DR' ATUL HUMAR

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INFECTIONS IN SOLID ORGAN TRANSPLANT RECIPIENTS

• DR. ATUL HUMAR
• INFECTIOUS DISEASES / MULTI-ORGAN TRANSPLANTATION

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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

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Definition

• Compromised host
• Patient lacks resistance to infection due to a
  deficiency in defense mechanisms against
  microbial invasion and/or disease
• Inherited or acquired

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PATHOGENESIS
Microbe
Host
DISEASE DETERMINANTS
Defense Mechanisms
Inoculum or Organisms Virulence Latency
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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

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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

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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

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HOST DEFENSE MECHANISMS

• Inflammatory response
• Number (mass) and function of circulating and
  tissue phagocytic cells
• Neutrophils, monocytes, macrophages, spleen
• Humoral Mediators
• Complement, fibronectin

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HOST DEFENSE MECHANISMS

• Specific Immune response
• T-lymphocytes
• CD4, CD (helper, cytotoxic)
• Number, function
• B-lymphocytes
• Make antibodies
• IgG, IgA

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Common problems
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Common problems
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Common problems
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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

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INFECTIONS IN TRANSPLANTATION

• Three main determinants of the risk of infection
• in transplant recipients
• Infections related to technical / surgical
  problems

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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

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INFECTIONS IN TRANSPLANTATION

• Major determinants of the risk of infection

The net state of Immunosuppression
Epidemiological exposures
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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

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NET STATE OF IMMUNOSUPPRESSION

• Metabolic conditions
• Uremia
• Malnutrition
• Diabetes
• Viral infection Immune modulation
• Cytomegalovirus
• Epstein-Barr virus
• Hepatitis B, C, HIV

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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

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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

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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 OIs (eg. PCP) absent in the first month
• Exceptions HSV, HHV6, Candida, Aspergillus

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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

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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

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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

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TIMETABLE - gt 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

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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

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CMV HEPATITIS
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CMV VIRAL LOAD
6
CMV hepatitis
5
4
3
Log viral load
2
1
0
0
25
50
75
100
125
Days Post-transplant
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CYTOMEGALOVIRUS

• Betaherpesvirus
• DS DNA
• Icoshedral capsid
• Lipid envelope
• Establishes latency
• Once infected always infected

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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

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INDIRECT EFFECTS
CMV INFECTION/DISEASE
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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

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CYTOKINE LEVELS AND CMV DISEASE
Humar et al. J Infect Dis 1999 179 484
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MULTIVARIATE ANALYSIS OF RISK FACTORS FOR CMV
DISEASE
Humar et al. Transplantation 2000
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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

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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-? 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

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VIRAL CULTURE MEDIA
6
CMV hepatitis
5
4
3
Log viral load
2
1
0
0
25
50
75
100
125
Days Post-transplant
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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

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HHV-6 RESULTS

• HHV-6 infection occurred in 28 (56/200) patients
  (defined as VL gt 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

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HHV-6 AND CMV
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CMV PREVENTION

• Universal prophylaxis anti-viral therapy to all
  at-risk 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

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PRE-EMPTIVE THERAPY
_
_
_
_
_







TEST
0
4
8
12 weeks
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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

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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 gt0 cells/slide gt400 copies/ml
• Sensitivity, specificity, PPV and NPV for
  different cut-off points
• Multivariate logistic regression for predictors
  of CMV disease

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RESULTS

• CMV disease 21/97 ( 21.7) patients mean 60
  days post-transplant
• 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.

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ROC CURVE FOR CMV QUANTITATIVE PCR
gt0
gt1000
1.00
gt2000
gt5000
0.75
gt7000
Sensitivity
gt12000
0.50
gt15000
gt20000
0.25
0.00
0.00
0.25
0.50
0.75
1.00
1- Specificity
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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
  pre-emptive strategy using optimal cut-offs
• The CMV viral load is the most important
  determinant for the development of CMV disease

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RESPONSE TO THERAPY
8 weeks after treatment relapsed with fever,
Recurrent CMV disease
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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
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VIRAL LOAD KINETICS
yy0eax
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Humar et al. JID 2002
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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

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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)

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Viral Infection
Tumor
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EPSTEIN-BARR VIRUS

• Lytic infection
• 100 genes expressed, lysis of B-cell
• Latent infection
• lt 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

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CASE PRESENTATION

• 34 y.o. male 2 years post-kidney transplant
• On Neoral, Prednisone and Immuran
• Fever, sore throat, and multiple subcutaneous
  nodules

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INVESTIGATIONS

• EBV Viral load gt 1000 copies / 106 PBL
• Biopsy Aggressive, undifferentiated monoclonal
  PTLD, EBV positive
• Withdrawal of MMF, treatment with IV ganciclovir

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6
)
5
-o-
Ganciclovir
4
3
Log viral load (
2
1
0
0
1
2
3
4
TIME (months)
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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 gt lung gt heart gt liver, kidney
• Herpesvirus interactions

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EBV SEMIQUANTATIVE PCR
Timing of Test PTLD No PTLD P-value (log/106)
(log/106) Prior to PTLD 2.9(1.5) 1.4(1.5)
0.005 PTLD Diagnosis 3.1(1.2) 1.4(1.5) lt
0.001 Peak value 3.4(0.5) 1.8(1.5) lt
0.001 (12 months post-transplant)
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EBV PROPHYLAXIS STUDY

• Multicentre RCT in EBV D/R- transplant
  recipients
• Group 1 Ganciclovir CMVIG
• Group 2 Ganciclovir placebo
• EBV viral loads taken at regular intervals
  post-transplant

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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 (n11), kidney
  (n10), lung (n6), and pancreas (n1).
• During the first 6 months post-transplant,
  detectable viremia occurred in 9/13 (69.2)
  placebo patients and 10/15 (66.7) cytogam
  patients

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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