Comparison of interferon-gamma whole blood assay with tuberculin skin test for the diagnosis of tuberculosis infection in tuberculosis contacts

Autor: Neşe Öztürk, Süheyla Sürücüoğlu, Nuri Özkütük, Hörü Gazi, Sinem Akçalı, Galip Köroğlu, Candan Çiçek
Přispěvatelé: Ege Üniversitesi
Jazyk: turečtina
Rok vydání: 2007
Předmět:
Popis: Latent tüberküloz (TB) enfeksiyonunun tanısı için kullanılan tüberkülin deri testinin, kullanılan antijenin çevresel mikobakteriler ve BCG susu ile çapraz reaksiyonuna bağlı yalancı pozitif sonuçlar vermesi, immünsüpresyon durumunda ya da yanlış uygulama sonucu yalancı negatif sonuçların alınabilmesi ve testin uygulama ve değerlendirme zorlukları gibi birçok dezavantajı vardır. Son yıllarda geliştirilen bir yöntemde ise, Mycobacterium tuberculosis'e özgül antijenlerin uyarısı ile tam kanda interferon (IFN)-gama üretimi ölçülebilmektedir. Bu yöntemde kullanılan ESAT-6 ve CFP-10 antijenleri, BCG aşı susunda ve birçok çevresel mikobakteride bulunmadığından, T hücre yanıtını belirleyen IFN-gama düzeyinin tüberküloz basiline özgül olduğu kabul edilmektedir. Bu çalışmanın amacı, temaslılarda latent tüberküloz enfeksiyonunun belirlenmesinde tüberkülin deri testi ile tam kan IFN-gama testinin (QuantîFERON®-TB Gold, Cellestis Ltd, Carnegie, Victoria, Australia) karşılaştırılmasıdır. İki test sonucunun karşılaştırılmasında Kappa (K) uyum analizi metodu kullanılmış; K değerinin 0.75 olması yüksek uyum olarak kabul edilmiştir. Çalışmaya üç farklı risk grubundan toplam 233 hasta alınmıştır. Grup 1; yayma pozitif indeks olgu ile temas eden aile içi temaslılardan (n=133), Grup 2; yayma pozitif indeks olgu ile temas eden aile dışı temaslılardan (n=46) ve Grup 3; TB'lu hastalarla ya da örnekleriyle ilişkisi olan sağlık personelinden (n=74) oluşmaktadır. Çalışılan olgularda tüberkülin deri testi %37, IFN-gama testi ise %42 pozitif sonuç vermiştir. Olgu grupları arasında tüberkülin deri testi pozitifliği yönünden önemli bir fark saptanmamış (p>0.05), ancak IFN-gama kan testi pozitifliği, aile içi temaslılarda diğer iki gruptan daha yüksek (%51.3, p=0.013) bulunmuştur. Toplam 233 olgunun %65.7'sinde test sonuçları zayıf ölçüde uyumlu (K=0.28, p
Tuberculin skin test which is used for the detection of latent tuberculosis (TB), has many disadvantages such as false positivities due to cross reactions between environmental mycobacteria and BCG strain, false negativities due to immunosuppression and malpractice, and also difficulties in application and evaluation. Recently a new diagnostic test which measures the production of interferon (IFN)-gamma in whole blood upon stimulation with specific ESAT-6 and CFP-10 antigens of Mycobacterium tuberculosis has been introduced. Since most of the mycobacteria other than tuberculosis and BCG strain do not contain these antigens, the detection of IFN-gamma levels indicates the specific T-cell response against M.tuberculosis. The aim of the study was to compare the tuberculin skin test and whole blood IFN-gamma assay (QuantiFERON®-TB Gold, Cellestis Ltd, Carnegie, Victoria, Australia) for the identification of latent TB infection in the contacts with active TB patients. The tests results were evaluated by using Kappa (K) analysis, and K coefficients of 0.75 were accepted as poor, moderate and excellent agreements, respectively. A total of 233 subjects from three risk groups were included to the study. Group 1 included the household members (n=133) who had contact with smear positive index cases, Group 2 included the subjects from community (n=46) who had contact with smear positive index cases, and Group 3 included health care workers (n=74) who had contact with TB patients or their specimens. The positivity rates of tuberculin skin test and IFN-gamma assay in the cases were found as 37% and 42%, respectively. There were no significant differences among the three patient groups with regard to the results of the tuberculin skin test (p>0.05). However, the positive result of the IFN-gamma assay in Group 1 was found statistically higher than the other groups (51.3%, p=0.013). A poor agreement between the two tests was detected in the results taken from 233 subjects (65.7%, K=0.28), while agreement was moderate in unvaccinated group (72.7%, K=0.44). Evaluation of agreement rates of the tests according to the risk groups yielded 64.6% (K=0.3) for Group 1, 71.7% (K=0.32) for Group 2, and 63.5% (K=0.21) for Group 3, which all coefficients showed poor agreement. Although IFN-gamma blood assay has many advantages such as objective and quantitative results, no interference with vaccination due to the use of specific antigens and being practical, the high cost and the need for well-equipped laboratory are its disadvantages. As a result it was concluded that, IFN-gamma blood assay has limited value for the detection of latent TB infection in our country, since the prevalence of TB infection and BCG vaccination rates are high in Turkey.
Databáze: OpenAIRE
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