Young Sook Kim, Sook-Jin Jang
Ann Clin Microbiol 2012 September, 15(3): 79-87. Published on 20 September 2012.
The three components of taxonomy are classification, nomenclature and identification. Traditionally, bacterial classification and identification were performed based on the morphology and the biochemical data of the bacteria. In newer theories, or so-called natural concepts, the relationships between bacteria are based on the overall similarities of both the phenotypic and genotypic characteristics. The polyphasic taxonomy, or current taxonomy, describes the integration of all of the available genotypic, phenotypic, and phylogenetic information into a consensus type of general-purpose classification. When routine identification methods that are based on the biochemical tests fail, alternative procedures such as complete 16s rRNA gene sequence analysis are required. Although the results of 16s rRNA gene sequence analysis have not been fully discriminatory to differentiate closely related species, they may guide the additional analyses that are required for species identification.
[in Korean]
Ji-Sook Yim, Seock-Mi Hwang, Myungsook Kim, Hee-Joung Lim, Saeam Shin, Hae-Sun Chung, Heejung Kim, Kyungwon Lee
Ann Clin Microbiol 2012 September, 15(3): 88-91. Published on 20 September 2012.
Background: Clostridium difficile is the main etiologic agent of antibiotic-associated diarrhea and the most common cause of hospital-acquired diarrhea. Recently, the incidence of C. difficile infections (CDI) has increased and new highly virulent C. difficile strains have emerged. Therefore, accurate and rapid diagnosis is needed. We compared the results of using chromID C. difficile (chromID CD, bioMeriéux, France) with the conventional C. difficile Selective Agar (CDSA; BD, USA) for the isolation of C. difficile.
Methods: A total of 738 stool specimens of suspected CDI patients at the Severance Hospital from July to August 2011 were inoculated onto CDSA. Among them, 104 stool specimens revealed colonies on CDSA that were then re-inoculated onto chromID CD. The stool samples were stored at −20oC until the time of the re-inoculation. Cultured agars were interpreted after 24 hrs and 48 hrs, respectively. Species identification was performed on the basis of colony characteristics on agar plates as well as the ATB 32A system (API System SA, France).
Results: The recovery rates of CDSA and chromID CD were 30.1% and 77.5% after 24 hrs, and 77.5% and 98.6% after 48 hrs, respectively. All of the C. difficile isolates were recovered as typical gray/black colonies on chromID CD.
Conclusion: The performance of chromID CD for the isolation of C. difficile was better than that of conventional CDSA. The chromID CD could provide easy and sensitive detection of C. difficile even after 24hrs of incubation.
[in Korean]
Kyoung-Jin Park, Kyung Sun Park, Nam Yong Lee
Ann Clin Microbiol 2012 September, 15(3): 92-97. Published on 20 September 2012.
Background: The aim of the present study was to investigate the epidemiologic characteristics of extrapulmonary tuberculosis (EPTB) in Korea. In addition, the results of culture-confirmed (CC) EPTB were compared with those of clinically-diagnosed (CD) EPTB.
Methods: We retrospectively reviewed non-duplicate data of tuberculosis from the Samsung Medical Center from 1995 to 2010. A total of 6,249 and 38,726 cases of tuberculosis were CC and CD EPTB cases, respectively. The cases were categorized according to the type of specimen or by the clinically- affected sites.
Results: The proportions of EPTB among all tuberculosis cases were 12% (745/6,249) and 22% (8,608/ 38,726) of the CC and CD cases, respectively. The distribution of both age and gender between pulmonary tuberculosis (PTB) and EPTB cases were significantly different (P＜0.001). The most common types of EPTB were tuberculous lymphadenitis, pleural TB, and abdominal TB. Pleural involvement was more common in males, while lymph node involvement was observed more frequently in females in both the CC and CD cases (M/F ratio in regards to pleura were 1.63 and 2.08, while M/F ratio in regards to the lymph node were 0.46 and 0.54).
Conclusion: The dataset of EPTB cases in Korea was first evaluated over a 16-year period and compared the cases of CC EPTB to those of CD EPTB. The epidemiologic characteristics of EPTB were different from that of PTB as well as the EPTB of other countries. The present study might provide useful information regarding the epidemiology of EPTB in Korea and other countries.
Min Kyoung Lee, Yiel Hea Seo, Ji Hoon Jeong, Pil Whan Park, Kyung Hee Kim, Jeong Yeal Ahn, Jin Yong Kim, Jeong Woong Park
Ann Clin Microbiol 2012 September, 15(3): 98-103. Published on 20 September 2012.
