Seung Hee Lee, Shine Young Kim, Hyung Hoi Kim, Eun Yup Lee, Chulhun L. Chang
Ann Clin Microbiol 2015 June, 18(2): 37-43. Published on 20 June 2015.
Background: Tuberculosis is globally the most important cause of death from single pathogen. Rapid and accurate identification of mycobacteria is essential for the control of tuberculosis. We evaluated a fluorescence in situ hybridization (FISH) method using peptide nucleic acid (PNA) probes for the differentiation of Mycobacterium tuberculosis complex (MTB) and nontuberculous mycobacteria (NTM) in direct smears of sputum specimens.
Methods: The cross-reactivity of MTB- and NTM-specific PNA probes was examined with reference strains of M. tuberculosis ATCC 13950, Mycobacterium kansasii ATCC 12479, Mycobacterium fortuitum ATCC 6841, several clinical isolates of mycobacteria (Mycobacterium abscessus, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium gordonae and Mycobacterium chelonae), and 11 frequently isolated respiratory bacterial species other than mycobacteria. A series of 128 sputa (89 MTB culture positive, 29 NTM culture positive, and 10 under treatment culture negative) with grades of trace to 4+ were used to evaluate the performance of the method.
Results: The MTB- and NTM-specific PNA probes showed specific reactions with the reference strains of MTB and M. kansasii and clinical isolates of mycobacteria except M. fortuitum ATCC 6841, and no cross-reactivity with other tested bacteria. The PNA probe-based FISH assay for detection of MTB had a sensitivity and specificity of 100%, respectively. The sensitivity and specificity of the NTM-specific PNA probe was 100%. The smear grades of the PNA FISH test were same as with those of the fluorescence AFB stain in 2+ or higher grade.
Conclusion: Detection and differentiation based on PNA FISH is sensitive and accurate for detecting mycobacteria and for differentiating MTB from NTM in clinical sputum smears.
Wonho Choe, Ehwa Kim, Seo Yeon Park, Jeong Don Chae
Ann Clin Microbiol 2015 June, 18(2): 44-51. Published on 20 June 2015.
Background: Polymerase chain reaction (PCR) methods from direct specimen are widely used for the rapid and accurate detection of mycobacteria infection. In this study, we evaluated two domestically developed detection kits for Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) using real-time PCR.
Methods: A total of 348 samples from patients with suspected tuberculosis were tested with real-time PCR over seven months. We performed real-time PCR using the recently developed Anyplex plus MTB/NTM Detection kit (Seegene) with the CFX 96TM Real- time PCR System (Bio-Rad Laboratories) and the conventional AdvanSure TB/NTM real-time PCR kit (LG Life Sciences) with the SLAN Real-time PCR detection system (LG Life Sciences) to evaluate their performance for detecting MTB and NTM.
Results: The two real-time PCR systems showed 96.8% concordance rate for MTB-positive, NTM-positive, and negative results. Based on culture results, the sensitivity and specificity for the detection of MTB using PCR were 71.0% and 94.9% for Anyplex plus, and 78.1% and 93.9% for AdvanSure, respectively. For the detection of NTM, the sensitivity and specificity were 33.3% and 98.4% for Anyplex plus, and 51.7% and 97.9% for AdvanSure. Both PCR systems showed high MTB positive results in bronchial washing and sputum samples.
Conclusion: In detecting MTB and NTM, Anyplex plus MTB/NTM (Seegene) and AdvanSure TB/NTM real-time PCR (LG Life Sciences) showed high concordance rate with each other in all samples. Therefore both detection kits can be used as rapid and reliable detection tool for MTB.
Hyeun Gyeo Lee, Gyu Yel Hwang, Soon Deok Park, Young Uh, Juwon Kim, Kap Jun Yoon, Won-Yeon Lee
Ann Clin Microbiol 2015 June, 18(2): 52-55. Published on 20 June 2015.
A total of 1,132 pleural fluid culture results obtained from October 2012 to July 2014 were analyzed to elucidate the microbiological characteristics according to transudative and exudative pleural fluid. The pleural fluid cultures were performed using aerobic and anaerobic blood culture bottles. The blood and pleural fluid for total protein, lactate dehydrogenase, and glucose measurement were submitted to laboratory at the same time with pleural fluid cultures. The rates for culture positivity, anaerobes isolation, and polymicrobials between transudative and exudative pleural fluid were 5.2% vs. 10.4%, 14.8% vs. 7.8%, and 14.8% vs. 10.9%.
[in Korean]
Zehwan Kim, Kyung Eun Song, Won-Kil Lee
Ann Clin Microbiol 2015 June, 18(2): 56-59. Published on 20 June 2015.
Since the report of disseminated trichosporonosis in 1970s, several cases of infection by various Trichosporon species in different clinical patients were published. We’ve isolated a strain of T. asahii from not only blood but also urine. We report 71 year-old male patient with Trichosporon asahii fungemia, who had renal stones. It was identified as T. asahii using conventional method and also confirmed by 18S rRNA gene sequencing. The patient was discharged without any complication, in which case only antibiotic agent was used without any antifungal one.
[in Korean]
Jong Eun Park, Hee Jae Huh, Young Eun Ha, Wook Sung Kim, Chang-Seok Ki, Nam Yong Lee
Ann Clin Microbiol 2015 June, 18(2): 60-63. Published on 20 June 2015.
Dialister pneumosintes is a nonfermentative, gram-negative anaerobic rod which is considered as a commensal organism of the oral cavity. A 77-year-old man with a history of aortic stenosis was visited to ER for dyspnea and fever. D. pneumosintes and Streptococcus anginosus were isolated from blood culture, and also D. pneumosintes was identified by 16S rRNA-based gene sequencing. This case report is the first case of isolation of D. pneumosintes from blood in Korea, and highlights the usefulness of DNA sequencing to identify pathogens in organism which is difficult to identify by biochemical identification method.
[in Korean]
Chang Ahn Seol, Young Jin Ko, Sung-Han Kim, Mi-Na Kim, Heungsup Sung, Je-Hwan Lee
Ann Clin Microbiol 2015 June, 18(2): 64-67. Published on 20 June 2015.
Human cytomegalovirus (CMV) infection has been a major concern in hematopoietic stem cell transplant recipients. Ganciclovir (GCV) resistance results mostly from mutations within the protein kinase UL97 gene. The three hot spots for GCV resistance (codons 460, 520, and 590-607) were well known. We describe a case of GCV-resistant CMV colitis caused by a 597-600 deletion in UL97 after haplo-identical peripheral blood stem cell transplantation (h-PBSCT) in a 46 year-old man with myelodysplastic syndrome. On post-PBSCT day 28, CMV antigenemia turned positive. Treatment of GCV was started and continued for 12 weeks but CMV antigenemia did not respond to the treatment and CMV colitis was worsened. The UL97 showed the in-frame deletion between codons 597 and 600 by direct sequencing. The treatment was switched to foscarnet and the antigenemia test was consecutively negative twice, and clinical symptoms improved. Despite the recovery of the patient from CMV colitis, the patient expired post-PBSCT day 146 from acute liver failure, hepatorenal syndrome and septic shock. This case is a first report of a deletion 597-600 in CMV UL97 in Korea. A 597-600 deletion in UL97 was responsible for the GCV resistance while preserving susceptibility to foscarnet.
[in Korean]
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