Transcript Interpretation of Lyme and Quantiferon Tests

Interpretation of Lyme and
Quantiferon Tests
Thomas M File, Jr MD MSc MACP FIDSA FCCP
Chair, Infectious Disease Division
Summa Health System
Akron, Ohio;
Professor of Internal Medicine,
Chair ID Section
Northeast Ohio Medical University
Rootstown, O
Lyme-stages
 Early (days to weeks after tick bite; minority
recall)
 Erythema migrans (80%), fatigue, malaise , HA, myalgia,
arthralgia, regional lymphadenopathy
 Early disseminated: (weeks to months)
• Musculoskelatal; neuro 15% (lymph meningitis, cranial
neruropathy); carditis 1%
 Late (months to years)
 MS 60%; Neurologic
Early Lyme
Characteristic Rash
Reaction as bacteria move
through body; not
multiple bites
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Photo: T File MD
Lyme-Diagnosis
 Early-clinical with rash; serology little value
 Serology
 2 tiered: ELISA (10% false +) then Western Blot
 VisE C6 ELISA
• Measures AB to major protein sequence
• More accurate, also good for European strains
 Antibodies may persist for years after Lyme disease has been
treated and cured
 PCR
LYME: WESTERN BLOT
Criteria for Western Blot for Lyme
Type of
Isotope
Infection
First few
IgM
weeks
After month IgG
Bands for Dx
Two of: 24,39,41
Five of:
18,23,30,39,41,45,58,6
6,93
Lyme-Diagnosis ??
1. Patient with Erythema Migrans
ELISA negative
2. Patient
with chronic fatigue
ELISA Positive; Western Blot IgG and IgM + band 41*
(+ ANA)
3.Patient with knee swelling X 2 weeks
ELISA Positive; Western Blot: IgM no bands; IgG
+ 18,23,28,30,39,41,45,58,66,93
4.Patient referred for “ Lyme test”
ELISA 1.13 (reference < 0.91); Western Blot: IgM
Neg.; IgG + 41
**Common
Commoncross
crossreactions
reaction
Lyme-Diagnosis ??
5.
37 y/o female with 4 months of neurologic
symptoms and fatigue
ELISA positive; Western Blot-IgM neg.; IGG-5 + bands
6.
41 y/o female with burning of feet
ELISA low +; Western Blot- IgM + one band; IgG-+ 2
bands
7. 38 y/o female with headaches
ELISA +; Wesern Blot IgM neg.; IgG +1 band
8. 57 y/o malePatient with knee swelling X 2 weeks
ELISA +; Western Blot: IgM +1 band; IgG +10 bands
* Common cross reactions
Southern Tick Associated Rash Illness ( STARI)
• B. lonestari; A. americanum feed on whitetailed deer.
• Mild illness with onset of skin lesions
• Doxy 100 mg BD or Amox 500 mg TD X
10 days.
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Transmission of M. tuberculosis



M. tb spread via airborne
particles called droplet
nuclei
Expelled when person with
infectious TB coughs,
sneezes, shouts, or sings
Transmission occurs when droplet nuclei inhaled
and reach the alveoli of the lungs, via nasal
passages, respiratory tract, and bronchi
Pathogenesis
Droplet nuclei containing
tubercle bacilli are inhaled, enter
the lungs, and travel to the
alveoli.
Tubercle bacilli multiply in the
alveoli.
Pathogenesis
A small number of tubercle
bacilli enter the bloodstream
and spread throughout the
body. The tubercle bacilli may
reach any part of the body,
including areas where TB
disease is more likely to
develop (such as the brain,
larynx, lymph node, lung,
spine, bone, or kidney).
Pathogenesis
Within 2 to 8 weeks, special immune
cells called macrophages ingest and
surround the tubercle bacilli. The
cells form a barrier shell, called a
granuloma, that keeps the bacilli
contained and under control (LTBI).
If the immune system cannot keep
the tubercle bacilli under control, the
bacilli begin to multiply rapidly (TB
disease). This process can occur in
different areas in the body, such as
the lungs, kidneys, brain, or bone.
Latent TB Infection (LTBI)




Granulomas may persist (LTBI), or may break down
to produce TB disease
2 to 8 weeks after infection, LTBI can be detected via
TST or interferon-gamma release assay (IGRA)
The immune system is usually able to stop the
multiplication of bacilli
Persons with LTBI are not infectious and do not
spread organisms to others
TB Classification System
Class
0
Stage of Disease
No exposure, no infection
1
2
Exposure, no evidence of
infection
TB infection, no disease
3
TB, clinically active
4
TB, not clinically active
5
TB suspect
Latent TB infection vs TB Disease
Latent TBI
TB Disease
Positive Skin test or Interferon Gamma
Release Assay (IGRA)
Skin Test or IGRA usually +
CXR normal
CXR usually Abnormal
No signs or symptoms
Signs, symptoms present
Culture neg.
Smear, Culture + 50%
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Latent TB (Quantiferon)
 Less subjectively than Skin Test
 No affect of BCG; but may have cross reactivity
with M. kansaii, marinum or szulgari
 Interpretation of Quantiferon test
Quantiferon
Result
comment
Mitogen – Nil
Should be > 0.5
If < 0.5=
“indeterminant”
TB Ag – Nil
Positve > 0.35;
Neg. < 0.35
BUT most < 1.0
are unlikely
LTBI!!
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General Recommendations for
Using IGRAs


Preferred when testing persons
 Who might not return for TST reading
 Who have received BCG vaccination
 Immune suppressed
Generally should not be used to test children <5
years of age, unless used in conjunction with TST
Interpret Quantiferon tests (CXR
neg.)
Patient
Control
Mitogen
TB antigen
50 y/o
Healthcare
Provider
10
5
55 y/o; on
steroids; for
Anti TNF Rx
<0.5
<0.1
45 y/o for Anti
TNF Rx
3
2
40 y/o for
AntiTNF Rx
2
.5
Treat for
LTBI?
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Interpret Quantiferon tests (CXR
neg.)
Patient
Control
Mitogen
10
TB antigen
<0.5
<0.1
45 y/o for Anti
TNF Rx
3
2
40 y/o for Anti
TNF Rx
2
.5
50 y/o
Healthcare
Provider
55 y/o; on
steroids; for
Anti TNF Rx
5
Treat for
LTBI?
yes
No; Repeat
periodically
after anti-TNF
Rx
yes
Repeat Test;
Individualize20