Background: The isolation of nontuberculous mycobacteria (NTM) has been increasing worldwide as well as its clinical importance. The aim of this study was to investigate the distribution and clinical significance of NTM that has been isolated from respiratory specimens during a recent two-year period at a tertiary hospital.
Methods: We analyzed respiratory samples that were obtained between January 2009 and December 2010 for AFB culture. We retrospectively reviewed the electronic medical records of these patients to obtain both clinical and radiologic information. NTM pulmonary disease was defined by using the guidelines provided by the America Thoracic Society/Infectious Diseases Society of America.
Results: Among the 1,601 specimens that resulted in a positive AFB culture, 310 (19.4%) were NTM. In 189 patients, the most common isolate was M. avium- intracellulare complex (MAC) (127, 67.2%), which was then followed by M. abscessus (31, 16.4%), M. fortuitum (10, 5.3%), M. kansasii (9, 4.8%), and other NTM species. Of these, 93 (49.2%) patients were diagnosed with NTM pulmonary disease. MAC, M. abscessus, and M. kansasii were more virulent than the other species. None of the cases of NTM pulmonary disease were caused by M. fortuitum, M. chelonae, M. peregrinum, M. terrae complex, or M. gordonae.
Conclusion: In Korea, the prevalence of NTM isolates is increasing, as are the cases of pulmonary disease. The pathogenic potential of NTM differs enormously by species and as a result the treatment of NTM lung disease depends on which species has caused the infection. The isolation and identification of NTM isolated from respiratory specimens are mandatory in order for clinical microbiology laboratories to make an accurate diagnosis and suggest the proper treatment of the NTM disease.
[in Korean]
Kye Hyun Kim, Tae-Hyoung Kim, Jun Hyung Lee, Tae Jin Lee, Mi-Kyung Lee
Ann Clin Microbiol 2012 September, 15(3): 104-109. Published on 20 September 2012.
Background: Infectious vaginitis is caused primarily by three different groups of microbial pathogens (Trichomonas vaginalis, Candida spp., and Gardnerella vaginalis). The objective of this study was to compare the Affirm VPIII assay using a DNA hybridization technique with the Papanicolaou (Pap) smear test and the Gram stain in the detection and identification of these three organisms.
Methods: A total of 300 vaginal samples were collected from women that were either symptomatic for vaginitis or asymptomatic women that were being seen for routine obstetric or gynecological care. The presence of T. vaginalis, Candida spp., and G. vaginalis was evaluated by using the Affirm VIII assay (Becton Dickinson, USA), Pap smear test, and Gram stain method, respectively.
Results: With the Affirm VPIII assay, 1 (0.3%) patient tested positive for T. vaginalis, 99 (33.0%) patients were positive for G vaginalis, and 18 (6.0%) were positive for Candida spp. The detection rates of Trichomonas infection, bacterial vaginosis and candidiasis by the Pap smear test and Gram stain method were 0.7% versus 0%, 16.3% versus 35.7%, and 1.7% versus 9.7%, respectively. The differences between the detection rates of the above three organisms between the Pap smear test and the Gram stain method were statistically significant (P＜0.05).
Conclusion: The Affirm VPIII assay was more sensitive than the Pap smear test and more specific than the Gram stain method for the detection and identification of these three organisms. In addition, the results of the Affirm VPIII assay are quick to obtain and are simple and easy to interpret.
[in Korean]
Bo Hyun Kim, Mi-Kyung Lee
Ann Clin Microbiol 2012 September, 15(3): 110-113. Published on 20 September 2012.
Microbacterium oleivorans is a gram-positive, coryneform rod bacterium. The pathogenic potential of the Microbacterium species has recently been reported to be increasing. Microbacterium comprises approximately 50 species. The differences in regards to the biochemical characteristics of Microbacterium species are unclear, and is why molecular investigations (e.g., using 16S rRNA gene sequencing) are the best method to identify the species. We report a case of bacteremia that was caused by Microbacterium oleivorans in a 4-year-old boy, who had no specific medical history. This represents the first report of M. oleivorans bacteremia in Korea.
[in Korean]
Kyung Sun Park, Chang-Seok Ki, Nam Yong Lee
Ann Clin Microbiol 2012 September, 15(3): 114-116. Published on 20 September 2012.
Blastomycosis, endemic in North America, has been hardly reported in Korea. We describe laboratory experience in phenotypic and molecular identification of Blastomyces dermatitidis first isolated in Korea. The patient was a 45-year-old male with pulmonary blastomycosis mimicking pulmonary tuberculosis. Diagnosis was based on culture and dimorphism combined with DNA target sequencing of internal transcribed spacers (ITS) and D1/D2 regions.
[in Korean]
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