  cases can easily go unnoticed
• Even when recognized early, suitable specimens
  can be difficult to obtain
• Tests for detecting fungal pathogens in clinical
  material (particularly blood) are available, but
  there is no consensus about their clinical
  utility
• Hence
• many expect nothing from diagnosis and do not
  even attempt to make one. The resulting lack of
  adequate diagnoses makes estimating the
  prevalence and incidence of IFI unreliable.

3
Epidemiology

• This dismal state of affairs serves only to
  emphasize the importance of epidemiology since,
  in order to determine the value of any diagnostic
  test or battery of tests, one has to know the
  underlying prevalence of the disease,
  particularly when this is low.
• The first questions are-
• Who gets IFI?
• What do they get and how?
• When do they get?

4
Who gets IFI?
5
Candidaemia in French hospitals
Incidence/ 1000 admissions Total 0.29 General
hospital 0.17 Teaching hospital 0.38 Cancer
center 0.71
origin central line 26 digestive tract 11
unknown 43
Andremont et al, ICAAC 1998, San Diego
6
Risk factors for invasive candidosis

• Risk factor Cancer ICU
• Neutropenia, HSCT, chemotherapy,
• GvHD, mucosal barrier injury
• Candida colonisation
• Broad-spectrum antibiotics
• Haemodialysis, azotemia
• Central venous catheter
• Severity of illness
• Hyperalimentation
• Recurrent/persistent GI tract perforation
• Prior surgery
• Neonatal ICU (age, low APGAR,
• LOS, shock, H2 blockers, intubation)

Rex Sobel Clin Infect Dis 2001 321191
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Incidence of invasive fungal infections among
solid organ transplant recipients

• Transplant IFI
• Renal 1.4 - 14
• Heart 5 - 21
• Liver 7 - 42
• Lung heart/lung 15 - 35
• Small bowel 40 - 59
• Pancreas 18 - 38

Aspergillus
Candida
Singh Clin Infect Dis. 2001 31 545
8
Timing of fungal infections after solid organ
transplant
CMV
Candida
Aspergillus
Cryptococcus
Endemic fungi
Pneumocystis
1
2
3
4
5
6
7
8
0
Snydman Clin Infect Dis. 2001 33 S5
9
Incidence of fatal fungal infections amongst
patients other than those with HIV in the USA
Candidiasis
Aspergillosis
Mc Neil et al 2001 Clin Infect Dis 33641
10
Invasive candidiasis, colonisation and bacteraemia
81 patients
NO
YES
46
35
Bacteraemia

Colonisation
-


-

14
24
8
7
13
15
Acute Invasive Candidiasis
1
0
0
0
1
8
Guiot et al, Clin Infect Dis 1994 18525-32 641
11
MBI and invasive Candida infections
Risk group Colonisation Mucosal barrier
injury Treatment Low no no no Intermediate
no yes no yes no yes or no High
risk yes yes yes
depending on other predisposing factors
12
Invasive aspergillosis and underlying disease

• Condition range ()
• Chronic granulomatous disease 25-40
• Lung heart transplant 19-26
• Liver transplant 1.5-10
• Heart renal transplant 0.5-10
• AIDS 0-12
• SCID 3.5
• Burns 1-7
• SLE 1
• Acute leukaemia 5-24
• Allogeneic HSCT 4-9
• Autologous HSCT (no growth factors) 0.5-6
• Autologous HSCT (with growth factors) lt1

Denning Clin Infect Dis 2001 26 pp781-805
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Incidence of invasive aspergillosis under various
conditions
haematopoietic stem cell transplant
0 10 20 30
40
Denning. Clin Inf Dis 1998
14
Incidence of invasive aspergillosis in transplant
recipients
Transplant type incidence () Lung
8.4 Haematopoietic stem cell 6.4 Autologous
2.6 Allogeneic Related donor 6.7 Unrelated donor
10.3 Heart 6.2 Liver 1.7 Pancreas
1.3 Kidney 0.7
Paterson et al. Medicine 199978123-38.
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Aspergillosis at autopsy - sites of infection
1187 autopsies 1993 - 1996 48 (4) aspergillosis
aspergillosis
Lungs only
Disseminated
CNS only
Disseminated (not lungs)
Vogeser et al Eur J Clin Microbiol Infect Dis
199918 42-45
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Explaining the current trends in opportunistic
fungal infections

• Increase in number of susceptible hosts
• New medical methods
• HSCT - CD 34 selection
• Advances in surgical techniques for solid
  transplant
• immunesuppressive regimens for solid transplant
• More conservative approach
• Less use of corticosteroids
• Use of novel agents
• Antimicrobial prophylaxis
• Fluoroquinolones for Gram negative bacilli
• Fluconazole for Candida
• Ganciclovir for CMV
• Improved laboratory expertise
• detection
• identification

Singh Clin Infect Dis 2001 331692
17
Who gets IFI?
Haematological malignancy Allogeneic HSCT
HIV
Invasive fungal infections
Transplant
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What do they get and how?
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The main players
Opportunity knocks!
Hi Bud!
Hi pal!
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How do they get it?
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Candida - colonisation
Candida albicans Candida tropicalis
Candida parapsilosis Candida albicans
Candida albicans Candida glabrata Candida krusei
22
Model for invasive candidiasis
GI tract
antibiotics
injury
selection
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Aspergillosis
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Aspergillus from the breeze or the bucket
Graybill Clin Infect Dis 2001 26 pp781-805
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What do they get and how ?

