Download INFECTIONS IN TRANSPLANTATION

INFECTIONS IN SOLID ORGAN
TRANSPLANT RECIPIENTS
DR. ATUL HUMAR
INFECTIOUS DISEASES / MULTI-ORGAN
TRANSPLANTATION
OBJECTIVES
• To review the concept of compromised host
• To gain an understanding of the common
infections after transplant
• To gain further understanding into herpesvirus
infections after transplant
– CMV
– EBV
Definition
• Compromised host
– Patient lacks resistance to infection due
to a deficiency in defense mechanisms
against microbial invasion and/or
disease
– Inherited or acquired
PATHOGENESIS
Microbe
Host
Defense
Mechanisms
Inoculum or
Organisms
Virulence
Latency
DISEASE
DETERMINANTS
HOST DEFENSE MECHANISMS
• Intact skin and mucous membranes
– Disrupted due to trauma, burns, ulceration, IV
catheters, surgery
• Types of infection
– Wound infections, burn sepsis, diabetic foot
infection, line sepsis
• Usual organisms
– Bacteria – environmental, endogenous
– Fungi – environmental, nosocomial
HOST DEFENSE MECHANISMS
• Physical removal / clearance of micro-organisms
– Respiratory muco-ciliary clearance
– Peristalsis and dynamics of hollow viscus (gut, bile
ducts, ureter, fallopian tube)
– Maybe abnormal due to underlying disease, surgery,
smoking etc.
• Intact sphincters/valves
• Types of infection
– Pneumonia, urosepsis, biliary sepsis
• Usual organisms
– Bacteria – environmental, endogenous
HOST DEFENSE MECHANISMS
• Endogenous microflora
– Oropharyngeal, gut, skin, vagina
– Important for preventing colonization with
disease causing organisms (competitive)
– Antibiotics remove natural flora
– E.g. C. difficile colitis
• Chemical antimicrobial agents
– Gastric acidity, cutaneous fatty acids
HOST DEFENSE MECHANISMS
• Inflammatory response
– Number (mass) and function of circulating and
tissue phagocytic cells
– Neutrophils, monocytes, macrophages, spleen
• Humoral Mediators
– Complement, fibronectin
HOST DEFENSE MECHANISMS
• Specific Immune response
– T-lymphocytes
• CD4+, CD*+ (helper, cytotoxic)
• Number, function
– B-lymphocytes
• Make antibodies
• IgG, IgA
Common problems
Host Defect:
Inflammatory
response
Common microbes
Neutropenia (<0.5)
Gram negative bacilli,
Staph, Candida,
Aspergillus
Splenectomy
S. Pneumonia, H.
influenza, N. Meningitis
Common problems
Host Defect:
Complement
Common microbes
Early (C3, C5)
S. Aureus, S. Pneumonia,
gram negative bacilli
Late (C6,7,8)
Neisseria species
Common problems
Host Defect:
Immune response
Common microbes
T- Lymphocyte
e.g. HIV, organ transplant Numerous microbes
B-Lymphocyte
S. Pneumonia, H.
influenza, Giardia
INFECTION: BASIC PRINCIPLES
• Inflammatory response attenuated by
immunosup.
