European Journal of Internal Medicine 19 (2008) 137 – 139
www.elsevier.com/locate/ejim
Brief report
Limitations of the QuantiFERON®-TB Gold test in detecting
Mycobacterium tuberculosis infection in immunocompromised patients
Mads Hornum a,⁎, Klaus Leth Mortensen b , Anne-Lise Kamper a , Åse Bengård Andersen b
a
b
Department of Nephrology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Received 14 December 2006; accepted 9 March 2007
Available online 14 September 2007
Abstract
Four cases are presented, immunosuppressed by at least three different mechanisms: one HIV-positive patient with a CD4 count of
0.29 × 106/ml, one malnourished patient, and two kidney-transplanted patients. All patients had a negative interferon (IFN)-γ test for suspected
tuberculosis (TB), but a positive culture. We conclude that a negative IFN-γ test does not exclude TB disease in immunosuppressed patients.
© 2007 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.
Keywords: Tuberculosis antigen test; Immunodeficiency; Diagnostic; Specificity; Sensitivity
1. Introduction
Tuberculosis (TB) infects 15 to 20 million people worldwide, of whom approximately 8 million develop active disease annually [1]. In developed countries, TB commonly
affects older individuals, ethnic migrants, and individuals
with human immunodeficiency virus (HIV) infection.
Isolation of Mycobacterium tuberculosis by culture is the
definitive diagnostic test. The tuberculin skin test (TST) is
useful for proving infection, but not necessarily disease. A
positive test only suggests prior exposure to the antigen, not
active infection. If the patient is in an immunosupressed
state, a negative test does not rule out TB infection.
In 2005, a new in vitro test, QuantiFERON®-TB Gold
(QFT; Cellestis, Carnegie, Australia), was introduced as an
aid for diagnosing M. tuberculosis infection, including both
latent infection and TB disease. The test has operational
advantages over the tuberculin test because results can be
available 24 hours after testing, no return visit is required, and
⁎ Corresponding author. Department of Nephrology 2131 Rigshospitalet
Blegdamsvej 9 DK-2100 Copenhagen Denmark. Tel.: +45 3545 1762; fax:
+45 3545 2607.
E-mail address: mads.hornum@rh.dk (M. Hornum).
repeated testing does not cause boosting [2]. Furthermore, the
QFT test is significantly more specific than the skin test, and
data suggest that it also may be more sensitive [3]. Information on the test in immunocompromised individuals is
limited and a warning is attached to the test instruction. The
present report describes four patients with active TB disease
and impaired immune function of various etiologies and with
negative QFT tests. One patient reverted to become responsive during antituberculous (anti-TB) treatment.
2. Case reports
2.1. Case 1
A 62-year-old male kidney-transplanted patient of Indian
origin was admitted to the hospital in June 2004 because of
fever. The patient had a history of arterial hypertension and
type 2 diabetes mellitus (DM) since the age of 44. He was
diagnosed with end-stage renal disease (ESRD) and on
hemodialysis since 2001 until a cadaveric renal transplantation was performed in 2003. He experienced an uncomplicated post-transplantation period with no rejection episodes.
Immunosuppressive treatment included steroids, mycophenolate mofetil (MMF), and cyclosporine. He was investigated
0953-6205/$ - see front matter © 2007 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.ejim.2007.03.020
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M. Hornum et al. / European Journal of Internal Medicine 19 (2008) 137–139
extensively and epithelioid granulomas were found in bone
marrow aspiration. LP was performed and cerebrospinal fluid
analysis tested positive for PCR-TB complex. Acid-fast
bacillus (AFB) microscopy was negative, but growth of
M. tuberculosis was obtained later. The patient fully recovered without sequelae. Analyses with IFN-γ assay in late
July and September tested negative.
2.2. Case 2
A 62-year-old female of Danish origin, HIV-positive since
1995 and under antiretroviral treatment since 1997, was
admitted in June 2004 because of 3 months of loose stools,
night sweats, weight loss, coughing, and tiredness. Expectorated sputum was found inconclusive for PCR-TB and antiTB medication was initiated for a short period. After
termination of anti-TB medication, renewed examinations
were initiated and a computed tomography (CT) scan of the
abdomen showed necrotizing, retroperitoneal lymph node
enlargement, histopathologically consistent with TB, but
negative AFB microscopy. A chest radiograph was normal.
TST was negative, but anti-TB treatment was initiated again in
August. In October 2004, because of slowly increasing lower
back pain and no decrease in C-reactive protein concentration,
a CT scan of the lumbar column was performed and showed a
4 × 7 × 14 cm abscess involving the right psoas muscle. Biopsy
and drainage of abscess material showed AFB on microscopy
and was PCR-TB-positive. An IFN-γ assay in August was
negative. Her immune status was only moderately depressed
with a CD4 count of 0.29 × 106/ml and a fully suppressed
HIV-RNA viral load. She survived without sequelae.
2.3. Case 3
A 58-year-old male, born in Greenland but living in
Denmark for the past 30 years, was admitted in June 2005
following 3 months of a general diseased condition with
significant weight loss, anorexia, fatigue, and productive
cough. He was a smoker and had a history of alcohol abuse.
