Hyunwoo Jin

Improved rapid molecular diagnosis of multidrug-resistant tuberculosis using a new reverse hybridization assay, REBA MTB-MDR

Rapid diagnosis of multidrug-resistant tuberculosis (MDR-TB) is essential for the prompt initiation of effective second-line therapy to improve treatment outcome and limit transmission of this obstinate disease. A variety of molecular methods that enable the rapid detection of mutations implicated in MDR-TB have been developed. The sensitivity of the methods is dependent, in principle, on the repertoire of mutations being detected, which is typically limited to mutations in the genes rpoB, katG and the promoter region of inhA. In this study, a new reverse hybridization assay, REBA MTB-MDR (M&D), that probes mutations in the oxyR-ahpC intergenic region, in addition to those in rpoB, katG and the inhA promoter region, was evaluated. A set of 240 Mycobacterium tuberculosis clinical isolates from patients receiving retreatment regimens was subjected to conventional phenotypic drug-susceptibility testing (DST) and the REBA MTB-MDR assay. The nucleotide sequences of the loci known to be involved in drug resistance were determined for comparison. In brief, the results showed that the REBA MTB-MDR assay efficiently recognized nucleotide changes in the oxyR-ahpC intergenic region as well as those in rpoB, katG and the inhA promoter region with higher sensitivity, resulting in an 81.0 % detection rate for isoniazid resistance. Inclusion of the oxyR-ahpC intergenic region in the REBA MTB-MDR assay improved the overall sensitivity of molecular DST for MDR-TB from 73.1 to 79.9 %.

A Simple and Efficient Multiplex PCR Assay for the Identification of Mycobacterium Genus and Mycobacterium tuberculosis Complex to the Species Level

Purpose The Mycobacterium tuberculosis complex comprises M. tuberculosis, M. bovis, M. bovis bacillus Calmette-Guérin (BCG) and M. africanum, and causes tuberculosis in humans and animals. Identification of Mycobacterium spp. and M. tuberculosis complex to the species level is important for practical use in microbiological laboratories, in addition to optimal treatment and public health. Materials and Methods A novel multiplex PCR assay targeting a conserved rpoB sequence in Mycobacteria spp., as well as regions of difference (RD) 1 and RD8, was developed and evaluated using 37 reference strains and 178 clinical isolates. Results All mycobacterial strains produced a 518-bp product (rpoB), while other bacteria produced no product. Virulent M. tuberculosis complex strains, M. tuberculosis, M. bovis and M. africanum, produced a 254-bp product (RD1), while M. bovis BCG, M. microti and nontuberculous mycobacteria produced no RD1 region product. Additionally, M. tuberculosis and M. africanum produced a 150-bp product (RD8), while M. bovis and M. bovis BCG produced a 360-bp product (deleted form of RD8). M. microti and nontuberculous mycobacteria produced no RD8 region product. This assay identified all Mycobacterium spp. and all M. tuberculosis complex strains to the species level. Conclusion The multiplex PCR assay of the present study could be implemented as a routine test in microbiology laboratories, and may contribute to more effective treatment and surveillance of tuberculosis stemming from the M. tuberculosis complex.

Comparison of the performance of the NucliSENS EasyQ HPV E6/E7 mRNA assay and HPV DNA chip for testing squamous cell lesions of the uterine cervix

This study aims to evaluate the clinical performance of the NucliSENS EasyQ assay and compare it with HPV DNA genotyping for the detection of high-grade squamous intraepithelial lesions (HSIL) and cancer in a Korean population. In 188 total thin prep samples, the remaining fluid after cytology slide preparation was tested with Goodgene HPV DNA chips and the NucliSENS EasyQ HPV E6/E7 messenger RNA (mRNA) assay. The sensitivity and specificity of each test were calculated with HSIL and squamous cell carcinoma (SCC) as the disease endpoint. Out of the 188 samples, 139 (74%) were positive for DNA of 14 HPV types, while 57 (30%) cases were positive for E6/E7 mRNA. The DNA test was positive in cytology cases of SCC, HSIL, and atypical squamous cell. The mRNA test yielded results of 75%, 74%, 60%, 56%, and 29% positivity in abnormal cytology cases of SCC, HSIL, atypical squamous cells - cannot exclude HSIL, atypical squamous cells of undetermined significance, and low-grade squamous intraepithelial lesion, respectively. In normal cytology cases, the positivity rates were 9% and 53% for the mRNA and DNA tests, respectively. For detection of HSIL and SCC, the sensitivity of the mRNA test was 74.36% and that of the DNA test was 100%, while the specificities of the tests were 85% and 40.83%, respectively. These findings suggest that the HPV E6/E7 mRNA assay can overcome the shortcoming of low specificity of DNA assays for clinical detection of high-grade cervical lesions and malignancies.

Performance of HPV E6/E7 mRNA RT-qPCR for screening and diagnosis of cervical cancer with ThinPrep Pap test samples.