• may abolish typical signs/symptoms
• decreased sensitivity of serological, radiological
tests
• Efffects of established infection may be
devastating
• Treatment may have more toxicities
• Rifampin - decrease CsA
• Erythromycin, azoles increase CsA
• Synergistic nephrotoxicity - aminoglycosides, AmB,
septra, cipro, vancomycin, pentamidine
INFECTIONS IN TRANSPLANTATION
Three main determinants of the risk of infection
in transplant recipients
• Infections related to technical / surgical problems
TECHNICAL COMPLICATIONS
• Liver - biliary tree - leaks, strictures
• Lung - bronchial anastomosis necrosis,
dehiscence ; mediastinal fluid collection
• Kidney - uroterocystostomy - leak,
urinoma
• Pancreas - duodenum-bladder;
duodenum-bowel: anastomotic leaks,
abscess
INFECTIONS IN TRANSPLANTATION
Major determinants of the risk of infection
The net state of
Immunosuppression
Epidemiological
exposures
NET STATE OF IMMUNOSUPPRESSION
• Immunosuppressive therapy: dose, duration,
temporal sequence - ‘area under the curve’
• Underlying immune deficiency
• Mucocutaneous barrier integrity: intubation,
drains, catheters, central lines
• Devitalized tissue, fluid collection
• Neutropenia, lymphopenia
NET STATE OF IMMUNOSUPPRESSION
• Metabolic conditions
• Uremia
• Malnutrition
• Diabetes
• Viral infection: Immune modulation
• Cytomegalovirus
• Epstein-Barr virus
• Hepatitis B, C, HIV
EPIDEMIOLOGICAL EXPOSURES
Community
–
–
–
–
Community acquired pneumonia pathogens
Environmental fungi
Enteric bacterial pathogens (salmonella)
TB, zoonosis, HIV, hepatitis viruses
Nosocomial
– MRSA,VRE
– Pseudomonas, MDR gram negatives
– Aspergillus
CASE PRESENTATION
• 61 y.o. male heart transplant 1991
• Stable immunosuppression x years
– cylosporin, prednisone
• 3 week history of progressive leg cellulitis,
fever unresponsive to antibiotics
• Intermittent confusion
TIMETABLE: 0-1 MONTH
• Infections usual to post-op patients
– nosocomial pneumonia, wound, line sepsis, UTI
• Key factors: nature of the operation, technical
skill
• Lung, heart, liver at highest risk
– longer intubation, ICU stay, lines, catheters
• Most OI’s (eg. PCP) absent in the first month
– Exceptions – HSV, HHV6, Candida, Aspergillus
TIMETABLE: 0-1 MONTH
• Also may see
– Infection transmitted with the allograft: eg.
lung transplant with pneumonia or a donor
bacteremia which seeds the vascular
anastamosis
– Pre-existing infection within the recipient made
worse by the transplant
TIMETABLE OF INFECTION
One to 6 months post-Tx
– Maximal period of immunosuppression
– Effect of sustained immunosuppression or
‘area under the curve’
– Opportunistic infections in the absence of
excessive epidemiological hazard
TIMETABLE - 1 TO 6 MONTHS
VIRAL
– CMV, EBV, VZV, HHV-6, Adenovirus, Influenza,
RSV
BACTERIAL
– Nocardia, Legionella, Listeria, TB
FUNGAL
– PCP, Aspergillus, Cryptococcus, endemic
mycosis
PARASITIC
– Toxoplasma, Strongyloides
TIMETABLE - > 6 MONTHS
GROUP 1: Good graft function, minimal
immunosuppression
– Community acquired pneumonia, UTI, OI
based on intense exposure
GROUP 2: Recurrent or chronic rejection,
high level immunosuppression, chronic
viral replication
– Continued risk of opportunistic infections
CASE PRESENTATION
• 55 year old female OLTx for PSC
• Acute rejection: Steroid resistant requiring OKT3
for 10 days (pre-emptive ganciclovir)
• Neoral, prednisone, MMF
• 2 months later presents with fever, malaise,
elevated transaminases
CMV HEPATITIS
CMV VIRAL LOAD
6
CMV hepatitis
Log viral load
5
4
3
2
1
0
0
25
50
75
100
Days Post-transplant
125
CYTOMEGALOVIRUS
• Betaherpesvirus
– DS DNA
– Icoshedral capsid
– Lipid envelope
• Establishes
latency
– “Once infected
always infected”
CLINCAL MANIFESTATIONS
DIRECT EFFECTS
– Asymptomatic viral shedding
