Comparative Evaluation of Three Preprocessing Methods for Extraction and Detection of Influenza A Virus Nucleic Acids from Sputum

Yu, Fei; Qiu, Ting; Zeng, Ying; Wang, Yiyin; Zheng, Shufa; Chen, Xiao; Chen, Yu

Moreover, the proportion for blood-tinged sputum specimens in the 17 specimens yielded inconsistent results of 52.94% (9/17), significantly higher than that of the specimens with consistent results in the three groups (28.00%, 56/200). For few negative specimens, concentration and purity were higher, which was inconsistent with the results. Therefore, the nucleic acid purity and concentration examined with a spectrophotometer were not the only factor that determined the positive rate. These findings indicated that false-negative results might be attributed to PCR inhibitor residues in nucleic acids. Further optimizing of liquefier combinations, preprocessing steps and nucleic acid extraction reagents could be conducted to decrease PCR inhibitors and increase target nucleic acid concentration.