Recent research has shown that oncogenic human papillomavirus (HPV) DNA, which is currently used in the screening and diagnosis of cervical cancer, can be detected not only in high-grade cervical lesions, but also in low-grade cervical lesions and normal tissues. For this reason, HPV tests targeting the E6 and E7 mRNA of five oncogenic HPV strains (HPV genotypes 16, 18, 31, 33, and 45), which are known to be responsible for the oncogenesis of cervical cancer, have been commercialized using a real-time nucleic acid sequence based amplification (NASBA) assay. Previous data has shown that the real-time NASBA assay has higher clinical specificity than HPV DNA testing (97.1% vs. 53.7%). However, the sensitivity of the real-time NASBA assay was lower than that of HPV DNA testing (41.1% vs. 100%). Despite the fact that there are more than 16 oncogenic HPV genotypes known to cause cervical cancer (HPV genotypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, and 69), the commercialized real-time NASBA kit was designed to detect only five genotypes (16, 18, 31, 33, and 45). Therefore, in the present study, CervicGen HPV RT-qDX (Optipharm), a commercial diagnostic kit targeting a HPV E6/E7 mRNA based on RT-qPCR assay was evaluated with RNA extracted from ThinPrep Pap samples, and the results were compared to real-time NASBA data. The sensitivity and specificity of the RT-qPCR assay were 91% and 98.6%, respectively, for the detection of cervical intraepithelial neoplasia CIN2(+) high-grade cervical lesions. Therefore, the CervicGen HPV RT-qDX assay showed a significantly higher sensitivity (91.1%) compared to the real-time NASBA assay (41.1%). In normal cytohistology cases, the specificity was 98.6% and 53.7% for HPV mRNA RT-qPCR and HPV DNA testing, respectively. These results demonstrate that HPV mRNA RT-qPCR better reflects clinical diagnosis. In conclusion, it is suggested that HPV mRNA RT-qPCR overcomes the shortcomings of lower specificity seen in the DNA assay and the lower sensitivity of the commercialized HPV mRNA real-time NASBA assay when testing from ThinPrep Pap samples.

Development of a highly sensitive one-tube nested real-time PCR for detecting Mycobacterium tuberculosis.

Rapid, accurate detection of Mycobacterium tuberculosis is crucial in the diagnosis of tuberculosis (TB), but conventional diagnostic methods have limited sensitivity and specificity or are time consuming. A new highly sensitive nucleic acid amplification test, combined nested and real-time polymerase chain reaction (PCR) in a single tube (one-tube nested real-time PCR), was developed for detecting M. tuberculosis, which takes advantage of two PCR techniques, i.e., nested PCR and real-time PCR. One-tube nested real-time PCR was designed to have two sequential reactions with two sets of primers and dual probes for the insertion sequence (IS) 6110 sequence of M. tuberculosis in a single closed tube. The minimum limits of detection of IS6110 real-time PCR and IS6110 one-tube nested real-time PCR were 100 fg/μL and 1 fg/μL of M. tuberculosis DNA, respectively. AdvanSure TB/non-tuberculous mycobacteria (NTM) real-time PCR, IS6110 real-time PCR, and two-tube nested real-time PCR showed 100% sensitivity and 100% specificity for clinical M. tuberculosis isolates and NTM isolates. In comparison, the sensitivities of AdvanSure TB/NTM real-time PCR, single IS6110 real-time PCR, and one-tube nested real-time PCR were 91% (152/167), 94.6% (158/167), and 100% (167/167) for sputum specimens, respectively. In conclusion, IS6110 one-tube nested real-time PCR is useful for detecting M. tuberculosis due to its high sensitivity and simple manipulation.

Real-time PCR TaqMan assay for rapid screening of bloodstream infection

BackgroundSepsis is one of the main causes of mortality and morbidity. The rapid detection of pathogens in blood of septic patients is essential for adequate antimicrobial therapy and better prognosis. This study aimed to accelerate the detection and discrimination of Gram-positive (GP) and Gram-negative (GN) bacteria and Candida species in blood culture samples by molecular methods.MethodsThe Real-GP®, -GN®, and -CAN® real-time PCR kit (M&D, Wonju, Republic of Korea) assays use the TaqMan probes for detecting pan-GP, pan-GN, and pan-Candida species, respectively. The diagnostic performances of the real-time PCR kits were evaluated with 115 clinical isolates, 256 positive and 200 negative blood culture bottle samples, and the data were compared to results obtained from conventional blood culture.ResultsEighty-seven reference strains and 115 clinical isolates were correctly identified with specific probes corresponding to GP-bacteria, GN-bacteria and Candida, respectively. The overall sensitivity and specificity of the real-time PCR kit with blood culture samples were 99.6% and 89.5%, respectively.ConclusionsThe Real-GP®, -GN®, and -CAN® real-time PCR kits could be useful tools for the rapid and accurate screening of bloodstream infections (BSIs).