– Acute viral syndrome
– Pneumonitis: BMT, Lung Transplant
– Infection of allograft: hepatitis,
pneumonitis, nephritis, myocarditis,
pancreatitis
– Infection of native tissue: GI, CNS,
retina
INDIRECT EFFECTS
CMV
INFECTION/DISEASE
Cellular effects:
Antigen/cytokineexpression
Allograft
Injury
acute
Allograft
Rejection
chronic
Immunosuppression
acute
OB, VBD, graft vasculopathy
PTLD-EBV
Bacterial and fungal infections
ANTILYMPHOCYTE
ANTIBODIES
OTHER
HERPES VIRUSES
REJECTION
SEPSIS/
SURGERY
INFLAMMATION
(CYTOKINES, NF-B)
LATENT
CMV INFECTION
CMV: THE ROLE OF CYTOKINES
•
TNF-a has been shown to stimulate the CMV-IE gene
enhancer/promotor region in a dose-dependent manner leading to
CMV reactivation
•
CMV has direct effects on cytokines: CMV-IE gene products
shown to increase IL-6 and IL-8 gene expression
•
This has been shown to enhance neutrophil trans-endothelial
migration
•
Cytokine mediated PMN recruitment may enhance CMV
dissemination
CYTOKINE LEVELS AND CMV DISEASE
Humar et al. J Infect Dis 1999; 179: 484
Steroids
CsA
MMF
Increasing
viral load
CMV INFECTION
CMV DISEASE
MULTIVARIATE ANALYSIS OF RISK FACTORS
FOR CMV DISEASE
Factor
CMV serostatus
D-/R+
D+/R-*
D+/R+
Peak viral load
(prior to disease)
Steroid boluses
P value
P = 0.57
P = 0.0001
P = 0.35
Induction immunosuppression
Double vs. triple therapy
P= 0.11
Humar et al. Transplantation 2000
OR (95% CI)
OR = 1.40 (1.111.49) †
HHV-6 AND TRANSPLANTATION
• Cytopathic lymphotrophic virus : roseola infantum
• Seroprevalence almost universal by age 2-3
• Post-transplant: implicated as a cause of febrile illness,
hepatitis, pneumonitis and other infections.
• Rates of reactivation estimated from 14 - 82 %
• Its main effect post-transplant may be immunomodulatory
including an interaction with CMV
HHV-6 AND TRANSPLANTATION
• Infection of T-cells results in down-regulation of IL-2 mRNA
and protein synthesis, and a reduction in mitogen-driven
proliferative responses resulting in a cell mediated immune
defect
• HHV-6 infection results in cytokine dysregulation; induction
of TNF-a and other immunomodulatory cytokines
• Interactions among herpesviruses may be more direct,
including specific binding via glycoproteins resulting in
cellular co-infections and facilitating viral spread
VIRAL CULTURE MEDIA
6
CMV hepatitis
Log viral load
5
4
3
2
1
0
0
25
50
75
100
Days Post-transplant
125
HERPESVIRUS INTERACTIONS
• Serial Quantitative HHV-6 in 200 liver transplant
recipients
• Serial Quantitative CMV PCR
• Direct effects and Indirect effects of viral
replication on development of graft rejection and
opportunistic infection were assessed
HHV-6 RESULTS
• HHV-6 infection occurred in 28% (56/200) patients
(defined as VL > 2 logs)
• peak VL occurred at a median of 35 days (mean
44.1 days; range 8-177)
• Symptomatic disease occurred in only 2/200
patients (1%) and presented as fever and
pancytopenia
HHV-6 AND CMV
Outcome
Multivariate model
OR (95% CI)
CMV disease
n=32
HHV-6 infection
Antilymphocyte globulin
Steroid boluses
Immunosuppression
3.27 (1.43-7.51)
3.13 (1.31-7.55)
1.00 (0.84-1.19)
2.15 (0.85-7.50)
P-value
0.005
0.01
0.99
0.094
CMV PREVENTION
• Universal prophylaxis: anti-viral therapy to all ‘atrisk’ patients
• Pre-emptive therapy: anti-viral therapy to
subgroups of ‘at-risk’ patients usually based on
further diagnostic tests aimed at identifying early
viral reactivation
PRE-EMPTIVE THERAPY
CMV disease
TEST
0
_
_ _
+ + + + + + +
4
8
_ _
12 weeks
Could have initiated pre-emptive therapy
CMV IN LIVER TRANSPLANT
RECIPIENTS
PRE-TRANSPLANT: Donor and recipient CMV serology
POST-TRANSPLANT:
• D+/R+, D-/R+
– Week 2-12: Every clinic visit:
 CMV antigenemia
 CMV quantitative PCR
• D+/R-:
– Ganciclovir prophylaxis 12 weeks
 Bloodwork at week 12, 14, 16, 18.
