Diagnostic value of nine nucleic acid amplification test systems for Mycobacterium tuberculosis complex

Abstract

Objective: In this study, nine commercial Nucleic Acid Amplification Test Systems (NAATs) were evaluated for diagnostic performance of Mycobacterium tuberculosis complex (MTBC) from smear positive sputum species (SPss) and smear negative sputum specimens (SNss). Methods: Sixty SPss and 55 SNss were examined microscopically by Ehrlich Ziehl Neelsen (EZN) staining method, and also inoculated on Lowenstein Jensen (LJ) medium for culture. The sensitivity and specificity of nine NAATs were calculated according to LJ culture method accepted as gold standard. Results: When LJ culture results were taken as gold standard; the sensitivity rates of method COBAS Amplicor MTB (Method A), GenProbe MTD (Method B), Cobas TaqMan MTB PCR (Method C), iCycler iQ RT PCR (Method D), TaqMan PCR AB 5700 (Method E), TaqMan PCR AB7700 (Method F), LightCycler® 480 RT PCR (Method G), Rotor Gene RT PCR (Method H) and the AdvanSure TB/NTM RT PCR (Method I) for SPss were 98.3 %, 93.3 %, 96.7 %, 100 %, 93.3 %, 100 %, 100 %, 100 % and 100 %, respectively. The sensitivity was 53.84% for the methods A, B, D, E, G and I; 38.46% for the method C and H; 61.5% for the method F for the method I in SNss. There were no statistical significant differences between the nine NAATs (p≥0.05). The specificity was 100% for all nine NAATs in SNss. The positivity rates of methods were 53.8% for methods A, B, D, E, G, I; 38.5% for methods C and H, and 61.5% for method F in SNss. These rates were 100% for D, F, G, H and I; 98.3% for method A; 96.7% for method C; 93,3% for methods B and E in SPss. Statistical analysis showed that there was no statistically significant differences among the nine NAATs (p≥0.05). Conclusion: It is concluded that the nine NAATs might be useful for detecting MTBC from SPss, but not effective for SNss. J Microbiol Infect Dis 2015;5(3): 103-109 Key words: Tuberculosis, polymerase chain reaction, nucleic acid amplification test, smear positive, smear negative, sputum