Diagnostic Performance of a Cytokine and IFN-γ–Induced Chemokine mRNA Assay after Mycobacterium tuberculosis–Specific Antigen Stimulation in Whole Blood from Infected Individuals

Interferon (IFN)-γ release assays have limited sensitivity and cannot differentiate between active tuberculosis (TB) disease and latent TB infection (LTBI). Numerous cytokines and regulator factors have been implicated in the pathogenesis and control of Mycobacterium tuberculosis infection. Additional cytokines and chemokines associated with M. tuberculosis infection may improve the performance of IFN-γ release assays. We developed a real-time RT-PCR TaqMan assay for targeting levels of eight human targets [IFN-γ, tumor necrosis factor (TNF)-α, IL-2R, IL-4, IL-10, CXCL9, CXCL10, and CXCL11] and evaluated the assay with three different study groups. Results showed that the sensitivity of TNF-α, IL-2R, and CXCL10 in the active pulmonary tuberculosis (PTB) group was 96.43%, 96.43%, and 100%, respectively. The sensitivity of IL-2R and CXCL10 in the latent tuberculosis infection group was 86.36% and 81.82%, respectively. Statistical results showed that TNF-α and CXCL9 were the best individual markers for differentiating between the PTB, LTBI, and non-TB groups. For optimal sensitivity and differentiation of M. tuberculosis infection status, the simultaneous detection of multiple targets was attempted. The combination of IFN-γ, TNF-α, and IL-2R, and the combination of TNF-α, IL-2R, CXCL9, and CXCL10 showed the best performance for detecting active PTB (both 100% positivity) and LTBI (86.36% and 81.82% positivity, respectively). These results imply that the combination of suitable markers is useful in efficiently diagnosing TB and differentiating M. tuberculosis infection status.

RT-PCR Targeting rpoB mRNA for Drug Susceptibility Test of Mycobacterium tuberculosis in Liquid Culture

The problems of tuberculosis and its drug resistance are very severe. Therefore, rapid and accurate drug susceptibility assay is required. Recently, there has been an increased understanding of the genetic mechanism of Mycobacterium tuberculosis (MTB) drug resistance as well as advancement of molecular technologies. While many gene mutations correlate well with drug resistance, many genes do not show a strong correlation with drug resistance. For this reason, the current study assessed the utility of rpoB mRNA as a target to detect live mycobacteria. In this study, RT-PCR targeting of rpoB mRNA in BCG treated with rifampin was performed. Conventional RT-PCR and real-time PCR targeting rpoB mRNA as well as 85B mRNA was performed to determine whether these two methods could distinguish between viable and non-viable MTB. The levels of rpoB and 85B mRNA detected by RT- PCR were compared in parallel with colony forming unit counts of BCG that were treated with rifampin for different periods of time. The data suggests that that even though both mRNA levels of rpoB and 85B decreased gradually when rifampin-treatment increased, the rpoB mRNA seemed to represent live bacteria better than 85B mRNA. This study clearly indicates that RT-PCR is a good method to monitor viable cell counts in the liquid culture treated with the anti-tuberculosis drug.

Evaluation of MolecuTech Real MTB-ID for MTB/NTM Detection Using Direct Specimens

Evaluation of MolecuTech Real MTB-ID for MTB/NTM Detection Using Direct Specimens Hye-young Wang*, Hyunwoo Jin*, Hyeeun Bang, Yeon-Im Choi, Eun-mi Park, Won-jung Koh, Hyeyoung Lee M&D, Inc. Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju, YD Diagnostics, Yongin, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

Evaluation of Human Papillomavirus Genotyping from Formalin-fixed Paraffin-embedded Specimens in Cervical Cancers

Cervical carcinoma is the second leading cause of cancer–related deaths in women around the world, and it is associated with the Human Papillomavirus (HPV) infection. HPV genotyping is important for vaccine policy, etiology, natural history, and epidemiology studies. The use of formalin-fixed paraffin-embedded (FFPE) tissues for HPV genotyping by reverse blot hybridization assays (REBA) has not been clearly confirmed in retrospective studies. The aim of this study was to evaluate the usefulness and efficiency of FFPE tissues from cervical cancers for HPV genotyping. HPV genotypes were detected in 52 FFPE tissues from cervical carcinoma specimens by REBA. HPV was detected in 32 (61.5%) of 52 specimens from FFPE, among which 27 (84.4%) harbored single infections and 5(15.6%) contained multiple infections. The HPV single infections (27) were analyzed by high-risk type 18(8), 58(6), 16(5), 33(1), 35(1), 39(1), 56(1) and low risk type 11(2), 6(1), 70(1). The HPV multiple infections (5) included 16/18(2), 18/52(1), 16/56(1), 16/18/33(1). Please consider being more specific here. Do you mean the analysis? Please clarify what you mean by “included.”Through this study, it has been determined that the FFPE specimen is feasible and can be used in HPV genotyping, as well as in retrospective studies.