 CMV antigenemia and quantitative PCR testing
STUDY PROTOCOL: CMV IN
LIVER TRANSPLANT RECIPIENTS
OUTCOME:
• CMV disease defined according to biopsy evidence; viral
syndrome based on specific clinical criteria
ANALYSIS:
• Predictive value for antigenemia and PCR
– Positive: >0 cells/slide; >400 copies/ml
– Sensitivity, specificity, PPV and NPV for different cut-off points
– Multivariate logistic regression for predictors of CMV disease
RESULTS
• CMV disease: 21/97 ( 21.7%) patients; mean 60 days posttransplant
• PCR: sensitivity of 100%, specificity 47.4%, PPV 34.4 % and
NPV 100% for prediction of CMV disease
• Antigenemia: 95.2%, 55.3%, 37.0% and 97.7 %.
• The optimal cut-off for PCR in the range of 2000-5000
copies/ml (sensitivity 85.7%, specificity 86.8%, PPV 64.3%,
NPV 95.7)
• The optimal cut-off for antigenemia was in the range of 6
positive cells/slide.
ROC CURVE FOR CMV QUANTITATIVE PCR
>1000
>0
1.00
>2000
>5000
0.75
Sensitivity
>7000
>12000
0.50
>15000
>20000
0.25
0.00
0.00
0.25
0.50
1- Specificity
0.75
1.00
PREEMPTIVE THERAPY
• CMV antigenemia or CMV quantitative PCR useful
for predicting the development of CMV disease
• Either of these tests could be employed in a preemptive strategy using optimal cut-offs
• The CMV viral load is the most important
determinant for the development of CMV disease
RESPONSE TO THERAPY
6
Log viral load
CMV hepatitis
5
4
3
2
1
0
0
25
50
75
100
125
Days Post-transplant
8 weeks after treatment relapsed with fever,
Recurrent CMV disease
RESPONSE TO THERAPY
• Virologic response to therapy assessed in
52 patients with CMV disease treated with
ganciclovir
• Viral loads done at regular intervals after
starting treatment
• Genotypic resistance testing
• Clinical response to treatment : Relapsing
disease occurred in 24% of patients
Humar et al. JID 2002
VIRAL LOAD KINETICS
y=y0eax
Viral load (log10 copies/ml)
6
5
4
3
2
1
0
0
10
Time20
(days)
30
40
FIGURE 1
Patient 1
Patient 2
6
5
5
4
4
3
3
2
2
T1/2 = 1.3d
1
T1/2= 1.6d
1
0
0
0
5
10
15
20
25
0
5
Time (days)
10
20
25
Time (days)
Patient 3
6
15
Patient 4
6
5
5
4
4
3
3
2
T1/2 = 4.5d
2
1
T1/2 = 6.2d
1
0
0
10
20
Time (days)
30
40
0
0
10
20
30
40
50
60
Time (days)
Humar et al. JID 2002
Factor
Viral load at onset
(log10 copies/mL)
Mean  S.D.
