[Comparison of Cobas Amplicor system and microscopic examination with bactec radiometric method for the detection of...

Tuberculosis is still a major health problem all around the world. Since the patients with tuberculosis spread the infection by means of aerosols containing tuberculosis bacilli, it is critically important to detect these patients and start the treatment as soon as possible. Therefore there is a need for highly sensitive and specific reliable diagnostic methods. In this study, Ehrlich-Ziehl-Neelsen (EZN) staining method and Cobas Amplicor system were evaluated for the diagnosis of tuberculosis in comparison with the standard reference Bactec radiometric method. A total of 2098 clinical samples collected between July 2002 and February 2004 in Clinical Microbiology Laboratory of Hacettepe University Adult Hospital, were studied by Bactec radiometric system for diagnosis of tuberculosis and M. tuberculosis was detected in 107 (5.1%) samples. The specificity, sensitivity, positive and negative predictive values of EZN staining method were found to be 98.5%, 42.9%, 62.1% and 96.9%, respectively. The specificity, sensitivity, positive and negative predictive values of Cobas Amplicor system were detected as 99.3%, 67.3%, 83.5% and 98.4%, respectively. These results were in concordance with the results of previous studies. In conclusion, microscopic examination and nucleic acid amplification methods should always be used together with culture methods for the laboratory diagnosis of tuberculosis.