实时荧光PCR法检测新型冠状病毒核酸单靶标阳性结果分析

Analysis of single target positive results of SARS-CoV-2 by real-time fluorescence PCR

目的分析新型冠状病毒(SARS-CoV-2)核酸检测中出现的单靶标阳性结果,为临床实验室检测和结果判断提供参考。方法收集分析2021年5月至2023年4月在该院进行的新冠病毒核酸检测结果,对检出的单靶标阳性结果及双试剂复测情况进行统计分析,并进一步追踪出现单靶标阳性结果的样本后续新型冠状病毒核酸检测情况。结果使用核酸提取仪加PCR仪及全自动工作站两种检测系统出现单靶标阳性的比率差异无统计学意义,单采标本中单靶标阳性出现频率显著多于混采标本中单靶标阳性出现频率,单靶标阳性中N基因阳性显著多于ORF1ab基因阳性。ORF1ab基因单靶阳性组Ct值与N基因单靶阳性组Ct值差异无统计学意义,两组在双试剂复检结果表现上差异无统计学意义。初检单靶Ct值按照复检最终结果判定分为阴性和阳性组,两组间Ct值差异无统计学意义。追踪69例经双试剂复查后仍为单靶阳性的样本后续新型冠状病毒核酸检测情况,单采单靶阳性人员下一次新型冠状病毒核酸检测结果为双靶阳性的有41例,其中37例Ct值为35以下;下一次核酸检测结果为阴性的有16例,其中11例为之前一个月内感染过新型冠状病毒的患者。12例混采单靶阳性标本均为一人阳性混管,单采Ct值中位数ORF1ab基因为33.229,N基因为33.732。结论对新冠核酸检测中遇到的单靶标阳性结果需要谨慎对待,复测后方可报告。实验室应加强对不同试剂,不同检测系统的评估,准备1~2种备用试剂作为可疑结果的补充验证试剂以利于对新型冠状病毒核酸检测结果的合理分析,提高对异常检测结果的判断能力。

Objective To analyze the single target positive results in the nucleic acid detection of novel coronavirus(SARS CoV-2),and provide reference for clinical laboratory detection and result judgment.Methods The results of SARS-CoV-2 nucleic acid testing conducted in Qinhuai Medical Area,General Hospital of Eastern Command Theater from May 2021 to April 2023 were collected and analyzed.The single target positive results and double reagents retesting were statistically analyzed,and the follow-up nucleic acid testing of the specimens with single target positive results was further tracked.Results There was no statistically significant difference in the rate of single target positivity between using nucleic acid extraction instrument plus PCR instrument and automatic workstation.The frequency of single target positivity in single collection specimens was significantly higher than that in mixed collection specimens,and the positive rate of N gene in single target positivity was significantly higher than that of ORF1ab gene.There was no significant difference in Ct values between ORF1ab single target positive group and N gene single target positive group,and there was no significant difference in double reagents retest results between the two groups.According to the final results of the reexamination,the single target Ct values of the initial test were divided into negative and positive groups,and there was no significant difference between the two groups.The follow-up detection of SARS-CoV-2 in 69 specimens which were still single target positive after double reagents review was tracked.Among the patients with single target positivity and single collection,41 cases showed double target positive results in the next SARS-CoV-2 nucleic acid detection,among which 37 cases had Ct values below 35.The next nucleic acid test was negative in 16 cases,11 of which were patients who had been infected with SARS-CoV-2 within the previous month.Each of the mixed tube 12 single target positive specimens was a single positivity.The median value of Ct was 33.229 in ORF1ab gene and 33.732 in N gene.Conclusion The single target positive results in the SARS-CoV-2 nucleic acid test should be treated with caution and reported only after retesting.Laboratories should strengthen the evaluation of different reagents and different detection systems,and prepare one or two backup reagents as supplementary verification reagents for suspicious results to facilitate the reasonable analysis of the SARS-CoV-2 nucleic acid test results and improve the judgment ability of abnormal test results.