External quality assessment of the detection of rickettsioses inChina

摘要

Objective:To report a training course on the laboratory diagnoses of rickettsioses that10 provincial/cityCDCs participated in laboratory external quality assurance(EQA)based on the serological specific antibodies detection and rapidPCR amplifying targeted genes of rickettsiae. Methods: An EQA program to evaluate the following laboratory procedures was developed to detect rickettsiae: (1)immunofluorescent assay (IFA) to detect specific antibodies ofA. phagocytophilum, R. heilongjiangensis andO. tsutsugamshi respectively.(2) Two sets of nested PCRwere used amplifying groEL genes for most members of the familyRickettsiaceae and amplifying16SrRNA genes for the most members of familyanaplasmae, respectively. A scoring scheme based on the distribution of the median antibody titer values of the serologic assays was designed and a ranking list of the scores of the PCRresults based on the detected minimal copy numbers of referenceDNA was created.Results: Among nine laboratories who reported the results on time, eight laboratories gave acceptable serologic results, the other one provided an unacceptable antibody titer (1:2 vs median1:64) results forO. tsutsugamshi. The limits of detection(LOD)for thePCR amplifying for five referencesDNA ranged from 1copy/μL to106 copy/μL.Conclusions:We successfully trained and popularized modern diagnostic methods of rickettsiae in10 provincialCDCs in China and first conducted the EQA projects and evaluated the results.