Evaluation of Diagnostic Performance of Three Real-Time PCR Assays for the Detection of Mycobacteria Species

Background: The disease burden caused by Mycobacterium tuberculosis (MTB) complex continues to decrease in most countries. However, the diseases caused by the nontuberculous mycobacteria (NTM) become a public health problem. This study aimed to compare the diagnostic accuracy of three real-time PCR assays: AdvanSure TB/NTM real-time PCR kit (AdvanSure; LG Chem., Korea), Genedia MTB/NTM detection kit (Genedia; Green Cross MS, Korea), and PowerChek MTB/NTM Real-time PCR kit (PowerChek; Kogenebiotech, Korea) for the detection of MTB complex and NTM. Methods: Total 102 acid-fast bacilli (AFB) smear-positive and 177 smear-negative specimens from Korea University Medical Center, Guro Hospital, were enrolled. The AFB smear-positive and negative specimens were collected from November 2016 to October 2017 and November to December 2018, respectively. DNA extraction was performed using Genedia Mycobacteria DNA prep Kit (Green Cross MS, Korea). The statistical analysis was performed using MedCalc 18.11.6 (MedCalc Software, Belgium). Results: Among 261 specimens, 64 showed MTB complex growth and 28 exhibited NTM growth. The sensitivity, specificity, positive predictive value, and negative predictive value of AdvanSure/Genedia/PowerChek kits for MTB were 96.9%/95.3%/96.9%, 98.5%/99.5%/98.5%, 58.9%/80.9%/58.9%, and 99.9%/99.9%/99.9%. Whereas those for NTM detection were 81.5%/44.4%/88.9%, 99.6%/100.0%/98.7%, 57.3%/100.0%/32.8% and 99.9%/99.6%/99.9%, respectively. The area under the receiver operating characteristic curve of AdvanSure and PowerChek for NTM detection was statistically different from that of Genedia (P<0.0001). Conclusion: Three real-time PCR assays were reliable for MTB complex in AFB-positive and -negative specimens. There was a difference between these three reagents for the accuracy of NTM detection.