BMI on admission was 14 kg/m2 and he had a plasma albumin
level of 20 g/l. A chest radiograph showed diffuse right-sided
infiltrates and pneumothorax on the left side. A sputum smear
was AFB-positive. TST was 6 mm. An anti-TB regimen
was initiated but had to be withheld for short periods due to
hepatic toxicity. His general condition, as well as his nutritional status, never really improved despite enteral and
parenteral nutritional supplements. The patient died after
5 months of TB treatment. IFN-γ assay was negative on
admission but reverted to positive after 3 months of treatment.
and ESRD in 2005. In addition, she had hepatitis C infection.
A cadaveric renal transplantation was performed in October
2005. Immunosuppressive treatment consisted of cyclosporine, MMF, and steroids. The post-transplantation course
was complicated by recurrent bacterial infection, which
was treated with antibiotics. A chest X-ray in March 2006
showed diffuse nodular infiltrates. In May, the patient developed pain and tenderness of the lower extremities. Magnetic
resonance imaging showed bilateral necrosis of the head of
the femora but no abscess.
The patient was treated empirically with broad-spectrum
antibiotics until culture of gastric lavage fluid, and later
direct microscopy of pus from an abscess at the femora,
revealed AFB. Also, CSF was PCR-TB-positive. An anti-TB
regimen was initiated. The patient survived. IFN-γ assay in
June tested inconclusive and negative in July.
3. Discussion
The QFT test has been introduced as an improvement in
the diagnosis of TB. The present case series demonstrates that
severe, active M. tuberculosis infection may be associated
with a negative QFT test in patients with impaired immune
function due to immunosuppressive therapy, HIV infection,
or malnutrition. Previously, a negative QFT test was reported
in post-transplant M. tuberculosis infection following liver
transplantation [4]. This is a limitation of the test since TB is
more difficult to detect in immunosuppressed patients.
The QFT test is based on the detection of IFN-γ released
by T cells in response to M. tuberculosis-specific antigens.
The test uses two proteins encoded by a unique genomic
segment that is present in M. tuberculosis. These proteins,
ESAT-6 and CFP10, are major targets for IFN-γ-secreting T
lymphocytes in M. tuberculosis-infected individuals. Patient
response to the ESAT-6 antigen is reported to be 60–80% [5]
and almost the same for the CFP10 antigen [6]. Specific
anergy observed in our patients may be caused by different
mechanisms–pharmacological immunosuppression, HIV-infection, and the poorly defined immunosuppression observed in malnourished patients–and interpretation of this
response in terms of diagnosis and M. tuberculosis infection
should be cautious. Further studies in clinical settings are
required to identify immunological correlates that may
predict when the test is reliable.
4. Learning point
• A negative interferon-γ test does not exclude tuberculous
disease in immunocompromised patients.
2.4. Case 4
5. Competing interest statement
A 54-year-old female of Pakistani origin and living in
Denmark was admitted to the hospital in 2004 due to uremia.
The patient had a history of type 2 DM since the age of 52,
hypertension, and was diagnosed with diabetic nephropathy
“Mads Hornum, Klaus Leth Mortensen and Anne-Lise
Kamper declare that they have no conflict of interests”.
“Åse Bengård Andersen is co-inventor of a patent regarding the use of ESAT-6 as a diagnostic reagent. The
M. Hornum et al. / European Journal of Internal Medicine 19 (2008) 137–139
Statens Serum Institut, Copenhagen, Denmark holds royalties related to this discovery.”
References
[1] Andersen P, Munk ME, Pollock JM, Doherty TM. Specific immunebased diagnosis of tuberculosis. Lancet 2000;356(9235):1099–104.
[2] Mazurek GH, Jereb J, Lobue P, Iademarco MF, Metchock B, Vernon A.
Guidelines for using the QuantiFERON-TB Gold test for detecting
Mycobacterium tuberculosis infection, United States. MMWR Recomm
Rep 2005;54(RR–15):49–55.
[3] Mori T, Sakatani M, Yamagishi F, Takashima T, Kawabe Y, Nagao K,
et al. Specific detection of tuberculosis infection: an interferon-
139
gamma-based assay using new antigens. Am J Respir Crit Care Med
2004;170(1):59–64.
[4] Codeluppi M, Cocchi S, Guaraldi G, Di Benedetto F, De Ruvo N,
Meacci M, et al. Posttransplant Mycobacterium tuberculosis disease
following liver transplantation and the need for cautious evaluation of
Quantiferon TB GOLD results in the transplant setting: a case report.
Transplant Proc 2006;38(4):1083–5.
[5] Ulrichs T, Munk ME, Mollenkopf H, Behr-Perst S, Colangeli R,
Gennaro ML, et al. Differential T cell responses to Mycobacterium
tuberculosis ESAT6 in tuberculosis patients and healthy donors. Eur
J Immunol 1998;28(12):3949–58.
[6] van Pinxteren LA, Ravn P, Agger EM, Pollock J, Andersen P. Diagnosis
of tuberculosis based on the two specific antigens ESAT-6 and CFP10.
Clin Diagn Lab Immunol 2000;7(2):155–60.