• Mainly Candida albicans or Aspergillus fumigatus
• prior colonisation with Candida species is a
  prerequisite for infection
• Spores of Aspergillus and other moulds are
  inhaled directly through the air or indirectly
  from aerosols of contaminated water

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When do they get it?
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Time to diagnosis of aspergillosis after BMT
20 18 16 14 12 10 8 6 4 2 0
Cases
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
160 170 180 gt180
days after transplant
Wald et al J Infect Dis 19971751459
28
Aspergillosis following HSC transplant
ENGRAFTMENT
EARLY POST-ENGRAFTMENT
41
40
39
Temperature C
38
37
36
10
Granulocytes (log10 1x 106/L)
1
0.1
Days
Months
Weeks
Transplant
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Source of stem cells and GVHD
Cutler et al 2002 J Clin Oncol 193685-3691
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Source of stem cells and GVHD
Cutler et al 2002 J Clin Oncol 193685-3691
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HEPATOSPLENIC CANDIDIASIS
FEVER
ALKALINE PHOSPHATASE
NEUTROPHILS
DISSEMINATION
MICROCOLONIES
"BULLS EYE"
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when do they get?

• Both candidiasis and aspergillosis occur during
  neutropenia but also manifest themselves later
  after bone marrow recovery.
• Patients are at risk of aspergillosis for as long
  as they have active GvHD or are receiving high
  dose corticosteroids

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Diagnosis
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Sites of infection
Moulds
Yeast
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Defining invasive fungal infection
Ascioglu et al 2002 Clin Infect Dis 347-14
36
Defining infection - Host factors
Ascioglu et al 2002 Clin Infect Dis 347-14
37
Defining infection - Clinical features
Ascioglu et al 2002 Clin Infect Dis 347-14
38
Defining infection - Clinical features
Ascioglu et al 2002 Clin Infect Dis 347-14
39
Defining infection - Mycology
antigen in BAL, CSF or blood
Ascioglu et al 2002 Clin Infect Dis 347-14
40
Proven invasive fungal infective disease
Ascioglu et al 2002 Clin Infect Dis 347-14
41
Probable invasive fungal infective disease
Ascioglu et al 2002 Clin Infect Dis 347-14
42
Possible invasive fungal infective disease
Ascioglu et al 2002 Clin Infect Dis 347-14
43
EORTC/MSG definitions of fungal infections
-aspergillosis
Clinical features
Host factor
Mycology


antigenaemia
GVHD
Probable disease
Halo sign on chest CT scan
OR
cough

pleural rub
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EORTC/MSG definitions of fungal infections
-candidosis
Clinical features
Host factor
Mycology

Neutropenia
Small, peripheral, target-like abscesses (Bulls
eye) in liver and/or spleen demonstrated by CT,
MRI or ultra sonogram.
Probable disease
/-
elevated alkaline phosphatase
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Strategy
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Aim of the strategy
By using techniques that offer a high negative
predictive value i.e. a low false-negative rate
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Risk factor selection
Risk factors
diagnosis
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Screening test for a potentially fatal disease
with a low prevalence
Controls
Tests

-
-
-


49
A strategy for managing pulmonary aspergillosis
At risk
EORTC/MSG criteria
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A strategy
At risk
eg. CT scan halo-sign or air-crescent sign
therapy
wait-and-see
Pre-emptive therapy
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Obtaining a specimen - tools of the trade
Bronchoscopy
Sputum
Bronchoalveolar lavage
Fine needle aspirate
Biopsy
Brush
Lung biopsy
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Bronchoscopy specimen - processing
BAL
Culture
Aerobic bacteria S. pneumoniae, Ps
aeruginosa Enterobacteria Klesiella
spp Legionella spp Mycobacteria M.
tuberculosis Nocardia spp Mycoplasma
spp Yeasts Candida spp Moulds A.
fumigatus Virus CMV, HSV, RSV
10-20 mL
cytology
Gram Giemsa Silver Acid-fast stain IFA -Legionella
10-20 mL
Cytospin
Centrifuge 500 g 5 min
Shell vial culture
IFA -CMV -HSV - RSV influenza A B
Martin et al 1987 Mayo Clin Proc 62549-557
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Invasive Fungal Infection
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Conclusions

• Patients at risk are better known
• The timing of the risk is better understood
• Diagnosis is improving
• Criteria now exist for defining invasive mycosis