(median; range)
Time to clear CMV
(days)
Mean  S.D
(median; range)
Viral load half-life
(days)
Mean  S.D
(median; range)
Number who cleared
viral load n (%)
No relapse
(n=40)
Relapse
(n=12)
P-value
4.82  4.94
(4.67; 2.865.66)
4.73  4.67 P=NS
(4.65; 3.795.22)
17.2  9.3
(16; 5-43)
33.8  11.6
(30; 21-47)
3.17  3.35
(1.94; 0.7218.2)
8.83  6.30 P=0.001
(6.61; 1.2319.7)
39 (97.5%)
5 (41.7%)
P=0.002
P<0.001
CONCLUSIONS
• Different people have different rates of
response to antiviral therapy
• Early phase kinetics are predictive of
relapsing disease.
• Differential response likely combination of
– Host factors - CTL, immunosuppression
– Viral Factors – genotype, immune evasion
genes
EBV AND PTLD
DEFINITION
• An abnormal proliferation of B-cells
driven by EBV
– May be polyclonal or monoclonal
– (occasional tumors are T-cell, NK cell)
PTLD
Viral Infection
Tumor
EPSTEIN-BARR VIRUS
• Lytic infection
– ~100 genes expressed, lysis of B-cell
• Latent infection
–
–
–
–
< 10 genes expressed
LMP 1,2, EBNA 1,2,3, EBER, BCRF, BHRF, BARF
Evades host immune response
Latent gene products drive B-cell proliferation
Lytic
Growth
advantage
Cytogenetic
abnormality
latent
BCRF-1
LMP-1
IL-1,6,10
Polyclonal
Monoclonal
Malignant
transformation
CASE PRESENTATION
• 34 y.o. male 2 years post-kidney transplant
• On Neoral, Prednisone and Immuran
• Fever, sore throat, and multiple
subcutaneous nodules
INVESTIGATIONS
• EBV Viral load > 1000 copies / 106 PBL
• Biopsy – Aggressive, undifferentiated
monoclonal PTLD, EBV positive
• Withdrawal of MMF, treatment with IV
ganciclovir
Log viral load (-o-)
6
5
Ganciclovir
4
3
2
1
0
0
1
2
3
TIME (months)
4
RISK FACTORS FOR PTLD
• EBV D+/R– 1-5% incidence in R+ vs. 20-30% in R-
• Intensity of Immunosuppression
• Type of transplant
– Small bowel > lung > heart > liver, kidney
• Herpesvirus interactions
EBV SEMIQUANTATIVE PCR
Timing of Test
PTLD
(log/106)
No PTLD
(log/106)
P-value
Prior to PTLD
2.9(1.5)
1.4(1.5)
0.005
PTLD Diagnosis
3.1(1.2)
1.4(1.5)
< 0.001
Peak value
(12 months
post-transplant)
3.4(0.5)
1.8(1.5)
< 0.001
EBV PROPHYLAXIS STUDY
• Multicentre RCT in EBV D+/Rtransplant recipients
– Group 1: Ganciclovir + CMVIG
– Group 2: Ganciclovir + placebo
• EBV viral loads taken at regular
intervals post-transplant
EBV PROPHYLAXIS STUDY
• Viral load data was analyzed from 28 (20 pediatric
and 8 adult) patients (15 cytogam and 13
placebo).
• Transplant types were liver (n=11), kidney (n=10),
lung (n=6), and pancreas (n=1).
• During the first 6 months post-transplant,
detectable viremia occurred in 9/13 (69.2%)
placebo patients and 10/15 (66.7%) cytogam
patients
SUMMARY
• Reactivation of herpesviruses post-transplant are
due to a complex interaction of multiple factors
• Viral infections likely produce multiple direct and
indirect effects on the post-transplant course of
these patients
• Efforts to minimize the impact of these infections
should lead to improvement in graft outcomes