Analytical and Clinical Validation of Six Commercial Middle East Respiratory Syndrome Coronavirus RNA Detection Kits Based on Real-Time Reverse-Transcription PCR

Kim, Mi-Na; Ko, Young Jin; Seong, Moon-Woo; Kim, Jae-Seok; Shin, Bo-Moon; Sung, Heungsup

The effect of PCR inhibition determined by testing the nine high inhibition specimens revealed that 3-5 of the six known positive specimens were found negative or invalid by each kit ( Table 3 ). The Ct values of the internal controls from all specimens were high or extended beyond the total amplification cycles, and, therefore, false negative results were eliminated owing to internal control failure, except for those of the PowerChek and AccuPower kits. With the AccuPower kit, the mean internal control Ct value for the high inhibition specimens was considerably prolonged to 30.1 ± 0.69 compared with 25.7 ± 0.31 for the sensitivity test specimens; however, there was no established cut-off point, indicating that PCR inhibition was not acceptable in the PCR reaction. On the other hand, Ct values for the sensitivity test specimens and the high inhibition specimens using the PowerChek kit were not significantly different at 25.3 ± 3.2 and 27.0 ± 3.1, respectively. The LightMix kit produced two uncertain results with known positive specimens and one uncertain result with a known negative specimen (Table 3) . There were no positive results detected by any of the kits among the four negative specimens included in the sensitivity test and high inhibition panels (Tables 2 and 3) .