Multiplex real-time quantitative polymerase chain reaction for simultaneous detection of Escherichia coli and Candida albicans genes in human whole blood / 中华临床营养杂志

ABSTRACT

Objective To establish a multiplex real-time quantitative polymerase chain reaction (MRQPCR) assay for fast and simultaneous detection of Escherichia coli (E.coli) and Candida albicans (C.albicans) genes in human whole blood,in order to facilitate differentiation of the types of microorganism and evaluation of the severity of bacterial or fungi translocation due to impaired gut barrier,hence providing help to select specific antimicrobial agents.Methods The β-D-galactosidase gene of E.coli and ITS2 gene of C.albicans were selected as the target genes for designing primers and probes.E.coli and C.albicans genomes were extracted with QIAamp(R) DNA Blood Mini Kit,and the 25 μl TaqMan MRQ-PCR amplification reaction system was established.18 simulated human whole blood samples and 10 whole blood samples from febrile surgical patients were detected for E.coli and C.albicans genes using MRQ-PCR.Results The specificity of the primers and probes were excellent.The correlation coefficients of the standard curves of E.coli and C.albicans were 0.994-0.999 and 0.994-0.998,respectively;and the efficiency of amplification were 0.894-1.022 and 0.905-1.028,respectively.In the standard samples,the lowest detection limits of E.coli and C.albicans were 13.9 copies/μl and 0.8 cfu/μl,respectively;the sensitivity was 100％ and 99.69％,the specificity was 100％ and 94.73％,respectively;the average recovery rates were (101.89 ± 5.69)％ and (103.74 ± 4.64)％ respectively;the intra-batch coefficients of variance (CV) in detecting the genes were (13.14 ± 10.27)％ and (19.18 ± 8.54)％,respectively,and the inter-batch CV were (14.35 ± 9.34)％ and (18.31 ± 10.25) ％,respectively.In human whole blood,the lowest detection limits of E.coli and C.albicans were 12 455.2 copies/ml and 800.3 cfu/ml,respectively;the average recovery rates were (111.60 ± 11.06) ％ and (99.96 ± 6.16) ％,respectively;the intra-batch CV in detecting the genes were (11.02 ± 5.65) ％ and (8.14 ± 7.29)％,respectively,and the average inter-batch CV were (12.88 ± 7.59)％ and (18.62 ± 9.14)％.Conclusions MRQ-PCR is a rapid,sensitive,specific,accurate,and reproducible method for simultaneous detection of E.coli and C.albicans genes in human whole blood,with sample-,cost-,and time-saving advantages.It is a promising technique for rapid differentiation between fungi and bacteria,which could help targeted administration and evaluation of antimicrobial agents,and help to assess the consequence of gut barrier damage and the efficacy of treatment.