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

BACKGROUND: The differentiation of Mycobacterium tuberculosis (MTB) from nontuberculous mycobacteria (NTM) is of primary importance for infection control and choice of antimicrobial therapy. The diagnosis of diseases caused by NTM is difficult because NTM are prevalent in the environment and have fastidious properties. In this study, we evaluated the real-time PCR-based MTB/NTM detection kit for its usefulness in discrimination of MTB and NTM species. METHODS: A total of 155 sputum specimens whose AFB staining smear and culture were positive were used for this study. Among them, 59 and 96 samples had been identified as MTB and NTM, respectively. DNA obtained from sputum specimens was subjected to analysis with MolecuTech Real MTB-ID(R) (M&D, Korea) real-time PCR-based MTB/NTM detection kit. Subsequently, the results of MolecuTech Real MTB-ID(R) were compared with AFB staining smear and culture results. RESULTS: The positive rate of MolecuTech Real MTB-ID(R) to detect MTB and NTM was 98.3% (58/59) and 97.9 (94/96), respectively, using sputum specimens. CONCLUSION: For detection of MTB/NTM, the sensitivity and specificity of MolecuTech Real MTB-ID(R) were comparable to those of conventional methods. Therefore, this study suggests the usefulness of real-time PCR-based MolecuTech Real MTB-ID(R) for rapid detection of MTB/NTM from direct specimens.

Co-Immunization of Plasmid DNA Encoding IL-12 and IL-18 with Bacillus Calmette-Guerin Vaccine against Progressive Tuberculosis

PURPOSE: Bacillus Calmette-Guerin (BCG) vaccine has widely been used to immunize against tuberculosis, but its protective efficacy is variable in adult pulmonary tuberculosis, while it is not efficiently protective against progressive infection of virulent Mycobacterium tuberculosis strains. In this study, the protective effects of plasmid DNA vaccine constructs encoding IL-12 or IL-18 with the BCG vaccine were evaluated against progressive infection of M. tuberculosis, using mouse aerosol challenge model. MATERIALS AND METHODS: Plasmid DNA vaccine constructs encoding IL-12 or IL-18 were constructed and mice were immunized with the BCG vaccine or with IL-12 DNA or IL-18 DNA vaccine constructs together with the BCG vaccine. RESULTS: The BCG vaccine induced high level of interferon gamma (IFN-gamma) but co-immunization of IL-12 or IL-18 DNA vaccine constructs with the BCG vaccine induced significantly higher level of IFN-gamma than a single BCG vaccine. The BCG vaccine was highly protective at early stage of M. tuberculosis infection, but its protective efficacy was reduced at later stage of infection. The co-immunization of IL-12 DNA vaccine constructs with the BCG vaccine was slightly more protective at early stage of infection and was significantly more protective at later stage infection than a single BCG vaccine. CONCLUSION: Co-immunization of IL-12 DNA vaccine with the BCG vaccine induced more protective immunity and was more effective for protection against progressive infection of M. tuberculosis.

PCR-reverse Blot Hybridization Assay for Species Identification of Dermatophytes / 대한의진균학회지

BACKGROUND: Dermatophytes (Trichophyton, Microsporum, and Epidermophyton) cause cutaneous mycoses called dermatophytosis. Forproper anti-dermatophytosis therapy, accurate and early diagnosis of dermatophytes is important. Laboratory diagnosis of dermatophytosis for dermatophytes still relies on microscopic and macroscopic examination of in vitro cultures and some physiological tests. These methods (conventional methods) are time-consuming (2~4 weeks) and yet, still have low sensitivity and specificity. Recently, in order to overcome such limitations of conventional methods, molecular-based methods have been developed to identify dermatophytes. The polymerase chain reaction-reverse blot hybridization assay (PCR-REBA) allows sensitive and specific identification of dermatophytes species. OBJECTIVE: This study was aimed to develop a new PCR-REBA with higher sensitivity using less amount of probe concentration, so the assay can be more practical in clinical settings. METHODS: For this, PCR primers and species-specific oligonucleotide probes were designed within the internal transcribed sequences 1 region between 5.8S and 18S rRNA. The species-specific probes designed in this study was to identify 6 species (T. rubrum, T. mentagrophytes, T. tonsurans, M. canis, M. gypseum, and E. floccosum) comprised 99% of dermatophytes isolatedin Korea. RESULTS: The detection efficiency of the PCR-REBA was compared with the microscopic method, and the results showed that the sensitivity of the PCR-REBA developed in this study is 100 times higher than previously developed one. Subsequently, the results of PCR-REBA were evaluated using clinical isolates. DNAs from a total of 68 clinical isolates were analyzed by PCR-REBA, and the inconsistent results between PCR-REBA and conventional microscopic identification results were confirmed by sequence analysis. CONCLUSION: In brief, the results showed that results of sequence analysis were identical with PCR-REBA implying newly developed PCR-REBA is very useful method for accurate and rapid identification of dermatophytes and would provide higher simplicity, specificity, sensitivity than conventional method.